Emerging Infectious Diseases
[Volume 5 No.4 / July - August 1999]

Special Issue: National Symposium on Medical and Public Health Response to Bioterrorism   

    * About the Symposium on Medical and Public Health Response to 
      Bioterrorism, D.A. Henderson 
    * How to Meet and Beat the Threat of Bioterrorism, D.E. Shalala 
    * The Emerging Threat of Bioterrorism, J.M. Hughes 
    * Congressional Efforts to Address Bioterrorism, S.A. McCann 
    * Finding the Right Balance against Bioterrorism, R.A. Clarke 
    * Historical Trends Related to Bioterrorism: An Empirical Analysis, J.B. 
      Tucker 
    * The Threat of Biological Attack: Why Concern Now? D.W. Siegrist 
    * Biological Weapons Programs of the Former Soviet Union and Iraq, C.J. 
      Davis 
    * Aum Shinrikyo: Once and Future Threat? K.B. Olson 
    * The Prospect of Domestic Bioterrorism, J. Stern 
    * Potential Biological Weapons Threats, M.G. Kortepeter 
    * Epidemiology of Bioterrorism, J.A. Pavlin 
    * Vaccines in Civilian Defense Against Bioterrorism, P.K. Russell 
    * Vaccines, Pharmaceutical Products, and Bioterrorism,   K.C. Zoon 
    * Smallpox: Clinical and Epidemiologic Features, D.A. Henderson 
    * Smallpox: An Attack Scenario, T. O'Toole 
    * Aftermath of a Hypothetical Smallpox Disaster, J. Bardi 
    * Clinical and Epidemiologic Principles of Anthrax, T.J. Cieslak 
    * Anthrax: A Possible Case History, T.V. Inglesby  
    * Applying Lessons from Anthrax Case History to Other Scenarios, J.G. 
      Bartlett 
    * Addressing Bioterrorist Threats M.A. Hamburg 

Dispatches 
    
    * Cytotoxin-Producing E. coli O157 in Wales, 1990 to 1998, R.M. Chalmers 
    * Deer Tick Virus Transmission in the Northcentral United States, G.D. 
      Ebel 
    * Dengue Reemergence in Argentina, G. Avils 
    * Chlorine Disinfection of Recreational Water for C. parvum, C. Carpenter 
    * C. cayetanensis Among Populations of West Java, Indonesia, D.J. Fryauff 
    * First Major Outbreak of Dengue Hemorrhagic Fever in Delhi, India, L. Dar 

Commentary 
    
    * Addressing the Potential Threat of Bioterrorism, J.E. McDade 

Letters 
    
    * Current Status of Smallpox Vaccine, J.W. LeDuc 
    * West Nile Fever in Czechland, Z. Hublek 
    * Ofloxacin-Resistant V. cholerae O139 in Hong Kong, K.-M. Kam 
    * Plant Pathology and Public Health, K.-B. G. Scholthof 
    * Pet-Associated Zoonoses, L.L. Barton 

Book Review
    
    * Clinical Infectious Diseases: A Practical Approach, J.M. Miller 

News and Notes
    
    * Epidemiology and Control of Communicable Diseases 
    * Antibiotic Resistance in Bacteria of Animal Origin 
    * Symposia on Molecular and Cellular Biology 
    * World Congress on Trauma, Shock, Inflammation, and Sepsis 
    * International Conference on Emerging Infectious Diseases 

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Special Issue
_____________________________________________________________________________

Preface

About the First National Symposium on Medical and Public Health
Response to Bioterrorism

D.A. Henderson
Johns Hopkins Center for Civilian Biodefense Studies

On February 16-17, 1999, in Arlington, Virginia, 950 public health
officials, physicians, and other medical personnel, along with
government, military, and intelligence experts gathered for the first
National Symposium on Medical and Public Health Response to
Bioterrorism. Participants were geographically diverse. Represented
were 46 states, plus Washington, D.C., and 10 countries: Australia,
Austria, Canada, England, Finland, France, Germany, Israel, Italy,
and the Netherlands.

The guiding force behind the symposium was the newly established
Johns Hopkins Center for Civilian Biodefense Studies, which hopes
the discussions will lead to a framework and partnership for
strategic planning. The other main sponsors were the Department
of Health and Human Services, Infectious Diseases Society of
America, and American Society for Microbiology. Twelve other
public health professional societies supported the conference.(ft 1)

The list of speakers included D.A. Henderson, director of the Johns
Hopkins Center for Civilian Biodefense Studies; Christopher J.
Davis, former senior intelligence analyst for chemical and biological
warfare matters on Britain's Defense Intelligence staff; Jessica
Stern, Council on Foreign Relations and author of the book The
Ultimate Terrorists; Joshua Lederberg, Nobel laureate and
professor and president emeritus of Rockefeller University; Col.
Gerald W. Parker, director of the U.S. Army Medical Research
Institute of Infectious Diseases; Thomas V. Inglesby and Tara
O'Toole, Johns Hopkins Center for Civilian Biodefense Studies; and
Philip K. Russell, Johns Hopkins School of Public Health.

Federal, state, and local officials reflected on the challenge of
coordinating a multidisciplinary and interagency response to a
biological attack. This array of speakers included Secretary of
Health and Human Services Donna Shalala; Richard Clarke,
National Security Council; Michael Osterholm, Minnesota
Department of Health; and Jerry Hauer, director of New York
City's Office of Emergency Management.

From their different backgrounds and perspectives, the more than
20 speakers addressed the following questions: Why are current
concerns about bioterrorism real? Why must the medical and public
health communities address the issue of bioterrorism? Which
biological threats warrant the most concern? What is the possible
aftermath of an act of biological terrorism?

A warning against complacency came from the symposium's closing
speaker, Margaret A. Hamburg, assistant secretary for planning and
evaluation, U.S. Department of Health and Human Services.

In making symposium presentations available here, the organizers
hope to raise awareness of the medical and public health threats
posed by biological weapons and to foster mutual understanding
and collaboration among the diverse groups addressing the threat of
bioterrorism.

(ft 1)American College of Preventive Medicine, Association for
Professionals in Infection Control and Epidemiology, Association
of Public Health Laboratories, Association of Schools of Public
Health, Association of State and Territorial Health Officials,
Commissioned Officers Association of the U.S. Public Health
Service, Council of State and Territorial Epidemiologists, National
Association of County and City Health Officials, National
Association of Local Boards of Health, Partnership for Prevention,
Public Health Foundation, and Society of Hospital Epidemiologists
of America.

_______________________________________________________________________

Special Issue

Bioterrorism: How Prepared Are We?

Donna E. Shalala
U.S. Secretary of Health and Human Services

Richard Preston's The Cobra Event, which he dedicates to public
health professionals, weaves a chilling, but compelling tale about a
lone terrorist's attack on Manhattan with a genetically engineered
virus. Preston's thought-provoking novel raises a logical question:
How do we successfully contain and combat the threat of
bioterrorism? To meet this emerging threat, we must address four
important challenges.

The first challenge is to be aware that an act of bioterrorism could
happen. Its likelihood is entirely unknown, and an attack may never
occur. However, we have seen terrorism emerge as one of the
thorniest problems of the post-cold war era, and we have seen that
terrorists are always searching for new weapons. We have already
seen sarin nerve gas released in the Tokyo subway. Somewhere,
sometime in the future, terrorists may well threaten to use, or
attempt to use, a biological weapon against the United States.
When discussing the possibility of a terrorist attack in the next few
years, the president unequivocally stated, "This is not a cause for
panic. It is cause for serious, deliberate, disciplined, long-term
concern." In other words, we must not be afraid, but we must be
aware.

Once we are fully aware that bioterrorism could happen, our second
challenge is to be prepared. That is why the Department of Health
and Human Services (HHS) is spending $158 million this fiscal year
to prepare for bioterorrism and why the president has proposed
increasing that investment by an additional $72 million in his Fiscal
Year 2000 budget.

This investment will fund our ongoing Anti-Bioterrorism Initiative.
To increase our level of preparedness, the initiative is expanding its
activities in a number of key areas: surveillance, medical and public
health response, building a stockpile of drugs and supplies, and
research and development. We are improving and strengthening the
U.S. public health surveillance network by enhancing our capability
to detect and report outbreaks, conduct epidemiologic
investigations, perform laboratory tests to identify biological agents,
and communicate necessary information and advisories rapidly
through electronic technology.

We are enhancing our medical and public health response capacity
by spearheading an administrationwide effort to develop
infrastructure at the local level by establishing in major American
cities medical response teams to deal with the consequences of
bioterrorism. We are also expanding our capacity to provide
prophylaxis, medical care, and infection control on a massive scale.
We are creating, and will be maintaining, an unprecedented national
stockpile of drugs and vaccines for civilian use in case of a
bioterrorist attack.

Finally, we are accelerating our research and development of rapid
diagnostics, drugs, and vaccines, so we can more effectively
address the threats and consequences of a bioterrorist attack. In
addition, we will continue our work on the genome sequencing of
organisms most likely to be used as bioweapons, so that we can not
only quickly identify the biological agent, but also develop effective
therapies. Our efforts in surveillance, medical and public health
response, stockpile provision, and research and development will
increase significantly our preparedness for bioterrorism.

If we want to be truly prepared, our third challenge is for the public
health and medical communities to take the lead in our fight against
bioterrorism. In a conventional terrorist attack, local "first
responders," such as the police, firefighters, and paramedics,
constitute the first line of defense. With bioterrorism, the public
health and medical communities stand directly on the front lines.
How well we respond to a threat or attack will depend on the
preparedness of our public health and medical communities. For
example, if a bioterrorist threat is issuedperhaps someone claims
to have released a deadly pathogen in a public placephysicians
must be able to recognize and report cases that come to attention in
emergency rooms and doctors' offices; public health officials must
be able to conduct investigations to establish the likely site/time of
exposure, the size and location of the exposed population, and the
prospects for secondary transmission; and appropriately traned
laboratory personnel must be available to identify the biological
agent. Whether the release of a bioweapon is announced or
surreptitious, affected persons may not have symptoms for days or
even weeks, and by then they would be geographically dispersed.
Quarantine is not practical because only one of the most common
biological agentssmallpoxis communicable. Even with
smallpox, it would be impossible to know whom to quarantine
because of the spread of disease by secondary transmission and the
difficulty in accurately identifying those who have been exposed. A
strong electronic communications network would be needed to
piece together early reports, as well as epidemiologic and
laboratory data, to determine what had happened so that public
health and law enforcement officials can take prompt action. The
Centers for Disease Control and Prevention would play an
important role in this process because of its particular expertise in
surveillance, infectious disease, and public health. Everyonefrom
the physicians who first see victims to the scientists who identify the
infectious agentsmust coordinate their efforts.

That brings me to the fourth, and final, challenge: We must all work
together. In the fight against bioterrorism, the federal government,
particularly HHS, has a leadership role. Among other things, we
need to support state and local planning efforts, provide training at
every level, develop an infrastructure for delivering mass medical
care, and offer expertise to our communities.

This is a fight we certainly cannot win by ourselves. Across the
board, we must forge new working partnerships among health,
public safety, and intelligence agencies. We need unprecedented
cooperation among the federal government, state and local health
agencies, and the medical community. We must ensure that plans
for managing the medical consequences of terrorist acts are well
integrated and coordinated with other emergency response systems.

Close collaborative efforts are necessary also because microbes do
not respect boundaries of culture, language, or territory. An act of
bioterrorism cannot be contained by any national border or barrier.
When it comes to microbes, we are not protected, in the words of
the Indian poet Tagore, "by narrow domestic walls." Since these
organisms recognize no boundaries, in our battle against them,
neither can we. Because we share a common future, we must share
a common resolve. As Dr. Gro Bruntland, the director-general of
the World Health Organization, has said, when it comes to public
health and safety, "Solutions, like the problems, have to be
global..." As we work together to counter bioterrorism, we must
pool our will and our resources to meet the challenges.
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Special Issue

The Emerging Threat of Bioterrorism

James M. Hughes
Centers for Disease Control and Prevention, Atlanta, Georgia, USA

The threat of bioterrorism focuses attention on overall preparedness
to address the challenges posed by new and reemerging infectious
diseases. Bioterrorism scenarios illustrate the diversity of disciplines
and perspectives required to confront these threats, whether
naturally occurring or purposely caused. The need to strengthen
existing and develop new partnerships is clear.

Since late 1992, a number of large, complex outbreaks have
occurred in the United States. These include the epidemic of over
400,000 cases of waterborne cryptosporidiosis in Milwaukee, the
outbreak of severe, unexplained acute respiratory disease now
known as hantavirus pulmonary syndrome in the Spring of 1993,
the nationwide foodborne salmonellosis outbreak caused by
contaminated ice cream that accounted for an estimated 250,000
cases in the fall of 1994, and the increasing problems posed by
antimicrobial-resistant organisms in community and health-care
settings. Epidemics of plague in India, Ebola hemorrhagic fever in
Central Africa, avian (H5N1) influenza in Hong Kong, Hendra virus
infection in Australia, and Nipah virus infection recently in Malaysia
and Singapore required an international response. During the
hantavirus, plague, and Ebola investigations, concerns regarding the
possibility of bioterrorism were raised early in the investigations,
though these concerns were not supported by subsequent findings.

Investigating these outbreaks in collaboration with local, national,
and international partners has provided a number of important
lessons, which are reinforced by the threat of bioterrorism. We must
avoid complacency and stress preparedness through careful
planning and testing of emergency response plans. There is a critical
need to strengthen surveillance systems and epidemiologic and
laboratory capacity in clinical and public health settings. The
outbreaks have illustrated disruptions of travel and commerce and
potential threats to national security. The complications of naturally
occurring, complex epidemics underline the global implications of
local problems. These lessons are directly relevant to the threat of
bioterrorism. The challenges of recognizing disease resulting from
the clandestine release of an infectious agent are considerable, given
the potential for geographic dispersion of the agent (through travel)
during the incubation period. The public health approach to
bioterrorism must begin with the development of local and state
plans formulated collaboratively by the public health, emergency
response, and law enforcement communities, which must work
together closely in this phase if an epidemic is to be detected in a
timely manner, which is critical to its appropriate management.
Local health departments and health-care workers will be on the
front lines in detection and response. Infection control practitioners,
emergency department personnel, microbiologists, first responders,
emergency management personnel, and local, state, and federal law
enforcement personnel will play vital roles and must engage with
each other during the planning stage. Close collaboration between
the clinical and public health communities will also be critical.

From a public health perspective, timely surveillance, clinician
awareness of syndromes potentially resulting from bioterrorism,
epidemiologic investigation capacity, laboratory diagnostic capacity
in both clinical and public health laboratory settings, and the ability
to rapidly communicate critical information at the local level to
those who have a need to know and to manage public
communication through the media will be vital. In addition,
ensuring the timely availability of an adequate supply of
antimicrobial drugs, antitoxins, and vaccines is a formidable
challenge. Deployment and administration of stockpiled
components to those affected or at greatest risk are also critical.

Recognition of the need for local, regional, and national
preparedness for bioterrorism provides an opportunity to strengthen
the public health system and its linkages with current and new
partners. As President Bill Clinton said in his address at the
National Academy of Sciences in January 1998, "These cutting
edge efforts will address not only the threat of weapons of mass
destruction, but also the equally serious danger of emerging
infectious diseases. So we will benefit even if we are successful in
avoiding these attacks"(1).

--------------------------------------------------------

Address for correspondence: James M. Hughes, National Center
for Infectious Diseases, Centers for Disease Control and
Prevention, 1600 Clifton Rd NE, Mail Stop C12, Atlanta, GA
30333, USA; fax: 404-639-3039; e-mail: jmh2@cdc.gov.

References

1. Clinton WJ. Remarks by the President on keeping America
secure for the 21st Century. National Academy of Sciences,    
Washington, D.C., January 22, 1999.
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Special Issue

View from the Hill: Congressional Efforts to Address Bioterrorism

S. Anthony McCann
U.S. House of Representatives, Washington, D.C., USA

In governmentand particularly in the federal governmentideas
normally come from the bottom up. When finally approved,
proposals are reasonably well thought out in terms of what we are
going to do and why we are going to do it. Sometimes knowledge
of "what" we are going to do far exceeds the ability to explain why
we are going to do it. However, for bioterrorism we are better able
to talk about the "why" than the "what." When Congress received a
request from the administration to address bioterrorism, we had
only the vaguest idea what they wanted to do. As a result, the
availability of funds was delayed until an operating plan was in
place. We are still fleshing out exactly how to approach this
problem, what the roles of the various agencies are, and what the
legal issues are.

It is incumbent upon the community to spend more time studying
the proposal and coming back to Congress with more detail.

As the scientific community examines the issues involved in
bioterrorism, an education campaign should be undertaken to
inform the public and the members of Congress at the local and
national levels. Many people equate bioterrorism with chemical or
explosive accidents that are obvious and identifiable. The insidious
nature of bioterrorist attacks should be better explored and
communicated.

Finally, over the last 20 or 25 years, efforts to bring about
structural reform in state and local governments and in local public
health departments have eroded. Efforts by Congress to fund the
bioterrorism initiative may have a dual effect: they may not only
improve our ability to respond to a bioterrorist incident but also
may strengthen state and local health departments.

--------------------------------------------------------

S. Anthony McCann is Staff Director for the House Appropriations
Subcommittee handling the budgets for the Departments of Labor,
Health and Human Services, and Education. In this capacity, Mr.
McCann provides support and makes policy recommendations to
the Chairman and majority members for over $70 billion in
discretionary programs under the subcommittee's jurisdiction. Mr.
McCann also served under the Bush Administration as Assistant
Secretary for Finance and IRM and Chief Financial Officer of the
Department of Veterans Affairs.

Address for correspondence: S. Anthony McCann, U.S. House of
Representatives, Appropriations Committee, Subcommittee on
Labor, Health and Human Services, Education, and Related
Agencies, 2358 Rayburn House Office Building, Washington, D.C.
20515-6024, USA; fax: 202-225-3509.
_______________________________________________________________________

Special Issue

Finding the Right Balance against Bioterrorism

Richard A. Clarke
The White House, Washington D.C., USA

For the first time the Deparment of Health and Human Services is
part of the national security apparatus of the United States. That
reflects a change in our views on chemical and biological defense
programs. Almost 5 years ago at the bidding of the president we
began to look at what has come to be known as "asymmetrical
threats," ways in which opponents (be they nations or terrorist
groups) could attack us without directly engaging our military
forces. At the same time we were faced with two events that drew
our attention to chemical and biological threats. Iraq used chemical
weapons on Iran and on its own citizens and appeared to be
concealing a biological weapons program. Also, the hitherto
unknown Japanese cult Aum Shinrikyo used sarin nerve agent in the
Tokyo subway; the cult failed in an attempt to use biological
weapons against Americans in Japan.

In 1998, the president launched the first national effort to create a
biological weapons defense for the United States. While some
believe that the response is not strong enough, many others think
that the proposed program exaggerates the threat, that biological
weapons are too unpredictable, and that the only big biological
weapons program died with the Soviet Union. However, the former
Soviet Union was not the only state engaged in biological weapons
research and development. Almost every nation on the State
Department's list of nations that sponsor terrorism has engaged in
chemical and or biological weapons development. If these nations
have armed, trained, funded, and advised terrorist groups, they
could cross the line and provide terrorists with chemical or
biological weapons. Finally, some critics say that until we really
know about a specific threat to use these weapons against the
United States, we should not be raising the specter of horror;
instead we should be quietly working in Geneva to improve the ban
on biological weapons. We are pushing in Geneva, but that is not
enough. When we learn of a specific threat, it will be too late to do
research and development, too late to procure medicines, too late
to train local authorities.

The current bioterrorism initiative includes a new concept: the
first-ever procurement of specialized medicines for a national
civilian protection stockpile. As new vaccines and medicines are
developed, that program can be expanded. The initiative includes
invigoration of research and development in the science of
biodefense; it invests in pathogen genome sequencing, new vaccine
research, new therapeutics research, and development of improved
detection and diagnostic systems. The 2-year program provides for
Department of Health and Human Services research, almost tripling
the previous 2-year effort, in addition to ongoing work in the
Defense Department, and it includes a reinitiation of the federal
program to help state and local public health infrastructure and
surveillance systems.

The biological weapons protection program is part of the overall
chemical and biological protection effort, which includes aid to
state and local governments for first-responder training, planning,
exercises, and equipment.

--------------------------------------------------------

    Richard A. Clarke serves as the country's first National
Coordinator for Security, Infrastructure Protection and
Counter-Terrorism. He was Deputy Assistant Secretary of State for
Intelligence in the Reagan Administration and served in the Bush
Administration as Assistant Secretary of State for Politico-Military
Affairs.

    Address for correspondence: Richard A. Clarke, National
Security Council, 17th and Pennsylvania Avenue, N.W.,
Washington, D.C. 20504; fax: 202-456-9360.
_______________________________________________________________________

Special Issue

Historical Trends Related to Bioterrorism: An Empirical Analysis

Jonathan B. Tucker
Monterey Institute of International Studies, Monterey, California,
USA

Since the Japanese doomsday cult Aum Shinrikyo released sarin
nerve gas on the Tokyo subway in March 1995, killing 12 people,
terrorist incidents and hoaxes involving toxic or infectious agents
have been on the rise. Before the late 1990s, the Federal Bureau of
Investigation (FBI) typically investigated a dozen cases per year
involving the acquisition or use of chemical, biological, radiologic,
or nuclear materials; however, FBI opened 74 such investigations in
1997 and 181 in 1998 (1). Although 80% of these incidents have
been hoaxes, some were unsuccessful attacks (2).

The vulnerability of civilian populations to chemical, biological,
radiologic, or nuclear terrorism has been widely discussed, but
information on historical cases is anecdotal and often inaccurate
(3). Without a realistic threat assessment based on solid empirical
data, government policymakers lack the knowledge they need to
design prudent and cost-effective programs for preventing or
mitigating future incidents.

Responding to this knowledge gap, the Chemical and Biological
Weapons Nonproliferation Project at the Monterey Institute's
Center for Nonproliferation Studies has compiled an open-source
database of all publicly known cases from 1900 to the present in
which domestic or international criminals or terrorists sought to
acquire or use chemical, biological, radiologic, or nuclear materials.
As of January 31, 1999, the database contained 415 incidents, both
domestic and international. Each entry draws on multiple sources
and includes a detailed description of the event and a list of
citations.

The project has conducted a preliminary analysis of the data to
discern patterns over time in the frequency of such incidents, the
underlying motives, and the choice of agent and target. The
ultimate goal is to identify which types of individuals or groups are
most likely to acquire and use toxic or infectious materials and for
what purposes.

Since the Monterey Database has been compiled from journalistic
accounts and other unclassified sources, it may not be
comprehensive or fully accurate. Incidents have been recorded only
if they came to the attention of law enforcement or the news media,
so the database does not include events that were not detected or
whose existence remains secret. Despite these limitations, the
information in the database indicates trends and patterns of
behavior that may assist intelligence and law-enforcement personnel
in focusing their monitoring efforts.

Database Findings

Most of the incidents in the Monterey Database involve chemical or
biological agents rather than radiologic or nuclear materials (Figure
1). The cases have been divided into three categories: terrorist
events, criminal events, and state-sponsored assassinations. To be
classified as a terrorist event, an incident must involve an
organization or person that conspires to use violence instrumentally
to advance a political, ideologic, or religious goal. Criminal
incidents, in contrast, involve extortion, murder, or some other
nonpolitical objective. Of the 415 incidents involving chemical,
biological, radiologic, or nuclear materials, 151 cases are terrorist
events for which information is sufficient to permit cross-case
comparison. These incidents have been classified according to type
of agent, event, target, motive, and group (Figure 2).

"Type of event" includes the following categories: 1) conspiracy to
acquire and use an agent, 2) attempted acquisition, 3) possession,
4) threatened use, 5) actual use, and 6) hoax or prank. Most of the
151 incidents involve threatened or actual use, although rarely with
the intent of inflicting mass casualties. Of the 151 terrorist
incidents, a subset of 33 involves biological agents (22 alleged
biological cases were dropped from the analysis because they
lacked key pieces of information). Many of the biological-agent
cases are hoaxes.

Since 1985, the number of terrorist incidents involving the
threatened or actual use of chemical, biological, radiologic, or
nuclear materials has risen sharply; a more modest increase has
occurred in efforts to acquire such agents. When criminal and
terrorist incidents involving chemical or biological agents are
examined, two large peaks become apparent (Figure 3a). The 1995
peak was associated primarily with Aum Shinrikyo and related
copycat attacks in Japan; in 1998, incidents of actual use again
increased abruptly (Figure 3a).

Hoaxes involving chemical or biological agents have shown two
peaks in frequency over the past 30 years (Figure 3b). The 1986
peak in chemical hoaxes was inspired by the second series of
Tylenol poisonings, while the dramatic rise in biological hoaxes in
1998 is attributable to the flurry of anthrax threats in the United
States. The first wave of anthrax hoaxes followed the
well-publicized arrest on February 18, 1998, of Larry Wayne
Harris, a microbiologist linked to white-supremacist groups, after
he allegedly threatened to release "military-grade anthrax" in Las
Vegas (4). Although Harris's anthrax turned out to be a harmless
veterinary vaccine strain, sensational media coverage appears to
have had the unintended effect of popularizing this agent among
potential perpetrators.

The categories of terrorist organizations involved in the acquisition
and use of chemical, biological, radiologic, or nuclear materials
have changed over time. Omitting incidents involving lone
terrorists, recent years have seen a rise in cases involving three
types of terrorist organizations: single-issue groups such as those
dealing with abortion and animal rights; nationalist and separatist
groups such as Chechen rebel organizations, the Kurdistan Workers
Party, and the Tamil Tigers of Sri Lanka; and apocalyptic religious
cults such as Aum Shinrikyo (although Aum accounts for nearly all
the latter cases). No clear pattern is apparent in the types of groups
involved in biological incidents, although religious fundamentalism
as a motivation has emerged within the past 5 years.

The preferred choice of target has also changed over time. If one
examines 135 terrorist incidents for which the target is known, two
types of targets have increased in frequency: the general civilian
population (with the apparent intent of inflicting indiscriminate
casualties) and a symbolic building or organization.

Motivations for the terrorist use of chemical, biological, radiologic,
or nuclear materials appear to encompass a wide range of
objectives. (For each case, two analysts separately determined the
"best fit" to a menu of motivations.) In descending order, the main
motivations are: 1) to promote nationalist or separatist objectives;
2) to retaliate or take revenge for a real or perceived injury; 3) to
protest government policies; and 4) to defend animal rights (Figure
4). A similar breakdown of motivations is found in the incidents
involving biological agents, except for the greater prominence of
apocalyptic prophecy (Figure 5). Nearly all the latter cases are
linked to Aum Shinrikyo, which may be either an outlier or a
trend-setter.

The motivations underlying terrorist incidents with chemical,
biological, radiologic, or nuclear materials appear to have shifted
over time. The predominant motivation from 1975 to 1989 was to
protest government policies. Since 1990, however, the leading
motivations have been to further nationalist or separatist objectives
and for retaliation or revenge. In 1993, because of Aum Shinrikyo,
apocalyptic prophecy also emerged as an important motivation. The
prominence of these three motivations becomes even greater when
only incidents involving biological agents are examined.

In addition to compiling the incidents database, the project
commissioned historical case studies of seven terrorist groups or
individuals that acquired or employed biological agents (Table 1).
Two of the cases appear to be apocryphal, but the five confirmed
cases share a number of characteristics that may be diagnostic of
groups and individuals most likely to engage in bioterrorism (Table
2). These characteristics include diffuse objectives, a sense of
grandiosity, and a paranoid, conspiratorial, or apocalyptic world
view that may lead to "defensive aggression." Such terrorists also
lack a domestic political constituency that might restrain them from
engaging in indiscriminate violence. Religiously motivated cults
such as Aum Shinrikyo and the Rajneeshees are cut off from the
outside world and are often guided by a charismatic, all-powerful
leader, making them less subject to societal norms. Other factors
not listed in the table include a tendency to escalate terrorist
violence over time and to use innovative weapons and tactics.

[fig]

Figure 1.  Overall  database:  Distribution of  incident by  type,
1960 Jan.  31, 1999 (415  cases).

[fig]

Figure 2.  Standardized  typology used in  analysis of  politically or 
ideologically  motivated  incidents. 

[fig]

Figure 3. (A)  Actual chemical  and biological  incidents vs. 
hoaxes,  1960 1998 (278  cases). (B)  Chemical and  biological 
hoaxes over  time, 1960 1998  (93 cases: 43  chemical, 50 
biological).

[fig]

Figure 4.  Distribution of  motivations for  chemical and  biological 
terrorism  incidents,  1960 Jan. 31,  1999 (147  cases). 

[fig]

Figure 5.  Distribution of  motivations for  biological  terrorism 
incidents,  1960 Jan. 31,  1999 (33 cases).

Table 1. Comparison of Values Across Selected Bioterrorist
Incidents
----------------------------------------------------------------------
                Motivation/
Case            Objective           Ideology          Target(s)   
----------------------------------------------------------------------
Weather       Temporarily           Revolutionary     Urban        
Underground   incapacitate          movement opposed  populations
incapacitate  U.S. cities to        to American       the United States
              demonstrate           imperialism and      
              impotence of the      the Vietnam War
              Federal government
   
R.I.S.E.      Kill off most of      Perpetrators were Initially entire
(1972)        humanity to prevent   college students  world population,
              the destruction of    influenced by     later narrowed to
              nature, then start    ecoterrorist      residents of five
              human race over with  ideology and      states around
              a select few          1960s drug        Chicago
                                    
Red Army      Allegedly planned BW  Marxist-          Specific targets
Faction       attacks against West  revolutionary     unknown
(1980)        German officials and  ideology
              business leaders

Rajneeshee    Scheme to             Indian            Residents of the 
Cult (1984)   incapacitate voters   religious cult    town of The Dalles
              to win local          headed by a       and Wasco County,
              election, seize       charismatic       Oregon
              political control     guru
              of county

Minnesota     Cause harm to the     Anti-government   IRS officials,  
Planned       federal government,   tax protesters;   U.S. deputy
Patriots      obtain personal       right-wing        marshal, local
Council       revenge               "patriot"         law enforcement
(1991)                              movement

Aum           Prove an              New Age doomsday  Mass civilian  
Shinrikyo     apocalyptic           cult seeking to   populations,     
(1995)        prophecy, eliminate   establish a       individual
              enemies and rivals,   theocratic state  opponents of
              halt an adverse court in Japan, with a  cult, judges
              ruling, seize control charismatic,      ruling against
              of Japanese           power-hungry      and police
              government            leader            investigating
                                                      cult
Larry Wayne   To alert Americans    Links to          Made vague threats 
Harris        to the Iraqi BW       Christian         against U.S.
(1998)        threat; seeks         Identity and      federal officials
              separate homeland     white             on behalf of right-
              for whites in the     supremacist       wing "patriot"
              United States         groups (e.g.,     groups
                                    the Aryan Nation)
-------------------------------------------------------------------------

Table 1, cont'd
--------------------------------------------------------------------
Agent(s)                  Delivery              Outcome
--------------------------------------------------------------------
Reportedly sought to    Reportedly planned to   Report originated with
obtain agents at Ft.    put incapacitaing CW/BW U.S. Customs informant;
Detrick by blackmail    agents in urban water   case probably 
of gay soldier                                  apocryphal

Eight microbial         Planned BW aerosol      Attack aborted when
pathogens including     attacks (dispersed by   cultures were 
agents of typhoid       aircraft) and           discovered; the two
fever, diphtheria,      contamination of        main perpetrators
dysentery, and          urban water             then fled to Cuba
meningitis              supplies

Group members           Unknown                 Probably an erroneous
allegedly cultivated                            report, later 
botulinum toxin in a                            repudiated by German
Paris safe-house                                government (BKA)

Salmonella              Multiple methods,       Plot revealed when
Typhimurium             mainly contamination    the cult collapsed and
                        of restaurant salad     members turned
                        bars                    informant

Ricin extracted from    Planned to deliver      Group was penetrated
castor beans obtained   ricin through skin      by FBI informants;
by mail-order           with DMSO and aloe      four key members
                        vera or as dry          arrested
                        aerosol

Biological agents       Attempted on at         Multiple CW attacks
(anthrax, botulinum     least 10 occasions      (in Matsumoto, Tokyo,
toxin, Q fever,         to disperse BW agents   and assassination
Ebola virus) and        in aerosol form;        campaign) killed at
chemical agents         all known attacks       20 people and injured
(sarin, VX, hydrogen    failed                  more than 1,000
cyanide

Obtained plague and     Discussed the           Arrested when he
anthrax (vaccine        dissemination of BW     talked openly about
strain), reportedly     agents with crop-       BW terrorism and
isolated several        duster aircraft         made threatening 
other bacteria          and other methods       remarks to U.S.
                                                officials
-----------------------------------------------------------------------
BW, biological weapons; CW, chemical weapons; DMSO, dimethylsulfoxide; 
IRS, Internal Revenue Service; FBI, Federal Bureau of Investigation.

Table 2. Selected Motivational Factors Associated with Bioterrorism
    
----------------------------------------------------------------------
                                            Loner  Sense of
                                    Apoca-    or   paranoia  
          Charismatic  No outside   lyptic splinter   and     Defensive
Cases      leadership constituency ideology group grandiosity aggression
------------------------------------------------------------------------
R.I.S.E.       X          X                   X        X          X
Rajneeshee     X          X                   X        X          X
  Cult
Minnesota      X          X            X      X        X          X
  Patriots
  Council
Aum Shinrikyo  X          X            X               X          X
Larry Wayne               X            X      X        X          X
  Harris

Apparently
Apocryphal
Cases
  Weather      X                                       X
   Underground
  Red Army     X                                       X
     Faction    
-----------------------------------------------------------------------

Conclusions

The Monterey Database indicates that incidents involving biological
agents have been quite rare, with 66 criminal events and 55 terrorist
events over the 40-year period from 1960 to 1999, although the
frequency of such incidents (mainly hoaxes) has increased sharply in
recent years. The historical record includes few cases in which
criminals or terrorists sought to inflict mass casualties with
biological agents, and none in which they succeeded. Only eight
criminal attacks with biological agents led to casualties, inflicting a
total of 29 deaths and 31 injuries. Of the terrorist attacks with
biological agents, only one resulted in casualties: the use by the
Rajneeshee cult in 1984 of Salmonella Typhimurium bacteria to
contaminate restaurant salad bars in The Dalles, Oregon. This event
caused 751 cases of food poisoning, none fatal (5).

Incidents of bioterrorism in the Monterey Database are extremely
diverse in terms of type of group and motivation. The trend in
recent years has been away from left-wing terrorism and toward
nationalist-separatist groups and individuals or ad hoc groups bent
on revenge. There has also been an apparent rise in incidents
perpetrated by violent sects or cults that believe in apocalyptic
prophecy.

Even if the motivation to inflict mass casualties exists, however,
few terrorist groups possess the scientific-technical resources
required for the successful large-scale release of a biological agent.
Aum Shinrikyo, which had considerable wealth and scientific
expertise, failed in 10 separate attempts to carry out open-air
attacks against urban targets with aerosolized anthrax spores or
botulinum toxin (6).

In summary, the historical record suggests that future incidents of
bioterrorism will probably involve hoaxes and relatively small-scale
attacks, such as food contamination. Nevertheless, the diffusion of
dual-use technologies relevant to the production of biological and
toxin agents, and the potential availability of scientists and
engineers formerly employed in sophisticated biological warfare
programs such as those of the Soviet Union and South Africa,
suggest that the technical barriers to mass-casualty terrorism are
eroding.
    
--------------------------------------------------------------------

Acknowledgments

The author thanks Jason Pate and Diana McCauley for their
outstanding work in compiling and analyzing the Monterey
Database of chemical, biological, radiologic, and nuclear incidents.

Dr. Tucker is director of the Chemical and Biological Weapons
Nonproliferation Project, Center for Nonproliferation Studies,
Monterey Institute of International Studies.

Address for correspondence: Jonathan B. Tucker, Chemical and
Biological Weapons Nonproliferation Project, Center for
Nonproliferation Studies, Monterey Institute of International
Studies, 425 Van Buren Street, Monterey, CA 93940, USA; fax:
831-647-6534; e-mail: jtucker@miis.edu.

References

  1. Parker-Tursman J. FBI briefed on district's terror curbs.
Pittsburgh Post-Gazette, May 5, 1999.
  2. Weiner T. Reno says U.S. may stockpile medicine for terrorist
attacks. New York Times 1998 Apr 23; Sect. A:12.
  3. For a revealing account of the inconsistencies and inaccuracies
in the secondary literature on CBW terrorism, see Ron Purver,
Chemical and biological terrorism: the threat according to the open
literature (Ottawa, Canada: Canadian Security Intelligence Service,
June 1995).
  4. Edwards TM. Catching a 48-hour bug. Time 1998 Mar 2; p.
56-7.
  5. Torok TJ, Tauxe RV, Wise RP, Livengood JR, Sokolow R,
Mauvais S, et al. A large community outbreak of salmonellosis
caused by intentional contamination of restaurant salad bars. JAMA
1997;278:389-95.
  6. WuDunn S, Miller J, Broad WJ. How Japan germ terror alerted
world. New York Times 1998 May 26; Sect A:1 (col 1), A:10 (col
1-5).
_______________________________________________________________________

Special Issue

The Threat of Biological Attack: Why Concern Now?

David W. Siegrist
Potomac Institute for Policy Studies, Arlington, Virginia, USA

For a biological attack to occur, three elements must be in place: a
vulnerable target, a person or group with the capability to attack,
and the intent (by the perpetrator) to carry out such an attack.
Much of what can be done to limit the capability and the intent of
potential attackers is already on its way to being accomplished. The
most work, and the highest return on investment, involve reducing
the vulnerability of the United States to both intentional and
unintentional pathogen releases.

Vulnerability to Biological Attack

Among weapons of mass destruction, biological weapons are more
destructive than chemical weapons, including nerve gas. In certain
circumstances, biological weapons can be as devastating as nuclear
onesa few kilograms of anthrax can kill as many people as a
Hiroshima-size nuclear weapon (Figure).

[Fig]

Figure.  Effects of a nuclear and biological weapons release.

The United States is unprepared to deal with a biological attack.
Over the past several years, preparedness strides have been made,
especially in the largest cities. However, much of the needed
equipment is not available. Pathogen sensors are not in place to
detect that a biological attack has taken place. New medicines are
needed. In combating terrorist attacks, treatment is a more practical
approach than prevention; yet many biological agents are extremely
difficult to treat with existing medicines once the symptoms appear.
In addition, many of the most important prophylactic drugs have
limited shelf lives and cannot be stockpiled. Moreover, their
effectiveness could be compromised by a sophisticated attacker.

Local emergency medical response capability is limited.
A number of localities define a "mass casualty event" as one with
more than a dozen casualties, far fewer than an intentional
biological release could cause. Emergency room capacity in major
cities can be overwhelmed all too quickly by more common
emergencies. Much emergency medical capability is also located in
downtown areas that may be targeted for attack.

The National Disaster Medical System has voluntary access to
approximately 100,000 hospital beds across the country to cope
with a large-scale medical emergency. However, not all of those
beds have the specialized means for patient respiration and
supportive therapy that may be needed in a crisis. Such equipment
is not available in large numbers (>5,000), even from deployable
field hospital Department of Defense war stocks (1). Further,
current federal plans favor not evacuating injured people from the
affected area but may relocate patients who were already in
hospitals to free up local bed space (2). This indicates that localities
need to increase their own capabilities. The federal government will
augment local efforts, not supersede them.

Steps are being taken to decrease U.S. vulnerability to biological
attack. Technical research is being supported, needed medicines and
vaccines will be acquired, and emergency response templates are
being developed. One of the reforms was setting up the Office of
State and Local Domestic Preparedness Support within the
Department of Justice. The office has developed a set of objective
criteria that measure domestic readiness to deal with an attack by a
weapon of mass destruction. No locality has yet qualified for the
top rankingbeing prepared for such a crisis (3).

Perpetrator Capability

Biological weapons can range in lethality from salmonella used to
temporarily incapacitate to super bubonic plague engineered for
mass casualities. Biological weapons include ricin, which an
extremist may use to assassinate a single local official, as well as
pathogens with high transmissibility and broad potential impact.
Biological agents may be used to kill or disable humans or to attack
plants or animals to harm a nation's economy. Given that broad
scope, biological attacks have already taken place and continue to
be a distinct probability for the foreseeable future (4). However, of
greatest concern is the capability to deliver a sizable lethal attack
against a population center.

Technical Capability

Making reliable biological weapons requires art as well as science.
Such weapons are not readily adaptable to "cookbook" type recipes
that can be implemented by novices. Nevertheless, technical
expertise and sophistication about biological processes have
become much more widespread. Moreover, even though technical
expertise is required to produce high-quality, military-grade
biological weapons and reliable means of dissemination, terrorist
applications are less demanding.

Making biological weapons requires sample cultures; the means to
grow, purify, and stabilize them; and the means to reliably
disseminate them. All these tasks pose substantial but not
insurmountable challenges. More than 1,500 biological culture
libraries worldwide, as well as numerous research institutions and
natural sources, maintain sample cultures (5). Growth media and
fermenters to multiply the sample cultures are widely available.
Purifying, concentrating, and stabilizing agents is demanding and
dangerous but not a great technical challenge. Freeze-drying the
product and milling it into particles of a uniform respirable size
requires even more technical capabilities. A state sponsor may be
needed to do it, although companies and institutes regularly spray
dry and mill commercial microbes. Moreover, a respirable aerosol
of germs can be achieved through other high-pressure devices.

Biological production and weapon-producing facilities can be small,
inexpensive, and inconspicuous. Equipment to develop biological
arms may have legitimate commercial and research purposes, as
well as nefarious ones. Unlike nuclear weapons, biological weapons
do not require unique ingredients that are ready objects of arms
control.

Institutional Capability

Depending on their sophistication, terrorist groups may or may not
have the capability to build broad-impact biological weapons.
However, most nations have the capability to make biological
weapons. Some 18 nations are believed to have done so, including
the former Soviet Union and several nations the State Department
lists as supporting terrorism.

Intention to Use Biological Weapons

Why would anyone wish to use biological weapons? A leading
entity with a motive to perpetrate a biological attack could be a
rogue state as an act of clandestine warfare. The very strength of a
superpower may provide an incentive to adversaries to challenge
this strength unconventionally.

If a rogue regime were to mount such an unconventional
asymmetric attack, they might choose biological weapons because
their extreme destructive potential is concentrated in a relatively
small and unremarkable package with virtually no detectable sensor
signature. Because of the agent's incubation period, the perpetrators
might be gone before anyone knew that an attack had been made.
Finally, biological agents, unlike ballistic missiles, lend themselves
to clandestine dissemination.

Warfare itself may be becoming more total and losing much of its
political character in some situations. Biological weapons, which
kill people but leave infrastructure intact, could become the "poor
man's neutron bomb."

In the past, the essence of terrorism was to make a political
statement through violence. It was a political act designed to
influence an audience. Levels of violence were carefully calculated
so as to draw attention but not to be so high as to alienate
supporters or trigger overwhelming response from authorities. That
continues to be a main theme of conventional terrorism. However,
in so-called postmodern or superterrorism, the aim is to maximize
the number of casualties (6). This reflects a shift in the goal of the
terrorists, from trying to make a political statement through
violence to maximizing damage to the target as an end in itself.
Such terrorists may be motivated by ethnic or religious
considerations, among others (7).

Even conventional terrorism tends to escalate levels of violence to
keep garnering attention. The threat of biological weapons imparts
high levels of fear that may make them desirable to perpetrators
who wish to terrorize, even more than to kill. Threats have to
become increasingly credible after the initial shock of specious
threats has diminished. Even a minor biological attack, made to
demonstrate credibility, could have a disproportionate impact.
Thus, a certain subset of terrorists may be motivated to commit
mass casualty terrorism, including biological terrorism.

Nonintentional Pathogen Releases

Certain kinds of biological assaults can be predicted with even
higher confidence than bioterrorist attacks. Stephen Morse, Defense
Advanced Research Projects Agency, has said that Mother Nature
is the greatest terrorist. Since infectious diseases were widely
dismissed as a world health threat some 30 years ago, nature has
loosed some 30 new or reemerging infectious diseases on the world
(Table) (8). An influenza pandemic was averted 2 years ago by the
alert and energetic actions of epidemiologists in Hong Kong and
around the world. Slower reactions might have permitted the
pathogen's genes to shuffle among human and avian infections to
make the flu strain readily transmissible from person to person.
Multidrug-resistant tuberculosis is increasing rapidly in Russia in
part because of lack of adequate antibiotics (9). More health
challenges are almost certainly in store. Causes contributing to
emerging disease outbreaks (overcrowding, deforestation, airline
travel) will likely continue (9).

Health security and national security needs overlap. If the United
States prepares to confront and defeat intentional human releases of
pathogens, we will be better prepared for the unpredictable but
robust threats likely to occur from nature. For emergency medical
response, patients need rapid and efficacious treatment, whether the
source of an outbreak of disease is intentional or natural. Medical
research needs drugs that treat disease after symptoms become
apparent. Such drugs might target common features of disease (10),
e.g., inflammation cascade and toxic shock. Aerosol challenge is
also typical of both military threats and other airborne pathogens;
vaccines that enhance mucosal immunity may mitigate them.
Expression of specific genes that may be critical and unique to a
number of pathogens might one day be inhibited by medicine.

Effective and safe multipurpose and specific drug treatments would
help in the battle against both naturally occurring and intentional
releases of infectious disease. Through advanced biotechnology, we
could begin to reverse the offense-defense mismatch that now
greatly favors disease over cure.

Conclusions

Vulnerability and capability, two prerequisites of bioterrorism, are
in place. Enhancing emergency medical preparedness and
supporting advanced pharmaceutical research for multivalent drugs,
among other measures, will help us deter and defeat deliberate and
naturally occurring pathogen releases, as well as increase the
general health and well-being of the population. The intention of
potential attackers is difficult to manage. Therefore, limiting our
vulnerability is the most promising way to prevent or mitigate
biological attacks on the United States.

Table. New and reemerging viruses (8)

--------------------------------------------------------
Viruses               Date    Family        Comments
--------------------------------------------------------
New
  Human herpesvirus 6 1986 Herpesvirus
(HHV-6)
  Human herpesvirus 7 1990 Herpesvirus
(HHV-7)
  GS viruses          1994 Flaviviru
(hepatitis)
  Human herpesvirus 8 1995 Herpesvirus
(HHV-8)
Reemerging
  Cocoa swollen shoot      Badnavirus    Destroyed 200
                                          million cocoa
                                          trees in West
                                          Africa.
  Dengue                   Bunyavirus
  Ebola                    Flavivirus
  Equine              1994 Morbillivirus Emerged in
    morbillivirus                         Brisbane
                                          Australia.
                                          Causes acute
                                          respiratory
                                          disease with
                                          high mortality
                                          in horses.
                                          Believed to
                                          cause a fatal
                                          encephalitis in
                                          humans.
  Hantaan group            Bunyaviruses
  Phocine distemper   1987 Morbillivirus Caused death
                                          rates in seals
                                          in the Baltic
                                          and North Sea.
                                          Similar viruses
                                          subsequently
                                          recognized as
                                          responsible for
                                          porpoise and
                                          dolphin deaths
                                          in the Irish
                                          Sea and the
                                          Mediterranean.
Rabbit calicivirus    1985 Calicivirus   Emerged in
disease /Viral                            China, spread
hemorrhagic disease                       naturally
                                          through UK and
                                          Europe.
                                          Introduced
                                          to Wardang
                                          Island off the
                                          coast of South
                                          Australia to
                                          test potential
                                          for rabbit
                                          population
                                          control
                                          accidentally
                                          spread to
                                          mainland
                                          decimating
                                          rabbit
                                          populations.
Rift Valley fever          Bunyaviruses
Tomato spotted wilt        Bunyavirus
Whitefly-transmitted       Geminivirus
geminiviruses (group
III geminiviruses)
--------------------------------------------------------

Mr. Siegrist is research fellow at the Potomac Institute for
Policy Studies and is director of Studies for Countering Biological
Terrorism. He is also an adjunct faculty member at Georgetown
University, where he was National Strategy Public Policy Fellow
and where he teaches classes on national security. He is the project
leader of Countering Biological Terrorism in the U.S., from Oceana
Press (May 1999).

Address for correspondence: David W. Siegrist, Potomac
Institute for Policy Studies, 1600 Wilson Boulevard, Suite 1200,
Arlington, VA 22209, USA; fax: 703-525-0299; e-mail:
siegrist@potomacinstitute.com.
     
References

  1. Army Reserve National Guard. Stakeholders III Conference
Medical Panel. National Guard Bureau, Arlington, VA, December
1998.
  2. Tonat K. Office of Emergency Preparedness, U.S. Department
of Health and Human Services. Panel discussion at conference
"Integrating Medical and Emergency Response," Washington, DC,
March 10, 1999.
  3. Mitchel A. Office of State and Local Domestic Preparedness
Support, U.S. Department of Justice. Panel discussion at
conference "Integrating Medical and Emergency Response,"
Washington, DC, March 10, 1999.
  4. Carus S. Bioterrorism and biocrimes: the illicit use of biological
agents in the 20th Century. Washington: Center for
Counterproliferation Research, National Defense University; 1998.
   5. Broad W, Miller J. The threat of germ weapons is rising. Fear,
too. The New York Times, December 27, 1998.
  6. Laqueur W. Postmodern terrorism. Foreign Affairs; Sep/Oct
1996.
  7. Ikle F. Waiting for the next Lenin. The National Interest; spring
1997.
  8. Cann AJ. Principles of molecular virology. 2d ed. San Diego:
Harcourt Brace & Co. Academic Press; 1997. p. 230.
  9. Lee C. US can't ignore implications of TB plaguing Russia.
USA Today, February 8, 1999, p. 16A and 232.
 10. Committee on R&D Needs for Improving Civilian Medical
Response to Chemical and Biological Terrorism Incidents,
Chemical and Biological Terrorism: Research and Development to
Improve Civilian Medical Response, Institute of Medicine, National
Research Council, National Academy Press, Washington: 1999; pp.
129-32.
_______________________________________________________________________

Special Issue

Nuclear Blindness: An Overview of the Biological Weapons
Programs of the Former Soviet Union and Iraq

Christopher J. Davis
Johns Hopkins University Center for Civilian Biodefense Studies

 The demise of the biological weapons capability of the United
States in 1969 and the advent of the Biological and Toxin Weapons
Convention in 1972 caused governments in the West to go to sleep
to the possibility of biological weapons development throughout the
rest of the world, as technically knowledgeable workers were
transferred and retired, intelligence desks were closed down, and
budgets were cut. By 1979, despite the Sverdlovsk anthrax release,
a senior British government policy official described any biological
weapons threat as nebulous. President Nixon's biological weapons
disarmament declaration in 1969 had conveyed the impression that
biological weapons were uncontrollable and that the U.S. program
had not been successful in producing usable weapons (when in fact
the opposite was true). Add to this the rise of truly intercontinental
ballistic missile delivery of nuclear weapons, and the stage was set
for what I have termed "nuclear blindness" and defined as "the
tunnel vision suffered by successive governments, brought on by
the mistaken belief that it is only the size of the bang that matters."
Throughout this period, both the former Soviet Union and Iraq
conceived, albeit in different ways, their new biological weapons
programs. It took until 1989-1991 for government technical experts
in the West to persuade the world and their own governments that
these programs were real and of enormous potential importance to
the security of the West, if not the whole world.

Too many times in the past we have failed to anticipate future
developments; refused to think the unthinkable and expect the
unexpected. Too many times we have been out maneuvered by
those who take the time to think and plan and do not simply rely on
reacting to events. We must learn to think like our potential
adversaries if we are to avoid conflict or blunt an attack, because
only superior thinking and planning (not just better technology) will
enable us to survive biological warfare.

The Former Soviet Union

The origins of the biological weapons program of the former Soviet
Union stretch back to statements by Lenin, and experimental work
was under way by the late 1920s. The modern era was ushered in,
however, only with the postwar military building program, which
established infrastructure for research, development, testing,
production, and delivery of a variety of agents and weapons.

On the other side of the globe, the allied biological weapons
program had grown from the fledgling efforts of British research
into anthrax and the development of the World War IIanthrax
cattlecake retaliation weapon into a large U.S.-based research and
development (R&D) and production capability. By 1969, the U.S.
military had accepted seven type-classified agents, and, at plants
such as the one at Pine Bluff in Arkansas, they could produce 650
tons of agent per month for filling into weapons. This thriving
offensive program was unilaterally abandoned in 1969 as a result of
a complicated mixture of politics, secret intelligence information,
new technological developments, and the Vietnam War. These
developments gave impetus to the creation of the Biological and
Toxin Weapons Convention, originally drafted by the British but
finalized by the Soviet Union. Although the Soviet Union signed the
Convention at its inception in 1972, it did not believe that the
United States would be so foolish as to abandon its biological
weapons capability, regarding the disarmament agreement as a
"worthless piece of paper."

In 1973 and 1974, the Soviet Politburo formed and funded the
organization known most recently as Biopreparat (Chief
Directorate for Biological Preparations), designed to carry out
offensive biological weapons R&D and production concealed
behind legal and civil biotechnology research. At no time did
civilian biotechnology work ever comprise much more than 15% of
the activity at any of the 52 sites under the aegis of Biopreparat.
Ultimately it was controlled by the Ministry of Defense, the Military
Industrial Commission, and other state organs, all the way up to the
Central Committee and what became eventually the Office of the
President. Its head, a general, retained special access to the Central
Committee from its inception, and through its links with the
Academies of Science and Medical Science, Ministry of Health, and
the Anti-Plague Institutes, recruited a generation of scientists who
elsewhere in the world underpinned the expanding pharmaceutical
and biotechnology industries and academic life-sciences research.
The whole system probably employed at its height at least 50,000
people, many of whom were scientists and technicians with very
high security clearance that identified them as part of a biological
weapons program more closely held and more secret than its
nuclear weapons counterpart. The system was always able to draw
on the best from any source but was, to a certain extent,
self-sufficient. Not all of the 52 establishments were occupied with
microbiology or weaponssome were workshops, garages, and
cover operations; others supported the program directly with
fermenter design and construction or building of weapons test
chambers; while yet others carried out advanced research, which
would then be given to other institutes for development. Often
there was internal competition, with one project being given to a
number of facilities to see who would come up with the best idea.
In its first 15 years alone, Biopreparat probably cost at least 1.5
billion rubles to create and runa large sum for life-sciences R&D
but relatively modest compared with the cost of nuclear weapons
R&D and, therefore, in terms of strategic weapons, extremely
cost-effective.

The main purpose of the enormous Biopreparat capability was to
hide biological weapons research, development, and production
formerly carried out solely in Ministry of Defense establishments
behind a facade of nominally civilian biotechnology and
pharmaceutical enterprises. The two systems, the former Ministry
of Defense complex of biological weapons facilities and the new
Biopreparat facilities, continued to operate side-by-side. The
Ministry of Defense facilities themselves probably employed
another 15,000 workers and had a separate budget, so that the
potential within the system as a whole, which is how it should be
considered, was large and dwarfed the by-then long-abandoned
U.S. offensive program. Its capacity for production of agent was
measured not in tons but in hundreds of tons for each of at least
nine separate sites, primarily plague, tularemia, glanders, anthrax,
smallpox, and Venezuelan equine encephalomyelitis.

Another mission of Biopreparat was to apply advances in
biotechnology (genetic engineering, in particular) to improving the
biological weapons capability of the former Soviet Union. This
mission took several forms, supported primarily by the then
vice-president of the Academy of Sciences, Yuri Ovchinnikov, the
most influential Soviet biomedical scientist of the 1970s. He saw a
way around arms control treaties and weapons conventions by
using microbes to produce biologically active substances that would
replace classic chemical weapons; their production could then be
concealed in the biotechnology or pharmaceutical industry. He also
envisaged that the government would use genetic engineering to
produce a new generation of biological weapons agents with
enhanced capability for expressing toxins and other biologically
active substances and to improve overall weapons effectiveness.
The outcome of the first of these two programs is not known, but
the latter was very successful. Moreover, the new
Biopreparat-based program was able to address all aspects of agent
production and delivery, not just the most advanced microbiological
ones. It built strength in depth, having as its main aims to improve
industrial production scale-up techniques, microbial production
rates, yields of viable microorganisms, virulence, and resistance of
microorganisms to antibiotics; to maximize viability of agent during
dissemination and increased survivability of biological aerosols; and
to enhance the ability of microorganisms to degrade the target's
natural defenses. The leaders of the program foresaw increasing
encroachment of international arms control processes into the
territory of sovereign states. Thus, they perceived the need for its
weapons to become invulnerable to first strike or counterattack.
Key technical targets associated with such an approach were the
development of dry solid particulate agent formulations,
miniaturized production facilities, mobile production and filling
facilities, strains resistant to multiple antibiotics, cruise missile
dissemination system, and combination organisms.

By addressing every aspect of weapon production, from selection
of new strains of organisms to the behavior of biological aerosols
under every possible condition of climate and topography, through
the genetic engineering of antibiotic resistance and the design of
optimum dissemination and delivery systems, the former Soviet
Union was able to envisage the achievement of a miniaturized
mobile production and weapon-making capability invulnerable to
clandestine monitoring, invasive arms inspection, or attack in the
event of war (because it was beyond identification); agents precisely
matched to particular scenarios and human targets and incapable of
being treated; a variety of dissemination systems, including cruise
missiles; agents resistant to degradation by heat, light, cold, UV
radiation, ionizing radiation, and various antibiotics; and dry
formulations of agents capable of remaining viable in long-term
storage.

By the time of the breakup of the former Soviet Union, from which
the Russian Confederation emerged in 1992, much had been
achieved and war mobilization plans were in place for the surge
production of huge quantities of the agents mentioned earlier, as
well as a number of others, such as Marburg virus. Of
overwhelming importance has been the capability to undertake a
strategic attack using plague or smallpox. Intercontinental ballistic
missiles with MIRVed warheads containing plague were available
for launch even before 1985, and SS-11 and SS-18 missiles have
been mentioned in this connection. Concepts of use had been
developed for each of the biological agents formally accepted into
use by the army. For instance, the principal agents designated as
tactical or operational for use on the battlefield were tularemia and
Venezuelan equine encephalomyelitis, whereas anthrax and
Marburg virus were nominated for attacking rear areas. The third
category of agents comprised the highly transmissible agents
smallpox and plague, which were categorized as strategic weapons
and destined for use against enemy population centers.

What happened after Vladimir Pasechnik (the former general
director of Science Production Organisation Farmpribor and
director of The All Union Scientific Research Institute of Ultra Pure
Biopreparations in Leningrad [St. Petersburg]) defected in 1989
constitutes a long and complex story, but in January 1991 the
first-ever visit to Biopreparat facilities was undertaken, by a joint
U.K./U.S. technical team, under a cloak of secrecy. After the
subsequent defection of Kanadjan Alibekov (a former senior deputy
director of Biopreparat) in 1992, the United States and the United
Kingdom were certain enough that the offensive biological weapons
program was continuing that they challenged the new Russian
regime openly about it as late as 1993. By then substantial changes
had taken place within Biopreparat, and today a concerted effort is
under way to help the Russians civilianize these former biological
weapons R&D establishments. However, questions remain about
the Russian program: What happened to the part of the program in
Ministry of Defence facilities that western experts have been unable
to visit? What happened to plans detailing every aspect of
production and deployment? What happened to the Ovchinnikov
bioregulator program? What happened to the thousands of
personnel involved in the Biopreparat program? What happened to
the R&D centered on anticrop, antiplant, and antilivestock
biological weapons? What happened to the stocks of seed cultures
of biological weapons agents designed to be used to fuel the
mobilized production of weapons? Was there space-based
biological weapons capability? Was there any human
genetics-related biological weapons research?

Despite the passage of nearly 10 years, the fundamental change in
political structure of Russia, the extreme economic upheaval and
budget restrictions, the reorientation of Biopreparat's work, and the
help and support given by the West to civilianize programs and stop
the transfer of technology and scientists into illegal biological
weapons programs, the capability of the old Russian Ministry of
Defence sites remains largely unknown.

Iraq

Iraq has stated that its biological weapons program dates to at least
1974. It was carried out in great secrecy, after the Biological and
Toxin Weapons Convention had been signed. The program was
first conducted in an ostensibly civilian organization called the State
Organization for Trade and Industry until this was superseded by
the Military Industrial Commission. As with all other major military
programs, biological weapons R&D was able to call upon many of
its leading scientists who undertook undergraduate or postgraduate
training in the west. Much of what happened between the supposed
inception of the program in 1974 and the establishment of a group
of biologists within the Al-Muthanna chemical weapons complex in
1984 is unknown.

In 1987, the Al-Muthanna research group was transferred to the
Al-Salman facility, and work was expanded to include the
investigation of fungal and antiplant agents; 1988 saw the
establishment of the Al-Hakam Factory, an industrial-scale
production facility designed to produce anthrax and botulinum
toxin for filling into weapons. This project was completed quickly
by using equipment from nominally civilian facilities, such as those
used to produce vaccines; the factory itself produced biological
agent, which was filled into weapons and deployed in late 1990.
The program was further expanded in 1990 when viruses were
added to the range of agents under development and production
capacity was enhanced by the acquisition and integration of civilian
biotechnology facilities by the Military Industrial Commission.

According to the Iraqis, the program was terminated in 1991, after
the adoption of UN SCR687, and agents, weapons, munitions, and
documents were destroyed. However, the United Nations Special
Commission (UNSCOM) believes that from 1991 to 1995 Iraq
actively preserved biological weapons capability.

The Agents, Weapons, and Means of Delivery

The UNSCOM belief that three biological agents were filled into
weapons is supported by Iraqi statements concerning the filling of
munitions and their deployment ready for delivery. For one of these
agents, Botulinum toxin, UNSCOM also possesses objective
evidence; the other two were probably anthrax and Clostridium
perfringens spores. Approximately 380,000 liters of Botulinum
toxin were manufactured, along with 84,250 liters of anthrax spores
and 3,400 liters of C. perfringens spores. In addition, 2,200 liters of
aflatoxin were produced. All these figures represent
preconcentration totals and may be underestimates. Ricin toxin and
the antiplant agents wheat bunt and corn smut were also produced.
Camel pox is known to have been under development as well. This
disparate list of biological agents, which at first seems to contain
substances not previously conceived as potential offensive
biological weapons agents, on closer inspection reveals a rationale
based on the possession of a multipotent arsenal having lethal,
incapacitating, oncogenic, ethnic, economic, terror, and variable
time-onset capabilities. In addition, these agents are capable of
being used to attack people through the lungs and the skin, as well
as with carriers such as triethylamine, CN or CS, or as a toxic
coating in fragmentation weapons.

Agents were filled into various weapons for dissemination. By the
end of 1990, according to Iraqi statements, 25 SCUD/Al-Hussein
missiles were readied for use with biological weapons warheads
(each carrying 145 liters of agent) and deployed for action. At least
160 R400 retarded aerial bombs, carrying the distinctive
black-stripe identification around them, may also have been filled
with 90-liter charges of Botulinum toxin and ready for use.
UNSCOM has evidence to corroborate the Iraqi claim. The Iraqis
also intended to fill R400 bombs with anthrax and aflatoxin.
Originally designed and filled with chemical agents, 155-mm shells
were also tested with a ricin toxin fill. At least three fuel drop tanks
were completely modified and fitted with Venturi mechanisms to
facilitate aerosol release, for dispersal of 2,200-liter loads of
anthrax and possibly Botulinum toxin, using F1 aircraft as the
delivery means. 

Postscript

UNSCOM has no confidence that Iraq has abandoned its biological
weapons program. The true scale and scope of the Iraqi biological
weapons program are, despite all UNSCOM's efforts, still not
known.

Dr. Davis is consultant in Pharmaceutical Medicine and Applied
Physiology and director of the ORAQ Consultancy Ltd., United
Kingdom.

Address for correspondence: Christopher J. Davis, Og House,
Ogbourne St. George, Marlborough, Wiltshire, SN8 1TF, United
Kingdom; fax: 44-(0)-1672-841418; e-mail:
christopher.davis1@virgin.net.
_______________________________________________________________________

Special Issue

Aum Shinrikyo: Once and Future Threat?

Kyle B. Olson
Research Planning, Inc., Arlington, Virginia, USA

On March 20, 1995, members of the Aum Shinrikyo cult entered
the Tokyo subway system and released sarin, a deadly nerve agent.
The subway attack was the most deadly assault in an ongoing
campaign of terror waged by this mysterious cult. Four years later,
with Aum Shinrikyo attempting to rebuild itself, many in Japan and
around the world are asking whether the "Supreme Truth Sect"
poses a current or future threat. Answering this question may
further our understanding, not only of the Aum but also of other
extremist and terrorist groups.

Aum Shinrikyo began its public campaign of terror on June 27,
1994. On that Monday in Matsumoto, a city of 300,000 population
322 kilometers northwest of Tokyo, a group of cult members drove
a converted refrigerator truck into a nondescript residential
neighborhood. Parking in a secluded parking lot behind a stand of
trees, they activated a computer-controlled system to release a
cloud of sarin. The nerve agent floated toward a cluster of private
homes, a mid-rise apartment building, town homes, and a small
dormitory.

This neighborhood was targeted for a specific reason. The
dormitory was the residence of all three judges sitting on a panel
hearing a lawsuit over a real-estate dispute in which Aum Shinrikyo
was the defendant. Cult lawyers had advised the sect's leadership
that the decision was likely to go against them. Unwilling to accept
a costly reversal, Aum responded by sending a team to Matsumoto
to guarantee that the judges did not hand down an adverse
judgment. A light breeze (3 to 5 knots) gently pushed the deadly
aerosol cloud of sarin into a courtyard formed by the buildings. The
deadly agent affected the inhabitants of many of the buildings,
entering through windows and doorways, left open to the warm
night air. Within a short time, seven people were dead. Five
hundred others were transported to local hospitals, where
approximately 200 would require at least one night's
hospitalization.

After successfully completing their mission, the cultists drove off to
Kamakuishki, a rural community at the foot of Mount Fuji, home to
golf courses, parks, dairy farms, small villages, and the
headquarters of Aum Shinrikyo in Japan. The cult's facilities
consisted of a number of motley buildings, factories, and
dormitories.

Aum Shinrikyo's next major act of violence would serve as a
wake-up call to the world regarding the prospects of weapons of
mass destruction and terrorism. On the morning of March 20, 1995,
packages were placed on five different trains in the Tokyo subway
system. The packages consisted of plastic bags filled with a
chemical mix and wrapped inside newspapers. Once placed on the
floor of the subway car, each bag was punctured with a sharpened
umbrella tip, and the material was allowed to spill onto the floor of
the subway car. As the liquid spread out and evaporated, vaporous
agent spread throughout the car.

Tokyo was experiencing a coordinated, simultaneous, multi-point
assault. The attack was carried out at virtually the same moment at
five different locations in the world's largest city: five trains, many
kilometers apart, all converging on the center of Tokyo. The
resulting deaths and injuries were spread throughout central Tokyo.
First reports came from the inner suburbs and then, very quickly,
cries for help began to flow in from one station after another,
forming a rapidly tightening ring around the station at
Kasumagaseki. This station serves the buildings that house most of
the key agencies of the Japanese government. Most of the major
ministries, as well as the national police agency, have their
headquarters at Kasumagaseki.

By the end of that day, 15 subway stations in the world's busiest
subway system had been affected. Of these, stations along the
Hbiya line were the most heavily affected, some with as many as
300 to 400 persons involved. The number injured in the attacks was
just under 3,800. Of those, nearly 1,000 actually required
hospitalizationsome for no more than a few hours, some for many
days. A very few are still hospitalized. And 12 people were dead.

Within 48 hours of the subway attack, police were carrying out
raids against Aum Shinrikyo facilities throughout Japan. Police
entered cult facilities carrying sophisticated detection systems and
wearing military-issued chemical gear (which was issued to the
Tokyo police the week before the subway attack).
 
The real target of the raids that began on March 17 was the
building known as Satyan 7, a supposed shrine to the Hindu god
Shiva, the most prominent figure in the Aum Shinrikyo religious
pantheon. In reality, the building housed a moderately large-scale
chemical weapons production facility, designed by cult engineers,
with first-rate equipment purchased over-the-counter.

Although the facility's design was crude by industry standards, it
was nonetheless very capable of producing the sarin used in the
Matsumoto attack. At the time of the Tokyo attack, however,
Satyan 7 was not in service, having been mothballed after an
accident during the previous summer. In an effort to get the plant
back into production, the cult had, during the fall of 1994,
unsuccessfully attempted to recruit Russian chemical-weapons
engineers. The cult was adept at recruiting educated professionals
(scientists and engineers), but most were young and largely
inexperienced. Satyan 7 was designed to produce sarin, not on a
small terrorist scale, but in nearly battlefield quantities: thousands of
kilograms a year.

Chemical weapons were not, however, the only option available to
the Aum. The first cult laboratory for toxin production was actually
in place by 1990 and was subsequently replaced with two new
laboratories, one at Kamakuishki and the other in Tokyo. Aum
dabbled in many different biological agents. They cultured and
experimented with botulin toxin, anthrax, cholera, and Q fever. In
1993, Ashahara led a group of 16 cult doctors and nurses to Zaire,
on a supposed medical mission. The actual purpose of the trip to
Central Africa was to learn as much as possible about and, ideally,
to bring back samples of Ebola virus. In early 1994, cult doctors
were quoted on Russian radio as discussing the possibility of using
Ebola as a biological weapon.

The cult attempted several apparently unsuccessful acts of
biological terrorism in Japan between 1990 and 1995. As early as
April 1990, the cult had tried to release botulin toxin from a vehicle
driving around the Diet and other government buildings in central
Tokyo. In early June of 1993, another attempt was made to release
botulin toxin, this time in conjunction with the wedding of the
crown prince. A vehicle equipped with a spray device was driven
around the imperial palace as well as the main government buildings
in central Tokyo.

Later that month, pursuing an alternative technology, the cult
attempted to release anthrax spores from its mid-rise Tokyo office
building laboratory. At that time, police and media reported foul
smells, brown steam, some pet deaths, and stains on cars and
sidewalks. Then, in March 1995, just before the sarin subway
attack, an attempt to spray botulin toxin in the subway at
Kasumagaseki Station was preempted by a cult member who opted
not to load the improvised briefcase sprayers with actual agent.

No injuries were reported in any of these biological events despite
the fact the cult was dealing with very toxic materials. The cult's
failures can be attributed to a variety of factors. The cult may not
have had the right agents or the right technologic facilities; they
could have overcooked the bioagents or not known how to use
them. While the cult was well financed, it was not very successful in
its efforts to recruit biological scientists. Still, the possibility exists
that casualties associated with some of these releases might have
not been detected or were attributed to other causes.

The cult's operations were worldwide, promoting a theology drawn
from different sources, including Buddhism, Christianity,
Shamanism, Hinduism, and New Age beliefs. Cult membership
around the world was likely 20,000 to 40,000. One cult leader
estimated the cult's net worth in March of 1995 at about $1.5
billion. The money was collected through donations, tithing, sales
of religious paraphernalia, videotape and book sales, and other
sources. The cult conducted seminars and hosted training courses
for members, offering indoctrination in Aum's teachings, charging
believers from hundreds to tens of thousands of dollars for
attending these sessions. Aum Shinrikyo also had a number of
commercial enterprises, even a company that manufactured
computers. Imported components from Taiwan were assembled in a
cult factory at Kamakuishki and sold in Aum's computer store in
downtown Tokyo. The cult also ran a chain of restaurants in Tokyo
and several other Japanese cities.

Another source of income was the practice of green mail. Aum
would threaten to establish a cult compound in a city and, if the city
fathers did not bribe them to go away, the cult would set up shop.
Several cities paid rather than have Aum establish operations there.
The cult manufactured illegal drugs and had a marketing agreement
with the Japanese Mafia (the Yakuza). In 1996, the Yakuza would
be found responsible for the assassination of the cult's lead scientist,
Dr. Hideo Murai, in the days following the Tokyo subway attack.
Concerned at his frequent televised appearances, the Yakuza
silenced him for fear that he would betray the linkage between the
two shadowy groups. Extortion, theft, and murder were also part of
the cult's fund-raising activities. Among the cult leaders,
"Doomsday guru" Shoko Ashahara is the undisputed head.
Ashahara (born Chizuo Matsumoto) had numerous exalted titles,
including venerated master, yogi, and holy pope. Highly
charismatic, this partially blind, apparently very talented yoga
instructor was very ambitious politically and financially. He and
more than 20 of his followers ran for Parliament in 1989. They
were defeated, which some Japanese analysts have suggested marks
the moment when the cult's leader elected to pursue weapons of
mass destruction and the violent overthrow of the established order.

Millennial visions and apocalyptic scenarios dominate the group's
doctrine, evidenced by the prominent role of Nostradamus as a
prophet in Aum Shinrikyo teaching. Ashahara has, on many
occasions, claimed to be the reincarnated Jesus Christ, as well as
the first "enlightened one" since the Buddha. He has frequently
preached about a coming Armageddon, which he describes as a
global conflict that would, among other things, destroy Japan with
nuclear, biological, and chemical weapons. According to Ashahara,
only the followers of Aum Shinrikyo will survive this conflagration.

Another cult leader, Fumihiro Joyu, now 35 years old, was a bright
young engineer with the Japanese space program, specializing in
artificial intelligence. He left that organization to go to work for
Aum, where he very quickly rose through the ranks, ultimately to
head the cult's operations in Russia. Joyu oversaw this important
cult expansion, among other things "investing" as much as $12
million in the form of payoffs to well-placed officials. The cult's
investment paid off with expedited access to office buildings,
dormitories, and other facilities throughout Russia. At the time of
the Tokyo subway attack, the cult's principle venture in Russia was
the Moscow-Japan University, with headquarters in offices across
the street from the Bolshoi Ballet. Their senior Russian partner in
the university was a man by the name of Oleg Lobov, at that time
also chairman of Russia's National Security Council and a close
confidant of Boris Yeltsin.

Joyu was convicted of perjury after the subway investigation, but he
received an extremely light sentence (3 years) for his involvement in
the cult's activities. Joyu has apparently maintained close ties to the
cult, and he is slated for release toward the end of this year. After
leaving prison, he may make a play for leadership of the remaining
cult elements. He is the most charismatic member of the cult, other
than Ashahara. In the days right after the Tokyo subway attack, he
was on Japanese television so frequently, and featured in magazines
and newspapers so often, that he became a teen heartthrob.

In the days and weeks immediately following the gas attack, more
than 200 key members of the cult were arrested. Approximately
120 are still in jail, on trial, or have been convicted. Ashahara
himself has been on trial for 3 years. The trial may continue for 5 or
6 years, a judicial timetable that is aggressive by Japanese standards
in cases where the defendant refuses to cooperate with the
prosecution. Three cult members involved in the attack are still at
large. Russian operations were ended by legal action and the assets
seized by the government. The cult's legal status in Japan as a
church has been revoked, but many of its assets are unaccounted
for.

Today, Aum Shinrikyo is once again soliciting donations, collecting
tithes, selling materials to members, holding seminars, conducting
training, and selling computers. Active recruiting is under way.
Aum Shinrikyo is holding 50 "educational" seminars a month for
current and potential members. The cult has offices throughout
Japan, around Tokyo and other cities, and, according to Japanese
sources, they maintain 100 hide-outs throughout that country as
"safe houses." These sources estimate that at least 700 members are
live-in, fully committed devotees. Mind control is still a part of the
cult's package. Cult members can be seen in Aum-owned houses
wearing bizarre electric headsets, supposedly designed to
synchronize their brain waves with those of the cult's leader.

What is the message that these events to impart policy-makers? The
objective of the Tokyo subway attack was not irrational. The
objective that day was to kill as many policemen as possible; Aum
Shinrikyo had become aware of police plans to conduct raids
against cult facilities, beginning on March 20. The cult's timetable
could not permit that interruption.

Aum's actions were perfectly logical within the context of their
value system. They were a self-legitimized group that had rejected
and, ultimately, felt obliged to confront society. Outnumbered as
they were by Japanese police and military might, one can argue that
developing and even using an asymmetric capability was a logical
consequence of their situation. Unable to achieve their
objectivepolitical powerthrough legitimate means, they
determined that a preemptive strike was necessary.

Is Aum Shinrikyo a potential threat? Is Shoko Ashahara just the
first of many, or has he been relegated to the scrap heap? These are
open questions we will be forced to grapple with for many years to
come.

--------------------------------------------------------

      Mr. Olson is adviser, consultant, and writer on high-technology
terrorism, the threat of chemical and biological weapons, and the
practical challenges of arms control; member of the Central
Intelligence's Nonproliferation Advisory Panel; guest lecturer on
chemical and biological weapons terrorism at the Defense Nuclear
Weapons School, Air War College, Naval War College, and U.S.
Air Force Special Operations School, and an adjunct faculty
member at George Washington University.

Address for correspondence: Kyle B. Olson, Research Planning,
Inc., 6400 Arlington Blvd., Suite 1100, Arlington, VA 22042,
USA; fax: 703-237-8085; e-mail: kolson@rpihq.com.
_______________________________________________________________________

Special Issue

The Prospect of Domestic Bioterrorism

Jessica Stern
Council on Foreign Relations, Washington, D.C., USA

Would domestic terrorists use biological weapons?(ft 1) The
conventional wisdom among experts has been that terrorists "want
a lot of people watching, not a lot of people dead" and are unlikely
to turn to weapons of mass destruction.(ft 2) A new school of thought
proposes that improved technology has made biological attacks
resulting in hundreds of thousands or millions of deaths all but
inevitable. While terrorists are increasingly interested in weapons of
mass destruction, proponents of the latter view exaggerate the
threat. Using biological weapons to create mass casualties would
require more than having biological agents in hand. The terrorists
would need to disseminate the agent, which presents technical and
organizational obstacles that few domestic groups could surmount.
In addition, relatively few terrorists would want to kill millions of
people, even if they could.

For most terrorists, the costs of escalation to biological weapons
would seem to outweigh the benefits. Most modern terrorists have
had substantively rational goals, such as attaining national
autonomy or establishing a government purportedly more
representative of the people's will. Escalating to such frightening
weapons would result in a massive government crackdown and
could alienate the group's supporters. Biological weapons are also
dangerous to produce. A number of Aum Shinrikyo members
reportedly damaged their own health while working on biological
agents. Additionally, some terrorists may perceive moral
constraints.(ft 3)

Candidates for successful use of biological weapons represent the
intersection of three sets: groups that want to use these weapons
despite formidable political risks; groups that can acquire the agent
and a dissemination device (however crude); and groups whose
organizational structure enables them to deliver or disseminate the
agent covertly. The intersection of these sets is small but growing,
especially for low-technology attacks such as contaminating food or
disseminating biological agents in an enclosed space. Major attacks
are also becoming more likely. In the sections that follow, we
consider eroding motivational, technical, and organizational
constraints.

Motivational Factors

 Getting Attention

Some terrorists may turn to biological weapons because they
believe it would attract more attention to their cause than
conventional attacks. Studies of perceived risk show an inexact
correlation between scientists' assessment of risk and the level of
fear invoked by risky technologies and activities.(ft 4) Biological
weapons are mysterious, unfamiliar, indiscriminate, uncontrollable,
inequitable, and invisible, all characteristics associated with
heightened fear.

Economic Terrorism

Unlike conventional weapons, radiologic, chemical, and biological
agents could be used to destroy crops, poison foods, or
contaminate pharmaceutical products. They could also be used to
kill livestock. (Conventional weapons could be used for the same
purposes, albeit less efficiently.) Terrorists might use these agents
to attack corporations perceived to be icons of the target country,
for example, by contaminating batches of Coca-Cola, Stolichnaya
vodka, or Guinness stout. Terrorists could attempt to disseminate
anthrax with the explicit goal of imposing expensive clean-up costs
on a target government.

Millenarianism

The millenarian idea is that the present age is corrupt and that a
new age will dawn after a cleansing apocalypse. Only a lucky few
(usually selected on the basis of adherence to doctrine or ritual) will
survive the end of time and experience paradise.(ft 5) Some
millenarians believe that the saved will have to endure the 7 years of
violence and struggle of the apocalypse, and they want to be
prepared.(ft 6) Shoko Asahara, leader of the doomsday cult that
released sarin gas in the Tokyo subway in 1995, killing 12, told his
followers that in the coming conflict between good and evil they
would have to fight with every available weapon.(ft 7) A similar belief
system explains the attraction to survivalism by Identity Christians,
white supremacists who believe in an imminent Armageddon.

Premillennial Tension

Slight tension connected with the millennium presumably affects
most people. Many are concerned about the Y2K problem, the
prospect that computer systems will malfunction or fail at the end
of 1999. Some fear the breakdown of air-traffic control systems and
are planning to avoid traveling around January 1, 2000. Others fear
an accidental launch of Russian nuclear missiles due to
malfunctioning computers. Many are stockpiling food and medicine
or will have extra cash on hand in case automated banking systems
fail. Some feel vague religious fears. Members of antigovernment
groups and religious cults are often vulnerable psychologically and
appear to be especially affected by premillennial tension. Larry
Wayne Harris, a white supremacist and born-again Christian,
predicts that the Y2K bug will cause a civil war in the United States
and that after January 1, 2000, the government will be unable to
deliver welfare checks and food stamps for at least 3 years.(ft 8) He
predicts that biological attacks could be carried out by domestic
groups fighting for their heritage, traditions, and communities,
causing devastating plagues like those described in the Bible's Book
of Revelation.(ft 9) He urges all U.S. citizens to prepare. For some
domestic groups, preparation involves stockpiling weapons and
training to use them.

Exacting Revenge or Creating Chaos

Politically motivated terrorists who desire to change societies rather
than destroy them might avoid killing very large numbers of people
because the political costs would exceed the benefits.(ft 10) Some
terrorists, however, want to annihilate their enemies or demolish the
societal order. William Pierce, leader of the neo-Nazi organization
National Alliance, aims to initiate a worldwide race war and
establish an Aryan state. "We are in a war for the survival of our
race," he explains, "that ultimately we cannot win... except by
killing our enemies... It's a case of either we destroy them or they
will destroy us, with no chance for compromise or armistice."(ft 11)
Creating social chaos is thus a worthwhile objective in Pierce's
view. Ramzi Yousef, organizer of the World Trade Center
bombing, claimed he was exacting revenge against the United
States.(ft 12) Osama bin Laden seems to have similar motives.

Mimicking God

Terrorists hoping to create an aura of divine retribution might be
attracted to biological agents. The fifth plague used by God to
punish the Pharaoh in the Bible's Book of Exodus was murrain, a
group of cattle diseases that includes anthrax. In the fifth chapter of
Samuel I, God turned against the Philistines and "smote them with
emerods." Medical historians consider these emerods a symptom of
bubonic plague.(ft 13) Some terrorists may believe they are emulating
God by employing these agents.

The Aura of Science

Terrorists may want to impress their target audience with high
technology or with weapons that appear more sophisticated than
conventional ones. Terrorists may find technology appealing for
various reasons. William Pierce, who studied physics at California
Institute of Technology, is interested in high-technology weapons.
In his novel The Turner Diaries, right-wing extremists use nuclear,
chemical, biological, and radiologic weapons to take over the
world. Pierce believes he can attract more intelligent recruits to his
organization over the Internet than through radio or leaflets.(ft 14)

The Copycat Phenomenon

Domestic extremists have shown greater interest in chemical and
biological weapons in the last 5 years. For example, in 1998,
members of the Republic of Texas were convicted of threatening to
assassinate with biological agents President Clinton, Attorney
General Janet Reno, and other officials.(ft 15) In May 1995, 6 weeks
after the Aum Shinrikyo incident on the Tokyo subway, Larry
Wayne Harris bought three vials of Yersinia pestis, the bacterium
that causes bubonic plague. No law prohibited Harris or any other
U.S. citizen from acquiring the agent. The law has been tightened
up since, although many fear it is still not restrictive enough. The
Federal Bureau of Investigation (FBI) Director Louis Freeh reports
that "a growing numberwhile still smallof `lone offender' and
extremist splinter elements of right wing groups have been
identified as possessing or attempting to develop or use" weapons
of mass destruction.(ft 16)

In February 1998, Harris boasted to an informant that he had
enough military-grade anthrax to wipe out all of Las Vegas. Eight
bags marked "biological" had been found in the back of a car he and
his accomplice were driving.(ft 17) Several days later, federal
authorities learned that the anthrax Harris had brought to Las
Vegas was a vaccine strain not harmful to human health.
Nevertheless, the incident frightened many people and sparked a
proliferation of anthrax hoaxes and threats in the second half of
1998 continuing into 1999 by groups including Identity Christians
and other antigovernment groups, extortionists, antiabortion
activists, and presumed prochoice groups. In many cases, the
perpetrator's motives were unknown, but some incidents appear to
have been student pranks, demonstrating the extent to which the
threat of anthrax has entered U.S. consciousness (Table).

Technical Factors

With the end of the cold war and the breakup of the Soviet Union,
weapons of mass destruction and their components have become
easier to acquire. Underpaid former Soviet weapons experts may be
providing biological weapons and expertise to Iran.(ft 18) South
African biological weapons scientists have offered their expertise to
Libya.(ft 19) State-sponsored groups are most capable of overcoming
technical barriers to mass-casualty attacks, but the sponsor would
presumably weigh the risk for retaliation before supporting this type
of terrorist attack.

Table. Anthrax incidents in the United States, 1992  1999(sup a)

------------------------------------------------------------------
                                    Year
-----------------------------------------------------------------
                        1992         1997              1998
-------------------------------------------------------------------
No.incidents            1             1                 37
No. persons            20           100              5,529
 affected(sup b)

Persons                20            30              1,202
decontaminated,
treated, or
quarantined(sup b)

Targets            Residence    Religious         Government
                                organization      buildings and
                                                  officials,
                                                  indiviuals,
                                                  clinics, religious
                                                  instiutions,
                                                  antiabortion
                                                  activists, financial
                                                  institutions,
                                                  schools, retail
                                                  establishments,
                                                  office buildings,
                                                  media, nightclub

Purported         Malicious   Anti-Semitism       Antigovernment,
 motivator                                        alleged research,
                                                  antiabortion,
                                                  pro-choice
                                                  retaliation,
                                                  student pranks,
                                                  delay court
                                                  appearance

Dissemination     Splattering Mail                Dispersal on
technique(s)                                      premises, modified
                                                  cigarette lighter,
                                                  moist towelettes,
                                                  mail (envelope),
                                                  explosive device,
                                                  ventilation systems

Responses        Perimeter   Perimeter sealed     On-site inspection,
                 sealed,     decontamination,     evaluation
                 medical     medical,             perimeter sealed,
                 treatment   treatment            pamphlets provided,
                                                  quarantine,
                                                  decontamination,
                                                  medical treatment
--------------------------------------------------------------------
(sup a)These data are presumed incomplete and may contain errors.
Numbers are based on press reports and are not available for all
years. Data not independently confirmed.
(sup b)Figures do not include incidents in which numbers are not
available; actual totals, therefore, may be understated.
Chart prepared by Darcy Bender.

College-trained chemists and biologists could presumably produce
biological agents, although they might have trouble disseminating
them as aerosols. Microorganisms can be disseminated by air in two
forms: as liquid slurries or as dry powders. While producing liquid
slurries is relatively easy, disseminating them as respirable infectious
aerosols over large open areas is not. Although dry powders can be
disseminated far more easily, high-quality powders require
substantial development, involving skilled personnel and
sophisticated equipment. Milling biological agents would require a
level of sophistication unlikely to be found among many domestic
terrorist groups. Far more likely are low-technology incidents such
as contaminating foods, poisoning livestock, or disseminating
industrial poisons in an enclosed space. Such attacks could still be
lethal. Major attacks cannot be ruled out; however, governments
need to prepare.

Organizational Factors

In the mid-1980s, a little-known survivalist group called The
Covenant, the Sword, and the Arm of the Lord (CSA) acquired a
large drum of cyanide with the intention of poisoning water supplies
in major U.S. cities. At the time, CSA was unusual among terrorist
groups in that its sole objective was large-scale murder rather than
influencing government policies. CSA overcame two of three large
obstacles to successful employment of a chemical agent. It had the
motivation to use a chemical agent to kill large numbers and no
political or moral constraints. The group had acquired a chemical
agent, although not in sufficient quantity to contaminate city water
supplies. The group's leaders had not recruited technically trained
personnel and chose an unworkable dissemination technique.
Moreover, the group lacked discipline and was easily penetrated by
FBI. It is unlikely that CSA would make such mistakes if it were
operating today, when antigovernment groups are so much more
aware of the potential of poison weapons for inflicting mass
casualties.(ft 20)

CSA was run as a relatively open compound. Some members wrote
articles in local papers espousing antigovernment beliefs, and some
worked in neighboring towns. Several former CSA members
became informants, often because they hoped to get their sentences
reduced for other, unrelated, crimes. In recent years, however,
antigovernment groups have become more aware of the danger of
penetration by law-enforcement authorities and have devised a new
way of organizing themselves called "leaderless resistance."(ft 21)
Members are encouraged to act on their own, minimizing their
communication with the leadership of the movement. Timothy
McVeigh operated according to this model. His bombing of the
Oklahoma City Federal Building was originally conceived of by
CSA, although it is not clear that McVeigh knew of CSA's earlier
plot. If future terrorists with chemical or biological agents act on
their own or in small, secretive groups, FBI may have difficulty
apprehending them.

One of CSA's objectives was to establish a computerized,
nationwide system linking right-wing groups. This goal has been
achieved, although CSA is not exclusivelyor even
principallyresponsible for this achievement. The nationwide linking
of right-wing groups has implications that have not been adequately
appreciated by the law enforcement community. The Internet makes
terrorist acts easier to carry out. It facilitates leaderless resistance
by allowing leaders of the movement to communicate with
sympathizers worldwide without having to meet face-to-face with
their followers.

The Likeliest Perpetrators

A small but growing number of domestic terrorists could attempt to
use biological weapons in the belief that doing so would advance
their goals. The most likely are religious and extreme right-wing
groups and groups seeking revenge who view secular rulers and the
law they uphold as illegitimate. They are unconstrained by fear of
government or public backlash, since their actions are carried out to
please God and themselves, not to impress a secular constituency.
Frequently, they do not claim credit for their attacks since their
ultimate objective is to create so much fear and chaos that the
government's legitimacy is destroyed. Their victims are often
viewed as subhuman since they are outside the group's religion or
race. 

Religiously motivated groups are increasing. Of 11 international
terrorist groups identified by the Rand Corporation in 1968, none
were classified as religiously motivated. By 1994, a third of the 49
international groups recorded in the Rand-St. Andrews Chronology
were classified as religious.(ft 22) Religious groups are not only
becoming more common; they are also more violent than secular
groups. In 1995, religious groups committed only 25% of the
international incidents but caused 58% of the deaths.(ft 23)

Identity Christians believe that the Book of Revelation is to be
taken literally as a description of future events. Many evangelical
Protestants believe in a doctrine of rapture: that the saved will be
lifted off the earth to escape the apocalypse that will precede the
Second Coming of Christ. Followers of Christian Identity (and
some other millenarian sects), however, expect to be present during
the apocalypse.(ft 24) Because of this belief, some followers of
Christian Identity believe they need to be prepared with every
available weapon to ensure their survival.

Organizational pressures could induce some groups to commit
extreme acts of violence. Followers tend to be more interested in
violence for its own sake than in the group's purported goals,
making them less inhibited by moral or political constraints than the
leaders. Leaders may have difficulty designing command and
control procedures that work. Offshoots of established groups may
be particularly dangerous. Groups may also become most violent
when the state is closing in on them, potentially posing difficulties
for those fighting terrorism. Another factor is the nature of the
leader. Charismatic leaders who isolate their followers from the rest
of society often instill extreme paranoia among their followers.
Such groups can be susceptible to extreme acts of violence.

Asked who he thought the most likely domestic perpetrators of
biological terrorism were, John Trochman, a leader of the Montana
Militia, said that extremist offshoots of Identity Christian groups
are possible candidates, as are disaffected military officers.(ft 25) Some
antigovernment groups are attempting to recruit inside the U.S.
military.(ft 26) William Pierce also foresees the use of biological
weapons by antigovernment groups. "People disaffected by the
government include not only the kind of people capable of making
pipe bombs. Bioweapons are more accessible than are nuclear
weapons."(ft 27)

Conclusions

Terrorism with biological weapons is likely to remain rare. This is
especially the case for attacks intended to create mass casualties,
which require a level of technologic sophistication likely to be
possessed by few domestic groups. While state-sponsored groups
are most likely to be capable of massive biological weapons attacks,
the state sponsor would presumably have to weigh the risk for
retaliation. As in the case of other low-probability high-cost risks,
however, governments cannot ignore this danger; the potential
damage is unacceptably high. Because the magnitude of the threat
is so difficult to calculate, however, it makes sense to focus on
dual-use remedies: pursuing medical countermeasures that will
improve public health in general, regardless of whether major
biological attacks ever occur. This would include strengthening the
international system of monitoring disease outbreaks in humans,
animals, and plants and developing better pharmaceutical drugs.

The risk for overreaction must be considered. If authorities are not
prepared in advance, they will be more susceptible to taking actions
they will later regret, such as revoking civil liberties. Attacks
employing biological agents are also more likely and will be far
more destructive if governments are caught unprepared.
---------------------------------------------------------------------

Acknowledgments

     I thank Darcy Bender for research assistance and Peter Lavoy,
Scott Sagan, and James Wirtz for comments.

     Dr. Stern is a Fellow at the Council on Foreign Relations. She is
the author of The Ultimate Terrorists (Harvard University Press,
1999). She is currently writing a book on religious extremism
worldwide.

     Address for correspondence: Jessica Stern, Council on Foreign
Relations, 1779 Massachusetts Ave. NW, Washington, D.C. 20007,
USA; fax: 202-986- 2984; e-mail: jessicas@alum.mit.edu.
---------------------------------------------------------------------

(ft 1) This essay summarizes Jessica Stern, "Terrorist Motivations and
WMD," in Peter Lavoy, Scott Sagan, and Jim Wirtz, ed., Planning
the Unthinkable, in press, 2000.
(ft 2) Brian Jenkins has made this statement about terrorists on
numerous occasions. For example, see Brian Michael Jenkins,
"International Terrorism: A New Mode of Conflict," in David
Carlton and Carolo Schaerf, eds., International Terrorism and
World Security (London: Croom Helm, 1975), 15. On terrorists'
purported aim to harass, see Kenneth Waltz, "Waltz Responds to
Sagan," in Scott D. Sagan and Kenneth Waltz, The Spread of
Nuclear Weapons: A Debate (New York: Norton, 1995), 94-96.
(ft 3) For examples, see Jessica Stern in Lavoy.
(ft 4) See for example Paul Slovic, Baruch Fischoff and Sarah
Lichtenstein, "Facts and Fears: Understanding Perceived Risk," in
Richard Schwing and Walter Albers, eds., Societal Risk
Assessment: How Safe is Safe Enough? (New York: Plenum Press,
1980), 181-216.
(ft 5) While millenarian doctrines are generally religiously based, some
are not. See Jean E. Rosenfeld, "Pai Marire: Peace and Violence in
a New Zealand Millenarian Tradition," Terrorism and Political
Violence, 7, no. 3 (autumn 1995), 83.
(ft 6)"End Times Jitters," interview with Michael Barkun, Klanwatch
Intelligence Report (summer 1997), 17. 7FBIS-SOV-97-09, 6 May
1997. Source Moscow Trud, 6 May 1997, 1-2.
(ft 8)Author Interview with Larry Wayne Harris, 9 February 1999.
(ft 9)Testimony of Larry Wayne Harris, State of Ohio v. Stephen
Michael Wharf.
(ft 10)The nature of the constituency is a key variable here. If the
terrorists' constituents see the targeted group as subhuman, or if
terrorists have no clear constituency, political constraints against
macro-terrorism are less likely to bind.
(ft 11)Quotes from Klanwatch Intelligence Report (May 1996), 6-8.
(ft 12)Gail Appleson, "Bomb Mastermind Gets Life in US Prison,"
Reuters, 9 January 1997.
(ft 13)Hans Zinsser, Rats, Lice and History (Boston: Little Brown and
Company, 1963), 110.
(ft 14)Author interview with William Pierce, 22 April 1997.
(ft 15) Madeline Baro, "FBI: Men Knew of Cactus Weapons, Threats,"
Associated Press/Corpus Christi Online, 27 October 1998; found
at:
http://www.callertimes.com/autoconv/newstexmex98/newstexmex5
7.html.
(ft 16) Statement for the Record of Louis J. Freeh, Director, Federal
Bureau of Investigation, before the United States Senate
Committee on Appropriations; Subcommittee for the Departments
of Commerce, Justice, and State, the Judiciary, and Related
Agencies; February 4, 1999.
(ft 17)One informant said that Harris said he had "military-grade
anthrax." Another said Harris referred to a vaccine or a placebo.
Proceedings before the Regular Federal Grand Jury, Testimony of
Robert James, February 25, 1998, United States District Court,
District of Nevada, p. 17. United States of America v. Larry Wayne
Harris, Complete Transcript of Proceedings, CR-2-95-093, March
6, 1998, United States District Court, Southern District of Ohio.
(ft 18)Judith Miller and William J. Broad, "Bio-Weapons in Mind,
Iranians Lure Needy Ex-Soviet Scientists," New York Times, 8
November 1998, A1 and Miller and Broad, "Germ Weapons: In
Soviet Past or in the New Russia's Future?" New York Times, 28
December 1998, A1.
(ft 19)James Adams, "Gadaffi Lures South Africa's Top Germ Warfare
Scientists," Sunday Times, 26 February 1995; Paul Taylor, "Toxic
S. African Arms Raise Concern; US Wants Assurance `80s
Program is Dead," Washington Post, 28 February 1995.
(ft 20)For example, Kerry Noble claimed that if CSA leader James
Ellison met someone who knew something about biological agents,
he might consider using them. Author interview with Kerry Noble,
March 2, 1998.
(ft 21)See Louis Beam, "Leaderless Resistance," The Seditionist, Issue
12, February 1992. Found at:
http://www.louisbeam.com/leaderless.htm.
(ft 22)Bruce Hoffman, "Viewpoint: Terrorism and WMD: Some
Preliminary Hypotheses," Nonproliferation Review (spring-summer
1997): 45-52. Hoffman provides slightly different numbers in "Holy
Terror": The Implications of Terrorism Motivated by a Religious
Imperative (Santa Monica: Rand Corporation, P-7834, 1993).
(ft 23)Hoffman, "Viewpoint," 48.
(ft 24)Author interview with Pastor Millar, 21 April 1998.
(ft 25)Author interview with Trochman, 9 February 1999.
(ft 26)Author interview with William Pierce, 22 April 1997.
(ft 27)Author interview with William Pierce.
_______________________________________________________________________

Special Issue

Potential Biological Weapons Threats

Mark G. Kortepeter and Gerald W. Parker
U.S. Army Medical Research Institute of Infectious Diseases, Fort
Detrick, Maryland, USA

The list of agents that could pose the greatest public health risk in
the event of a bioterrorist attack is short. However, although short,
the list includes agents that, if acquired and properly disseminated,
could cause a difficult public health challenge in terms of our ability
to limit the numbers of casualties and control the damage to our
cities and nation.

The use of biological weapons has occurred sporadically for
centuries, culminating in sophisticated research and testing
programs run by several countries. Biological weapons proliferation
is a serious problem that is increasing the probability of a serious
bioterrorism incident. The accidental release of anthrax from a
military testing facility in the former Soviet Union in 1979 and
Iraq's admission in 1995 to having quantities of anthrax, botulinum
toxin, and aflatoxin ready to use as weapons have clearly shown
that research in the offensive use of biological agents continued,
despite the 1972 Biological Weapons Convention (1,2). Of the
seven countries listed by the U.S. Department of State as
sponsoring international terrorism (3), at least five are suspected to
have biological warfare programs. There is no evidence at this time,
however, that any state has provided biological weapons expertise
to a terrorist organization (4).

A wide range of groups or individuals might use biological agents
as instruments of terror. At the most dangerous end of the spectrum
are large organizations that are well-funded and possibly
state-supported. They would be expected to cause the greatest
harm, because of their access to scientific expertise, biological
agents, and most importantly, dissemination technology, including
the capability to produce refined dry agent, deliverable in milled
particles of the proper size for aerosol dissemination. The Aum
Shinrikyo in Japan is an example of a well-financed organization
that was attempting to develop biological weapons capability.
However, they were not successful in their multiple attempts to
release anthrax and botulinum toxin (4). On this end of the
spectrum, the list of biological agents available to cause mass
casualties is small and would probably include one of the classic
biological agents. The probability of occurrence is low; however,
the consequences of a possible successful attack are serious.

Smaller, less sophisticated organizations may or may not have the
intent to kill but may use biological pathogens to further their
specific goals. The Rajhneeshees, who attempted to influence local
elections in The Dalles, Oregon, by contaminating salad bars with
Salmonella Typhimurium, are an example (5). Rather than having a
sophisticated research program, these organizations could use
biological pathogens that are readily available.

The third type are smaller groups or individuals who may have very
limited targets (e.g., individuals or buildings) and are using
biological pathogens in murder plots or to threaten havoc. The
recent anthrax hoaxes are examples of this. Many biological agents
could be used in such instances and the likelihood of their
occurrence is high, but the public health consequences are low.

There are many potential human biological pathogens. A North
Atlantic Treaty Organization handbook dealing with biological
warfare defense lists 39 agents, including bacteria, viruses,
rickettsiae, and toxins, that could be used as biological weapons
(6). Examining the relationship between aerosol infectivity and
toxicity versus quantity of agent illustrates the requirements for
producing equivalent effects and narrows the spectrum of possible
agents that could be used to cause large numbers of casualities. For
example, the amount of agent needed to cover a 100-km2 area and
cause 50% lethality is 8 metric tons for even a "highly toxic" toxin
such as ricin versus only kilogram quantities of anthrax needed to
achieve the same coverage. Thus, deploying an agent such as ricin
over a wide area, although possible, becomes impractical from a
logistics standpoint, even for a well-funded organization (7). The
potential impact on a city can be estimated by looking at the
effectiveness of an aerosol in producing downwind casualties. The
World Health Organization in 1970 modeled the results of a
hypothetical dissemination of 50 kg of agent along a 2-km line
upwind of a large population center. Anthrax and tularemia are
predicted to cause the highest number of dead and incapacitated, as
well as the greatest downwind spread (8).

For further indication of which pathogens make effective biological
weapons, one could look at the agents studied by the United States
when it had an offensive biological weapons research program.
Under that program, which was discontinued in 1969, the United
States produced the following to fill munitions: Bacillus anthracis,
botulinum toxin, Francisella tularensis, Brucella suis, Venezuelan
equine encephalitis virus, staphylococcal enterotoxin B, and
Coxiella burnetti (9). As a further indication of which pathogens
have the requisite physical characteristics to make good biological
weapons, one need only look next at the agents that former Soviet
Union biological weapons experts considered likely candidates. The
agents included smallpox, plague, anthrax, botulinum toxin, equine
encephalitis viruses, tularemia, Q fever, Marburg, melioidosis, and
typhus (10,11). Criteria such as infectivity and toxicity,
environmental stability, ease of large-scale production, and disease
severity were used in determining which agents had a high
probability of use. Both the United States before 1969 and the
former Soviet Union spent years determining which pathogens had
strategic and tactical capability.

The National Defense University recently compiled a study of more
than 100 confirmed incidents of illicit use of biological agents
during this century (W.S. Carus, pers. comm. [4]). Of the 100
incidents, 29 involved agent acquisition, and of the 29, 19 involved
the actual nongovernmental use of an agent, and most were used
for biocrimes, rather than for bioterrorism. In the context of this
study, the distinguishing feature of bioterrorism is that it involves
the use of "violence on behalf of a political, religious, ecologic, or
other ideologic cause without reference to the moral or political
justice of the cause." The balance of incidents involved an
expressed interest, threat of use, or an attempt to acquire an agent.
In the 1990s, incidents increased markedly, but most have been
hoaxes. The pathogens involved present a wide spectrum, from
those with little ability to cause disease or disability, such as Ascaris
suum, to some of the familiar agents deemed most deadly, such as
B. anthracis, ricin, plague, and botulinum toxins (Table). During
this period, the number of known deaths is only 10, while the total
number of casualties is 990. However, the numbers should not give
a false sense of security that mass lethality is not achievable by a
determined terrorist group. The sharp increase in biological threats,
hoaxes, information, and Internet sources on this subject seen in
recent years indicates a growing interest in the possible use of
biological pathogens for nefarious means (4).

In general, the existing public health systems should be able to
handle most attempts to release biological pathogens. A working
group organized by the Johns Hopkins Center for Civilian
Biodefense Studies recently looked at potential biological agents to
decide which present the greatest risk for a maximum credible event
from a public health perspective. A maximum credible event would
be one that could cause large loss of life, in addition to disruption,
panic, and overwhelming of the civilian health-care resources (12).

To be used for a maximum credible event, an agent must have some
of the following properties: the agent should be highly lethal and
easily produced in large quantities. Given that the aerosol route is
the most likely for a large-scale attack, stability in aerosol and
capability to be dispersed (17m to 5 m particle size) are
necessary. Additional attributes that make an agent even more
dangerous include being communicable from person to person and
having no treatment or vaccine.

When the potential agents are reviewed for these characteristics,
anthrax and smallpox are the two with greatest potential for mass
casualties and civil disruption. 1) Both are highly lethal: the death
rate for anthrax if untreated before onset of serious symptoms
exceeds 80%; 30% of unvaccinated patients infected with variola
major could die. 2) Both are stable for transmission in aerosol and
capable of large-scale production. Anthrax spores have been known
to survive for decades under the right conditions (13). WHO was
concerned that smallpox might be freeze-dried to retain virulence
for prolonged periods (8). 3) Both have been developed as agents
in state programs. Iraq has produced anthrax for use in Scud
missiles and conducted research on camelpox virus, which is closely
related to smallpox (2). A Soviet defector has reported that the
former Soviet Union produced smallpox virus by the ton (11). 4)
Use of either agent would have a devastating psychological effect
on the target population, potentially causing widespread panic. This
is in part due to the agents' well-demonstrated historical potential to
cause large disease outbreaks (14). 5) Initial recognition of both
diseases is likely to be delayed. For anthrax, this is secondary to the
rare occurrence of inhalation anthrax. Only 11 cases of inhalation
anthrax have been reported in the United States from 1945 to 1994
(15), and recognition may be delayed until after antibiotic use
would be beneficial. For smallpox, given that few U.S. physicians
have any clinical experience with the disease, many could confuse it
for more common diseases (e.g., varicella and bullous erythema
multiforme) early on, allowing for second-generation spread
(12,16). 6) Availability of vaccines for either disease is limited.
Anthrax vaccine, licensed in 1970, has been used for persons at
high risk for contact with this disease. The U.S. military has
recently begun vaccinating the entire force; however, there is
limited availability of the vaccine for use in the civilian population.
Routine smallpox vaccination was discontinued in the United States
in 1971. Recent estimates of the current number of doses in storage
at CDC range from 5 to 7 million (12), but the viability of stored
vaccine is no longer guaranteed.

Table.  Biological agents involved in bioterrorism or biocrimes(sup a)

---------------------------------------------------------------------
                Traditional                Agents associated
                biological                 with biocrimes
                warfare agents             and bioterrorism
---------------------------------------------------------------------
Pathogens       Bacillus anthracis(sup b)  Ascaris suum
                Brucella suis              Bacillus anthracis(sup b)                                 
                Coxiella burnetii(sup b)   Coxiella burnetii(sup b)
                Francisella tularensis     Giardia lamblia
                Smallpox                   HIV
                Viral encephalitides       Rickettsia prowazekii
                Viral hemorrhagic fevers   (typhus)
                  (sup b)
                Yersinia pestis(sup b)     Salmonella Typhimurium
                                           Salmonella typhi
                                           Shigella species
                                           Schistosoma species
                                           Vibrio cholerae
                                           Viral hemorrhagic
                                             fevers (Ebola)b
                                           Yellow fever virus
                                           Yersinia enterocolitica
                                           Yersinia pestis(sup b)
Toxins         Botulinum(sup b)            Botulinum(sup b)
               Ricin(sup b)                Cholera endotoxin
               Staphylococcal		       Diphtheria toxin
                 enterotoxin B             Nicotine
                                           Ricin(sup b)
                                           Snake toxin
                                           Tetrodotoxin
Anti-crop      Rice blast
agents         Rye stem rust
               Wheat stem rust
---------------------------------------------------------------------
(sup a)Includes agents which were used, acquired, attempted to
acquire, involved in a threat of use or an expressed interest in using. 
Reprinted with permission from Carus WS.   Table 6: Biological
agents involved. In: Carus WS. Bioterrorism and biocrimes: the
illicit use of biological agents in the 20th Century. Working Paper,
Center for Counterproliferation Research, National Defense
University. August 1998, revised March 1999.
(sup b)These agents appear on both lists.

Obtaining smallpox virus as opposed to other agents (e.g., anthrax,
plague, and botulinum toxin) would be difficult, but if obtained and
intentionally released, smallpox could cause a public health
catastrophe because of its communicability. Even a single case
could lead to 10 to 20 others. It is estimated that no more than 20%
of the population has any immunity from prior vaccination (12).
There is no acceptable treatment, and the communicability by
aerosol requires negative-pressure isolation. Therefore, these
limited isolation resources in medical facilities would be easily
overwhelmed.

Anthrax can have a delayed onset, further leading to delays in
recognition and treatment. In the outbreak of inhalation anthrax in
Sverdlovsk in 1979, some patients became ill up to 6 weeks after
the suspected release of anthrax spores (1). The current
recommendation for prophylaxis of persons exposed to aerosolized
anthrax is treatment with antibiotics for 8 weeks in the absence of
vaccine or 4 weeks and until three doses of vaccine have been given
(17). The amount of antibiotics required for postexposure
prophylaxis of large populations could be enormous and could
easily tax logistics capabilities for consequence management.

Other bacterial agents capable of causing a maximum credible event
include plague and tularemia. Plague, like smallpox and anthrax,
can decimate a population (as in Europe in the Middle Ages). An
outbreak of plague could easily cause great fear and hysteria in the
target population (as in the 1994 outbreak in India), when hundreds
of thousands were reported to have fled the city of Surat, various
countries embargoed flights to and from India, and importation of
Indian goods was restricted (18). Both plague and tularemia are
potentially lethal without proper treatment; however, the availability
of effective treatment and prophylaxis may reduce possible damage
to a population. Both are infectious at low doses. Pneumonic
plague's person-to-person communicability and untreated
case-fatality rate of at least twice that of tularemia make it more
effective than tularemia as an agent to cause mass illness.

Other agents of concern include the botulinum toxins and viral
hemorrhagic fevers. Once again, both are highly lethal. Botulinum
toxin is a commonly cited threat, and Iraq has admitted to
producing it. Since intensive care would be required in treating both
illnesses and ventilator management is life-saving for botulinum,
both would easily tax existing medical care facilities. However,
botulinum toxin may be a less effective agent because of relatively
lower stability in the environment and smaller geographic coverage
than other agents demonstrated in modeling studies. Producing and
dispensing large amounts are also difficult (W.C. Patrick, pers.
comm.,19).  

A number of different viruses can cause hemorrhagic
fever. These include (but are not limited to) Lassa fever, from the
Arenaviridae family; Rift Valley fever and Crimean Congo
hemorrhagic fever, from the Bunyaviridae family; and Ebola
hemorrhagic fever and Marburg disease, from the Filoviridae
family. These organisms are potential biological agents because of
their lethality, high infectivity by the aerosol route shown in animal
models, and possibility for replication in tissue culture (16).

In summary, we know that biological pathogens have been used for
biological warfare and terrorism, and their potential for future use is
a major concern. Therefore we must be prepared to respond
appropriately if they are used again. The technology and intellectual
capacity exist for a well-funded, highly motivated terrorist group to
mount such an attack. Although the list of potential agents is long,
only a handful of pathogens are thought to have the ability to cause
a maximum credible event to paralyze a large city or region of the
country, causing high numbers of deaths, wide-scale panic, and
massive disruption of commerce. Diseases of antiquity (including
anthrax, smallpox, and plague), notorious for causing large
outbreaks, still head that list. In addition, other agents, such as
botulinum toxin, hemorrhagic fever viruses, and tularemia, have
potential to do the same. By focusing on a smaller list of these
low-likelihood, but high-impact diseases, we can better prepare for
potential intentional releases, and hope to mitigate their ultimate
impact on our citizens.

Many other pathogens can cause illness and death, and the threat
list will always be dynamic. We must, therefore, have the
appropriate surveillance system and laboratory capability to identify
other pathogens, and we must improve our public health and
medical capabilities to respond to the short list of the most
dangerous naturally occurring biological pathogens that could be
used as bioterrorism weapons.

---------------------------------------------------------------------

Dr. Kortepeter is a preventive medicine officer in the Operational
Medicine Division at the U.S. Army Medical Research Institute of
Infectious Diseases, where he teaches the medical management of
biological weapons casualties.

 Dr. Parker is Commander, U.S. Army Medical Research Institute
of Infectious Diseases (USAMRIID) at Fort Detrick, MD.
USAMRIID conducts research to develop vaccines, medications,
and diagnostics to protect U.S. service members from biological
warfare threats and endemic infectious diseases.

 Address for correspondence: Mark G. Kortepeter, Operational
Medicine Division, U.S. Army Medical Research Institute of
Infectious Diseases, Fort Detrick, MD 21702-5011, USA; fax:
301-619-2312; e-mail: Mark_Kortepeter@DET.AMEDD.
ARMY.MIL.
 
References

  1. Meselson M, Gillemin J, Hugh-Jones M, Langmuir A, Popova
I, Shelokov A, et al. The Sverdlovsk anthrax outbreak of 1979.
Science 1994;209:1202-8.
  2. Zilinskas RA. Iraq's biological weapons: the past as future?
JAMA 1997;278:418-24.
  3. U.S. Department of State. 1996 Patterns of Global Terrorism
Report. Available from: URL: http://www.state.gov.
  4. Carus WS. Bioterrorism and biocrimes: the illicit use of
biological agents in the 20th Century [working paper]. Washington:
Center for Counterproliferation Research, National Defense
University; Aug 1998, revised Mar 1999.
  5. Torok TJ, Tauxe RV, Wise RP, Livengood JR, Sokolow R,
Mauvais S, et al. A large community outbreak of salmonellosis
caused by intentional contamination of restaurant salad bars. JAMA
1997;278:389-95.
  6. Departments of the Army, Navy, and Air Force. NATO
Handbook on the Medical Aspects of NBC Defensive Operations.
Washington: The Department; 1996.
  7. Spertzel RO, Wannemacher RW, Patrick WC, Linden CD,
Franz DR. Technical ramifications of inclusion of toxins in the
chemical weapons convention (CWC). Technical report no.
MR-43-92-1. Fort Detrick (MD): U.S. Army Medical Research
Institute of Infectious Diseases; 1992.
  8. World Health Organization Group of Consultants. Health
aspects of chemical and biological weapons. Geneva: The
Organization; 1970.
  9. Department of the Army. U.S. army activity in the U.S.
biological warfare programs. Vol II. Publication DTIC B193427L.
Washington: The Department; 1977.
10. Vorobjev AA, Cherkassey BL, Stepanov AV, Kyuregyan AA,
Fjedorov YM. Key problems of controlling especially dangerous
infections. In: Proceedings of the International Symposium of
Severe Infectious Diseases: Epidemiology, Express-Diagnostics and
Prevention; 1997 Jun 16-20; Kirov, Russia. State Scientific
Institution, Volgo-Vyatsky Center of Applied Biotechnology; 1997.
11. Alibek K, Handelman S. Biohazard. Random House. New
York, NY; 1999.
12. Henderson DA. The looming threat of bioterrorism. Science
1999;283:1279-82.
13. Manchee RJ, Stewart WDP. The decontamination of Gruinard
Island. Chemistry in Britain 1988;690-1.
14. The Holy Bible, new international version. Exodus Chapter 9.
Indianapolis and Grand Rapids: B.B. Kirkbride Bible Company,
Inc. and The Zondervan Corporation; 1978.
15. Centers for Disease Control and Prevention. Summary of
notifiable diseases, 1945-1994. MMWR Morb Mortal Wkly Rep
1994;43:70-8.
16. Franz DR, Jahrling PB, Friedlander AM, McClain DJ, Hoover
DL, Byrne WR, et al. Clinical recognition and management of
patients exposed to biological warfare agents. JAMA
1997;278:399-411.
17. Centers for Disease Control and Prevention. Bioterrorism
alleging use of anthrax and interim guidelines for
managementUnited States, 1998. MMWR Morb Mortal Wkly
Rep 1999;48:69-74.
18. Campbell GL, Hughes JM. Plague in India: a new warning from
an old nemesis. Ann Intern Med 1995;122:151-3.
 19. McNally RE, Morrison MB, Berndt JE, Fisher JE, Bo'Berry
JT, Puckett V, et al. Effectiveness of medical defense interventions
against predicted battlefield levels of botulinum toxin A. Joppa
(MD): Science Applications International Corporation; 1994.
_______________________________________________________________________

Special Issue

Epidemiology of Bioterrorism

Julie A. Pavlin
Walter Reed Army Institute of Research, Washington, D.C., USA

Since the discovery of Iraq's biological weapons program, concern
regarding the threat of biological warfare has increased (1). Anthrax
immunizations; increased nuclear, biological, and chemical defense
training; improved detection systems and protective gear; and
increased vigilance have been instituted to protect the military.

However, the military is not the only population at risk for
biological attack. To effectively counter the potentially devastating
effects of an attack, we need to understand the basic epidemiologic
principles of biological agents used as weapons.

A biological agent is commonly portrayed as a genetically
engineered organism resistant to all known vaccines and drugs,
highly contagious, and able to harm thousands of people. However,
alleged attacks by the Aum Shinrikyo did not result in a single
illness from a biological agent (2), and the successful 1984
contamination of salad bars in The Dalles, Oregon, by a religious
cult involved a common salmonella strain that was not lethal or
contagious and was susceptible to antibiotics (3).

Therefore, our level of suspicion and diligence in identifying and
reacting to a biological attack must remain high, since the attack
may not follow an expected pattern. Furthermore, a small outbreak
of illness could be an early warning of a more serious attack, and
recognition and prompt institution of preventive measures (such as
effective vaccines and antibiotics) could save thousands of lives.

To facilitate the rapid identification of a bioterrorist attack, all
health-care providers and public health personnel should have basic
epidemiologic skills and knowledge of what to expect in such a
setting.

Differential Diagnosis

Any small or large outbreak of disease should be evaluated as a
potential bioterrorist attack. This initial investigation does not have
to be time consuming or involve law enforcement. A look at the
facts surrounding the outbreak to determine if anything seems
unusual or indicative of bioterrorism should suffice. Since a disease
outbreak can be the result of intentional contamination, the
differential diagnosis of an outbreak should first be considered. The
possibilities include a spontaneous outbreak of a known endemic
disease, a spontaneous outbreak of a new or reemerging disease, a
laboratory accident, or an intentional attack with a biological agent.
Epidemiologic tools can assist in differentiating between these
possibilities.

The cause of a disease or even the occurrence of something unusual
may be very difficult to determine, especially if the initial cases are
few. Surveillance needs to be more than routine. Not only unusually
high rates of illness but also unusual diseases should signal a
warning. For example, even one case of inhalation anthrax should
cause immediate concern and action.

Unlike chemical terrorism, biological terrorism is not immediately
obvious but may appear insidiously, with primary-care providers
witnessing the first cases. However, it may not even be emergency
room personnel who first detect a problem. The first to notice could
be a hospital laboratory seeing unusual strains of organisms, or the
county epidemiologist keeping track of hospital admissions, or even
pharmacists distributing more antibiotics than usual, 911 operators
noticing an increase in respiratory distress calls, or funeral directors
with increased business. All epidemiologic data should be tracked
and aggressively followed to ensure the most rapid recognition and
response.

Epidemiologic Approach

The basic epidemiologic approach in the evaluation of a potential
bioterrorist or biowarfare attack is not different from any standard
epidemiologic investigation. The first step is to use laboratory and
clinical findings to confirm that a disease outbreak has occurred. A
case definition should be constructed to determine the number of
cases and the attack rate. The use of objective criteria in the
development of a case definition is very important in determining an
accurate case number, as both additional cases may be found and
some may be excluded, especially as the potential exists for hysteria
to be confused with actual disease. The estimated rate of illness
should be compared with rates during previous years to determine if
the rate constitutes a deviation from the norm.

Once the case definition and attack rate have been determined, the
outbreak can be characterized in the conventional context of time,
place, and person. These data will provide crucial information in
determining the potential source of the outbreak.

Epidemic Curve

Using data gathered on cases over time, an epidemic curve can be
calculated. The disease pattern is an important factor in
differentiating between a natural outbreak and an intentional attack.
In most naturally occurring outbreaks, numbers of cases gradually
increase as a progressively larger number of people come in contact
with other patients, fomites, and vectors that can spread disease.
Eventually, most of the population has been exposed and is immune
to further disease, and the number of cases, or epidemic curve,
gradually decreases. Conversely, a bioterrorism attack is most likely
to be caused by a point source, with everyone coming in contact
with the agent at approximately the same time. The epidemic curve
in this case would be compressed, with a peak in a matter of days
or even hours, even with physiologic and exposure differences. If
the biological agent is contagious, it is possible to see a second
curve peak after the first, as original cases expose originally
unexposed persons to the agent. The steep epidemic curve expected
in a bioterrorism attack is similar to what would be seen with other
point source exposures, such as foodborne outbreaks. Therefore,
the compressed epidemic curve is still not pathognomonic for an
intentional bioterrorism attack.

If a specific group has been exposed, the epidemic curve may
indicate the time of exposure. From this information, a possible
incubation period can be calculated, which can assist in determining
the potential cause of illness, as well as suggesting a possible
intentional attack (if the incubation period is shorter than usual as a
result of an unusually high inoculum or more effective exposure
route). Calculating the incubation period may also help determine if
the disease is spread from person to person, which is extremely
important to effective disease control measures.

Epidemiologic Clues

As steep epidemic curves can be seen in natural point-source
exposures, additional characteristics of the outbreak should be
investigated in determining whether it is the result of a biological
attack (4,5). None of the following clues alone constitute proof of
intentional use of a biological agent, but together they can assist
greatly in determining if further investigation is warranted. 1) The
presence of a large epidemic, with greater case loads than expected,
especially in a discrete population. 2) More severe disease than
expected for a given pathogen, as well as unusual routes of
exposure, such as a preponderance of inhalational disease as was
seen in Sverdlovsk after the accidental release of aerosolized
Bacillus anthracis spores (6). 3) A disease that is unusual for a
given geographic area, is found outside the normal transmission
season, or is impossible to transmit naturally in the absence of the
normal vector for transmission. 4) Multiple simultaneous epidemics
of different diseases. 5) A disease outbreak with zoonotic as well as
human consequences, as many of the potential threat agents are
pathogenic to animals. 6) Unusual strains or variants of organisms
or antimicrobial resistance patterns disparate from those circulating.
7) Higher attack rates in those exposed in certain areas, such as
inside a building if the agent was released indoors, or lower rates in
those inside a sealed building if an aerosol was released outdoors.
8) Intelligence that an adversary has access to a particular agent or
agents. 9) Claims by a terrorist of the release of a biologic agent.
10) Direct evidence of the release of an agent, with findings of
equipment, munitions, or tampering.

Even with the presence of more than one of the above indicators, it
may not be easy to determine that an attack occurred through
nefarious means. For example, it took months to determine that the
outbreak of salmonellosis in Oregon was caused by intentional
contamination of salad bars (3). Other outbreaks, such as the
hantavirus outbreak in the Four Corners area of the United States,
have been thought of as possible results of intentional
contamination (7). Even if no conclusive answer can be derived
quickly, the means employed in determining the cause of an attack
will still provide medical personnel with information that may
prevent illness and death.

Recommendations for Preparedness

Improved awareness and readiness should a bioterrorism attack
occur include education of all medical personnel, especially
primary-care providers and emergency personnel first to see
patients affected by a biological attack. Training should include
basic epidemiologic principles as well as clinical information on
diagnosing and treating agents that pose the highest threat. Training
should be refreshed periodically to ensure that skills remain current.
 
Improved surveillance efforts should be instituted with as close to
real-time data gathering as possible. All facets of surveillance
should be used, to include emergency visits, laboratory data,
pharmacy use, school absenteeism, or any other data that correlate
with an increase in infectious disease. Robust surveillance systems
are essential to detecting any emerging or reemerging disease.
Quick recognition of any change in disease patterns will facilitate
determining the source and preventing further exposure, which
should be the key driving force behind any epidemiologic
investigation. Through strong epidemiologic training, a close
attention to disease patterns, and a healthy respect for the threat of
biological terrorism, potential problems can be discovered rapidly,
and actions can be taken to decrease the impact of disease,
regardless of its origin.

--------------------------------------------------------

    Major Pavlin is chief of the Field Studies Department, Division
of Preventive Medicine, Walter Reed Army Institute of Research.
She has worked in the area of medical biodefense education.
Currently she is developing national and international surveillance
systems for emerging diseases with the Department of Defense's
Global Emerging Infections Surveillance and Response System.

Address for correspondence: Julie A. Pavlin, Department of Field
Studies, Division of Preventive Medicine, Walter Reed Army
Institute of Research, Washington, D.C. 20307-5100, USA; fax:
202-782-0613; e-mail: pavlinj@wrsmtp-ccmail.army.mil.

References

 1. Proliferation: threat and response. Office of the Secretary of
    Defense; November 1997.
 2. Broad WJ, Miller J. The threat of germ weapons is rising. Fear,
    too. New York Times 1998 Dec 27; sec. 4, col. 1, pg. 1.
 3. Torok TJ, Tauxe RV, Wise RP, Livengood JR, Sokolow R,
    Mauvais S, et al. A large community outbreak of salmonellosis
    caused by intentional contamination of restaurant salad bars. JAMA
    1997;278:389-95.
 4. Weiner SL. Strategies of biowarfare defense. Mil Med
    1987;152:25-8.
 5. Noah DL, Sobel AL, Ostroff SM, Kildew JA. Biological
    warfare training: infectious disease
    outbreak differentiation criteria. Mil Med 1998;163:198-201.
 6. Meselson M, Guillemin J, Hugh-Jones M, Langmuir A, Popova
    I, Shelokov A, et al. The Sverdlovsk anthrax outbreak of 1979.
    Science 1994;266:1202-8.
 7. Horgan J. Were Four Corners victims biowar casualties? Sci
    Am 1993;269:16.
_______________________________________________________________________

Special Issue

Vaccines in Civilian Defense Against Bioterrorism

Philip K. Russell
Johns Hopkins School of Public Health, Baltimore, Maryland, USA

In the United States, over the past half century, we have lived under
the protective umbrella of vaccination programs that shield our
population from a dozen serious and sometimes fatal naturally
transmitted illnesses. Vaccination has been the single most
cost-effective public health intervention. However, the value of
vaccines in protecting the population against the deliberate release
of infectious organisms is not so clear-cut.

The U.S. armed forces have recognized the military value of
vaccines against biological threats and have a long-standing
research and development program for a series of vaccines to
protect service members from hostile use of a biological agent.
Vaccination against anthrax is under way in all three armed
services. The Department of Defense has a large program to
develop and license additional vaccines for biological defense. For
the military, vaccination is an effective means of countering a
known threat because the population at risk is easily defined and a
high level of vaccine coverage can be achieved.

In evaluating the role of vaccines for protecting the civilian
population, quite different answers are reached. Despite the
protective efficacy of vaccines against individual organisms, the
very high costs and the great difficulties involved in vaccinating
large populations, along with the broad spectrum of potential
agents, make it impossible to use vaccines to protect the general
population against bioterrorism. Thus, vaccines cannot be
considered a first line of defense against bioterrorism for the general
population, as they can be for the relatively small military
population. However, if suitable vaccines can be made available,
they have several potential uses: control of a smallpox epidemic and
prevention of a global pandemic, postexposure prophylaxis against
anthrax (with antibiotics), and preexposure prophylaxis in
first-responders at high risk, laboratory workers, and health-care
providers.

Smallpox and anthrax, which pose the greatest risk for causing
large numbers of casualties in the event of an effective release by a
terrorist group, are at the top of the list of threat agents. Licensed
vaccines against both anthrax and smallpox that protect against
aerosol transmission are available. An existing licensed plague
vaccine is protective against flea-transmitted disease but not against
aerosol challenge in animal experiments or against pneumonic
plague. This vaccine is in limited supply, and the manufacturer has
recently ceased production.

The Department of Defense Joint Vaccine Acquisition Program has
several experimental vaccines in development (Table). These
vaccines will be further developed and tested with the intent of
obtaining products licensed by the U.S. Food and Drug
Administration.

Table. Vaccines against biological agents
  ------------------------------------------------------
  Licensed vaccines        Vaccines in research
                           and development
  ------------------------------------------------------
  Anthrax                  Vaccinia (cell culture)

  Smallpox (vaccinia)      Botulinum toxoids

  Plague                   Tularemia

                           Q fever

                           VEE EEE WEE

  ------------------------------------------------------
VEE, Venezuelan equine encephalitis; EEE, Eastern equine  
encephalitis; WEE, Western equine encephalitis.

Smallpox

One vaccine in development that is of great importance to civilian
biodefense is the vaccinia virus vaccine made in cell culture. A new
national stockpile of vaccinia vaccine is urgently needed to respond
to the possible threat of a deliberate release of smallpox virus. Even
though such release is unlikely, the consequences of being
unprepared would be a global catastrophe. An unchecked epidemic
in today's unvaccinated, densely packed urban populations linked by
rapid air travel could kill millions. The only possible course of
action would be to mount a global effort to control the spread and
eradicate the disease using vaccinia virus vaccine. The number of
deaths due to secondary and subsequent spread of this highly
contagious virus would be determined by the rapidity of the public
health response, the effectiveness of a vaccination campaign, and,
most importantly, the availability of vaccine.

The national stockpile (fewer than 7 million doses of vaccinia virus
vaccine) is insufficient to meet national and international needs in
this scenario. The stockpile is also deteriorating and has a finite life
span. The vaccine was made using the traditional method of
scarifying and infecting the flanks and bellies of calves and
harvesting the infected lymph. No manufacturer exists today with
the capability to manufacture calf lymph vaccine by the traditional
method. Replacing the stockpile will require the development and
licensure of a new vaccine using modern cell-culture methods. This
development program, which will include process development,
validation of a new manufacturing process, and extensive clinical
testing, will be expensive and may take several years (1).

Obstacles to the development of the vaccine include the lack of
satisfactory stocks of vaccinia immune globulin necessary for
managing complications of vaccination. Clinical testing cannot
proceed without a supply of vaccinia immune globulin. As part of
the development effort, the problems associated with manufacture
of sufficient quantities of vaccinia immune globulin will have to be
addressed and solved. The Department of Defense program is
moving ahead with development of a cell-culture vaccine by using a
cloned strain of vaccinia derived from another strain. Both civilian
and military requirements could be met by a combined and
expanded development effort using either the cloned strain or one
of the licensed vaccinia strains. The development costs will
undoubtedly be high, as for any new biologic product, but the cost
of preparedness is insignificant when weighed against the costs of
an unchecked smallpox epidemic.

Anthrax

Anthrax is the second threat that requires a major research and
development effort to meet civilian needs. A covert attack, which
exposes an urban population to an anthrax spore aerosol, is thought
by some to be the most likely scenario for a bioterrorism attack. If
the release is detected or the first cases are rapidly diagnosed, rapid
action can save many lives. Providing the exposed population with
antibiotics followed by vaccination could be lifesaving for exposed
persons who would otherwise become ill with untreatable inhalation
anthrax in the subsequent few weeks. Prophylactic antibiotics alone
will prevent disease in persons exposed to antibiotic-susceptible
organisms, but incorporating vaccination into the treatment regime
can greatly reduce the length of treatment with antibiotics. Without
vaccination, antibiotics must be continued for 60 days; if effective
vaccination can be provided, this can be reduced to 30 days.
Vaccination of persons affected by an attack will also face the issue
of environmental contamination of urban areas after an attack.
Stockpiling a vaccine capable of inducing protective immunity with
two doses could be extremely valuable in reducing the impact of a
terrorist release of anthrax.

The current anthrax vaccine manufactured by Bioport (formerly the
Michigan Department of Public Health Laboratory) is an
alum-adsorbed, partially purified culture filtrate of Bacillus
anthracis with a high protective antigen content. The schedule for
administration is 0, 2, and 4 weeks and 6, 12, and 18 months. This
vaccine is safe and efficacious and is being used by the armed forces
to protect personnel against the use of anthrax as a weapon.
Immunization of rhesus monkeys followed by a high-dose aerosol
challenge has convincingly demonstrated the capability of this
vaccine to protect against aerosol challenge with B. anthracis
spores. The multiple dose requirement, however, is a drawback for
civilian use.

Studies in progress may find ways to allow modification of the
schedule. Vaccine supply is limited, as is production capacity. As a
result, at least for the immediate future, the armed forces will
require the entire available supply. This vaccine is made by a
method developed before the advent of molecular biology and
requires dedicated facilities because B. anthracis is a spore-forming
organism. In addition to having a multiple-dose requirement, the
vaccine is not highly purified and contains multiple extraneous
proteins. The characteristics of the vaccine and the constraints on
the present method of manufacturing argue strongly against
procuring large amounts for civilian use when the technology and
the science base exist to rapidly develop a second-generation,
improved anthrax vaccine.

Anthrax depends on two toxins (lethal factor and edema factor) for
virulence. A protein called protective factor is an essential
component of both toxins. The protective factor content is the basis
for the effectiveness of the current vaccine. A vaccine based on
purified protective factor made by recombinant technology has been
protective in animals (2). Use of a modern adjuvant with purified
recombinant protective factor should make it possible to have a
very effective two-dose vaccine. A recent report of the Institute of
Medicine Committee on Research and Development to Improve
Civilian Medical Response to Chemical and Biological Terrorism
makes a strong case for a major research and development effort
leading to an improved second-generation vaccine (1).

Questions regarding the ability of existing anthrax vaccines to
protect against anthrax strains engineered to contain additional
virulence genes have been raised in Russia (3). Research is needed
to address this and related questions about the pathogenesis of
anthrax and protective immunity.

The value of vaccinating law-enforcement and emergency response
personnel, who must respond to threats (real or otherwise),
depends on the nature of their work and the immediacy of the
threat. Laboratory personnel who must work with unknown
materials and with high concentrations of known infectious
materials must be vaccinated. These are additional justifications for
moving ahead with a vigorous development program for anthrax
and smallpox vaccines.

--------------------------------------------------------

 Dr. Russell is professor, Center for Immunization Research, Johns
Hopkins School of Public Health; former Commander, United
States Army Medical Research and Development Command.

 Address for correspondence: Philip K. Russell, Johns Hopkins
Center for Civilian Biodefense Studies, Candler Building, Suite
850, 111 Market Place, Baltimore, MD 21202, USA; fax:
410-223-1665; e-mail: biodefen@jhsph.edu.

References

  1. Committee on R&D Needs for Improving Civilian Medical
Response to Chemical and Biological Terrorism Incidents. Institute
of Medicine, National Academy of Sciences. Chemical and
Biological Terrorism. Research and Development to Improve
Civilian Medical Response. Washington: National Academy Press;
1999.
  2. Zajtchtchuk R, Bellamy RF, editors. Textbook of military
medicine: medical aspects of chemical and biological warfare.
Office of the Surgeon General, Department of the Army.
Washington, D.C.; 1997.
  3. Pomeratnsev AP, Startsin NA, Mockov YV, Marnin LI.
Expression of cereolysin AB genes in Bacillus Anthracis vaccine
strain ensures protection against experimental hemolytic anthrax
infection. Vaccine 1997;15:1846-50.
_______________________________________________________________________

Special Issue

Vaccines, Pharmaceutical Products, and Bioterrorism: Challenges
for the U.S. Food and Drug Administration

Kathryn C. Zoon
U.S. Food and Drug Administration, Rockville, Maryland, USA

In regards to bioterrorism, the goal of the U.S. Food and Drug
Administration (FDA) is to foster the development of vaccines,
drugs and diagnostic products, safeguards of the food supply, and
other measures needed to respond to bioterrorist threats. Many
products (vaccines, therapeutic drug and biological products, food,
devices, and diagnostics) regulated by FDA could be affected by
bioterrorism. Pathogens or pathogen products adapted for
biological warfare include smallpox (variola), anthrax (Bacillus
anthracis), plague (Yersinia pestis), tularemia (Francisella
tularensis), brucellosis (Brucella abortus, B. melitensis, B. suis, B.
canis), Q fever (Coxiella burnettii), botulinum toxin (produced by
Clostridium botulinum) and staphylococcal enterotoxin B. New
products are needed to diagnose, prevent, and treat these public
health threats.

FDA is participating in an interagency group preparing for response
in a civilian emergency. This group includes representatives of the
Department of Defense; the Veterans Administration; and
components of the Department of Health and Human Services
(DHHS), such as the Centers for Disease Control and Prevention
(CDC), National Institutes of Health (NIH), and Office of
Emergency Preparedness. In addition, FDA will be proposing
standards for the use of animal efficacy data in approving new
products to counter chemical and biological agents. The agency is
also participating in setting a broad-based federal research agenda
to facilitate the government's preparedness against bioterrorism; is
identifying facilities and activities suitable for the production of
biological weapons; is involved in product development, review,
and testing; and is ensuring that appropriate product surveillance
and sponsor compliance are executed in accordance with
regulations.

FDA's regulation of medical products is based on science, law, and
public health considerations (Figure 1). Research conducted at FDA
(in particular at the Center for Biologics Evaluation and Research)
contributing to biological warfare defense and other
counterbioterrorism efforts is in the following areas: design of new
vaccines (e.g., pox viruses); pathogenesis and mechanism of
replication of biological warfare agents; new methods and standards
to expedite the review of new vaccines and immunoglobulins (e.g.,
mucosal protection against a pathogen); and stem cell protection
and chemokine/cytokine and angiogenic agent defense mechanisms.
The development framework of most biological and traditional drug

[fig]
Figure 1. Regulation of medical products.

[fig]
Figure 2. Development of biological and tradition drug products.

products is shown in Figure 2. The principal evaluation and
research and development phases before a drug is submitted to
FDA for approval can take 1 to 3 years. The clinical research and
development program (investigational phase), depending on the
agent and clinical indication, can take 2 to 10 years. The marketing
application review period generally is 2 months to 3 years (average
1 year). Once a product is approved, long-term postmarketing
surveillance, inspections, and product testing are performed to
ensure the quality, safety, and efficacy of the product, as well as
appropriate product labeling. Accelerating product development is
important in many situations, including bioterrorism. Mechanisms
for advancing medicines through the approval process have been
developed for severe and life-threatening illnesses. For drugs and
biologic products, these mechanisms include expedited review and
fast-track development, as well as accelerated approval and priority
review of marketing applications. For a priority product, complete
review of marketing applications is 6 months.

Many of the biological warfare defense products pose difficult
problems with regard to obtaining clinical efficacy data. For many
of these infectious agents or toxins, human efficacy trials cannot be
performed, as such studies would involve exposing healthy human
volunteers to a lethal or permanently disabling agent without
proven therapy and field trials. In most cases, such trials are not
feasible because pockets of natural exposure do not exist. To
address this dilemma, FDA will be proposing that the use of animal
efficacy data be allowed when appropriate (1). This proposed rule
would identify the types of data required. Safety, pharmacokinetic,
and immunogenicity data will still be necessary in humans. Product
safety will likely be evaluated in healthy human volunteers at doses
and routes of administration anticipated in field use.

Some scientific considerations for animal studies include the toxic
agent's pathophysiologic mechanism of toxicity and how the test
drug or biologic product prevents it and the validity of the animal
study endpoint in humans. In addition, data showing that drug
effectiveness in animals predicts efficacy in humans would be
needed. Finally, product recipients should be given follow-up after
treatment to affirm product safety and efficacy.

For licensure or other approval, a biological warfare defense
product must have an acceptable quality, safety, efficacy, and
potency profile. Likewise, the product must have acceptable
stability characteristics and be produced in compliance with current
good manufacturing practices.

A case study of anthrax vaccine can serve as an example of our
capability to respond to a bioterrorist threat. Only one licensed
anthrax vaccine (Bioport Corp.) is available. This vaccine consists
of a membrane-sterilized culture filtrate of B. anthracis
V770-NP1-R, an avirulent, nonencapsulated strain. The culture
filtrate is adsorbed to aluminum hydroxide and formulated with
benzethonium chloride (preservative) and formaldehyde (stabilizer).
The administration schedule consists of 0.5 ml injected
subcutaneously at 0, 2, and 4 weeks, 6, 12, and 18 months, and
then annually thereafter. The vaccine was licensed in 1970. The
efficacy data in support of the license consisted of a single-blind,
well-controlled field study (2). The vaccine efficacy was 92.5%
(lower 95% confidence limit of 65%). Of the 26 cases of anthrax in
this study, 21 were cutaneous and 5 (4 fatal) were inhalation (2 in
the placebo group, 0 in the vaccinated group, 3 in the unvaccinated
group).

In December 1985, the Federal Register (3) published the FDA's
advisory panel review of the efficacy of anthrax adsorbed. The
panel recommended that this product be placed in category I (safe,
effective, and not misbranded) and that the appropriate license be
continued because there was substantial evidence for this product.

Studies of new anthrax vaccine products are in progress. They
include protective antigenbased vaccines, e.g., purified protein
from B. anthracis culture or live-attenuated spore vaccine.
Production and product testing will differ for each of these
candidate vaccines. The immunogenicity of the product in humans
and animal models should be assessed. The cell-mediated immunity
elicited by the vaccine may also need to be evaluated. One of the
immune correlates of protection of anthrax vaccines is likely to be
the antibody response to protective antigen. However, the
quantitative relation of antiprotective antigen antibody to protection
has not been established in humans but is being investigated by the
Department of Defense. Animal challenge and protection models,
especially rabbit and nonhuman primate models, may be particularly
useful. Passive transfer of protection, also an indication of the
importance of antibodies for protection, has been observed in
animal models. Therefore, human challenge protection studies and
new field efficacy trials are not feasible in studying the efficacy of
new anthrax vaccines. Animal challenge and protection studies
against spores will be important for new vaccines based on
protective antigen. Comparisons of immune responses in human
cohorts receiving new or licensed vaccines should be performed.

Data should be obtained on various target populations, including
adults and children, to evaluate the safety of new anthrax vaccines.
Systemic and local adverse events are particularly important to
monitor. For live-attenuated and vector vaccine approaches, the
potential for transmission to others will be an important
consideration in clinical development and use. After these vaccines
are licensed and administered, the safety and adverse reactions of
these vaccines should be assessed.

In conclusion, FDA will be providing a critical link in access of new
medicines for biowarfare defense (Table). The expected outcomes
of these activities include safe and effective products to treat or
prevent toxicity of biological and chemical agents; methods to
rapidly detect, identify, and decontaminate hazardous organisms; a
greater ability to ensure the safety of the food supply; and a greater
ability to provide appropriate medical care and a public health
response.

Table. Proposed activities of the U.S. Food and Drug
Administration to counter bioterrorism

  -------------------------------------------------------
  1. Enhancing the expeditious development and licensure 
of new vaccines and biological therapeutics through research
and review activitiesanthrax vaccine and antisera to
botulinum toxin, for example.

  2. Enhancing the timeliness of application reviews of
new drugs and biological products and new uses of 
existing products.

  3. Participating in the planning and coordination of
public health and medical response to a terrorist
attack involving a biological or chemical agent(s).

  4. Participating in the development of rapid detection
and decontamination for agents of bioterrorism
such as Clostridium botulinum toxins, Yersinisa
pestis, Bacillus anthracis.

  5. Ensuring the safety of regulated foods, drugs,
medical devices, and biological products; arrange
for seizure and disposal of affected products.

  6. Developing techniques for detection of genetic
modifications of microorganisms to make them
more toxic or antibiotic-or vaccine-resistant.

  7. Rapidly determining a microbe's sensitivity to drug
therapy.

  8. Determining the mechanism of replication and
pathogenicity or virulence of identified organisms
including elements that can be transferred to other
organisms to circumvent detection, prevention, or
treatment 

  9. Enhancing adverse product reporting surveillance
capabilities.

--------------------------------------------------------

      Kathryn Zoon is Director of the Center for Biologics
Evaluation and Research (CBER) at the Food and Drug
Administration. As former Director of the Division of Cytokine
Biology in CBER, Dr. Zoon was actively involved with regulatory
issues related to cytokines, growth factors, studies on interferon
purification and characterization, and interferon receptors.

      Address for correspondence: Kathryn C. Zoon, Center for
Biologics Evaluation and Research, Food and Drug Administration,
Mailstop HFM-1, 1401 Rockville Pike, Rockville, MD 20852,
USA; fax: 301-827-0440; e-mail: zoon@cber.fda.gov.

References

  1. Federal Register Vol 63 #80, Monday, April 27, 1998, p. 1957.
  2. Brachman PS, Gold H, Plotkin SA, Fekety FR, Werrin M,
Ingraham NR. Field evaluation of a human anthrax vaccine. Am J
Public Health 1962;52:632-45.
  3. Federal Register. Vol 50 #240, Friday, Dec. 13, 1985, p. 
51002-17.
_______________________________________________________________________

Special Issue

Smallpox: Clinical and Epidemiologic Features

D. A. Henderson
Johns Hopkins Center for Civilian Biodefense Studies, Baltimore,
Maryland, USA

Clinical and Epidemiologic Characteristics of Smallpox

Smallpox is a viral disease unique to humans. To sustain itself, the
virus must pass from person to person in a continuing chain of
infection and is spread by inhalation of air droplets or aerosols.
Twelve to 14 days after infection, the patient typically becomes
febrile and has severe aching pains and prostration. Some 2 to 3
days later, a papular rash develops over the face and spreads to the
extremities (Figure 1). The rash soon becomes vesicular and later,
pustular (Figure 2). The patient remains febrile throughout the
evolution of the rash and customarily experiences considerable pain
as the pustules grow and expand. Gradually, scabs form, which
eventually separate, leaving pitted scars. Death usually occurs
during the second week.

     [Fig]

Figure 1. Most  cases of  smallpox are  clinically  typical and  
readily able to  be diagnosed.  Lesions on each  area of the body 
are at the same  stage of  development, are deeply embedded  
in the skin, and  are more densely  concentrated on  the face 
and  extremities.

    [Fig]

Figure 2. The  lesions of chickenpox  develop as a  series of  
"crops" over  several days and are very  superficial.  Papules, 
 vesicles,  pustules, and  scabs can be seen adjacent to each 
other. The  trunk is usually  more affected than the face or  
extremities.

The disease most commonly confused with smallpox is chickenpox,
and during the first 2 to 3 days of rash, it may be all but impossible
to distinguish between the two. However, all smallpox lesions
develop at the same pace and, on any part of the body, appear
identical. Chickenpox lesions are much more superficial and
develop in crops. With chickenpox, scabs, vesicles, and pustules
may be seen simultaneously on adjacent areas of skin. Moreover,
the rash in chickenpox is more dense over the trunk (the reverse of
smallpox), and chickenpox lesions are almost never found on the
palms or soles.

In 5% to 10% of smallpox patients, more rapidly progressive,
malignant disease develops, which is almost always fatal within 5 to
7 days. In such patients, the lesions are so densely confluent that
the skin looks like crepe rubber; some patients exhibit bleeding into
the skin and intestinal tract. Such cases are difficult to diagnose, but
they are exceedingly infectious.

Smallpox spreads most readily during the cool, dry winter months
but can be transmitted in any climate and in any part of the world.
The only weapons against the disease are vaccination and patient
isolation. Vaccination before exposure or within 2 to 3 days after
exposure affords almost complete protection against disease.
Vaccination as late as 4 to 5 days after exposure may protect
against death. Because smallpox can only be transmitted from the
time of the earliest appearance of rash, early detection of cases and
prompt vaccination of all contacts is critical.

Smallpox Vaccination

Smallpox vaccination is associated with some risk for adverse
reactions; the two most serious are postvaccinal encephalitis and
progressive vaccinia. Postvaccinal encephalitis occurs at a rate of 3
per million primary vaccinees; 40% of the cases are fatal, and some
patients are left with permanent neurologic damage. Progressive
vaccinia occurs among those who are immunosuppressed because
of a congenital defect, malignancy, radiation therapy, or AIDS. The
vaccinia virus simply continues to grow, and unless these patients
are treated with vaccinia immune globulin, they may not recover.
Pustular material from the vaccination site may also be transferred
to other parts of the body, sometimes with serious results.

Routine vaccination is only recommended for laboratory staff who
may be exposed to one of the orthopoxviruses. There are two
reasons for this. First is the risk for complications. Second, U.S.
national vaccine stocks are sufficient to immunize only 6 to 7
million persons. This amount is only marginally sufficient for
emergency needs. Plans are now being made to expand this reserve.
However, at least 36 months are required before large quantities
can be produced.

The potential of smallpox as a biological weapon is most
dramatically illustrated by two European smallpox outbreaks in the
1970s. The first occurred in Meschede, Germany, in 1970 (1). This
outbreak illustrates that smallpox virus in an aerosol suspension can
spread widely and infect at very low doses.

Another outbreak occurred in Yugoslavia in February 1972 (1).
Despite routine vaccination in Yugoslavia, the first case in the 1972
outbreak resulted in 11 others; those 11, on average, each infected
13 more. Other outbreaks in Europe from 1958 on showed that
such explosive spread was not unusual during the seasonal period
of high transmission, i.e., December through April. One can only
speculate on the probable rapidity of spread of the smallpox virus in
a population where no one younger than 25 years of age has ever
been vaccinated and older persons have little remaining residual
immunity.

Where might the virus come from? At one time, it was believed that
the smallpox virus was restricted to only two high-security
laboratories, one at the Centers for Disease Control and Prevention
in Atlanta, Georgia, and one at the Russian State Centre for
Research on Virology and Biotechnology, Koltsovo, Novosibirsk
Region. By resolution of the 1996 World Health Assembly (WHA),
those stocks were slated to be destroyed at the end of June 1999.
The desirability of such an action was reaffirmed by a World Health
Organization Expert Committee in January 1999. On May 22,
1999, WHA, however, passed a resolution postponing destruction
until 2002, by which time any promise of the variola virus stocks
for public health research could be determined. Destruction of the
virus would be at least one step to limit the risk for the reemergence
of smallpox. However, despite widespread acceptance of the 1972
Bioweapons Convention Treaty, which called for all countries to
destroy their stocks of bioweapons and to cease all research on
offensive weapons, other laboratories in Russia and perhaps in
other countries maintain the virus. Iraq and the Soviet Union were
signatories to the convention, as was the United States. However,
as reported by the former deputy director of the Russian
Bioweapons Program, officials of the former Soviet Union took
notice of the world's decision in 1980 to cease smallpox
vaccination, and in the atmosphere of the cold war, they embarked
on an ambitious plan to produce smallpox virus in large quantities
and use it as a weapon. At least two other laboratories in the former
Soviet Union are now reported to maintain smallpox virus, and one
may have the capacity to produce the virus in tons at least monthly.
Moreover, Russian biologists, like physicists and chemists, may
have left Russia to sell their services to rogue governments.

Smallpox is rated among the most dangerous of all potential
biological weapons, with far-reaching ramifications.

--------------------------------------------------------

      Dr. Henderson is a distinguished service professor at the Johns
Hopkins University, holding an appointment in the Department of
Epidemiology. Dr. Henderson directed the World Health
Organization's global smallpox eradication campaign (1966-1977)
and helped initiate WHO's global program of immunization in 1974.
He also served as deputy assistant secretary and senior science
advisor in the Department of Health and Human Services.

      Address for correspondence: D. A. Henderson, Johns Hopkins
Center for Civilian Biodefense Studies, 111 Market Place, Ste. 850,
Baltimore, MD 21202, USA; fax: 410-223-1665; e-mail:
dahzero@aol.com.

Reference

1. Henderson DA. Bioterrorism as a public health threat. Emerg
Infect Dis 1998;4:488-92.
_______________________________________________________________________

Special Issue

Smallpox: An Attack Scenario

Tara O'Toole
Johns Hopkins School of Public Health, Baltimore, Maryland, USA

Smallpox virus, which is among the most dangerous organisms that
might be used by bioterrorists, is not widely available. The
international black market trade in weapons of mass destruction is
probably the only means of acquiring the virus. Thus, only a
terrorist supported by the resources of a rogue state would be able
to procure and deploy smallpox. An attack using the virus would
involve relatively sophisticated strategies and would deliberately
seek to sow public panic, disrupt and discredit official institutions,
and shake public confidence in government.

The following scenario is intended to provoke thought and dialogue
that might illuminate the uncertainties and challenges of
bioterrorism and stimulate review of institutional capacities for
rapid communication and coordinated action in the wake of an
attack.

Capacity To Detect a Bioterrorist Attack and To Diagnose an
Unusual Disease

April 1

The vice-president visits Northeast, a city of 2.5 million. His
itinerary includes an awards ceremony, an appearance at a local
magnet school, and a major speech at the local university. A crowd
of 1,000 people, including students, is gathered in the university
auditorium. Hundreds more wait outside, where the vice-president
stops to shake hands and respond to queries from the media.

The Federal Bureau of Investigation (FBI) has information
suggesting a possible threat against the vice-president from a
terrorist group with suspected links to a rogue state. The group is
known to have made inquiries about acquiring biological pathogens,
including smallpox, and is suspected of having procured
aerosolization equipment. FBI decides its information is too vague
and too sensitive to pass on to the
Department of Health and Human Services, local law enforcement
authorities, or the state health department.

April 8

FBI informants report rumors that something happened while the
vice-president was in Northeast.

April 12

A 20-year-old university student goes to the university hospital
emergency room with fever and severe muscle aches. She is pale,
has a temperature of 103F, and is slightly leukopenic, but the
physical exam and laboratory results are otherwise normal. She is
presumed to have a viral infection and is sent home with
instructions to drink fluids and take aspirin or ibuprofen for muscle
aches. Later that day, a 40-year-old electrician arrives at the
emergency room with severe lower backache, headache, shaking
chills, and vomiting. He appears pale and has a temperature of
102F and a pale erythematous rash on the face. The patient is a
native of Puerto Rico, where he visited 10 days earlier. A diagnosis
of dengue fever is considered, and the patient is discharged with
ibuprofen and instructions to drink fluids.

April 13

Over the course of the day, four young adults in their twenties
come to the university hospital emergency room with influenzalike
symptoms and are sent home.

April 14

The female student returns to the emergency room after collapsing
in class. She now has a red, vesicular rash on the face and arms and
appears acutely ill. Her temperature is 102F; her blood pressure is
normal. She is admitted to an isolation room with presumptive
diagnosis of adult chickenpox. She has had no contact with others
known to have chickenpox.

April 15

The electrician first seen on April 12 returns to the emergency room
by ambulance. He too has a vesicular rash and appears very ill. He
is also admitted to an isolation room with presumptive diagnosis of
chickenpox.

That evening at 6 p.m. the infectious disease consultant and the
hospital epidemiologist meet on the elevator. The infectious disease
specialist has just finished examining the student and the electrician,
both of whom have vesicular rash on the face, arms, hands, and
feet. The skin lesions are evolving in phase. The possibility of
smallpox is raised. The infectious disease specialist takes a swab
specimen from the electrician's skin lesions, sends it to the
laboratory, and requests that it be examined by electron microscopy
by an experienced technician. The doctor assures the technician that
he will be vaccinated if the specimen shows smallpox. At 7:00 p.m.,
electron microscopy shows an orthopoxvirus consistent with
variolathe smallpox virus.

At 7:15 p.m. the hospital epidemiologist declares a contagious
disease emergency. The two patients are moved to
negative-pressure rooms with HEPA filters. Visitors and hospital
staff not already caring for and in contact with patients are
forbidden to enter the floor. Infection-control nurses begin
interviewing staff to determine who has been in face-to-face contact
with the patients during initial emergency room visits and
admission. The hospital epidemiologist calls the chair of the
department of medicine and the hospital vice-president for medical
affairs.

Within 45 minutes the chair of the department of medicine and the
president of the hospital are meeting with the infectious disease
physician, the hospital epidemiologist, the hospital vice-president
for public relations, and the hospital's general counsel. The city and
state health commissioners join the meeting by phone. The need to
vaccinate and isolate all contacts of the patients is recognized and
discussed. It is decided to secure the hospital. No one is allowed to
leave until all persons are identified so that they can be vaccinated
as soon as vaccine can be obtained from the Centers for Disease
Control and Prevention (CDC). The possibility of identifying and
vaccinating other patient contacts (e.g., family members not now in
the hospital) is discussed, but no decisions are made because the
hospital's legal authority for doing this is unclear.

Half an hour later, the state health commissioner calls FBI. He also
contacts CDC to request that smallpox vaccine be released for
hospital staff and patient contacts. Because vaccine supplies are
limited, CDC requests that the diagnosis of smallpox first be
confirmed at CDC. CDC calls FBI and arranges to fly a
three-person Epidemic Intelligence Service team to Northeast for
assistance.

By 9:30 p.m., an FBI special agent arrives at the hospital, secures
biological samples taken from the patients, and drives them to
Andrews Air Force Base, where a military aircraft flies the samples
to CDC's Biosafety Level 4 laboratory in Atlanta, Georgia. FBI
requests that city police be called to help maintain order and ensure
that no patients, staff, or visitors leave the hospital until all
occupants have been identified and their addresses have been
recorded. More FBI agents and city police arrive on the hospital
grounds.

Hospital visitors are confused and angered by police refusal to
allow anyone to leave the hospital. No explanation is given for the
containment to staff, visitors, or the police. Ambulances are
rerouted to other hospitals. The rumor that smallpox has broken
out rapidly spreads through the building, as do rumors that a
terrorist wanted by FBI is in the building. A fight erupts between
people trying to leave the facility and the police. Three people are
injured and sent to the emergency room. More police and FBI
agents arrive and surround the building.

The local television networks report the scene outside the hospital
on the late night news. The hospital public relations representative
explains that the lock-in is temporary and intended only to gather
names and addresses so that people can be contacted and treated if
a suspected, but unnamed, contagious disease is confirmed. CNN
arrives and demands access to the hospital and affected patients.
Rumors about what the contagious disease might be include Hong
Kong flu, meningitis, Ebola virus, smallpox, and measles.

The mayor and state attorney general's office are contacted by the
health commissioner. There is a phone discussion with the hospital's
general counsel and epidemiologist about the right to impose
quarantine. Visitors, nonessential personnel, and new patients are
blocked from entering the hospital, but visitors already in the
building are allowed to leave after their names and addresses are
recorded.

FBI, however, is reluctant to allow anyone to leave the building.
This provokes a lengthy exchange among the FBI agent-in-charge,
the city police chief, and hospital administrators and attorneys. The
dispute is resolved after a series of phone calls between FBI
headquarters and the state attorney general's office.

Early Response

11:30 p.m.

The specimen arrives at CDC. At midnight, the diagnosis of
smallpox is confirmed. A phone conference with hospital staff, the
city police chief, the state health commissioner, the state attorney
general, the governor, CDC, FBI, an assistant secretary of the
Health and Human Service (HHS), and staff from the National
Security Council and the White House (32 people in all) focuses on
whether and how to release the information to the media. The
mayor and the governor will go on television in the morning with
the health commissioner. The FBI director will also make a
statement. The president will address the country at noon.

CDC makes arrangements to release smallpox vaccine early the
next morning for use by patient contacts and the health-care teams
caring for hospitalized victims.

April 16

Morning conference calls between CDC, FBI, HHS, the National
Security Council, and state health authorities are set up. Federal
officials now assume that a bioterrorist attack has occurred in
Northeast. There is concern that other attacks might also have
taken place but not yet come to light or that further attacks might
be imminent.

A representative from the counterterrorism office of the National
Security Council asks if it is necessary or desirable to attempt a
complete quarantine of Northeast, including closure of the city
airport and a ban on rail traffic leaving from or stopping in the city.
The group agrees that such a step is neither feasible nor warranted.
A heated debate follows about the advisability of vaccinating all
hospital staff and visitors at all facilities where a single case of
smallpox is clinically suspected. The state health commissioner
presses for enough vaccine for the entire city of Northeast.

FBI and CDC are reluctant to begin mass vaccination until the
dimensions of the outbreak are better understood. It is decided to
vaccinate all hospital staff and any visitors to the floor where the
patients were located. All direct contacts of the patients will also be
vaccinated. By the end of the long phone conference, the decision is
made to vaccinate all health-care personnel, first responders, police,
and firefighters in any city with confirmed cases of smallpox.

CDC Epidemic Intelligence Service officers arrive in Northeast to
assist the state epidemiologist, who is establishing a statewide
surveillance and case investigation system. Efforts begin to develop
a registry of all face-to-face contacts of smallpox patients and to
monitor, daily, all contacts for fever. Anyone who has fever >101F
is to be isolated, at home if possible, and be followed for rash.

The state health department activates a prearranged phone tree to
query all hospitals and walk-in clinics in the state about similar
cases and counsels immediate isolation of all suspected patients.

An additional eight admissions for fever and vesicular rash are
discovered. All patients are extremely ill; two are delirious. The
university hospital emergency room records are searched, and staff
attempt to contact all patients who had fever during the previous
week. Three more probable smallpox cases are discovered.
Telephone follow-up reveals that one has been admitted to another
hospital out of state.

CDC and state health officials discuss possible strategies for
managing the epidemic if there is insufficient vaccine for all patient
contacts, as seems likely. Home isolation of nonvaccinated patient
contacts is considered, but the legal authorities, practical logistics,
and ethical implications of such a strategy remain unclear and
unresolved.

After discussion among state health authorities and university
hospital staff, it is decided that the university will serve as the city's
smallpox hospital and will accept transfers of smallpox patients now
hospitalized at other facilities in the state. Other hospitals will refer
patients to the university hospital or to the state armory but will not
admit patients with suspected smallpox. Physicians will be urged to
avoid seeking admission for most smallpox patients and to care for
patients in their homes.

Arrangements are made by the state health commissioner to
activate a state disaster plan, which establishes the armory as an
emergency hospital for the quarantine of smallpox patients, in case
the number of smallpox patients exceeds hospital isolation
capabilities. 

Quarantine and Vaccination

During the morning interagency phone conference, Department of
Justice representatives raise questions about potential legal
liabilities associated with adverse vaccine effects. The questions
remain unresolved, but vaccination will proceed.

On the evening of April 16, the president goes on television to
inform the nation of the bioterrorist attack by unknown terrorists,
vows that the assailants will be identified and brought to justice,
and urges calm and cooperation with health authorities.

The initial epidemiologic evidence and FBI information suggest that
the smallpox release likely occurred during the vice-president's
January speech at the university in Northeast. Efforts are begun to
identify and vaccinate everyone who attended the speech.
Additional health department personnel are detailed to help in the
epidemiologic investigation. Media reports say that the government
does not know how many people are sick or how widespread the
outbreak might be.

By evening, 35 more cases are identified in eight emergency rooms
and clinics around the city; 10 cases are reported in an adjoining
state. CDC alerts all state health departments to be on alert for
possible smallpox; CDC also urges prompt and strict isolation
measures and instructs states to send specimens from suspected
patients to its headquarters in Atlanta for definitive laboratory
diagnosis.

April 17

In Northeast, 10,000 residents are vaccinated by the city and state
health departments with assistance from volunteer physicians and
nurses. Vaccination of the entire university student body, faculty,
and staff is discussed and rejected by federal officials for fear that
vaccine supplies will be needed for contacts of confirmed cases.
State health officials continue to press for a statewide vaccination
effort. Unions representing nurses and other health-care workers
call for vaccination of all employees whose jobs involve direct
patient contact.

April 18

An additional 20,000 residents of Northeast are vaccinated.

April 19

CDC and the U.S. Army Medical Research Institute of Infectious
Diseases (USAMRIID) determine that the infecting strain of
smallpox was not bioengineered. The genomic sequence is entirely
typical of known smallpox strains.

The student with the first diagnosed case dies. Ten more smallpox
cases have been identified, bringing the number of confirmed cases
to 50. The patients are located in four states, all in the mid-Atlantic
area. Suspected cases are identified in five other states.

April 20

Governors of affected and unaffected states press, both behind the
scenes and publicly, for emergency vaccine stocks to be distributed
to states so that immediate action can be taken should an outbreak
occur.
 
At the close of day 4 of the vaccination campaign, 80,000 have
been vaccinated.

April 22-27

No new cases of smallpox with onset after April 19 have been
confirmed, although many suspected cases with fever and rash due
to other causes are being seen. In the states reporting confirmed
smallpox cases, thousands of people are seeking medical care
because of worrisome symptoms. CDC and state health authorities
decide to issue a recommendation that patients with fever who
cannot be definitively diagnosed be strictly quarantined and
observed until the fever subsides. CDC and state health
departments are flooded with calls from health-care providers
seeking guidance on isolation procedures.

Some hospitals and health maintenance organizations (HMOs)
complain to HHS that they cannot afford to isolate the many
patients with fever and rash at their facilities and demand that the
government pay quarantine costs. State health departments are
similarly worried about the costs of quarantine.

Local media report an outbreak of sick children with rash in an area
elementary school. It is unclear whether the illness is chickenpox or
smallpox. Television stations show film of parents arriving at school
in midday to remove children from classrooms. A college basketball
star is rushed to hospital by ambulance with an unknown illness.
Local television reports that the athlete has high fever but no rash.
Both stories are covered on the national evening news.

April 28

Smallpox is diagnosed in two young children in Megalopolis, a
large city in another state. FBI and the National Security Council
worry that these cases might signal another attack since the children
have had no discernible contact with a smallpox patient or contacts.
The possibility that there has been a new attack is weighed against
the possibility that the children were infected by a contact of one of
the first wave of patients who was missed in the epidemiologic
investigation.

Members of the state congressional delegation demand that the
federal government implement a massive citywide vaccination
program. CDC notes that a Megalopolis-wide vaccination program
would deplete the entire civilian vaccine supply.

The media report that the president, vice-president, cabinet
representatives, and prominent members of Congress have been
vaccinated, and the military has already begun to vaccinate the
troops in affected states and Washington, D.C.

The Epidemic Expands

April 29

Over the course of the day, CDC receives reports of an additional
100 new cases of potential smallpox. Sixty of these are in the
original state. The others are scattered over eight states. It is not
immediately clear if these are truly smallpox or mistaken diagnoses.
By evening, laboratory confirmation of smallpox is obtained at
CDC. Two cases in Montreal and one in London are also reported.
CDC and health agencies now recognize that they are seeing a
second generation of smallpox cases. It is presumed that the latest
victims were infected by contact with those who attended the
vice-president's speech, but a second bioterrorism attack cannot be
immediately ruled out. CDC enlists additional epidemiologists from
around the country to join teams tracking patients and their
contacts.

Another 200 probable cases are reported during the day. CDC
receives thousands of requests for vaccine from individual
physicians and announces that vaccine will be distributed only
through state health departments. Governors of a dozen states are
calling the White House, demanding vaccine. One state attorney
general announces a suit against the federal government to force
release of vaccine for a large-scale vaccination campaign.

The federal government announces that 90% of available vaccine
stocks will be distributed to affected states, but cautions that the
available quantity of vaccine can cover only 15% of those states'
populations. Governors are to determine their own state-specific
priorities and mechanisms of vaccine distribution. Federal officials
also announce an accelerated crash vaccine-production program
that will reduce vaccine-manufacturing time to 24 months.

April 30

A well-known college athlete dies of hemorrhagic smallpox. The
rumor is reported that he was the victim of a new biological attack
using a different organism since he did not develop the rash
associated with classic smallpox. Television commentators
misinterpret technical statements from a health-care expert; the
commentators report that the athlete died of hemorrhagic fever, and
they read clinical descriptions of Ebola virus infection on the air.

The White House and CDC receive dozens of calls from furious
governors, mayors, and health commissioners, demanding to know
why they were not informed of additional bioterrorist attacks using
Ebola. Nurses, doctors, and hospital-support personnel in health
centers walk off the job. Thousands of people who attended college
basketball games where the deceased athlete played call the health
department and ask for treatment.

HHS issues a press release explaining that the athlete did not have
Ebola virus. FBI affirms that there is no reason to believe that an
attack using any hemorrhagic fever virus has occurred, but FBI
refuses to rule out the possibility that there has been more than a
single bioterrorist attack using smallpox.

April 31

The widely publicized death of the college basketball star, plus
dramatic footage of young children covered with pox, drive
thousands of people to emergency rooms and doctors' offices with
requests for vaccination and evaluation of fever and other
symptoms. This escalation in requests for evaluation and care
hampers the ability of state health authorities and CDC to confirm
the number of actual new cases.

May 1

The number of smallpox cases continues to grow. There are now
>700 reported cases worldwide. In Northeast, the capacity of local
hospitals to accommodate patients needing isolation has long been
exceeded. Smallpox cases and suspected contacts are being isolated
in the local armory and convention center, where volunteer
physicians and nurses are providing care.

May 5

Epidemiologists are working around the clock to interview patients,
trace the chain of infection, place contacts under surveillance, and
isolate smallpox victims. The evidence continues to indicate that the
vice-president's visit to Northeast was the occasion for the release,
but some authorities remain concerned about multiple releases.

May 15-29

The third generation of the epidemic begins. Cases are reported in
Northeast, parts of the country far beyond Northeast, and
worldwide. The death rate remains 30%. Vaccine supplies are
exhausted. Public concern is mounting rapidly. The president has
declared states with the largest numbers of victims and people in
quarantine to be disaster areas. Congress votes to release federal
funds to pay for costs of quarantine. Over the next 2 weeks, 7,000
cases will have been reported.

May 30

The fourth generation of cases begins. By mid-June, 15,000 cases
of smallpox will be reported in the United States. Twenty states
report cases, as do four foreign countries. More than 2,000 will
have died. The deceased include two members of the
vice-president's staff and a secret service agent.

The city of Northeast, which is hardest hit by the epidemic, has
experienced several outbreaks of civil unrest. The National Guard
has been called in to help police keep order and to guard the
facilities where smallpox cases and contacts are isolated. The mayor
of Northeast is hospitalized with a heart attack.

Conclusions

The rate of development of new smallpox cases reported worldwide
now appears to be stabilizing and perhaps subsiding. Vaccination of
contacts has undoubtedly been of benefit. Perhaps more important
is the seasonal decrease in the spread of virus as warmer weather
returns.

Many business conventions scheduled to convene in Northeast
during the early summer are canceled. Tourist trade, a major source
of state income, is at a standstill. Many small businesses in the city
have failed because suppliers and customers are reluctant to visit
the area. Attendance at theaters and sports events is down
markedly. In several states, public schools are dismissed 1 month
early, in part because parents, fearful of contagion, are keeping
their children home, and partly because teachers are refusing to
come to work. Across the country, people refuse to serve on juries
or attend public meetings for fear of contracting smallpox. In
hospitals and HMOs where staff have not been vaccinated,
health-care personnel have staged protests, and some have walked
off the job.

The exponential increase in cases around the globe has caused some
governments to institute strict, harshly enforced isolation and
quarantine procedures. Human rights organizations report
numerous cases of smallpox patients being abandoned to die or of
recovering patients being denied housing and food.

Domestic and international travel is greatly reduced. Travelers
avoid countries known to have smallpox. Some countries refuse to
admit U.S. citizens without proof of recent smallpox vaccination.
Others have imposed 14-day quarantines on all persons entering the
country from abroad. A lucrative black market in falsified
vaccination certificates has sprung up.

Congress has begun oversight investigations into the epidemic. A
congressman accuses the U.S. Food and Drug Administration of
deliberately obstructing the development of smallpox vaccine and
vows to hold hearings into the matter. Congressional investigations
of what FBI knew, when they knew it, and whom they talked with,
are ongoing. Multiple lawsuits have been filed on behalf of and
against HMOs, hospitals, and state and federal governments.
Several large HMOs refuse to pay states for costs associated with
caring for patients in isolation wards and quarantine facilities. The
states with largest numbers of cases have spent millions of dollars
on the epidemic, including establishing quarantine operations,
paying for added public health personnel, and overtime pay for
police.

In the United States, periodic rumors of miracle treatments, many
fueled by the media, provoke ardent demands on a beleaguered
health-care system. Since vaccine supplies were depleted, many
people seeking protection have turned to ancient techniques. Some
physicians are practicing arm-to-arm transfer of vaccinia, with a few
attempting immunization with inoculation of smallpox virus from
pustules.

Smallpox continues to spread in many parts of the world, echoing
its formerly endemic character. Without vaccine, the only control
method is isolation, which hinders, but cannot halt, the spread of
the disease. By year's end, endemic smallpox is reestablished in 14
countries. The World Health Assembly schedules a debate on
reenacting a global smallpox eradication campaign.

--------------------------------------------------------

      Dr. O'Toole is a senior fellow at the Johns Hopkins University
Center for Civilian Biodefense Studies. The Center, sponsored by
the Hopkins Schools of Public Health and Medicine, is dedicated to
informing policy decisions and promoting practices that would help
prevent the use of biological weapons.

      Address for correspondence: Tara O'Toole, Johns Hopkins
Center for Civilian Biodefense Studies, Candler Building, Suite
850, 111 Market Place, Baltimore, MD 21202, USA; fax:
410-223-1665; e-mail: biodefen@jhsph.edu.
_______________________________________________________________________

Special Issue

Aftermath of a Hypothetical Smallpox Disaster

Jason Bardi
Johns Hopkins University, Baltimore, Maryland, USA

The second day of the symposium featured a discussion of a
scenario in which a medium-sized American city is attacked with
smallpox. Four panels represented various time milestones after the
attack, from a few weeks to several months. Panelists discussed
what they and their colleagues might be doing at each of these
milestones. The goal of the responses was to communicate the
complexity of the issues and to explore the diverse problems that
might arise beyond the care and treatment of patients.

The scenario itself was a step-by-step account of a smallpox
epidemic in the fictional city of Northeast. Tara O'Toole, the
scenario's lead author, read the narrative account before each panel.

The panelists responded to the events as if the epidemic were real
and they were actually trying to identify, contain, communicate, and
otherwise deal with it. Panel members included experts on hospital,
city, state, federal, and media responses. Representing the hospitals
were John Bartlett and Trish Perl, Johns Hopkins Hospital; Julie
Gerberding, Hospital Infections Program, Centers for Disease
Control and Prevention; and Gregory Moran, Emergency Medicine,
University of California at Los Angeles. Jerome Hauer represented
New York City's response. Representing the state were Michael
Ascher, California Department of Health Services Laboratory; Arne
Carlson, former governor of Minnesota; Terry O'Brien, a
Minnesota State Assistant Attorney General; and Michael
Osterholm, Minnesota Department of Public Health. The federal
representatives on the panels were Robert Blitzer, former
counterterrorism chief with the Federal Bureau of Investigation;
Robert DeMartino, Substance Abuse and Mental Health Services
Administration; Robert Knouss, Office of Emergency Preparedness,
Department of Health and Human Services; and Scott Lillibridge,
Centers for Disease Control and Prevention. Joanne Rodgers, Johns
Hopkins Medical Institutions Public Affairs, spoke to the response
of the media. George Strait, the medical news director for ABC
News, acted as moderator for each of the panels scheduled on day
two. D.A. Henderson also helped to moderate.

Identifying the Agent

At the start of the epidemic, 2 weeks after the bioterrorist attack,
confusion reigns. There is uncertainty as to what the infection is and
reluctance to diagnose smallpox even when it is suspected. It is
unclear who is in charge of investigating and containing the
epidemic. Outside, reporters are knocking on the hospital doors.
The question of what took so long to identify the agent opens the
panel. Smallpox, a nonspecific flulike illness, is hard to diagnose,
replies an emergency medicine physician. The disease is not
suspected because it was eradicated in the late 1970s. Any
laboratory work on the first cases would initially be testing for a
battery of other causes, such as other viral infections (e.g.,
monkeypox) or reactions to recent vaccinations. A window of 2
weeks before positive identification of smallpox may even be
optimistic. The diagnosis would probably take much longer because
of physicians' lack of familiarity with the disease.
 
When all the tests for other infections turn up negative and
smallpox is strongly suspected, suggests a state laboratory chief, a
conclusive result from the laboratories at the Centers for Disease
Control and Prevention (CDC) or the U.S. Army Medical Research
Institute of Infectious Diseases (USAMRIID) would still be needed.
These are the only two places in the United States equipped to
identify smallpox virus in tissue samples. This part of the diagnosis
is fairly straightforward but it would take at least 1 day before the
definitive results could be obtained.

Responding at the Hospital Level

Hospitals would probably isolate the early cases presumptively,
even if smallpox was not suspected, since the symptoms would
appear infectious. This is the opinion of a hospital infections expert.
In the city, argues a state health department professional, several
hospitals would each see one or two of the first few cases. The city
health department would quickly become aware of the similarity of
the cases in the various hospitals, recognize a potential outbreak
(probably measles) and mobilize early to contain it.

Once smallpox is identified, the following organizations within city
government would be notified: the police department, the local
emergency management office, the city health commissioner's
office, and, ultimately, the mayor's office. This process may be
difficult since it requires integrating the health department into
emergency management plans, an event with little precedent, notes
a city emergency official.

Coordinating Response Efforts

Who is in charge, agree panelists, is one of the most important
questions yearly in the epidemic, because any large-scale relief
effort would require good management. Complicating the answer,
however, are various levels of government, each with its own
responsibilities and perspective on response, as reflected in
panelists' remarks.

Acts of domestic terrorism are under the jurisdiction of the federal
government, so several federal agencies become involved, starting
with FBI. FBI is involved from the very beginning since any cases
of smallpox would indicate a deliberate terrorist attack. A criminal
investigation begins immediately. CDC is involved as soon as
samples are sent for laboratory diagnosis.

The state government becomes involved at the outset, since major
threats to public health are dealt with on the state level. The state
health department starts its own investigation, and to reassure the
public, the governor may act as a spokesperson for the management
of the epidemic.

The city is involved from the outset, explains the city emergency
management official, understanding that "bioterrorism is a local
issue," which escalates very rapidly to state and federal levels. The
local police and emergency management teams, as well as the city
health commissioner, the city health department, and the mayor, are
involved.

The problems of the city become state problems immediately,
counters the former governor, because the news media treat any
potential infectious disease outbreak as a regional problem. This
forces the governor's hand. The governor has to move in because
there is a need for one person to be in charge.

The most difficult situation is how to deal with the hospital patients.
One danger in the early days is losing control of the crisis through
panic. Once rumors about smallpox start to spread, many workers
within the hospital walk off the job. Understaffing also leads to
increased stress and confusion for patients and providers alike.

Even before federal and state command structures are in place,
suggests a hospital infections control expert, hospital
epidemiologists would already be addressing infection control
issues. She notes that hospital infection control specialists would be
on the phone to colleagues in other city hospitals alerting one
another. Hospital epidemiologists, adds a state health official,
would have a contact list of state, local, and federal public-health
authorities who also would be notified.

Another problem in coordination becomes clear to panelists: the
difficulty in sharing classified risk information among agencies and
various levels of government. Any early warning, which could have
contributed to a more effective response, was missing in the
scenario. Even though the FBI had some early intelligence of the
attack, the alerting of health care workers was nonexistent. The
problem lies in the fact, assesses a state health department official,
that health departments have never been seen as intelligence
communities, nor has there ever been a precedent for passing such
information to them.

On the federal level, CDC addresses the public health issues of the
epidemic, and FBI addresses the law enforcement issues. These
aims are not necessarily exclusive of one another, and the possibility
of linking efforts is raised. Everyone interviewed as a part of the
epidemiologic investigation may have to be interviewed as part of
the criminal investigation as well. Perhaps the most effective way to
accomplish this is to conduct both interviews simultaneously.

Some aspects of the two federal agencies may overlap, perhaps
even conflict, in agendas. Specimens that are sent to CDC for
positive identification of the smallpox virus may be needed by FBI
as evidence for any eventual prosecution. In many ways, it may
appear as if FBI is running the investigation. However, dealing with
the sick, obtaining vaccine, and mobilizing the epidemiologic
investigation at the local, state, and federal levels are outside the
scope of FBI. CDC takes the lead on these public health issues, and
together with FBI, coordinates the management of federal
resources.

However, who is coordinating activities at the hospitals is still
unclear, and the question of authority on that level is unresolved.
Can outsiders come into a hospital and wield power, and if so, who
are they? Federal responders may have ambiguous authority within
a hospital and may add to the chaos. An FBI offical notes that his
agency's role in the hospitals will simply be to inform the doctors
and administrators of what the hospital needs to do to assist in the
criminal investigationkeeping evidence and coordinating interviews
with patients. However, this may still leave gaps of authority within
the hospital.

In the scenario under consideration, the state identifies one hospital
as the smallpox hospital, and this also presents a problem of
coordination. The hospital itself has to work out the details of local
quarantine and the distribution of medicine to the patients, and
there is a need to protect the health-care workers and other hospital
staff. Vaccine should be immediately available to these workers,
and its distribution will have to be coordinated with CDC.

Outside the hospitals, an epidemiologic investigation will be taking
place that will need to be coordinated with CDC. A CDC official
points out the need for surveillance in the early days of the
epidemic. To assist in collecting data necessary to identify the
release source and people at risk, he recommends that CDC provide
additional staff for much of the epidemiologic work, including mid-
and senior-level investigators. Bringing in these outside experts
should not represent a problem for local officials, he suggests, since
CDC already has strong ties with state epidemiologists.

Informing the Public

How to control the message going to the public weighs heavily
upon the minds of all panelists. Reporters on the hospital scene will
quickly become aware of any rumors and will demand answers of
any worker or official who is handy. Official channels will not be
the only source of information during the epidemic, argues the
public affairs specialist.

First responders, such as the police or fire officials, might show up
with full biohazard protection; such an image immediately raises
questions. The media will digest information from day one, whether
or not there is an official statement from the city, state, or federal
level.

Controlling the message that goes out over the airwaves could be
extremely difficult, especially since there may not even be any
consensus on what the message should be in the first place. Several
panelists point out the need to ensure that information presented to
the media is consistent and credible. The city emergency manager
suggests that the mayor will work with federal and state officials to
get consistent and credible information out to the public. One viable
alternative to speculation and misinformation, proposes an FBI
official, is to have a centralized joint information center, such as the
one his agency set up in Oklahoma City after the bombing, with
several experts answering all the questions that arise.

Regardless of how information is disseminated, the message must
be carefully considered. If the flulike symptoms of smallpox are
identified on the evening news, a flood of noninfected persons with
stuffy noses or headaches could swell emergency rooms across the
state. Other reports, such as upcoming quarantine efforts, may also
spread panic and should be handled carefully. The types of stories
the media choose to write present a challenge. The press will not
only cover the crisis but the managers of the crisis. Plans for
responding to questions about crisis management must be in place.
Whether or not the message that goes out to the public includes
mention of terrorism should be weighed.

The hospital infections expert pursues a different angle to the issue
of information exchange. The difficulties in interviewing the public
have not been solved, she points out. Who will do the interviews?
How they will be coordinated with criminal investigations? Who
will receive vaccine? And how will health-care workers be
protected? Will the system be overwhelmed by false casespeople
who think they have smallpox? Moreover, a basic problem in the
early days of the epidemic is the need for an infrastructure to handle
the large volume of calls flooding the hospitals.

Handling Logistics

What will be the plan of action? Hundreds of people will have to be
mobilized to interview the public, and hundreds more will be
needed to administer vaccine. The distribution of antibiotics and
vaccines represents a logistical problem that must be overcome.

As the epidemic grows and spreads to several states, friction
between the levels of government grows. Governors are demanding
vaccine supplies, fueling a larger debate of how vaccination should
be handled. Tens of thousands of people are vaccinated, but many
more still need vaccine. Media reports begin to be critical of the
government's handling of the crisis.

What still needs to be done? With a growing number of deaths, the
rise in the number of patients in quarantine, the loss of critical
health-care workers and city emergency workers, within the city
things are beginning to get out of focus, notes a city official. Asking
how leadership will function inside the hospital, the hospital
epidemiologist identifies a need for official responses that are well
thought out, strong, and based on hard science.

The vaccine campaign poses significant issues. The limited supply
of vaccine must be divided up and distributed according to greatest
riskpersons who may have been infected or who care for those
infected, argues an official in federal emergency management.
Political leaders and essential city workers are other priority
groups. A consensus must be reached as to how to proceed with
the vaccinations. CDC is best suited to coordinate vaccine efforts,
but the public health community must work towards an emergency.
The governor, warns the city emergency manager, may step in and
call the shots. There is a need for a public health emergency plan.
Did the outbreak start from a single source or from multiple
sources? This determination would help with vaccine management
and allocation, but there is no answer. Moreover, testing facilities at
CDC and USAMRIID are overwhelmed at this point in the
epidemic.

Hospitals must deal with quarantine. Restrictions are imposed in the
first days or weeks of an epidemic. Workers' fear of being
sequestered causes them to leave hospitals understaffed. Many
people are likely to stay at their posts if they feel they have reliable
information and support, argues a mental health provider. Some,
however, may leave the front lines to go home to their own
families.

Legal Ramifications

According to a 1905 Massachusetts case, cites a state's assistant
attorney general, compulsory vaccinations are not a violation of due
process and are therefore legal. So the local, state, and federal
levels of government have no obstacle to vaccinating those
designated at risk.

A more difficult legal question is that of quarantining smallpox
patients. Many of the public health codes used to allocate powers to
government officials are old and may not be valid or useful. Also,
court precedents from HIV cases may have heavily weighted
matters in favor of due process. Minnesota, for example, requires a
separate court hearing for each case of quarantine. Thus, quarantine
may be possible in a hospital but not in the community.

Another basic legal question is whether the lines of legal support
are clear to all officials, such as hospital guards and police officers.
How far can police go to detain quarantined patients? The limits of
emergency powers should be clearly delineated in any predisaster
planning.

The epidemic is threatening to expand beyond the city into the rest
of the country and even beyond. The World Health Organization
(WHO) will probably become involved, and travel notifications
have to be introduced.

Vaccine Supply

Even without adequate supplies of vaccine, much can be done with
the existing stocks. Prevaccinating some health-care workers is a
proactive approach. Having a sizable pool of prevaccinated
professionals who can mobilize and act as emergency responders
takes much of the pressure off local hospitals. One way to reduce
secondary transmission (outside of vaccinating the contacts of the
infected person), instructs the hospital epidemiologist, is good
infection controlwearing filter masks and washing hands well.
Another way of controlling the epidemic is through quarantine.
While these measures are not a substitute for adequate vaccine
supply, they can slow the epidemic.

One problem with the vaccine supply is that many more people
want to be vaccinated than limited stores permit. There are not even
enough stores of vaccine to prevent the spread of the epidemic. The
existing 6 to 7 million doses of smallpox vaccine will not last
forever, and the 36 months it takes for additional large-scale
preparations is prohibitive, argues a vaccine campaign expert.
Health officials will likely not have the time or resources to target
precisely those people who have an actual need for vaccine. The
need for vaccine will overwhelm the supply.

The cost of vaccine development may inhibit stockpiling, proposes
a CDC official. Since an attack with smallpox is of low probability,
large-scale production may be difficult to justify. A partnership
between private industry and the government would help, however.
Also, the cost of getting caught without an adequate supply could
be disastrous.

Possible emergency measures to stretch the vaccine supply,
proposes a smallpox expert, include arm-to-arm vaccination as
pustules form on the arms of vaccinated people; vaccinia could be
grown in massive amounts in tissue culture; and 30 million doses of
vaccine could be contracted from South Africa.

The Final Stage

The smallpox epidemic has become a major public health
emergency affecting several cities in many states and at least four
other countries. The event is identified as a terrorist attack, because
no other source of smallpox outside a deliberate release exists. For
those who have already contracted smallpox, antiviral drugs, such
as cydolfivir, may be useful but these medicines may be just as
scarce as the vaccines.

Secondary transmission got out of hand, vaccine use did not
contain the epidemic, and standard planning did not work. Thus a
state health official sums up the deficiencies of response. Hospital
resources have been overwhelmed, with people flooding emergency
rooms in the belief they have smallpox. These cases are added to
hospitalized cases before and during the epidemic; yet there are not
even enough beds for all the sick. The hospital staff have become
physically and emotionally exhausted from the long hours and from
seeing about a third of infected patients die.

Failure of containment has turned the outbreak from local to
national and international. However, the epidemic would have been
much worse, had it gone unchecked, notes a state health official.
Containment was significant. The 15,000 smallpox cases could have
easily been more than 100,000.

No perpetrators have yet been identified, despite combining the
criminal and the epidemiologic investigations. Such methodical
work, however, is important because, unless the intelligence
community comes up with information or a tip, there is no other
way to identify the source of the epidemic, explains an FBI offical.

Many of the problems in the epidemic could have been avoided or
controlled if extensive plans had existed, panelists agree. The
panelist speaking from a governor's perspective identifies leadership
as the most pressing void. Should the city have been placed under
immediate quarantine? Should martial law have been implemented?
Is the designation of a single smallpox hospital a reasonable thing
for any city to do? These are difficult questions to face in the wake
of a disaster. Such issues must be addressed long before trouble
strikes.

Who Will Pay for the Smallpox Epidemic?

The significant cost of curtailing the epidemic is debated. How will
a smallpox hospital be financed, inquires a physician. The money
might come from the federal government as emergency
management funding, suggests a city emergency manager. The
infrastructure and linkages within the public health community
could be improved, the capacity for laboratory testing of samples
could be increased, surveillance methods could be enhanced, and a
health information strategy could be developed.

While the smallpox scenario is certainly frightening, experience with
earlier epidemics (smallpox among them), knowledge of the issues,
and expertise to deal with them show that in a crisis people from all
disciplines pull together.
--------------------------------------------------------

      Mr. Bardi is a freelance writer in Baltimore who holds degrees
in biophysics and science writing from Johns Hopkins University.

     Address for correspondence: Jason Bardi, Johns Hopkins
University, Center for Civilian Biodefense Studies, 111 Market
Place, Ste. 850, Baltimore, MD 21202, USA; fax 410-223-1665;
jsb14@jhunix.hcf.jhu.edu.
_______________________________________________________________________

Special Issue

Clinical and Epidemiologic Principles of Anthrax

Theodore J. Cieslak and Edward M. Eitzen, Jr.
U.S. Army Medical Research Institute of Infectious Diseases, Ft.
Detrick, Maryland, USA

Background and Epidemiology

Anthrax is one of the great infectious diseases of antiquity. The fifth
and sixth plagues in the Bible's book of Exodus (1) may have been
outbreaks of anthrax in cattle and humans, respectively. The "Black
Bane," a disease that swept through Europe in the 1600s causing
large numbers of human and animal deaths, was likely anthrax. In
1876, anthrax became the first disease to fulfill Koch's postulates
(i.e., the first disease for which a microbial etiology was firmly
established), and 5 years later, in 1881, the first bacterial disease for
which immunization was available (2). Large anthrax outbreaks in
humans have occurred throughout the modern eramore than 6,000
(mostly cutaneous) cases occurred in Zimbabwe between October
1979 and March 1980 (3), and 25 cutaneous cases occurred in
Paraguay in 1987 after the slaughter of a single infected cow (4).

Anthrax, in the minds of most military and counterterrorism
planners, represents the single greatest biological warfare threat. A
World Health Organization report estimated that 3 days after the
release of 50 kg of anthrax spores along a 2-km line upwind of a
city of 500,000 population, 125,000 infections would occur,
producing 95,000 deaths (5). This number represents far more
deaths than predicted in any other scenario of agent release.
Moreover, it has been estimated (6) that an aerial spray of anthrax
along a 100-km line under ideal meteorologic conditions could
produce 50% lethality rates as far as 160 km downwind. Finally, the
United States chose to include anthrax in the now-defunct offensive
biological weapons program of the 1950s, and the Soviet Union
and Iraq also admitted to possessing anthrax weapons. An accident
at a Soviet military compound in Sverdlovsk in 1979 resulted in at
least 66 deaths due to inhalational anthrax, an inadvertent
demonstration of the viability of this weapon. The epidemiology of
this inadvertent release was unusual and unexpected. None of the
persons affected were children (7). Whether this is due to
differences in susceptibility between children and adults or purely to
epidemiologic factors (children may not have been outdoors at the
time of release) is unclear.

Anthrax is caused by infection with Bacillus anthracis, a
gram-positive spore-forming rod. The spore form of this organism
can survive in the environment for many decades. Certain
environmental conditions appear to produce "anthrax zones," areas
wherein the soil is heavily contaminated with anthrax spores. Such
conditions include soil rich in organic matter (pH <6.0) and
dramatic changes in climate, such as abundant rainfall following a
prolonged drought. Partly because of its persistence in soil, anthrax
is a rather important veterinary disease, especially of domestic
herbivores. In addition to encountering anthrax while grazing in
areas of high soil contamination, these herbivores may also acquire
the disease from the bite of certain flies (8). Vultures may
mechanically spread the organism in the environment (9). Anthrax
zones in the United States closely parallel the cattle drive trails of
the 1800s (10).

Anthrax spores lend themselves well to aerosolization and resist
environmental degradation. Moreover, these spores, at 2-6 microns
in diameter, are the ideal size for impinging on human lower
respiratory mucosa, optimizing the chance for infection. It is the
manufacture and delivery of anthrax spores in this particular size
range (avoiding clumping in larger particles) that presents a
substantial challenge to the terrorist attempting to use the agent as a
weapon. The milling process imparts a static charge to small
anthrax particles, making them more difficult to work with and,
perhaps, enabling them to bind to soil particles (11). This, in part,
may account for the relatively low secondary aerosolization
potential of anthrax, as released spores bind to soil, now clumping
in particles substantially in excess of 6 microns. This clumping
tendency, together with a high estimated ID(sub 50) of 8,000-10,000
spores may help explain the rarity of human anthrax in most of the
Western world, even in areas of high soil contamination. Other
potential bioweapons, such as Q fever and tularemia, have ID(sub 50) 
values as low as 1 and 10 organisms, respectively.

The Disease

Most endemic anthrax cases are cutaneous and are contracted by
close contact of abraded skin with products derived from infected
herbivores, principally cattle, sheep, and goats. Such products
might include hides, hair, wool, bone, and meal. Cutaneous anthrax
is readily recognizable, presents a limited differential diagnosis, is
amenable to therapy with any number of antibiotics, and is rarely
fatal. While common in parts of Asia and sub-Saharan Africa,
cutaneous anthrax is very rare in the United States; the last case
was reported in 1992 (12). Inhalational anthrax, also known as
woolsorters' disease, has been an occupational hazard of
slaughterhouse and textile workers; immunization of such workers
has all but eliminated this hazard in Western nations. As a weapon,
however, anthrax would likely be delivered by aerosol and,
consequently, be acquired by inhalation. A third type of anthrax,
acquired through the gastrointestinal route (e.g., consuming
contaminated meat) is exceedingly rare but was initially offered by
Soviet scientists as an explanation for the Sverdlovsk outbreak.

Inhalational anthrax begins after exposure to the necessary
inoculum, with the uptake of spores by pulmonary macrophages.
These macrophages carry the spores to tracheobronchial or
mediastinal lymph nodes. Here, B. anthracis finds a favorable milieu
for growth and is induced to vegetate. The organism begins to
produce an antiphagocytic capsule and at least three proteins, which
appear to play a major role in virulence. These proteins are known
as edema factor (EF), lethal factor (LF), and protective antigen
(PA). Following the A-B model of toxicity (13), PA serves as a
necessary carrier molecule for EF and LF and permits penetration
into cells. Edema toxin results from the combination of EF + PA,
lethal toxin results from the combination of LF + PA. These toxins
result in necrosis of the lymphatic tissue, which in turn causes the
release of large numbers of B. anthracis. The organisms gain access
to the circulation, and an overwhelming fatal septicemia rapidly
ensues. At autopsy, widespread hemorrhage and necrosis involving
multiple organs is seen.

Inhalational anthrax generally occurs after an incubation period of 1
to 6 days (14). During the Sverdlovsk outbreak, however,
spontaneous cases appeared to arise as late as 43 days after the
assumed release date (7). Such late cases are unexplained but have
potentially serious implications for postexposure management of
victims of aerosol exposure. After the incubation period, a
nonspecific flulike illness ensues, characterized by fever, myalgia,
headache, a nonproductive cough, and mild chest discomfort. A
brief intervening period of improvement sometimes follows 1 to 3
days of these prodromal symptoms, but rapid deterioration follows;
this second phase is marked by high fever, dyspnea, stridor,
cyanosis, and shock. In many cases, chest wall edema and
hemorrhagic meningitis (present in up to 50% of cases [15]) may be
seen late in the course of disease. Chest radiographs may show
pleural effusions and a widened mediastinum, although true
pneumonitis is not typically present. Blood smears in the later
stages of illness may contain the characteristic gram-positive
spore-forming bacilli. Death is universal in untreated cases and may
occur in as many as 95% of treated cases if therapy is begun more
than 48 hours after the onset of symptoms.

While early recognition of anthrax is likely to require a heightened
degree of suspicion, the diagnosis is supported by gram-positive
bacilli in skin biopsy material (in the case of cutaneous disease) or
in blood smears. A preponderance of gram-positive bacilli in swabs
of the nares or in appropriate environmental samples might support
a diagnosis of anthrax where intentional release is suspected. Chest
radiographs exhibiting a widened mediastinum in the proper setting
of fever and constitutional signs and in the absence of another
obvious explanation (such as blunt trauma, deceleration injury, or
postsurgical infection) should also lead to a diagnosis of anthrax.
This finding is only likely to occur late in the course of disease.
Confirmation is obtained by culturing B. anthracis from blood.

Disease Management

While endemic strains of B. anthracis are typically sensitive to
various antibiotics, including penicillin G, antibiotic-resistant strains
do (on rare occasion) occur naturally (16) and can be readily
isolated in laboratories. For this reason, as well as the convenience
of twice-daily dosing, many experts consider ciprofloxacin (400 mg
intravenously (i.v.) q 12 h) the drug of choice for treating victims of
terrorism or warfare. Doxycycline (100 mg i.v. q 12 h) is an
acceptable alternative, although rare doxycycline-resistant strains of
B. anthracis are known. Conversely, however, the much lower cost
of tetracyclines compared to quinolones may factor into therapeutic
decisions, especially where large numbers of patients are involved.
These recommendations are based solely on in vitro data and data
from animal models (17); no human clinical experience with these
regimens exists. In cases of endemic anthrax, or where organisms
are known to be susceptible, penicillin G (2 million units i.v. q 2 h
or 4 million units i.v. q 4 h) is recommended.

Postexposure prophylaxis against anthrax may be achieved with
oral ciprofloxacin (500 mg orally q 12 h) or doxycycline (100 mg
orally q 12 h), and all persons exposed to a bioterrorist incident
involving anthrax should be administered one of these regimens at
the earliest possible opportunity. In cases of threatened or
suspected release of anthrax, chemoprophylaxis can be delayed 24
to 48 hours, until the threat is verified. Chemoprophylaxis can be
discontinued if the threat is found to be false. Levofloxacin and
ofloxacin would be acceptable alternatives to ciprofloxacin. In
addition to receiving chemoprophylaxis, exposed persons should be
immunized. On the basis of animal data (wherein an appreciable
number of unvaccinated primates died when antibiotics were
withdrawn after 30 days of therapy) (18), chemoprophylaxis is best
continued until the exposed persons has received at least three
doses of vaccine (thus, for a minimum of 4 weeks). If vaccine is
unavailable, some recommend that chemoprophylaxis be continued
for 8 weeks (19). The available vaccine was licensed (for
preexposure prophylaxis) by the U.S. Food and Drug
Administration in 1970 and is prepared from a formalin-treated
culture supernatent of an avirulent B. anthracis strain. It is given in
a preexposure regimen at 0, 2, and 4 weeks, and at 6, 12, and 18
months. Persons at continuing risk for exposure should receive
yearly boosters. Exposed persons should receive at least three
doses (at 0, 2, and 4 weeks), assuming no further exposure is likely,
before discontinuing chemoprohylaxis.

Recently, a number of hoaxes involving a threatened release of
anthrax have been promulgated (19,20), and guidelines have now
been published to assist in the management of such threats (19).
When evaluating a threatened release of anthrax, the lack of
volatility of the disease, as well as its inability to penetrate intact
skin, should be taken into account. These factors make it unlikely,
in most cases, that persons coming in contact with letters,
packages, and other devices purported to contain anthrax will be at
risk for aerosol exposure. Moreover, because energy is required to
aerosolize anthrax spores, opening a letter, even if it contained
anthrax, would be unlikely to place a person at substantial risk. For
these reasons, postexposure prophylaxis may not be necessary in
many cases of threatened anthrax dissemination.

Anthrax has little potential for person-to-person transmission;
standard precautions are thus adequate for health-care workers
treating anthrax patients. Anthrax, as well as other bacteriologic
and viral weapons, has an incubation period of >24 hours. This
characteristic is not shared by conventional, chemical, and nuclear
weapons and makes decontamination of infected persons admitted
to hospitals days after exposure unnecessary in most cases.
However, in certain cases, such as exposure to a threat letter
involving an unidentified substance, where anthrax cannot readily
be ruled out by Gram stain or other rapid diagnostic procedures,
decontamination may be warranted. In such cases, decontamination
may be accomplished by removing clothing, sealing it in a plastic
bag, and showering with copious amounts of soap and water.
Environmental surfaces and personal effects may be treated with
0.5% hypochlorite after the area in which the agent was released is
investigated (19).

In summary, even though anthrax may be among the most viable of
biological weapons, it is also a weapon for which a licensed vaccine
and good antimicrobial therapy and postexposure prophylaxis exist.
Given the relatively short incubation period, and rapid progression
of disease, however, identification of the exposed population within
24 to 48 hours and employment of therapeutic and prophylactic
strategies are likely to present a challenge. Good intelligence
regarding the capabilities of terrorist groups, as well as heightened
awareness of the threat on the part of clinicians, first responders,
and public health personnel remains a cornerstone of bioterrorism
defense.

--------------------------------------------------------

Dr. Cieslak is chief of Field Operations Department in the Division
of Operational Medicine at the U.S. Army Medical Research
Institute of Infectious Diseases at Ft Detrick, MD. Dr. Cieslak is
working in the area of medical defense against biological warfare
and terrorism.

Dr. Eitzen is chief of the Division of Operational Medicine at the
U.S. Army Medical Research Institute of Infectious Diseases and
adjunct associate professor of pediatrics and of military and
emergency medicine at the Uniformed Services University of the
Health Sciences in Bethesda, Maryland. He has worked in the area
of medical defense against biological warfare and terrorism for the
past 8 years.

Address for correspondence: Theodore J. Cieslak, Operational
Medicine Division, USAMRIID, 1425 Porter Street, Ft. Detrick,
MD 21702, USA; fax: 301-619-2312, e-mail:
Ted_Cieslak@Detrick.Army.Mil.

References

1. Exodus 9:1-12.
2. Pasteur L, Chamberlain C-E, Roux E. Compte rendu sommaire
des experiences faites a Pouilly-le-Fort, pres Melun, sur la
vaccination charbonneuse [French]. Comptes Rendus des seances
De L'Academie des Sciences 1881;92:1378-83.
3. Turner M. Anthrax in humans in Zimbabwe. Cent Afr J Med
1980;26:160-1.
4. Harrison LH, Ezzell JW, Abshire TG, Kidd S, Kaufmann AF.
Evaluation of serologic tests for diagnosis of anthrax after an
outbreak of cutaneous anthrax in Paraguay. J Infect Dis
1989;160:706-10.
5. Report of a WHO group of consultants. Health aspects of
chemical and biological weapons. Geneva: World Health
Organization; 1970. p. 97-9.
6. Science Applications International Corporation. Effectiveness of
medical intervention against battlefield levels of Bacillus anthracis.
1993.
7. Meselson M, Guillemin J, Hugh-Jones M, Langmuir A, Popova
I, Shelokov A, Yampolskaya O, et al. The Sverdlovsk anthrax
outbreak of 1979. Science 1994;266:1202-7.
8. Turell MJ, Knudson GB. Mechanical transmission of Bacillus
anthracis by stable flies and mosquitoes. Infect Immun
1987;55:1859-61.
9. Titball RW, Turnbull PCB, Hutson RA. The monitoring and
detection of Bacillus anthracis in the environment. Journal of
Applied Bacteriology 1991; Suppl 70:9S-18.
 10. Coker PR, Smith KL, Hugh-Jones ME. Anthrax in the USA.
Proceedings of the Third International Conference on Anthrax,
Plymouth, England, September 7-10, 1998:44 [abstract].
 11. Sidell FR, Patrick WC, Dashiell TR, editors. Jane's chem-bio
handbook. Alexandria (VA): Jane's Information Group; 1998. p.
229-44.
 12. Centers for Disease Control and Prevention. Summary of
notifiable diseases, United States, 1997. MMWR Morb Mortal
Wkly Rep 1998;46:74.
 13. Gill DM. Seven toxic peptides that cross cell membranes. In:
Jeljaszewicz J, Walstrom T, editors. Bacterial toxins and cell
membranes. New York: Academic Press; 1978. p. 291-332.
 14. Brachman PS, Friedlander AM. Anthrax. In: Plotkin &
Mortimer, editors. Vaccines. Philadelphia (PA): W.B. Saunders;
1994. p. 730.
 15. Abramova FA, Grinberg LM, Yampolskaya OV, Walker DH.
Pathology of inhalational anthrax in 42 cases from the Sverdlovsk
outbreak of 1979. Proc Natl Acad Sci U S A 1993;90:2291-4.
 16. Lightfoot NF, Scott RJD, Turnbull PCB. Antimicrobial
susceptibility of Bacillus anthracis. Salisbury Medical Bulletin Suppl
1990;68:95-8.  17. Kelly DJ, Chulay JD, Mikesell P, Friedlander
AM. Serum concentrations of penicillin, doxycycline, and
ciprofloxacin during prolonged therapy in rhesus monkeys. J Infect
Dis 1992;166:1184-7.
 18. Friedlander AM, Welkos SL, Pitt MLM, Ezzell JW, Worsham
PL, Rose KJ, et al. Postexposure prophylaxis against experimental
inhalation anthrax. J Infect Dis 1993;167:1239-42.
 19. Centers for Disease Control and Prevention. Bioterrorism
alleging use of anthrax and interim guidelines for
management-United States, 1998.
MMWR Morb Mortal Wkly Rep 1999;48:69-74.  20. Sanchez R.
California anthrax threats spawn costly wave of fear. Washington
Post, January 11, 1999, section A, page 1.
_______________________________________________________________________

Special Issue

Anthrax: A Possible Case History

Thomas V. Inglesby
Johns Hopkins School of Medicine, Baltimore, Maryland, USA

Federal Bureau of Investigation (FBI) offices in five U.S. cities
have received warnings of an imminent bioterrorist attack. Each
threat indicated that a "shower of anthrax would rain on U.S.
cities," unless certain demands were met immediately. One of these
calls was in Northeast, a large city on the Eastern Seaboard with a
metropolitan population of 2 million. The threats were credible, but
no information was relayed to city officials in Northeast or
elsewhere.

On the evening of November 1, a professional football game is
being played in Northeast's outdoor stadium before an audience of
74,000. The evening sky is overcast, the temperature mild, a breeze
blows from west to east. During the first quarter of the game, an
unmarked truck drives along an elevated highway a mile upwind of
the stadium. As it passes the stadium, the truck releases an aerosol
of powdered anthrax over 30 seconds, creating an invisible,
odorless anthrax cloud more than a third of a mile in breadth. The
wind blows the cloud across the stadium parking lots, into and
around the stadium, and onward for miles over the neighboring
business and residential districts. After the anthrax release, the truck
continues driving and is more than 100 miles away from the city by
the time the game is finished. The anthrax release is detected by no
one.

Approximately 16,000 of the 74,000 fans are infected by the
anthrax cloud; another 4,000 in the business and residential districts
downwind of the stadium also are infected. After the game, the fans
disperse to their homes in the greater Northeast metropolitan area;
some return to homes in neighboring states. A few are from other
countries. The driver of the truck and his associates leave the
country by plane that night. They will be many time zones away by
the time the first symptoms of anthrax appear 2 days later.

Two days after the game, hundreds of people in and around
Northeast become ill with fever, cough, and (in some cases)
shortness of breath and chest pain. Some of the sick self-administer
over-the-counter cold remedies; some seek phone advice from
physicians and nurses; others are seen in clinics, doctors' offices,
and emergency departments throughout the city.

Influenza cases had been seen in Northeast 2 weeks before the
game. Health-care providers seeing the new patients recommend
bed rest and fluids for presumed flu. Specimens are sent to confirm
influenza. A few of the sickest patients get chest radiographs to
exclude pneumonia. Only in retrospect, after the source of illness is
clear, will the widened mediastinum seen on a number of chest
radiographs be recognized for the signal it carries. A few patients
are hospitalized; some have blood cultures drawn. The 400 ill
persons in the region are receiving care from so many different
sources that the health emergency is not detected.

By November 4, nurses and physicians note the increased volume
of serious upper respiratory illness, and some contact the city health
department for treatment recommendations and a regional flu
update. Blood cultures from the earliest patients grow
gram-positive bacilli in seven laboratories around the city. The
laboratories identify these as Bacillus species. No further
identification is requested, and none is pursued.

By the evening of November 4, patients with the earliest symptoms
are dying. The illness has been rapidly fatal, killing previously
healthy young adults within 24 to 48 hours. Members of the
medical community, now alarmed by these unexpected and
unexplained deaths, urgently contact the state and city health
departments. Health department officials contact the Centers for
Disease Control and Prevention (CDC). By midnight November 4,
1,200 people around the city have fallen ill, 80 of whom have died.

Word that previously healthy persons are dying of a rapidly fatal
illness spreads quickly among health-care providers in the state, and
is featured on local and national morning news shows. News media
interview families of the deceased, physicians, and city health
officials. Expert consultants appear on television to discuss
potential diagnoses, including the new Spanish flu, Hong Kong bird
flu, and many other infectious and noninfectious diseases. A rapid
survey of city emergency departments and health clinics finds that
persons of all ages and from all sectors of the city continue to come
down with similar illness. The numbers have doubled since the
previous day, inundating many health-care facilities.

The mayor convenes an emergency meeting of leading medical
experts and health officials as reporters gather outside city hall. The
assembled experts debate possible causes and responses to the
illness. Many express great concern that a virulent strain of
influenza or another highly contagious disease may be present.
Isolation of all persons with fever, cough, or chest pain; expanded
laboratory analyses; and rapid epidemiologic investigation are
recommended. Blood and tissue specimens are sent to CDC for
urgent analysis. CDC investigators are en route. During a news
conference, the mayor describes the city's response to what appears
to be a serious influenza outbreak, appeals for public calm, and is
surprised by questions about the possibility of bioterrorism.

By noon November 5, intensive-care units and isolation beds across
the city are full. Even patients receiving the most advanced medical
care are dying. Patients are febrile, hypotensive, and seem to be in
septic shock; some have meningitis. Still, there is no diagnosis. At
some locations, the shock of rapid and unexplained deaths has
created an atmosphere of desperation and confusion among hospital
and clinic staff.

The recommended isolation protocols quickly fall apart as hospital
and clinic staffs struggle to cope with the surge of patients. Fears of
a contagious disease prompt hospital staff to don protective
positive-pressure hoods; the news shows physicians working in this
gear and explains that there are only two dozen or so such hoods
available per hospital.

In the early evening of November 5, a university laboratory makes a
preliminary diagnosis of anthrax from the blood culture of a young
patient who died. The laboratory immediately notifies city and state
health departments, which in turn notify CDC and FBI. The
specimen is transferred to the U.S. Army Medical Research
Institute of Infectious Diseases (USAMRIID), where within hours
experts report that rapid diagnostic tests support the preliminary
diagnosis of anthrax.

The mayor of Northeast consults with officials from the city and
state health departments, CDC, FBI, and USAMRIID. The working
assumptions are that the disease in Northeast is anthrax and that it
is the result of a bioterrorist attack. Widespread exposure to an
anthrax aerosol is feared.

The mayor is outraged to learn that the FBI had not informed her of
the credible anthrax threat to Northeast. She is also shocked that it
has taken more than 80 deaths and hundreds of illnesses before
anyone from the medical community came up with the diagnosis.
She is informed that an anthrax vaccine exists, but it is unclear
whether any will be made available for civilian use in Northeast. No
one can yet estimate the probable scale of the epidemic or whether
there has been a single or multiple attacks. CDC is seeking news of
similar syndromes in other locations around the country. The
mayor's medical advisors recommend that quinolone antibiotics be
used for initial treatment of the sick. They also advise the same
antibiotics for those exposed to anthrax but not yet sick, even
though identifying the exposed will take time and requires more
information. All that is known is that many (but not all) of the dying
had been at the football game on November 1.

The mayor also is told that to prevent death, antibiotics must be
given before symptoms occur, or at the latest, in the earliest hours
after symptoms begin. Patients with serious symptoms are likely to
die, no matter what anyone does. Available information suggests
that the local supply of needed antibiotics will soon be exhausted;
many local pharmacies were already emptied of antibiotics as the
initial news of a lethal epidemic spread through the city. Given this
shortage of antibiotics, one senior advisor asks the mayor to
consider a triage plan that uses all available antibiotics to protect
the exposed who are not yet sick. In this plan, antibiotics would be
kept from those already sick and thus likely to die, regardless of
treatment. The mayor requests immediate federal assistance in
obtaining and distributing large supplies of antibiotics. Antibiotic
shipments from other states are also urgently requested.

State officials notify hospitals around the city of the anthrax
epidemic and warn them to prepare for a new surge of patients in
the wake of the mayor's forthcoming TV address.
Recommendations for the care of infected patients are sent to
hospitals and clinics around the region.

The late night news is interrupted by the mayor announcing that
anthrax had been released in the city. She outlines the
recommended medical response and describes assistance Northeast
is seeking from state and federal agencies. She urges that the
needed antibiotics be taken by all those attending the football game.
For those who attended the game and remain well, arrangements
are being made to distribute antibiotics at 20 police stations and
schools around the city starting immediately. Antibiotics will be
distributed in packages sufficient for a 1-week supply. A second
phase of distribution will commence with the arrival of new supplies
of antibiotics. Eventually all those exposed will need to receive
enough antibiotics to take for 60 days.

Persons feeling ill are instructed to report immediately to hospitals
for treatment. The mayor reports that an official request for vaccine
has been made to the federal government. She underscores that
anthrax is not contagious. She again appeals for calm.

Tens of thousands rush to police stations and distribution centers
before the antibiotics arrive. Communication between the
distribution centers, the mayor's office, and the antibiotic suppliers
is haphazard. No city plan exists or had even been considered for
mass distribution of antibiotics. Some centers receive almost no
antibiotics. At other centers, antibiotic supplies are rapidly
exhausted.

At this point, there are effectively no antibiotics left in the city.
Approximately 50,000 persons had obtained some quantity before
supplies ran out, but there is no record of who has received them.
Health-care facilities are unprepared to cope with the continually
rising number of patients. By the early hours of November 6, 2,700
persons have become ill with anthrax, 300 of whom have died.
Thousands more flood doctors' offices, clinics, and emergency
departments, fearing that they are infected with anthrax.

On the morning of November 6, the mayor announces that schools
and homeless shelters will be opened to the ill because hospitals can
no longer accommodate new patients. The National Guard will
keep order. The Office of Emergency Preparedness, Department of
Health and Human Services, and the Federal Emergency
Management Agency will provide some logistical support. The city
has temporarily run out of antibiotics, but supplies from
neighboring states are expected. Meanwhile, the media report that
some of the dead were not at the football game and in fact were
miles away from the stadium that day. Some reporters openly
speculate that "antibiotics are being held back by city officials" and
that "local authorities are losing control of the epidemic." They also
report that false rumors of arriving antibiotic shipments have
sparked mobs and violence at antibiotic distribution centers.

At midday November 6, epidemiologists report that some anthrax
patients had not attended the game, suggesting that exposure had
occurred over a wider area. In addition, computer models show
that wind patterns may have blown anthrax spores downwind of the
stadium for some miles. The antibiotic recommendations are now
being expanded to include all persons living or working within an
area defined by 8 miles east and 1 mile north or south of the
stadium on November 1. The mayor is told by her advisors that, in
fact, no antibiotic arrivals are imminent. Some states report they
have no antibiotics to give, some are refusing to send shipments,
and the federal government reports that it will be at least another 6
hours before its antibiotic resources arrive. Despite assurances that
anthrax is not contagious, people with the ability to do so flee
Northeast, causing traffic jams and increasing panic. Some train
conductors, bus drivers, and pilots refuse to travel to Northeast,
citing personal safety concerns and threatening to walk off the job if
forced. As a result, train, bus, and plane traffic to and from
Northeast is sharply disrupted. By midnight November 6, anthrax
has sickened 3,200 people, 900 of whom have died.

Federal shipments of antibiotics have begun to arrive by November
7. The distribution centers, now increased to 40, continue to be
variably stocked with medicine. A heavy National Guard presence
is now evident at distribution centers to prevent violence. FBI
officials report preliminary evidence that a truck was the source of
the dispersal, though no suspects have been arrested and no group
has claimed responsibility. They confirm that threats of an anthrax
attack were made in the week before the event. On televised
interviews, families of the deceased promise legal action against the
FBI for not revealing the threats, and against local and federal
government for not supplying sufficient antibiotics and vaccine.
Management of dead bodies becomes a growing crisis. Hospital and
city mortuaries are full. Many funeral homes have closed. The state
health department and CDC report that the deceased must be
cremated. Some citizen and religious groups threaten that if
cremation is enforced, there may not be full reporting of the dead,
and private burial ceremonies would continue. By nightfall, 4,000
persons have fallen ill, 1,600 of whom have died.

By November 8, increasing numbers of the city's critical work force
are absent, including police, firefighters, bus and subway operators,
building managers, sewage treatment workers, electricity and water
officials, and supermarket staff. Some are absent because of illness
or death due to anthrax. Some skip work fearing contagious spread
despite official statements to the contrary. Some simply fear
violence in the city. Many of those with the means to leave the city
do so.

National Guardsmen are able to fill some roles, but many tasks
require specialized expertise. As a result, the public transit system is
barely operational; some of the city's office buildings are shut down;
response time for calls made to fire, police, and ambulance
lengthens. Schools and universities are closed. State and city
officials become increasingly concerned about an imperiled city
infrastructure. Looting erupts.

The mayor holds a press conference to address false allegations that
anthrax vaccine is being administered to select individuals in the
city. She reports that federal authorities will make available some
vaccine for those deemed at highest risk. But due to a national
shortage of vaccine and military concerns that this attack may
herald further attacks, there is only a highly limited amount of
vaccine available. For the most part, the city will have to manage
with antibiotics alone.

By evening, a total of 4,800 persons have become ill; 2,400 have
died.

Aftermath

Of the 20,000 persons originally infected in Northeast, 4,000 died,
most in the first 10 days after the attack. Some anthrax cases
occurred in other cities, states, and countries where citizens
attending that football game had returned home. Occasional cases
occur beyond 10 days among persons refusing or discontinuing the
long course of antibiotics. In all, approximately 250,000 persons
receive antibiotics.
 
The media report that hundreds, if not thousands, needlessly died
because of delays in antibiotic distribution, and further, that
lifesaving antibiotics would have cost $100 per persona price local
and federal authorities had not been willing to pay. Military
intervention in the form of martial law is avoided, despite calls by
some federal authorities for a "modest military presence to keep
peace and stability in a region clearly under attack." No group can
be identified as the perpetrator, though FBI continues one of the
largest investigations in its history. Many refuse to return to their
homes downwind of the stadium and demand official compensation.
Businesses downwind of the stadium are shut down. The stadium is
largely abandoned. Newspapers brand the downwind area "the dead
zone." Overall, city commerce suffers tremendous losses. The
tourism industry collapses. City officials estimate it will be months
or years before the city resumes a normal routine. Fear of anthrax
may keep some away from Northeast indefinitely. On December 1,
FBI receives a threat that anthrax will be released in five major U.S.
cities over the next week.

This scenario is ominous. Such an epidemic would create
extraordinary challenges for a modern American city. However,
there is no need to give in to the ending of this story. Practical,
modest preparedness efforts could make a difference and change
the outcome. Many of the most useful efforts may be the result of
ingenuity and depend on collaboration of experts from many
disciplines.  

Could the outcome have changed if state and local
health officials had prior notification of the anthrax threats? Should
laboratory practices be changed to increase the chance of early
detection of anthrax? Should health-care workers become familiar
with the early symptoms and signs of anthrax? What could hospitals
do to prepare for epidemics of seriously ill patients? Could
communities have plans for rapid mass antibiotic acquisition and
distribution? Should anthrax vaccine be more widely available?
How might health professionals and government officials interact
with the media to best inform the public and avoid
misunderstanding and panic? What should the community,
hospitals, and professional societies be doing? What should you be
doing?

--------------------------------------------------------

      Dr. Inglesby is assistant professor in the Division of Infectious
Diseases at the Johns Hopkins University School of Medicine. He
works primarily with the Johns Hopkins Center for Civilian
Biodefense Studies. He is also a physician, treating patients with
human immunodeficiency virus at the Moore Clinic of the Johns
Hopkins Hospital.

      Address for correspondence: Thomas V. Inglesby, Johns
Hopkins Center for Civilian Biodefense Studies, Candler Building,
Suite 850, 111 Market Pl., Baltimore, MD 21202, USA; fax:
410-223-1665; e-mail: tvi@welchlink.welch.jhu.edu.
_______________________________________________________________________

Special Issue

Applying Lessons Learned from Anthrax Case History To Other
Scenarios

John G. Bartlett
Johns Hopkins School of Medicine, Baltimore, Maryland,USA

Northeast, the city described in the anthrax scenario (Inglesby, this
issue, pp. 556-60) is actually Baltimore, a metropolitan area of 2
million population, with a football stadium that holds 74,000. Route
95 would be where the anthrax dispersion took place.

My test case started on February 13 at 6 a.m. when I went to the
emergency room at Johns Hopkins University Hospital and asked to
see the physician in charge. I described the typical case and asked
what the procedure would be if a patient came down with these
symptoms. The physician in charge had actually taken the
specialized 8-hour training course on bioterrorism (one of five
physicians in Maryland to have completed this course entitled
"Train the Trainer"). Nevertheless, she confessed that the typical
early case of inhalation anthrax would have a presumed diagnosis of
flu, and the patient would probably be sent home. Despite the
emphasis on emergency room physicians as the "early response
team," the actual diagnosis would be made after hospitalization.
Many seriously ill patients arriving at the same time might arouse
suspicion, but the initial cases would likely be isolated events or
would be dispersed in multiple emergency rooms.

There was a further problem. At the time of my visit, the emergency
room was on "blue alert," meaning that all 28 beds were filled; the
hospital was also filled. Furthermore, the whole city was on blue
alert, probably because of the flu epidemic. Hospitals routinely run
on marginal excess capacity. The pressures of managed care have
resulted in a health-care system that has minimal elasticity, so on
February 13, there were no beds for an anthrax epidemic.

I then went to radiology; I showed the radiologist a classic case of
inhalation anthrax and asked him how he would interpret the X-ray.
He said that he would read it as widened mediastinum; the
differential diagnosis did not include anthrax.

Then I went to the laboratory and asked the lead technician who
has been in the laboratory for 25 years. He said that Bacillus
anthraxis had never been isolated during his tenure. If it was
recovered in blood cultures, it would be called "Bacillus species, a
probable contaminant." However, more than three cases of Bacillus
species would prompt a full identification, which would be available
in 48 hours. That would trigger a call to the chief of Infectious
Disease and to Infection Control. It would take 72 hours to get
sensitivity test resultswhich is important since this information
would drive the subsequent decisions regarding antibiotic
prophylaxis to those patients or persons who had been exposed. My
own response (if given the possibility of a case of inhalation
anthrax) would be to call the state health departmentthe Maryland
Department of Health and Mental Hygiene.

I got a recording and left a message that I had a query about
bioterrorism, and it was important. The call was returned 3 days
later. The state does have a response mechanism that is far along in
planning and can be activated with a single phone call. The problem
is that I did not know the number. No one else seemed to know the
number; it is not in the hospital directory or on 911 listings.

How were we set in Baltimore to deal with antibiotics? What was
the supply? At any moment, the city of Baltimore had 69,000
capsules of ciprofloxicin and 99,000 capsules of doxycycline. We
could probably use a number of other flouroquinolones, and if the
sensitivities proved that penicillin was active, we could use that as
well. Access to antibiotics would not be a major problem in this
scenario of anthrax contamination.

Then I reviewed the statewide facilities and planning for a 
bioterrorist attack. One phone call to the state health department 
would set into motion a cascade of events that would include an 
immediate effort by state epidemiologists to review the data and 
confirm the diagnosis. They would then contact the Maryland 
Emergency Management Agency, the Federal Bureau of Investigation, 
Maryland Institute for Emergency Medical Services System, and other 
appropriate agencies. The Maryland Emergency Medical Agency coordinates
relevant state agencies and also acts as spokesperson to the press.

Maryland Institute for Emergency Medical Services System has the
capability for flash faxes to emergency rooms throughout the state
but does not communicate with infection control programs and
other parts of the hospital because somebody in the emergency
room can always get that information. My perception is that
Maryland does not have a good system to reach its practicing
physicians, whose involvement is critical. To give antibiotics to tens
or hundreds of thousands of persons in several days, it will be
necessary to use more than the health department clinics and
personnel. Notification and direction would have to be done
through the press and through the medical society, but it is not clear
how well this would work. There had been a few examples,
however, of how this system would work in other settings. The
Maryland Emergency Medical Agency, the system for public
communication, is active about two to three times a year, primarily
for ice storms and hurricanes. It has not been tested for a major
epidemic, but at least it is a system that is established. The capacity
for bodies in a morgue would be approximately 100, but there are
contracts to get refrigerated trucks that would hold 40 bodies per
truck. The system is set up so that Maryland Institute for
Emergency Medical Services System can readily identify bed
capacity for every hospital in Maryland including the number of
available intensive care unit beds to facilitate referrals. No plan is
available for stockpiling antibiotics or vaccines. Stockpiling of
antibiotics is not necessary because the city could get an adequate
supply from regional sites, and the Centers for Disease Control and
Prevention has a $50 million budget allocated to this need. The
great need is for deploying antibiotics in an expeditious way to
thousands, presumably by using regional care sites and the
thousands of physicians' offices; 3,000 emergency medical service
providers could be available to assist, but the mainstay of care in
any large epidemic would come from the private sector.

How does all this work? The good news is that we have a system
set up where there is one person or one group that is coordinating
the events and one point of contact that initiates the relevant
cascade of events necessary for a response. Can this system respond
the way it is expected to respond? The system has worked in
natural disasters, but it may break down in a large outbreak of
inhalation anthrax. For example, during a pfisteria crisis, many
groups took the outbreak on as their issue. Representatives of
Congress and influential citizens bypassed the governor, the mayor,
the Maryland Emergency Management Agency and every other
system to contact the White House, CDC, other agencies and
various medical experts to deal with it. Many did not like the
answers they got, so they bypassed standard channels, and many are
unaware of the rules. A system with a single voice for
communication with the press and providers is needed. The state
has 13,000 beds, but a flu epidemic recently overwhelmed hospital
capacity, and this was not even a big year for influenza. A recent
large fire in Baltimore demonstrated that the city could not handle
100 casualties.

Finally, there is the issue of medical-care personnel resources to
respond. Maryland has 16,000 physicians, 262 members of the
Infectious Disease Society, and 400 emergency room physicians; in
addition, every hospital has infection control personnel. In the event
of a bioterrorist attack, these will be the first responders. They are
the front line for patient contact with the health system. They will
suspect or establish the diagnosis, develop systems to regulate
hospital flow, make therapeutic policy, give treatment, and will
provide prophylactic antibiotics and vaccines. Federal, state, and
local health agencies play a central role in planning but do not have
the facilities or field forces necessary to deal with sick patients and
the thousands who need vaccines or antibiotics.

The gap in planning at the federal level has been the failure to include 
these diverse groups at the table. We anticipate two responses. Different 
groups will make territorial claims on the issue; infectious disease
physicians will say bioterrorism is what they are trained for,
infection control practitioners will claim that epidemics are their
special skill, emergency room physicians will claim that they will be
the first to see those patients, and microbiologists will claim that
they make the diagnosis. All have a role, and all should be included.
The second response seems diametrically opposed. We suspect that
it will be difficult to engender participation by relevant groups,
despite their claims regarding discipline relevance. A bioterrorist
attack is a low-probability event for nearly all cities when
considered individually. Cleveland, Tulsa, or Sacramento are
unlikely targets, just as Oklahoma City was an unlikely target.
Medical providers are busy, and most of us have volunteered to the
breaking point. It is not surprising that the "Train the Trainers"
sessions on bioterrorism in Baltimore were attended by only five
emergency room physicians and no representative of hospitals.
Thus, enthusiastic participation by the critical players from the
private sector is unlikely.

The major mechanism for recruitment is a carrot or a stick.
Possibilities include making bioterrorism plans by hospitals a Joint
Commission on Accreditation of Organization requirement,
requiring this in RRC selected training programs, asking it on
American Board of Internal Medicine boards, and incorporating it
in medical school curricula. These possibilities would increase
visibility of the issue but would not provide the proper regional
training needed. The resources that now total $20 million should
include an allocation to the private sector to permit training and
planning programs that represent a true partnership between public
and private sources.
--------------------------------------------------------

Dr. Bartlett is professor and chief of the Division of Infectious
Diseases, Johns Hopkins University School of Medicine and
president of the Infectious Diseases Society of America.

Address for correspondence: John G. Bartlett,Johns Hopkins
Center for Civilian Biodefense Studies,Candler Building, Suite 850,
111 Market Place,Baltimore, MD 21202, USA; fax: 410-223-1665;
e-mail:biodefen@jhsph.edu.
_______________________________________________________________________

Special Issue

Addressing Bioterrorist Threats: Where Do We go from Here?

Margaret A. Hamburg
Department of Health and Human Services, Washington, D.C.,
USA

In discussing the threat of bioterrorism, planning, coordination, and
preparedness are recurrent themes. State and local planning are of
particular concern to me, having served as a local health officer and
as health commissioner in New York City during the World Trade
Center bombing. I have no doubts that the threat of terrorism
within our borders is real. And several years later, when the sarin
attack occurred in the Tokyo subway system, it was hard not to
imagine what such an event would have meant in the New York
subway system. A fundamental step toward addressing the threat of
bioterrorism is comprehensive planning that focuses first and
foremost on local preparedness and response capacityintegrating
the role of state, regional, and federal governments, as well as state,
regional, and national assets. To plan effectively, we have to think
through the different types of scenarios that may confront us,
including the announced release of a biological agent, the silent
release of a biological agent, or some kind of hybrid event, such as
having a bomb go off, that is followed by the release of a biological
or chemical agent. In addition, we have to think about the scenarios
where person-to-person transmission can occur or those with
noncommunicable infectious diseases. Bioterrorism covers a very
broad spectrum of concerns, from catastrophic terrorism with mass
casualties, to microevents using low technology but producing civil
unrest, disruption, disease, disabilities, and death. All these
scenarios must be considered. We need to identify the assets and
capabilities at all different levels and identify the gaps, critical
players, policymakers, and stakeholders, and we must forge
working relationships within the public health and health-care
community as well as with outside partners. We need to develop
shared understandings and mechanisms of communication. All of
these efforts are best undertaken before an emergency or crisis.

We need to strengthen our nation's public-health infrastructure.
This means enhancing our surveillance and epidemiologic capacity;
our laboratory capacity to support surveillance efforts; and our
communications systems to collect, analyze, and share data. A
strong and robust public health system requires effective working
partnerships with the medical care community. For a host of
reasons over many years, the worlds of public health and medicine
have existed too far apart, even though they share a common set of
goals and the mission of promoting health and preventing disease.
We need to build linkages and understanding.

We also need to make sure that the public health community works
with medical providers to give them the kind of information they
need to respond to infectious disease threats in the community,
understand emerging disease trends, and implement appropriate
prevention and control strategies. Improvements to health can be
achieved through more effective daily working relationships and
even through a crisis. In addition, we have to link with other
partners beyond the public health and medical community,
particularly law enforcement and intelligence. Through working
together, we learn to share common understanding and language.
Federal Bureau of Investigation surveillance is different from public
health surveillance; yet, if we are going to be able to rapidly detect,
diagnose, and control a bioterrorist event, we need to use both
types of surveillance to inform our activities and ensure adequate
preparedness.

Communication is vital. We must learn how to educate and
communicate with policymakers. We should define policies to
support our preparedness efforts, the true needs for new resources,
and the places in which to invest.

Legal and regulatory issues dealing with quarantine laws and
jurisdictional concerns, as well as with the availability or use of
certain drugs or vaccines not licensed by the U.S. Food and Drug
Administration for use in certain populations in an epidemic
context, need to be addressed.

And lastly, we must address the challenge of informing the public
and educating them about the reality of bioterrorism. We must
develop the framework of understanding and support required to
both put in place the systems to respond effectively in a crisis and
to achieve a level of understanding that can form the foundation for
sharing information and developing knowledge when a crisis
occurs.

Hoaxes, a growing problem, offer an opportunity to examine our
coordination and response. Thinking through the different types of
hoaxes helps us develop protocols and strategies that lead to
recognition of a true event.

Medical consequence management is an area to be explored. The
conventional bombwhere something blows up, you come in,
respond, take care of the injured, clean up, and then return, more or
less, to life as it was beforeis not going to be the case in a
bioterrorist attack, particularly in a scenario with human-to-human
transmission. Instead, cases will initially appear in a scattered,
sporadic manner, but rapidly increasing and overwhelming the
capacity of the health-care system and continuing in concentric
circles of infection and disease. We cannot address consequence
management in the way emergency plans traditionally have for
earthquakes, fires, or bomb blasts. We need to build a system that
brings together local, state, and national capacities in an ongoing
way. We also must recognize the need to supplement our
health-care delivery capacity with nonmedical support that may
come in the form of police, National Guard, or possibly military
support, both to assist in the provision of services and for crowd
control and the maintenance of order. New systems of delivering
care and treating patients will be needed. For example, how are we
going to deliver off-site care? How are we going to ensure proper
infection-control measures in that context and provide ancillary
support services for medical care?

Another crucial aspect of effective medical consequence
management requires access to necessary therapeutic products. We
are in the process of creating a national stockpile of drugs and
pharmaceutical products for civilian use. Given that a bioterrorist
event is low probability and high consequence for any given
locality, the federal government can step in and provide the
leadership for creating and administering a national stockpile.

A related concern is the need to develop new tools for the medical
management of bioterrorist threats. The research and development
agenda needs to be addressed both through governmental efforts,
including the National Institutes of Health, the Centers for Disease
Control and Prevention, and the U.S. Army Medical Research
Institute of Infectious Diseases, but also through private industry
and other research institutions. Improved and more rapid diagnostic
methods, new and better drugs for treatment or prophylaxis, and
new vaccines, especially against anthrax and smallpox, are needed.
In addition to biomedical research, further research into such
diverse concerns as defining appropriate personal protective gear or
decontamination procedures is fundamental to our overall
preparedness for a bioterrorist attack.

The public health and medical community must look to the issue of
prevention in terms of how to reduce access to dangerous
pathogens. Are there strategies to prevent these often-frightening
microbes from getting into the hands of those who might want to
misuse them, and how can we reduce the likelihood that they will
be misused? This means being concerned on an international level
about such issues as the need to support the strengthening and
enforcement of the Biological Weapons Convention. Finally, as a
scientific community we should play a proactive role in scientific
research. We need to shape policies against the nefarious use of
biological agents, while safeguarding legitimate research. We need
to ensure that research institutions and individual researchers keep
track of the whereabouts of dangerous pathogens, handle them
safely, and store them securely.

--------------------------------------------------------

      Dr. Hamburg is assistant secretary for Planning and Evaluation,
U.S. Department of Health and Human Services, and former
commissioner of health for the City of New York.

      Address for correspondence: Margaret A. Hamburg, Office of
Planning and Evaluation, Department of Health and Human
Services, HHH Building, Room 415F, 200 Independence Avenue,
S.W., Washington, D.C. 20201, USA; fax: 202-690-7383.

_______________________________________________________________________
DISPATCHES 
_______________________________________________________________________

Dispatches

The Surveillance of Vero Cytotoxin-Producing Escherichia coli
O157 in Wales, 1990 to 1998

Rachel M. Chalmers,* Sharon M. Parry, Roland L. Salmon,*
Robert M.M. Smith,* Geraldine A. Willshaw, and Tom Cheasty
*Public Health Laboratory Service Communicable Disease
Surveillance Centre, Cardiff, United Kingdom; Welsh Combined
Centres for Public Health, Cardiff, United Kingdom; Central
Public Health Laboratory, Colindale, London, United Kingdom

 Population-based surveillance for Vero cytotoxin-producing 
Escherichia coli (VTEC) O157 has been carried out in Wales since
1990. The annual incidence has remained stable during  the 9-year
period (mean: 1.6 cases per 100,000 population); the rate is
highest in children younger than 5 years of age. Blood in the stool
is reported in fewer than half the cases,  indicating the importance
of screening all fecal specimens for VTEC O157.

Vero cytotoxin-producing Escherichia coli serogroup O157 (VTEC
O157) was first recognized as a human pathogen in 1982 (1).
Infection results in symptoms ranging from mild diarrhea to
hemorrhagic colitis (abdominal pain, diarrhea, and blood in the
stool). Hemolytic uremic syndrome (HUS), characterized by
microangiopathic hemolytic anemia, thrombocytopenia, and renal
failure, develops in 2% to 7% of cases (2). The number of
laboratory isolations of VTEC O157 from human infections in
England and Wales has risen from 76 in 1986 (3) to 1,087 in 1997
(4). However, the number of laboratories examining feces for
VTEC O157 has increased in England, as have protocols
emphasizing the importance of laboratory examination. Many
surveillance networks worldwide have selection criteria for testing
for VTEC O157, such as the presence of blood in the stools and
clinical or age parameters (5). In contrast, population-based
surveillance has been undertaken in Wales since February 1990,
with all first-time acute-phase fecal specimens tested for VTEC
O157 (6). The objectives of this surveillance are to measure the
incidence of VTEC O157, identify outbreaks of infection, and
describe the persons involved and the microbiologic characteristics
of the isolates. We report on 9 years of surveillance through the end
of 1998. Since the system is population-based, the figures differ
from those in some published reports of specimens submitted to the
reference laboratory (4,7,8).

Fecal samples were cultured on Sorbitol MacConkey agar (Oxoid,
Basingstoke, UK) and incubated at 37C for 18 hours (3). Sorbitol
nonfermenting colonies were tested for latex agglutination with
O157 antiserum (Oxoid) and were biochemically confirmed as
Escherichia coli by API 20E (BioMerieux sa69280 Marcy L'Etoile,
France). Laboratories were asked to send all presumptive VTEC
O157 isolates to the Laboratory of Enteric Pathogens, Central
Public Health Laboratory, London, for confirmation, phage-typing,
and Vero cytotoxin typing (8).
 
Cases, defined as "isolation of VTEC, confirmed by standard
methods, from a fecal specimen submitted by a resident of Wales,"
were reported to the Public Health Laboratory Service
Communicable Disease Surveillance Centre (CDSC) (Wales). Nine
cases were excluded because the E. coli O157 isolate did not
express Vero cytotoxin genes. Epidemiologic and clinical
information was recorded on a standard structured questionnaire.
Household contacts were screened where practicable and were
included if they met the case definition. HUS, which in the United
Kingdom is defined as renal impairment including oligouria and
plasma creatinine elevated for age, microangiopathic hemolytic
anemia, and thrombocytopenia, was diagnosed clinically.

The annual incidence was calculated by using as the denominator
the mid-year population estimates for Wales (Office of National
Statistics [ONS]), and the age and sex distribution of patients was
calculated by using the mid-1996 population estimate (ONS). The
Poisson distribution was used to calculate 95% confidence intervals
(CI) for age-specific rates. To assess seasonality, the frequency of
cases by month of onset was examined. (For asymptomatic cases,
the date of the sample was used.) Incidence by health authority
areas was calculated by using post-1996 boundaries. The
proportions of cases with various symptoms were determined, and
95% CI were calculated by using standard error of proportions.
The duration of illness (up to the date of interview), admission to
hospital and length of stay, and proportion with HUS (95% CI)
were calculated.

From 1990 through 1998, 415 cases were reported (mean = 1.6 per
100,000 population per year), with little change in incidence (1.0
per 100,000 population in 1994 to 2.8 per 100,000 population in
1995, when an outbreak of 49 cases occurred) (Table 1) (9).
Seventy-four cases (17.8%) were part of six outbreaks involving
Welsh residents (Table 1). Three of the outbreaks have been
reported elsewhere (9-11). The remaining 341 (82.2%) were
sporadic cases, of which 283 (83.0%) were index cases (the first
reported from each household) (from 72.3% in 1998 to 96.2% in
1993). Fifty-eight (17.0%) sporadic cases were in household
contacts; 26 of these patients had diarrhea, including five with
blood in the stools.

Table 1. Occurrence and annual incidence of VTEC O157 in Wales,
19901998
-------------------------------------------------------------------------
       Total no.       
       of cases        No. of   
       (rate per	 sporadic cases     No. of       Outbreak summary    
       100,000         no. of        outbreak  (setting, mode of spread, 
Year   population)   index cases)     cases    phage and verotoxin types) 
-------------------------------------------------------------------------
1990   32 (1.1)        28 (24)          4      Psychogeriatric ward, person
                                               to person, PT14, VT1&2.

1991   39 (1.3)        30 (28)          9      Day nursery, person to
                                               person, PT49, VT2.

1992   41 (1.4)        41 (33)          0                   -

1993   34 (1.2)        26 (25)          8      Community, Meat from 1 shop,    
                                               PT49, VT2.

1994   29 (1.0)        29 (24)          0                   -

1995   82 (2.8)        33 (30)         49      Day nursery, person to
                                               person, PT2 VT2.

1996   38 (1.3)        38 (31)          0                   -

    
1997   55 (1.9)        51 (41)          3      Home for the elderly mentally 
                                               infirm, person to person,
                                               PT2, VT2.

                                        1      Part of a European outbreak

1998   65 (2.2)        65 (47)          0

-------------------------------------------------------------------------

Of 415 patients, 207 (49.9%) were males, ages 3 months to 89
years (mean = 25 years, median = 18 years, mode = 1). The
incidence of VTEC O157 was highest in children younger than 5
years (8.8 per 100,000 population) (Table 2). The number of cases
peaked in August, and more than half (227) of the cases occurred
during July, August, and September. Only four cases occurred
during December. Cases were reported from all five health
authority areas in Wales. The highest incidence was in the northern
and western areas (North Wales and Dyfed/Powys) (mean annual
incidences 2.5 and 2.4 per 100,000 population, respectively). The
lowest incidences were reported in the more densely populated
areas of Gwent (1.1 per 100,000), Bro Taf (1.1 per 100,000), and
Iechyd Morgannwg (1.0 per 100,000).

Table 2. Age and sex distribution of cases of VTEC O157, Wales,
19901998
---------------------------------------------------------------------
Age range           Total                   Male         Female
---------------------------------------------------------------------
<1           24 (7.9, CI = 4.9-11.9)       13 (8.3)     11 (7.5)
1-4         117 (9.0, CI = 7.4-10.7)       71 (10.7)    46 (7.2)
5-14         56 (1.6, CI = 1.2-2.1)        32 (1.8)     24 (1.4)
15-24        44 (1.4, CI = 1.0-1.8)        19 (1.1)     25 (1.6)
25-34        44 (1.2, CI = 0.8-1.6)        19 (1.0)     25 (1.3)
35-44        30 (0.9, CI = 0.6-1.2)        14 (0.8)     16 (0.9)
45-54        33 (1.0, CI = 0.7-1.3)        11 (0.6)     22 (1.3)
55-64        25 (0.9, CI = 0.6-1.5)        10 (0.7)     15 (1.1)
>65          35 (0.9, CI = 0.5-1.1)        15 (0.9)     20 (0.8)
Total       415 (1.6, CI = 1.4-1.7)       207 (1.6)    208 (1.5)
(mean)
---------------------------------------------------------------------
Figures in parentheses are mean annual rates per 100,000
population, followed by 95% confidence intervals (CI) for 
age-specific rates.

Of the 415 patients, 339 (81.7%, CI = 78.3%-85.7%) had diarrhea,
259 (62.4%, CI = 57.3%-66.7%) reported abdominal pain, and 192 (46.3%, CI =
41.3%-50.7%) had blood in the stool; 172 (41.4%, CI = 36.3%-45.7%) 
had hemorrhagic colitis. One third of the patients reported
vomiting (32.3%, CI = 27.5%-36.5%) or feeling feverish (34.0%,
CI = 29.5%-38.5%); 62 (14.9%, CI = 11.5%-18.5%) were asymptomatic. 
The highest proportion of asymptomatic cases was in the 25- to 34-year-
old age group (18 [40.1%] of 44) who are often the caretakers of
symptomatic patients; in 17 cases HUS developed (4.1%, CI =
2.4%-6.5%), age range: 1 to 50 years (mean = 9 years, median = 3 years); 
10 HUS patients were less than 1 to 4 years of age, for
a complication rate in this age group of 8.5%.

Diarrheal illness lasted as long as 330 days (median and mode = 6
days); 118 (28.4%) patients were admitted to hospital. The length
of stay, first recorded in 1994, was from 1 to 71 days (mode 1 day,
median 4.0 days). The highest rate of hospitalization was among
those >65 years old (25 [62.5%] of 40). The mean annual
proportion of index cases hospitalized was 36.1% (24.0% in 1993
to 48.5% in 1992). From 1994 through 1998, only one person, an
88-year-old woman with diarrhea, died as a result of the infection.

Three hundred seventy-eight (91.1%) isolates were sent to the
Laboratory of Enteric Pathogens for confirmation and typing. Of
these, 62 (16.4%, CI = 6.4%-26.4%) had both verotoxin type (VT)
1 and VT2 genes, and 316 (83.6%, CI = 79.9%-87.3%) had VT2
only. Isolates belonged to at least 19 phage types (PT). The two
most common PT were PT2 (160 isolates [42.3%]) and PT49 (48
isolates [12.7%]). Other PT accounting for 5% (19) or more
isolates were PT1, PT4, PT8, and PT14. PT2 was the most
common type in each year, with the exception of 1993, when PT49
predominated. PT and verotoxin type were linked: VT2-only strains
included 98% (158 of 160) of the PT2 and all the PT49 isolates.

No relationship was found between the major PTs and clinical
symptoms. More cases with strains producing VT1+2 had
hemorrhagic colitis (39 [63.9%] of 61) than cases with VT2 only
(120 [42.9%] of 280) (relative risk = 1.69, 95% CI = 1.18-1.88). In
contrast, 16 of the 17 isolates from cases of HUS had the VT2 gene
only. These isolates were predominantly PT2 (n = 10), but also
included PT49 (n = 4), PT21 (n = 1) and RDNC (n = 1).

Foreign travel in the week before onset of symptoms was reported
by 37 (8.9%) patients (0 in 1990 to 12 in 1998 [18.5%] of cases).
The PTs among those who had traveled abroad differed from the
overall pattern, the most common being PT8 (10 cases), RDNC (5
cases), and PT21 (4 cases).

Population-based surveillance of VTEC O157 in Wales has been
undertaken since 1990 and is the most complete in the world. There
is no evidence that pathology referrals have changed during the
study period. General practitioners (primary-care physicians) were
given no specific incentives for submitting specimens. Palmer et al.
(12) showed that in 1996, 26% patients with suspected food
poisoning attending general-practitioner clinics submitted fecal
specimens. This is similar to the 27% reported during a study of
patients with infectious gastroenteritis reporting to general
practitioners in England (13). Although VTEC O157 is regarded as
an emerging pathogen, in Wales its incidence has remained stable
through 1998, and VTEC O157 is a rare (1.6 cases per 100,000
population) but serious disease.

Public health policy concerning VTEC O157 has been driven by the
circumstances surrounding outbreaks (14). However, in Wales most
cases (82.2%) occur sporadically, and because all first-time
specimens and PTs are examined and epidemiologic investigations
are conducted, it is unlikely that outbreaks were missed. The
surveillance data, as well as providing a background against which
to measure changes in incidence, have provided useful information
about VTEC O157 infections. The presence of blood in the stool is
often used in many countries as a criterion for examining for VTEC
O157, yet fewer than half the Welsh patients reported the presence
of blood, demonstrating the value of screening all acute-phase fecal
specimens. Although 14.9% of cases were asymptomatic, the risk
for transmission is still present because of the low infectious dose
(11).

Strains of VTEC O157 can be differentiated rapidly by PT and
Vero cytotoxin typing, although even from apparently sporadic
cases a large number of isolates belonged to a few types,
predominantly PT2/VT2 and PT49/VT2. Determining the VT
produced appears to be a microbiologic marker of severity, since
hemorrhagic colitis was more often associated with VT1+2 strains,
and all the cases complicated by HUS had VT2-only strains. These
strains are consistently more prevalent than other VT types in cases
of HUS in the United Kingdom (7) and elsewhere. Demonstration
of VT by phenotypic tests or the presence of VT genes is definitive
for VTEC O157. The presence of the H7 antigen is closely
associated with VT positivity but is of secondary importance, as a
significant minority of VTEC O157 isolated in England and Wales
(14%-20% in 1992-1994) are nonmotile (8). There was some
annual variation in PTs, although as in England the predominant
phage type was PT2.

As with other surveillance reports, the highest incidence was in
children younger than 5 years of age (8). Although fecal specimens
are more likely to be available for this age group, the isolation rate
is also high (6), and person-to-person spread is most likely (15). In
Wales, person-to-person spread was the most important factor in
four out of five outbreaks, including those in the children's day
nurseries, which were the setting for the two largest outbreaks.
 
Continued surveillance for VTEC O157 will provide timely
reporting of cases and detection and containment of outbreaks.
Ongoing surveillance over the last 9 years in Wales has provided
valuable information about VTEC O157 infections and
demonstrated the wide range of associated clinical illness.

Acknowledgments

  The authors thank the microbiology laboratories and their link
personnel, District Environmental Health Departments, Health
Authority Consultants in Communicable Disease Control, and the
Welsh Office Standing Specialist Advisory Group (Microbiology).
Unipath/Oxoid organized the distribution of reagents to
participating laboratories.

  This work was funded by grants from the Department of Health,
London (DH code 145 and 254) and a PHLS Small Projects grant.

  Dr. Chalmers is a senior scientist with the U.K. Public Health
Laboratory Service Communicable Disease Surveillance Centre in
Cardiff. She has a research background in veterinary microbiology
and protozoology and current interests in the epidemiology of
occupational and food- and waterborne zoonoses.

  Address for correspondence: Rachel Chalmers, PHLS CDSC
(Wales), Abton House, Wedal Road, Cardiff CF4 3QX, United
Kingdom; fax: 44-1-222-521-987; e-mail: rachel.chalmers
@cdsc.wales.nhs.uk.

References

  1. Riley LW, Remis RS, Helgerson SD, McGee HB, Walls J,
Davis BR, et al. Hemorrhagic colitis associated with a rare
Escherichia coli serotype. N Engl J Med 1983;308:681-5.
  2. Tarr PI. Escherichia coli O157:H7: clinical, diagnostic and 
epidemiological aspects of human infection. Clin Infect Dis 
1995;20:1-10.
  3. Advisory Committee on the Microbiological Safety of Food.
Report on  Vero cytotoxin-producing Escherichia coli. London:
The Committee; 1995.
  4. Vero cytotoxin producing Escherichia coli O157 in England and 
Wales. Commun Dis Rep CDR Wkly 1998;8:169.
  5. Parry SM. The incidence and sources of Vero cytotoxin
producing  Escherichia coli O157 in Wales and the English Borders
[Ph.D. thesis]. University of Leeds; 1997.
  6. Salmon RL, Smith RMM. How common is Escherichia coli
O157 and where is it coming from? Total population surveillance
in Wales 1990-1993. In: Karmali MA, Golglio AG, editors. Recent
advances in  Vero-cytotoxin-producing Escherichia coli infections.
Amsterdam:  Elsevier Science BV; 1994.
  7. Thomas A, Chart H, Cheasty T, Smith HR, Frost JA, Rowe B.
Vero cytotoxin-producing Escherichia coli, particularly serogroup
O157, associated with human infections in the United Kingdom:
1989-1991.  Epidemiol Infect 1993:110;591-600.
  8. Thomas A, Cheasty T, Frost JA, Chart H, Smith HR, Rowe B.
Vero cytotoxin-producing Escherichia coli, particularly serogroup
O157, associated with human infections in England and Wales:
1992-1994. Epidemiol Infect 1996:117;1-10.
  9. Al-Jader L, Salmon RL, Walker AM, Williams HM, Willshaw
GA, Cheasty  T. An outbreak of Vero cytotoxin producing
Escherichia coli O157 in a private nursery in North Wales: lessons
for prevention. Arch Dis Child 1999: 81;60-3.
 10. Furtado C, Rojas A, Pebody R, Nylen G, McCarthy N,
Donnelly M, et al. Investigation of an outbreak of Escherichia coli
O157 in Europe 1997. Journal d'Epidemiologie de Terrain le
Bulletin  d'Epiter;11;90.
 11. Willshaw GA, Thirwell J, Jones AP, Parry S, Salmon RL,
Hickey M. Vero cytotoxin-producing Escherichia coli O157 in
beefburgers linked to an outbreak of diarrhoea, haemorrhagic
colitis and haemolytic uraemic syndrome in Britain. Letts Appl
Microbiol 1994;19:304-7.
 12. Palmer S, Houston H, Lervy B, Ribiero D, Thomas P.
Problems in the diagnosis of foodborne infection in general
practice. Epidemiol  Infect 1996;117:479-84.
 13. Wheeler JG, Sethi D, Cowden JM, Wall P, Rodrigues LC,
Tompkins DS, et al. Study of infectious intestinal disease in
England: rates in the community, presenting to general practice,
and reported to national surveillance. BMJ 1999;318:1046-50.
 14. Pennington Group. Report on the circumstances leading to the
1996 outbreak of infections with E. coli O157 in central Scotland.
The implications for food safety and the lessons to be learned. 
Edinburgh: The Stationery Office; 1997.
 15. Parry SM, Salmon RL. Sporadic STEC infection: secondary
household  transmission in Wales. Emerg Infect Dis 1998;4:657-61.
_______________________________________________________________________

Dispatches

A Focus of Deer Tick Virus Transmission in the Northcentral
United States          

Gregory D. Ebel, Ivo Foppa, Andrew Spielman, and Sam R. 
Telford, III
Harvard School of Public Health, Boston, Massachusetts,
USA

We screened salivary glands from adult deer ticks collected near
Spooner and Hayward, Wisconsin, to determine whether deer tick 
virus, a recently described flavivirus, occurs with other tickborne
agents in the upper Midwest. Intraacinar inclusions suggestive of 
replicating virus were detected in 4 (4.6%) of 87 ticks. The virus
was isolated by suckling-mouse inoculation.

Pathogens transmitted by deer ticks (Ixodes dammini) affect the
health of residents in areas of the northcentral United States. The
diversity of infecting agents, the intensity of their transmission, and
the concomitant risk for human infection are well documented and
approach levels found in the Northeast (1-4). In northwestern
Wisconsin, the risk to health from these ticks may increase as
human recreational and industrial activities more frequently
intersect with areas of enzootic transmission. In addition to the 
agents of Lyme disease (Borrelia burgdorferi), human granulocytic
ehrlichiosis (Ehrlichia microti), and human babesiosis (Babesia
microti), deer ticks in these foci might be infected with deer-tick
virus (DTV), a recently described Powassan (POW)-like agent of
the genus Flavivirus (5), and might pose an additional threat to
human health in this region.

To determine whether this newly recognized agent infects deer
ticks in a focus outside New England, we sampled ticks from two
heavily infested sites in northern Wisconsin and assayed them for
all four agents. Host-seeking adult ticks were collected by 
dragging a piece of flannel cloth over the vegetation during
October of 1997 and 1998. We collected 481 adult deer ticks near
Spooner and Hayward, Wisconsin, during 8 hours of sampling. A
sample of the female ticks (87 of 271) was selected for analysis.
Nonengorged female ticks were fed on uninfected laboratory
rabbits to stimulate replication of infectious organisms and were 
removed after 4 to 5 days. Ticks were dissected individually on
acid-washed microscope slides by using flame-sterilized forceps
and razor blades. One of each pair of salivary glands was stained
by the Feulgen reaction and examined by bright-field microscopy.
The other was pooled with the salivary glands of four other ticks
in Hanks' Balanced Salt Solution supplemented with fetal bovine
serum (HBSS/FBS) for mouse inoculation and polymerase chain
reaction (PCR) analysis. The slides used for dissection were
examined for B. burgdorferi by direct fluorescent antibody (6). 
Male ticks were assayed for spirochetal infection only; they were
homogenized in 50 l PBS, and 10 l of the resulting suspension
was applied to 12-well microscope slides, air dried, and stained.

 Deer ticks sampled near Spooner and Hayward, Wisconsin, 
maintain pathogens similar to those found in New England ticks
and in comparable proportions (Table). In addition to the three
agents enzootic near Spooner (4,7,8), we observed a staining
pattern suggestive of viral replication (5) in the salivary glands of
four ticks. To determine whether this agent was viral, we 
inoculated suckling mice intracerebrally with 0.03 ml of a clarified
and sterile-filtered homogenate of the combined pools containing
Feulgen-positive salivary glands. A sample of this homogenate was
reserved for reverse transcriptase (RT)-PCR analysis. Siblings of 
suckling mice received 0.03 ml of sterile HBSS/FBS. On the
morning of day 6 after inoculation, the mice that received salivary
gland homogenate showed signs of profound neurologic
dysfunction: their gait was disrupted, and they failed to right
themselves when placed on their backs. By mid-afternoon they
were moribund and died shortly thereafter. The time between 
inoculation and death was similar to that seen in DTV and POW
infections, which kill suckling mice in 5 to 7 days (5,9).

Table. Pathogens maintained by deer ticks, Spooner and
Hayward, Wisconsin, 1997-98
----------------------------------------------------------
                                                 %
                             No.     No.      positive
Agent         Assay       examined positive   (95% CI)
----------------------------------------------------------
Borrellia     Direct       
 burgdorferi   fluorescent   220      83   37.7 (31.3,44.5)
               antibody     
    
Babesia sp.   Microscopy      87       6    6.9 (2.6,14.4)

Ehrlichia     Microscopy      87       4    4.6 (1.3,11.4)
 microti

Deer tick     Microscopy      87       4    4.6( 1.3,11.4)
 virus
 --------------------------------------------------------
               
To determine whether the putative viral agent was DTV, POW, or
a related flavivirus, salivary glands that appeared infected were 
analyzed by RT-PCR. The clarified homogenate used for mouse 
inoculation was added to 350 ml of a lysis buffer, and RNA was 
extracted by RNEasy spin columns (Qiagen) as directed by the 
manufacturer. The resulting  RNA-containing solution was reverse
transcribed by using random hexamers at 42C for 20 minutes. We
added 5 ml of cDNA to an amplification mixture containing
primers (TBE-1[5'-3'ACATGGCAGTACTGGGG) and TBE-2 
(5'-3'CCCATCATGTTGTACAC]) designed to amplify an 
approximately 450-bp fragment of the ns5 gene of Central
European tickborne encephalitis (TBE). Reaction conditions were
as follows: initial denaturation at 94C for 1 minute, followed by
35 cycles of 94C for 45 seconds, 40C for 45 seconds, and 72C
for 1 minute. A final extension step of 72C for 6 minutes was
also performed. Bands of the correct size were excised and
sequenced by the dideoxy-chain termination method and an
automated DNA sequencer (Applied Biosystems, Foster City,
CA). Sequences were compared with those accessioned in 
GenBank. Sequence alignments were generated with the PILEUP
program of the Wisconsin Genetics Computer Group and then
analyzed by the distance method using  MEGA (10). Third codon
positions were omitted to minimize sequence convergence due to
homoplasy and to better reflect nucleotide changes resulting in
amino acid differences. Analyses including third codon positions
resulted in identical topologies with higher bootstrap values and
longer branch lengths. Evolutionary distances were computed by
the Kimura 2-parameter method, including both transitions and 
transversions. Distance trees were constructed by the 
neighbor-joining method, and their robustness was estimated by
performing 500 bootstrap replicates. Phylogenetic analysis of this
fragment (GenBank accession af135459) indicated that the virus
was most closely related, but not identical, to DTV from 
northwestern Connecticut (af135460) (Figure 1). Because  the ns5
gene from our Spooner isolate was more closely related to DTV
than to POW, this isolate is provisionally designated as deer-tick
virus-Spooner (DTV-SPO).

[fig]

Figure 1. Phylogenetic relationships among tickborne  
flaviviruses based on a 376-bp fragment of the ns5 gene.   
Distance analysis omitting third position nucleotides. Branch
numbers are bootstrap confidence estimates on the basis of 500   
replicates. GenBank accession numbers in parentheses. LI  =
Louping Ill; TBE-West = Western subtype tickborne   
encephalitis (Central European encephalitis); POW = Powassan   
virus; DTV = deer tick virus.

To more completely characterize the Wisconsin viral isolate, we
amplified a 650-bp fragment of the viral envelope gene from the
suckling mouse brain tissue. Extraction and reverse-transcription
of RNA was conducted as previously described; PCR were also
conducted as described, except that the primers ENV-A and 
POW-6 were used (5). PCR products were subjected to
electrophoresis on a 2% agarose gel, yielding a product of the
expected size, which was subsequently excised and sequenced. 
The nucleotide sequence of this fragment differs by 16% and 4%
from published POW and DTV sequences, respectively.
Phylogenetic analysis of this fragment (af135461) confirmed that
the Spooner isolate clusters with DTV and  POW (Figure 2). The
resulting topology was virtually identical to that of other published 
trees analyzed by means of different optimality criteria (11,12).

 This is the first report of an isolation of a TBE-group flavivirus
from Wisconsin, and only the second report of a flavivirus in deer 
ticks. The antigenic relatedness of DTV and POW has not yet been
determined. Arboviral classification has been on the basis of 
serologic methods (International Catalogue). A fourfold or greater
difference in titer measured by one or more serologic tests 
(neutralization, complement fixation) between homologous and
heterologous antisera raised to the viruses being compared is
considered to support novelty (15). However, molecular 
phylogenetic analyses are increasingly becoming routine and can
rapidly provide information on relatedness. Initial findings may
subsequently be complemented by the time-tested serologic 
techniques. This paradigm for viral identification, where an agent
of unknown pathogenic potential may be initially examined by
PCR sequencing, has been recently used with much success with
hantaviruses. New York virus, for example, was suggested to be a
distinct subtype of Sin Nombre virus because its nucleocapsid
protein gene sequence differed by 10% to 12% (16). Other
northeastern U.S. hantavirus isolates from Peromyscus leucopus
clustered with each other in phylogenetic analysis (forming a
"clade") rather than with Sin Nombre virus from the southwestern
United States. Similarly, despite the geographic distance of their
transmission foci, DTV-SPO forms a clade with the two original
DTV isolates from New England rather than with the sole
molecularly characterized POW isolate, which derives from nearby
Ontario. Accordingly, although conclusions regarding the novelty
of DTV should be regarded as tentative pending serologic studies,
molecular evidence strongly suggests that DTV is a new subtype of
POW. The clinical implications of human infection with DTV are
not known. Powassan encephalitis, however, often follows a severe
clinical course, with a 10.5% case-fatality rate and severe sequelae
(hemiplegia, wasting, severe headaches) in 47.1% of survivors (9).
The genetic distance (Figure 2) between DTV and POW isolates is
roughly similar to the difference between eastern TBE isolates
(Russian spring-summer encephalitis) and Omsk hemorrhagic fever,
viruses with radically different clinical presentations. We suspect
that in contrast to infection with POW, human disease caused by
DTV may be mild or asymptomatic. Although residents of
northeastern and midwestern states are heavily exposed to deer
ticks, an associated severe neurologic disease has not yet been
described. Prevalence of DTV in host-seeking adult deer ticks was
similar to that of the human granulocytic ehrlichiosis agent (4.3%),
which indicates that residents of this region may be exposed
frequently to the bites of DTV-infected ticks, and perhaps even
more frequently than residents of our New England study sites (5).
Alternatively, we may fortuitously have sampled in Wisconsin in an
intense focus of transmission. European TBE group viruses persist
in such enzootic microfoci, located within larger regions of lesser 
overall prevalence (14). Because these foci are so small, few 
residents of the region are exposed. The distribution of DTV, like
that of babesiosis and Lyme disease, may spread from its initial  foci
to exposing the residents of much broader regions. 

[fig]

Figure 2. Phylogenetic relationships among tickborne flaviviruses
on the basis of a 575-bp fragment of the envelope gene. Distance
analysis omitting third position nucleotides. Branch numbers are
bootstrap confidence estimates on the basis of 500 replicates.
GenBank accession numbers in parentheses. LI = Louping Ill; SSE
= Spanish sheep encephalitis; TSE = Turkish sheep encephalitis;
GGE = Greek goat encephalitis; TBE-West = Western subtype
tickborne encephalitis (Central European encephalitis); OHF =
Omsk hemorrhagic fever; TBE-East = Eastern subtype tickborne
encephalitis (Russian spring-summer encephalitis); KFD = Kyasanur
Forest disease; POW = Powassan encephalitis; DTV = deer tick
virus; SRE = Saumarez Reef virus; TYU = Tyuleniy virus; YF =
yellow fever.

 Acknowledgments

   The authors thank Philip Armstrong for thoughtful suggestions,
Rich Pollack and Heidi Goethert for reading the manuscript, and
Melissa Culhane for field assistance. All animal experiments were
conducted according to the approved International Animal Care
and Use Committee guidelines for the Harvard Medical Area.

   This work was supported by NIH grants AI 39002, AI 37993,
and AI 19693. Mr. Ebel is a doctoral candidate in the Laboratory
of Public Health Entomology, Department of Immunology and
Infectious Diseases. His research interests focus on the population
biology of deer tick- and small-mammal-associated viruses.

Address for correspondence: Sam R. Telford, III, Department of 
Immunology and Infectious Diseases, 665 Huntington Avenue,
Boston,  MA 02115, USA; fax: 617-738-4914; e-mail:
stelford@hsph.harvard.edu.

References

 1. Kitron U, Kazmierczak JJ. Spatial analysis of the distribution
of Lyme disease in Wisconsin. Am J Epidemiol 1997;145:558-66.
 2. Sweeney CJ, Ghassemi M, Agger WA, Persing DH.
Coinfection with Babesia microti and Borrelia burgdorferi in a
western Wisconsin  resident. Mayo Clin Proc 1998;73:338-41.
 3. Tsai TF, Bailey RE, Moore PS. National surveillance of Lyme
disease, 1987-1988. Conn Med 1989;53:324-6.
 4. Dryer RF, Goellner PG, Carney AS. Lyme arthritis in
Wisconsin.  JAMA 1979;241:498-9.
 5. Telford SR III, Armstrong PM, Katavolos P, Foppa I, Olmeda 
Garcia AS, Wilson ML, et al. A new tick-borne encephalitis-like 
virus infecting New England deer ticks, Ixodes dammini. Emerg 
Infect Dis 1997;3:165-70.
 6. Mather TN, Piesman J, Spielman A. Absence of spirochaetes
(Borrelia burgdorferi) and piroplasms (Babesia microti) in deer
ticks (Ixodes dammini) parasitized by chalcid wasps (Hunterellus
hookeri). Med Vet Entomol 1987;1:3-8.
 7. Dumler JS, Bakken JS. Human granulocytic ehrlichiosis in
Wisconsin and Minnesota: a frequent infection with the potential
for persistence. J Infect Dis 1996;173:1027-30.
 8. Herwaldt BL, Springs FE, Roberts PP, Eberhard ML, Case K, 
Persing DH, et al. Babesiosis in Wisconsin: a potentially fatal
disease. Am J Trop Med Hyg 1995;53:146-51.
 9. Artsob H. Powassan encephalitis. In: Monath T, editor. The
arboviruses. Boca Raton (FL): CRC Press; 1989. p. 29-49.
10. Kumar S, Tamura K, Nei M. MEGA: Molecular evolutionary
genetics analysis. University Park (PA): The Pennsylvania State
University; 1993. p. 16802.
11. Zanotto PM, Gao GF, Gritsun T, Marin Ms, Jiang WR,
Venugopal K, et al. An arbovirus cline across the northern
hemisphere. Virology 1995;210:152-9.
12. Zanotto PM, Gould EA, Gao GF, Harvey PH, Holmes EC.
Population dynamics of flaviviruses revealed by molecular
phylogenies [see comments]. Proc Natl Acad Sci U S A
1996;93:548-53.
13. Mandl CW, Holzmann H, Kunz C, Heinz FX. Complete
genomic sequence of Powassan virus: evaluation of genetic
elements in tick-borne versus mosquito-borne flaviviruses. Virology 
1993;194:173-84.
14. Gresikova M, Calisher C. Tick-borne encephalitis. In: Monath
T, editor. The arboviruses: epidemiology and ecology. Boca Raton
(FL): CRC Press; 1989. p. 177-202.
15. Calisher C, Karabatsos N, Dalrymple J, Shope RE, Porterfield
JS, Westaway EG, et al. Antigenic relationships between
flaviviruses as determined by cross-neutralization tests with
polyclonal antisera. J Gen Virol 1989;70:37-43.
16. Monroe MC, Morzunov SP, Johnson AM, Bowen MD,
Artsob H, Yates T, et al. Genetic diversity and distribution of 
Peromyscus-borne hantaviruses in North America. Emerg Infect  
Dis 1999;5:75-86
_______________________________________________________________________

Dispatches

Dengue Reemergence in Argentina

G. Avils,* G. Rangen, V. Vorndam, A. Briones, P. Baroni,*
D. Enria,* and M.S. Sabattini*
*Instituto Nacional de Enfermedades Virales Humanas (INEVH)
"Dr. J.I. Maiztegui", Administracin Nacional de Laboratorios
e Institutos de Salud "Dr. C. Malbrn", Pergamino,
Argentina; Ministerio de Salud, Salta, Argentina; Centers for
Disease Control and Prevention, San Juan, Puerto Rico; and
Delegacin Sanitaria Federal, Salta, Argentina

Aedes aegypti, eradicated from Argentina in 1963, has now
reinfested the country as far south as Buenos Aires. In 1997, four
persons with travel histories to Brazil, Ecuador, or Venezuela had
confirmed dengue, and  surveillance for indigenous transmission
allowed the  detection of 19 dengue cases in Salta Province. These 
cases of dengue are the first in Argentina since 1916  and represent
a new southern extension of dengue virus.

Dengue History in Argentina

Several cases of dengue fever were reported in Argentina at the
beginning of this century. Indigenous cases were reported in 1905,
1911, and 1916 in northern Argentina (Chaco, Corrientes,
Formosa, and Misiones Provinces) (1). In February and March
1916, an epidemic with 15,000 reported cases occurred in Entre
Rios Province along the Uruguay and ParanRivers in eastern
Argentina. None of these patients had hemorrhagic symptoms.
Since this epidemic, no indigenous cases had been reported until
1997 (1).

Aedes aegypti

In 1955, when the Aedes aegypti eradication campaign began in
Argentina, an estimated 1,500,000-km(sup 2) area was infested (Figure
1) (1). Santiago del Estero Province had the highest infestation rate,
with Ae. aegypti found in 9.4% of localities and 5.3% of houses.
This province is characterized by a warm summer and low
socioeconomic conditions, with many houses lacking running water
(1). The southern extension of Ae. aegypti distribution was 35
degrees south, the latitude of Buenos Aires (1). Buenos Aires was
only minimally affected, with only 6 of 199,172 houses infested. By
1963, Ae. aegypti was considered eradicated from the country (1),
but in 1986 the National Ministry of Health reported reinfestation in
the north (2). The reinfested area is the area that was infested in
1955, including Salta Province. Buenos Aires Province was
reinfested in 1991 and the Federal District in 1995 (2,3). In autumn
1997, high infestation levels (35% in 1996 and 18% in 1997) were
found in houses in Buenos Aires Province and the Federal District
(3). In Villa Maria, Crdoba Province (32 degrees south), Ae.
aegypti was found in summer (February) of 1995, disappeared in
winter, and reappeared in early summer (December 1995) (4). The
mosquito was also found in Buenos Aires Province (Zrate and
Campana, 34.2 degrees and 34.4 degrees  south, respectively) in
February 1996 and October 1996 (early  spring) (Avils G,
unpublished data). These findings indicate that Ae. aegypti may
spend winter in refuges in temperate areas and may not necessarily
be reintroduced during summer. The presence of Ae. aegypti in
most of the country and the reappearance of dengue fever in
neighboring countries (Brazil, Paraguay, and Bolivia) increases the
risk for dengue infection in Argentina. The Instituto Nacional de
Enfermedades Virales Humanas "Dr. J.I. Maiztegui" is the National
Reference Center of Dengue Diagnosis. This article summarizes the
first dengue cases diagnosed in Argentina in recent years and
documents the southernmost expansion of dengue in South
America.

The Study

DEN 1 HAW, DEN 2 NGC, DEN 3 H87, and DEN 4 H241
strains were obtained from the Centers for Disease Control
Laboratory, San Juan, Puerto Rico. Plaque reduction neutralization
tests (PRNTs) were performed as described by Russel et al. (5),
with an 80% plaque reduction endpoint. The enzyme-linked
immunosorbent assay (ELISA) capture IgM test was done as
described by Innis et al. (6) and Kuno et al. (7). Polymerase chain
reaction (PCR) was done according to the protocol of Lanciotti et
al. (8). The isolation attempts and immunofluorescence tests were
done by injecting sera into C6/36 cells and using monoclonal
antibodies against each of the serotypes (9).

Study Area
Salta Province is located in northwestern Argentina (Figure 2) in
the subtropical area between 22 and 26, 30 minutes south. A
serosurvey was done in Orn, Salvador Mazza, and Guemes
(Figure 2). Active surveillance was also conducted in Tartagal.
Median temperatures in northern localities (Tartagal and Orn) are
26C in summer and 19C in winter. In Salta city the median
temperatures are 22C in summer and 15C in winter.

Study Participants

Blood samples were collected at regional hospitals from patients
seeking treatment for any illness.

Surveillance of Imported Cases

During the epidemiologic surveillance of the cases compatible with
dengue, from January to November 1997 our laboratory received
16 samples from returning travelers who had suspected dengue
(Table 1). Sera of four patients, returning from Brazil, Ecuador,
and Venezuela, were positive by IgM-capture-ELISA. Cases from
Ecuador and Venezuela were positive by PRNT, but the serotype
could not be determined because of cross-reactions, possibly
indicating secondary flavivirus infections.

Table 1. Imported dengue cases-Argentina, 1997
-----------------------------------------------------------------
                            Plaque reduction neutralization tests
Patient  Travel   Onset of   
no.     history   symptoms  MAC-ELISA    D1     D2     D3      D4                
 ----------------------------------------------------------------
 1      Brazil    02/14/97   Pos         ---    ---    ---    ---

 2      Ecuador   unknown/97 Pos       1,280  1,280     80    <20

 3      Venezuela 11/16/97   Pos          ---    ---   ---   ---

 4      Venezuela unknown/97 Pos      >1,280 >1,280 >1,280 >1,280

 ----------------------------------------------------------------
 ---Not done

Surveillance of Cases in Salta Province

A total of 404 sera were studied from Orn, Salvador Mazza,
Santa Victoria, Tartagal, General Mosconi, Salta city, Junta del San
Antonio, Aguaray, and Guemes during April through November
1997. Nineteen serologically positive samples were detected from
four of these locations (Orn, Salvador Mazza, Tartagal, and
Guemes) (Table 2). Twelve samples were positive by MAC-ELISA,
indicating current or recent infections, and three of these had PRNT
titers indicating primary DEN 2 infections. Three other samples had
cross-reactive antibody patterns indicative of secondary flavivirus
infections. Seven other samples were immunoglobulin (Ig)M
negative, but positive by PRNT. Three of these showed PRNT
titers indicating DEN 2 infections. Six additional samples were
positive by PRNT, but the serotype could not be determined. Virus
isolation attempts on 36 acute-phase samples had negative results,
but one sample was diagnosed as dengue 2 by reverse
transcriptase-PCR.

Epidemiologic and Clinical Data

We obtained epidemiologic and clinical information from nine
patients. One, a man from Salvador Mazza, had fever, retroocular
pain, malaise, muscle pain, and arthralgias and had traveled to Santa
Cruz de la Sierra, Bolivia, before onset of symptoms. Seven other
patients reported symptoms including headache, muscle pain,
abdominal pain, arthralgias, rash, pharyngitis, and epistaxis. No
hemorrhagic manifestations were reported. Six of these patients
reported no travel history and must have become infected in Orn
or Tartagal. Travel histories were not available from the other two
patients.

Conclusions

Laboratory results show that imported cases of dengue arrived in
Argentina during 1997, enabling local transmission in cities like
Rosario and Buenos Aires. In northern Argentina, there is
continuous traffic with Bolivia, Paraguay, and Brazil, where dengue
is known to occur. We report early evidence of DEN 2 virus
circulating in northern Argentina, where indigenous cases have
occurred in Orn, Tartagal, Guemes, and Salvador Mazza. These
cities are generally located along a highway going north into
Bolivia, where DEN is endemic. Clinically, all cases were classic
dengue fever. High PRNT antibody titers in the acute-phase
samples indicated that dengue or other flavivirus infections had
probably been present but had gone undetected. Only sporadic
cases were found in the area under active surveillance, as in Texas
in 1995 when isolated cases of indigenous transmission were
detected (10).

[fig]

Figure 1. Geographic distribution of Aedes aegypti,1955: 
Dengue risk area in Argentina.

[fig]

Figure 2. Surveillance for dengue virus infections in Salta 
Province: Localities with cases.

Table 2. Surveillance for dengue virus infections, Salta
Province,Argentina 
-----------------------------------------------------------------
          positive/         ELISA                 PRNT
Locality*  tested    Onset   IgM       D1     D2     D3      D4
-----------------------------------------------------------------
Orn       6/161      --     Pos       20    320    <20      80
                      --     Neg       80    160     20      80
                  04/22/97** --       <20    <20    <20      80
                  04/28/97   --        20   >160     40      20
                  05/16/97   Pos      640  1,280    640      80
                  11/16/97   Pos       --     --     --      --
Salvador   7/113      --     Pos      <20    <20    <20      20
Mazza                 --     Pos      <20    <20     80      20
                      --     Pos      160   >640   >640      20
                      --     Neg      <20    <20     80      40
                      --     Neg       --     20     80      80
                      --     Neg       20     --    <20      40
                      --     Pos      <20    <20    <20     <20
Tartagal     3/7  08/30/97   Pos       80   >160   >160     <20
                  10/26/97   Pos      <20    160    <20     <20
                  11/23/97   Pos      640 >1,280    640      40
Guemes     1/100      --     Neg      <20    <20    <20      40
Unknown      2/6      --     Pos      <20    <20    <20     <20
                             Pos       40   >160    <20      80
---------------------------------------------------------------------
*Samples from the following localities were negative by IgM
capture-enzyme-linked immunosorbent assay: Santa Victoria (2),
General Mosconi (2), Salta city (11), Junta del San Antonio (1) and
Aguaray (1).
**An acute-phase sample from this case was positive for DEN 2 by
RT-PCR.

The reestablishment of dengue in Argentina is of concern because
of  the following risk factors (11): 1) the presence of Ae. aegypti
vector in high densities in several places (3); 2) the low levels
ofimmunity in the human population in all areas that have been
studied  (1); 3) endemic virus in neighboring countries (12); and 4)
the  widespread presence of substandard living conditions, including
the lack of running water, in areas where the virus is most likely to
be introduced. Air conditioning is uncommon throughout the
country, and  the climate is subtropical in the north and temperate
in the central region, where conditions are suitable for dengue
transmission in  summer. Surveillance should be continued and
expanded in the most  susceptible areas to monitor introduction and
spread of this  reemerging disease.

Acknowledgments

The authors thank Robert Shope and Elsa Segura for revising  this
manuscript; Liliana Canini, Nora M. Mellano, Milton Bejarano,
Jose A. Rodriguez, Silvia Gonzalez Ayala, and Roque Brun, who
attended patients and provided samples; and Cristina C. Bono and
Maria Luisa Cacase, who also provided samples.

Dr. Avils is a biologist in charge of the Arbovirus Laboratory,
National Reference Center of Dengue Diagnosis, Collaborative
Center PAHO/WHO, Instituto Nacional de Enfermedades  Virales
Humanas "Dr. J.I. Maiztegui"-Administracion Nacional de
Laboratorios e Institutos de Salud, Pergamino, Argentina. Her
areas of expertise are arbovirology and medical entomology
(mosquitoes). Her research interests include arboviruses (in humans
and vertebrates), DEN, YF, WEE, EEE, VEE, and the competence
of  mosquitoes as vectors for arboviruses.

Address for correspondence: G. Avils, Instituto Nacional de 
Enfermedades Virales Humanas "Dr. Julio I. Maiztegui",
Monteagudo  2510 (2700) Pergamino, Argentina; fax:
54-24-774-33045; e-mail: Gaby@inevh.sld.ar.

References

  1. Sabattini MS, Avils G, Monath TP. Historical,
epidemiological and ecological aspects of arboviruses in Argentina:
Flaviviridae, Bunyaviridae and Rhabdoviridae. In: An overview of
arbovirology in Brazil and neighboring countries. Travassos da
Rosa APA, Vasconcelos PFC, Travassos da Rosa JFS, editors.
Belem, Brazil: Instituto Evandro Chagas; 1998. p. 113-34.
  2. Boffi R. Programa de prevencin del dengue y control del
Aedes aegypti. In: Temas de zoonosis y enfermedades emergentes. 
2do Congreso Argentino de Zoonosis, 1er Congreso Argentino y 
Latinoamericano de Enfermedades Emergentes y Asociacin 
Argentina de Zoonosis, editors. 1998;413-419, Buenos Aires.
   3. Schweigmann N, Boffi R. Aedes aegypti y Aedes albopictus:
situacin entomolgica en la region. In: Temas de zoonosis y
enfermedades emergentes. 2do Congreso Argentino de Zoonosis,
1er Congreso Argentino y Latinoamericano de Enfermedades
Emergentes y Asociacin Argentina de Zoonosis (eds.)
1998;259-263, Buenos Aires.
  4. Avils G, Cecchini R, Harrington ME, Cichero J, Asis R, Rios
C. Aedes aegypti in Crdoba Province, Argentina. J Am Mosq
Control Assoc 1997;13:255-8.
  5. Russel PK, Nisalak A, Sukhavachana P, Vivona S. A plaque
reduction test for dengue virus neutralizing antibodies. J Immunol
1967;99:291-6.
  6. Innis BL, Nisalak A, Nimmannitya S, Kusalerdchariya S,
Chongwasdi V, Suntayakorn S, et al. An enzyme-linked
immunosorbent assay to characterize dengue infections where
dengue and Japanese encephalitis co-circulate. Am J Trop Med Hyg
1989;40:418-27.
  7. Kuno G, Gmez I, Gubler DJ. An ELISA procedure for the
diagnosis of dengue infections. J Virol Methods 1991;33:101-13.
  8. Lanciotti RS, Calisher CH, Gubler DJ, Chang GJ, Vorndam
AV. Rapid detection and typing of dengue viruses from clinical
samples by using reverse transcriptase-polymerase chain reaction. J
Clin Microbiol 1992;30:545-51.
  9. Gubler DJ, Kuno G, Sather GE, Velez M, Oliver A. Mosquito
cell cultures and specific monoclonal antibodies in surveillance for
dengue viruses. Am J Trop Med Hyg 1984;33:158-65.
 10. Centers for Disease Control and Prevention. Dengue fever at
the  U.S.Mexico border, 1995-1996. MMWR Morb Mortal Wkly
Rep 1996;45:841-4.
 11. Gubler DJ. Dengue. In: The arboviruses: epidemiology and
ecology. Monath TP, editor. II. Boca Raton, FL: CRC Press; 1988.
p. 223-60.
 12. Pan American Health Organization. Dengue and dengue
hemorrhagic fever in the Americas: guidelines for prevention and
control. Washington, D.C. 1994; Scientific publication No. 548.
_______________________________________________________________________

Dispatches

Chlorine Disinfection of Recreational Water for Cryptosporidium 
parvum

Colleen Carpenter,* Ronald Fayer,* James Trout,* and Michael J. 
Beach
*U.S. Department of Agriculture, Beltsville, Maryland,
USA; and Centers for Disease Control and Prevention, Atlanta,
Georgia, USA

  We examined the effects of chlorine on oocyst viability, under the
conditions of controlled pH and elevated calcium concentrations
required for most community swimming pools. We found that fecal
material may alter the Ct values (chlorine concentration in mg/L,
multiplied by time in minutes) needed to disinfect swimming pools
or other recreational water for Cryptosporidium parvum.

 The small size of the Cryptosporidium parvum oocyst (4-6 mm)
and its resistance to many chemical disinfectants (e.g., chlorine) 
pose a challenge for standard filtration and disinfection  procedures
(1). Moreover, the low dose required for infection and the
prolonged excretion of high numbers of oocysts make C. parvum
ideal for waterborne transmission. Chlorinated recreational water
facilities, such as public swimming pools and water parks
frequently used by large numbers of diapered  children, have been
implicated in numerous outbreaks of cryptosporidiosis during the
last decade (Table 1).

 Previous studies of chlorine inactivation of oocysts have used 
oxidant demand-free water and glassware or chlorine demand-free 
reactors (1,24-31); none were performed in simulated recreational
water (i.e., pH balanced, CaC(subl2) added for hardness, organic
material added). Therefore, Ct values (chlorine concentration in
mg/L multiplied by time in minutes) calculated under oxidant
demand-free laboratory conditions for disinfection of
microorganisms such as Cryptosporidium may not be directly 
applicable to recreational water environments where additional 
organic material, such as urine, feces, hair, sweat, sloughed  cells,
and lotion, is present, pH is controlled, and calcium concentration
is elevated. We report that under recreational water conditions
fecal material alone has a large negative effect on chlorine
inactivation of C. parvum oocysts, and therefore on pool water
quality and the potential for disease transmission.

 Study Design

Oocysts of the AUCP-1 isolate were extracted from the feces of 
experimentally infected calves and cleaned of fecal debris with 
cesium chloride (32). The short exposure to cesium chloride 
followed by thorough rinsing with deionized water has no 
deleterious effects on the oocyst wall or oocyst survival. Oocysts
cleaned by this method appear free from all organic  fecal debris
and other microorganisms and thus are potentially  more susceptible
to disinfectants than are oocysts surrounded by  debris. Oocysts
were stored at 4C until use and were less than 1 month old when
used.

Table 1. Outbreaks of cryptosporidiosis in recreational water 
facilities
 -------------------------------------------------------------------
                                          No. of cases
                                           estimated/   Date  
Facility   Location       Disinfectant     confirmed)  (year)  Ref. 
--------------------------------------------------------------------
Pool      Doncaster, UK   Chlorine     (sup a)/79      1988    2
Pool      Los Angeles     Chlorine          44/5       1988    3
            County
Pool      British         Chlorine          66/23      1990    4
            Columbia
Pool      Gloucester-,   Ozone/chlorine(sup a)/13      1992    5
            shire, UK
Water     Idaho           Chlorine         500/(sup a) 1992    6
 slide    
Pool      Oregon          Chlorine     (sup a)/52       1992    7
 (wave)   
Pool      Wisconsin       Chlorine          51/22      1993    8,9
 (motel)  
Pool      Wisconsin       Chlorine          64/(sup b) 1993    9
 (motel)
Pool      Wisconsin       Chlorine           5/(sup b) 1993    9
Pool      Wisconsin       Chlorine          54/(sup b) 1993    9
Pool      Missouri        Chlorine         101/26      1994   10
 (motel) 
Lake      New Jersey      None          2,070/46       1994   11
Pool      Sutherland,     Chlorine    (sup a)/70       1994   12
          New South Wales
Pool      Kansas          (sup a)         101/26       1995   13

Water     Georgia         Chlorine      2,470/62       1995   13
 park  
Water     Nebraska        (sup a)     (sup a)/14       1995   13
 park 
Pool      Florida         (sup a)          22/16       1996   14(sup c)
Water     California      Chlorine      3,000/29       1996 13,15(sup c) 
 park 
Pool      Andover, UK     Chlorine          8/(sup a)  1996   16
Lake      Indiana           None            3/(sup a)  1996   13
River    NW England &       None           27/7        1997   17(sup c)
          Wales
Pool     SW England &     Ozone &      (sup a/9)       1997   17(sup c)
          Wales            chlorine
Fountain Minnesota       Sand filter      369/73       1997   18
Three    Canberra,        (sup a)     (sup a)/210      1998   19(sup c),
 pools    Australia                                           20(sup c)
Pool     Oregon           (sup a)          51/8        1998   21(sup c)
Pools    Queensland       (sup a)         129/(sup a)  1997   21(sup c)
Pools    New South Wales  (sup a)         370/(sup a)  1998   22(sup c)
Pools    Hutt Valley, New (sup a)    (sup a)/171       1998   23(sup c)
          Zealand
-----------------------------------------------------------------
(sup a)No data available.
(sup b)Reference did not identify cases as estimated or confirmed.
(sup c)Reference is not peer reviewed and may not reflect a rigorous 
investigation of the outbreak.

Two experiments were conducted to determine how long oocysts 
would remain infectious when exposed to two concentrations of 
chlorine at two temperatures. Stock solutions of 2.0 ppm and  10.0
ppm HOCl in demineralized water (resistance measured 18 
mega-ohm) were prepared with commercial laundry bleach
(CLOROX).  Chlorine concentrations were monitored with a digital
chlorine colorimeter kit (LaMotte model no. DC 1100,
Chestertown, MD). In  experiment 1, one centrifuge tube (15 ml
polypropylene, screw-top Falcon, Becton Dickinson, Franklin
Lakes, NJ) was  prepared containing 1 x 10(sup 6) oocysts for each of
the 28  temperature and time combinations. Tubes were centrifuged
at  1,500 g for 15 minutes; supernatants were decanted, and oocyst 
pellets were resuspended in 12 ml of stock chlorine solution. Tubes
were then placed in controlled temperature water circulators
(model 9101; Polyscience, Inc., Niles, IL) and incubated at 20C or
30C. For all mice to be the same age at the time of infection, tubes
were prepared on 7 successive days and placed in the water
circulators so that all incubations ended and all mice were
inoculated on the same day (Table 2).

Because of the small volume in each tube, it was not possible to 
monitor the chlorine concentration daily. Therefore, readings were
taken initially and after incubation, immediately before the mice
were inoculated. Upon removal from the water  circulators, all
tubes were centrifuged at 1,500 g for 15 minutes, supernatant was
aspirated, and pelleted oocysts were resuspended in 1 ml of
demineralized water. Oocysts in each tube  were then administered
orally to four neonatal BALB/c mice by gastric intubation. Each
mouse received 150,000 oocysts. Oocysts remaining in each tube
were counted with a hemacytometer to verify dosage levels.
Individual oocysts were counted in the clumps of 2 to 4 oocysts
observed on days 5 through 7. Mice were euthanized by CO(sub 2) 
overexposure 96 hours after intubation. To assess infectivity,
hematoxylin- and eosin-stained histologic sections of ileum from
each mouse were examined by brightfield microscopy for
developmental stages of C. parvum (24).

 Because the results from experiment 1 indicated a need to  examine
shorter times of oocyst exposure to chlorine, a second  experiment
was conducted in which oocysts were tested for viability after
exposure to chlorinated water for 6, 12, 24, 48, and 72 hours
(Table 2). To simulate actual pool conditions (33), chlorinated
water was balanced between pH 7.2 and 7.8, and CaC(sup 12) was added
to a concentration of 200 ppm to 400 ppm.

Table 2. Contact times and infectivity for purified Crytosporidium
parvum oocysts subjected to chlorination (Experiments 1 and 2)(sup a)
----------------------------------------------------------------
                                  2 ppm              10 ppm
                              -------------     ---------------
                               Infectivity          Infectivity
                    Ct(sup b)                Ct(sup b)
Expt.  Days (min.)    value    20C    30C    value   20C   30C
 2           (360)     720      4/4    4/4     3,600    4/4    0/4
 2           (720)   1,440      4/4    3/4     7,200    0/4    0/4
 1      1   (1440)   2,880      4/4    0/4    14,400    0/4    0/4
                               (sup c)
 2      1   (1440)   2,880      4/4    0/4    14,400    0/4    0/4
 1      2   (2880)   5,760      0/4    0/4    28,800    0/4    0/4
 2      2   (2880)   5,760      0/4    0/4    28,800    0/4    0/4
 1      3   (4320)   8,640      4/4    0/4    43,200    0/4    0/4
 2      3   (4320)   8,640      0/4    0/4    43,200    0/4    3/4
 1      4   (5760)  11,520      0/4    0/4    57,600    0/4    0/4
 1      5   (7200)  14,400      0/4    0/4    72,000    0/4    0/4
 1      6   (8640)  17,280      0/4    0/4    86,400    0/4    0/4
 1      7 (10,080)  20,160      0/4    0/4   100,800    0/4    0/4
----------------------------------------------------------------
(sup a)Treatments in which mice were found infected are shown in bold
(sup b)Hypothetical Ct value calculated by assuming constant chlorine 
concentration.
(sup c)Fraction represents number of mice showing developmental 
stages of C. parvum in the intestinal epithelium over the total 
number of mice inoculated, e.g., 4/4 indicates 4 mice were 
found infected out of 4 mice inoculated.

To simulate a swimming pool fecal incident and thereby test the 
effectiveness of chlorine on oocysts in the presence of organic 
material, three aquariums were each filled with 30 L of tap water
balanced to meet standard pool regulations (33). The pH was
maintained by adding NaOH or HCl, and the calcium level was 
maintained by adding CaC(sub 12). In one aquarium, sufficient chlorine 
was added to achieve and maintain 2.0 ppm, a normal pool 
concentration. In another aquarium used to represent a response to
water contamination, chlorine was maintained at 10 ppm. In the
third aquarium, calcium and pH were held at standard pool 
conditions, but no chlorine was added. The aquariums were 
maintained at room temperature and were covered with a glass 
plate to prevent evaporation. Chlorine, pH, and calcium values 
were monitored 4 times a day between 8:00 a.m. and 4:30 p.m. and 
adjusted to target levels when necessary.

 Calculations for simulating a pool fecal accident in an aquarium 
were based on a 700,000-L swimming pool and an infected person 
excreting an estimated 490 g of fecal material into the water 
(490,000 mg feces per 700,000 L pool = 0.7 mg/L; 0.7 mg/L x 30
L  aquarium = 20 mg feces). The estimated ratio of fecal mass to 
water volume necessarily correlates with large contamination to 
maintain a ratio based on the small size of the aquarium and the 
need for a sufficient quantity of feces and oocysts for testing. The
number of oocysts added was based on laboratory experience for
recovery of oocysts from numerous 5-g fecal samples of  bovine
feces.

To simulate a loose fecal mass but not fully dispersed feces, 
dialysis tubing (SPECTRUM Medical Industries, Inc., Los Angeles, 
CA) with a molecular weight cutoff of 6,000 to 8,000 was used to 
contain the oocysts and fecal mixture. Fecal material came from a
calf that tested negative for C. parvum. Feces were mixed with 
water to form a diarrhea-like consistency. To ensure the  recovery
of sufficient oocysts for later bioassay in mice, 2 x 10(sup 6) oocysts in
20 mg of the fecal slurry were introduced into the dialysis tubing
and then filled with water from the appropriate aquarium. Time
points of 0, 6, 12, 24, and 48 hours of exposure were tested.
Therefore, additional dialysis tubing containing oocysts and fecal
material was added to each aquarium at specified intervals, and all
were removed at the end of the incubation time. Oocysts were
aspirated from the dialysis tubing, they were concentrated by
centrifugation (1,500 g, 15 minutes), and 150,000 were intubated
into each of 3 to 5 neonatal BALB/c mice as before. Necropsy of
mice and assessment for infectivity were performed as in the
previous experiment.

Findings              

In the first experiment, oocysts maintained at 20 in 2 ppm 
chlorine for 1 and 3 days were infectious for mice. Oocysts 
maintained at higher temperatures or chlorine concentrations were
not infectious for mice (Table 2).

In the second experiment, oocysts maintained at 20C in 2 ppm 
chlorine remained infectious after exposure of 6 to 24 hours (Table
2). At 20C and 10 ppm chlorine, oocysts exposed for 6 hours
infected mice, whereas those exposed longer did not. At 30C and
2 ppm chlorine, oocysts exposed for 6 hours infected all mice,
those exposed for 12 hours infected 3 of 4 mice, and those
exposed longer were not infectious. At 30C and 10 ppm chlorine,
oocysts held for 6, 12, 24, and 48 hours did not initiate infection;
however, those held for 72 hours were infectious for 3 of 4 mice.

In the third experiment, tissues from all mice inoculated with the
oocysts exposed to all incubation time points at 0, 2, or 10 ppm
chlorine were found to contain developmental stages of the 
parasite in the intestinal epithelium. These findings indicated that
oocysts in the presence of fecal material remained infectious even
after exposure to 10 ppm chlorine for 48 hours.

Conclusions

Swimming is the second most popular recreational activity in the 
United States, with more than 350 million persons participating 
each year (34). The emergence of C. parvum as a major cause of 
recreational waterborne disease has prompted public health 
workers to reevaluate existing recommendations and regulations 
for water quality and use. Frequent fecal contamination of 
recreational water and the high level of C. parvum oocyst 
resistance to chlorine, the low oocyst dose required for infection,
and high numbers of bathers make it imperative that we understand
how oocyst inactivation is affected by recreational water
conditions, including fecal contamination.

 In our first experiment, to become noninfectious, purified C. 
parvum oocysts in chlorine demand-free deionized water required 
exposure to chlorine at a Ct value higher than 8,640. This value 
is relatively close to that obtained for disinfection under similar
chlorine demand-free conditions (Ct = 7,200-9,600) (28). Purified
C. parvum oocysts in chlorine demand-free water balanced to meet
swimming pool standards (experiment 2) required even less time to
be rendered noninfectious, i.e., exposure to 2 ppm chlorine for 2
days at 20C or 1 day at 30C. Incubation in 10 ppm chlorine
rendered oocysts noninfectious in 6 hours or less at both
temperatures, respectively.

 The findings that oocysts in experiment 1 were infectious when 
exposed to 2 ppm at 20C for 1 and 3 days but not for 2 days and 
that oocysts in experiment 2 infected 3 of 4 mice after exposure  
to 10 ppm chlorine at 30C for 72 hours but not for shorter periods
underscores the difficulty of performing these experiments. Such
findings may be explained by the stickiness of the oocyst surface,
which leads to clumping that can result in nonuniform sampling or
possibly protection from inactivation. However, these outlying
datapoints in experiments 1 and 2 are inconsistent with total oocyst
inactivation observed in the shorter incubation times under the
same conditions. It is unclear whether a few oocysts survived the
exposure period or whether the infections were experimental
artifacts. Environmental contamination of the mouse colony used
for the bioassays is unlikely because no mice from the negative
control litter used for this study or from >1,000 previous negative 
control mice used in this laboratory had developed a C. parvum 
infection. These data suggest that disinfection of C. parvum, in  the
absence of feces or other organic contaminants, may be less 
difficult than thought, particularly at the higher temperatures found
in chlorinated recreational venues.

 In contrast to experiment 2, in which fecal matter was absent, 
oocysts in experiment 3 were incubated under identical water and 
chlorine conditions but in the presence of feces (i.e., a simulated
fecal accident) and remained infectious at all time  points through
48 hours. Because this simulated accident was contained in a
dialysis bag rather than being dispersed, it may not represent the
best model for a dispersed diarrheal accident. Containment of
oocysts with the organic material may actually have afforded some
protection from inactivation. This highlights our incomplete
understanding of C. parvum inactivation and the detrimental effect
that organic or fecal contamination can play in recreational water.

 Although the fecal accident simulated here could be considered 
major, the decrease in effective chlorine action is probably a 
conservative measure for recreational water since the simulation 
did not include additional biologic contaminants found in 
recreational water (i.e., sweat, hair, skin cells, lotion, urine, and
algae). Because oocysts attach readily to biologic particles (35),
such particles may provide a protective surrounding. The retarded
inactivation of an already chlorine-resistant organism suggests that
the current recommendation (36) for responding to fecal accidents
(20 mg  chlorine/L for 9 hours to achieve a Ct value of 10,800)
needs to  be tested under appropriate conditions of water quality
(33) in  the presence of fecal and organic contaminants (both as
tested  here or dispersed in a pool) and revised as necessary.

 Routine use of recreational venues by diapered children from 
day-care facilities, who have an elevated prevalence of C. parvum
infection, increases the potential for waterborne disease 
transmission. Prevention plans that combine engineering changes 
(improved filtration and turnover rates, separate plumbing and 
filtration for high-risk "kiddie" pools), pool policy modifications
(fecal accident response policies, test efficacy of barrier garments
such as swim diapers), and patron and staff education should
reduce the risk for waterborne disease transmission in public
recreational water venues. Education efforts should stress current
knowledge about waterborne disease transmission and suggest
simple prevention measures such as refraining from pool use during
a current or recent diarrheal episode, not swallowing recreational
water, using proper diaper changing and handwashing practices,
instituting frequent timed bathroom breaks for younger children,
and promoting a shower before pool use to remove fecal residue.
-----------------------------------------------------------------

Ms. Carpenter is a graduate student at Virginia Commonwealth 
University's Center for Environmental Studies. She is studying 
amoebae in Asian freshwater clams as biologic indicators of runoff
from combined sewer outfalls into the James River. Ms. 
Carpenter's interests include the epidemiology of foodborne and 
waterborne parasitic protozoa.

Address for correspondence: R. Fayer, USDA, ARS, LPSI, 10300 
Baltimore Avenue, Bldg 1040, Beltsville, MD 20705, USA; fax: 
301-504-5306; e-mail: rfayer@lpsi.barc.usda.gov.

References

 1. Fayer R, Speer CA, Dubey JP. The general biology of  
Cryptosporidium. In: Cryptosporidium and cryptosporidiosis.  
Fayer R, editor. Boca Raton (FL): CRC Press; 1997. p. 1-41.
 2. Joce RE, Bruce J, Kiely D, Noah ND, Dempster WB, Stalker
R, et al. An outbreak of cryptosporidiosis associated with a  
swimming pool. Epidemiol Infect 1991;107:497-508.
 3. Sorvillo FJ, Fujioka K, Nahlen B, Tormey MP, Kebabjian RS,  
Mascola L. Swimming-associated cryptosporidiosis. Am J Public
Health 1992;82:742-4.
 4. Bell A, Guasparini R, Meeds D, Mathias RG, Farley JD. A  
swimming pool-associated outbreak of cryptosporidiosis in British
Columbia. Canadian J Public Health 1993;84:334-7.
 5. Hunt DA, Sebugwawo S, Edmondson SG, Casemore DP.  
Cryptosporidiosis associated with a swimming pool complex.  
Commun Dis Rep CDR Rev 1994;4:R20-2.
 6. Moore AC, Herwaldt BL, Craun GF, Calderon RL, Highsmith
AK, Juranek DD. Surveillance for waterborne disease  
outbreaksUnited States, 1991-1992. MMWR Morb Mortal Wkly  
Rep 1993;42(SS-5):1-22.
 7. McAnulty JM, Fleming DW, Gonzalez AH. A community-wide 
 outbreak of cryptosporidiosis associated with swimming at a  
wave pool. JAMA 1994;272:1597-600.
 8. MacKenzie WR, Kazmierczak JJ, Davis JP. An outbreak of  
cryptosporidiosis associated with a resort swimming pool.  
Epidemiol Infect 1995;115:545-53.
 9. Kramer MH, Herwaldt BL, Craun GF, Calderon RL, Juranek
DD. Waterborne disease: 1993 and 1994. J Am Water Works
Assoc 1996;88:66-80.
10. Wilberschied L. A swimming-pool-associated outbreak of  
cryptosporidiosis. Kansas Medicine 1995;96:67-8.
11. Kramer M, Sorhage F, Goldstein S, Dalley E, Wahlquist S,  
Herwaldt B. First reported outbreak in the United States of  
cryptosporidiosis associated with a recreational lake. Clin Infect
Dis 1998;26:27-33.
12. Lemmon JM, McAnulty JM, Bawden-Smith J. Outbreak of 
cryptosporidiosis linked to an indoor swimming pool. 
Med J Aust 1996;165:613-6.
13. Levy DA, Bens MS, Craun GF, Calderon RL, Herwaldt BL.
Surveillance for waterborne disease outbreaksUnited States,
1995-1996. MMWR Morb Mortal Wkly Rep 1998;47(SS-5):1-34.
14. Past water-related outbreaks in Florida. Crypto Capsule  
1998;3:3.
15. Effects of last summer's outbreak on Wild Water Adventure's  
theme park. Crypto Capsule 1997;2:1-3.
16. Sundkvist T, Dryden M, Gabb R, Soltanpor N, Casemore D,  
Stuart J, et al. Outbreaks of cryptosporidiosis associated with a
swimming pool in Andover. Commun Dis Rep 1997;7:R190-2.
17. Outbreaks in England and Wales: first half of 1997. Crypto  
Capsule 1998;3:4.
18. Outbreak of cryptosporidiosis associated with a water  
sprinkler fountain-Minnesota, 1997. MMWR Morb Mortal Wkly  
Rep 1998;47:856-60.
19. Swimming pools implicated in Australia's largest  
cryptosporidiosis outbreak ever reported. Crypto Capsule  
1998;3:1-2.
20. Number of cryptosporidiosis cases increase in Australia.  
Crypto Capsule 1998;3:1-2.
21. Most cases in Australia linked to swimming pool exposure.  
Crypto Capsule 1998;3(7):5-6.
22. Recreational outbreak in Oregon. Crypto Capsule  
1998;4(1):1.
23. New Zealand's pool related outbreak is over.
Crypto Capsule 1998;3(9)5-6.
24. Fayer R. Effect of sodium hypochlorite exposure on  
infectivity of Cryptosporidium parvum oocysts for neonatal  
BALB/c mice. Appl Environ Microbiol 1995;61:844-6.
25. Finch GR, Black EK, Gyurek LL. Ozone and chlorine  
inactivation of Cryptosporidium. Proceedings of the AWWA  
Water Quality Technical Conference, San Francisco, CA 1994;  
1303-8.
26. Venczel LV, Arrowood M, Hurd M, Sobsey MD. Inactivation
of Cryptosporidium parvum oocysts and Clostridium perfringens  
spores by a mixed-oxidant disinfectant and by free chlorine. Appl
Environ Microbiol 1997;63:1598-601.
27. Gyurek LL, Finch GR, Belosevic M. Modeling chlorine  
inactivation requirements of Cryptosporidium parvum oocysts. J
Environ Eng 1997;123:865-75.
28. Korich DG, Mead JR, Madore MS, Sinclair NA, Sterling CA.  
Effects of ozone, chlorine dioxide, chlorine, and monochloramine
on Cryprosporidium parvum oocyst viability. Appl Environ
Mirobiol 1990;56:1423-7.
29. Parker JFW, Smith HV. Destruction of oocysts of  
Cryptosporidium parvum by sand and chlorine. Water Res  
1993;27:729-31.
30. Pavlasek I. Effect of disinfectants in infectiousness of oocysts
of Cryptosporidium sp. Cs Epidemiol 1984;33:97-101.1.
31. Campbell I, Tzipori S, Hutchison G, Angus KW. Effect of  
disinfectants on survival of Cryptosporidium oocysts. Vet   Rec
1982;111:414-15.
32. Kilani RT, Sekla L. Purification of Cryptosporidium oocysts  
and sporozoites by cesium chloride and percoll gradients. Am J
Trop Med Hyg 1987;36:505-8.
33. ANSI/NSPI 1 Standards for public swimming pools. In: Pool  
and spa water chemistry. Taylor Technologies, Inc., Sparks, MD.
1994. p. 40.
34. U.S. Bureau of the Census, Statistical Abstract of the United
States: 1995. 115th ed. Washington: The Bureau; 1995. p. 260.
35. Medema GJ, Schets FM, Yeunis PFM, Havelaar AH.  
Sedimentation of free and attached Cryptosporidium oocysts and
Giardia cysts in water. Appl Environ Microbiol 1998;64:4460-6.
36. Kebabjian RS. Disinfection of public pools and management  
of fecal accidents. J Environ Health 1995;58:8-12.
_______________________________________________________________________

Dispatches

Cyclospora cayetanensis Among Expatriate and Indigenous
Populations of West Java, Indonesia

David J. Fryauff,* Reinhard Krippner, Purnomo Prodjodipuro,*
Christa Ewald, Shirley Kawengian, Katrin Pegelow, Thomas
Yun, Claudia von Heydwolff-Wehnert, Buhari Oyofo,* and
Rainer Gross# 
*U.S. Naval Medical Research Unit No. 2, Jakarta, Indonesia;
Embassy of the Federal Republic of Germany, Jakarta, Indonesia;
University of Indonesia, Jakarta, Indonesia;
SEAMEO-TROPMED Regional Center for Community Nutrition,
Jakarta, Indonesia; Embassy of the United States of America,
Jakarta, Indonesia; #Deutsche Gesellschaft fr Technische
Zusammenarbeit (GTZ) GmbH, Eschborn, Germany 

 From January 1995 through July 1998, we investigated the
occurrence of Cyclospora cayetanensis infection associated with
gastrointestinal illness or diarrhea in foreign residents and natives
of West Java, Indonesia. We found that C. cayetanensis was the
main protozoal cause of gastrointestinal illness and diarrhea in
adult foreign residents during  the wet season. The parasite rarely
caused illness in the indigenous population or in children.

Cyclospora cayetanensis is a newly recognized coccidian parasite
associated with sudden onset of gastrointestinal illness and chronic
diarrhea. In developing countries, cases occur sporadically, in a
seasonal pattern, and primarily among western expatriates and
travelers (1,2).
 
We recently reported multiple symptomatic cases of C. cayetanensis
infection among European expatriates living in Jakarta, Indonesia;
C. cayetanensis and Giardia lamblia were the intestinal parasites
most frequently identified (6.4%) in cases of gastroenteritis or
chronic diarrhea (3). We report here the results of a longitudinal
evaluation of Cyclospora infection among expatriate populations of
Jakarta and the results of two recent surveys of intestinal parasite
infections in Indonesian children.

Three clinical diagnostic laboratories, each serving subpopulations
of expatriate residents of Jakarta, Indonesia, participated in the
longitudinal evaluation. The medical unit of the Embassy of the
Federal Republic of Germany, a diagnostic center for an estimated
300 European expatriates, screened for ova and parasites in cases
of gastrointestinal illness and diarrhea from January 1995 through
July 1998. The Parasitology Department of the U.S. Naval Medical
Research Unit No. 2 (NAMRU-2) provided diagnostic services for
U.S. military staff and their families living in Jakarta during January
1996 to January 1998. The U.S. Embassy Medical Unit in Jakarta
performed diagnostic parasitic tests for approximately 500 U.S.
expatriate residents from January to December 1998. 

All three laboratories performed wet-mount microscopy of fresh
and formalin-ethyl acetate-concentrated feces stained with dilute
iodine or merthiolate-iodine-formalin solution. All specimens were
from persons with self-reported cases of gastrointestinal illness and
diarrhea who sought medical attention. Confirmation of Cyclospora
was based primarily on size and morphologic features relative to
reference slides provided by J.H. Cross, Uniformed Service
University of Health Sciences, Washington, D.C., and secondarily
on acid-fast staining characteristics. The NAMRU-2 laboratory also
routinely applied a modified, 22 mm x 40 mm Kato thick-smear
technique to estimate parasite/ova density. Analyses were limited to
autochthonous cases by evaluating patient histories and excluding
those that were probably acquired outside Indonesia.

All 8- to 10-year-old Indonesian children attending 10 public
schools in rural Sukaraja District, West Java, Indonesia, were
examined for parasites and ova during December 1995. Direct
wet-mount microscopy and modified Kato thick-smear examination
of a fresh fecal specimen were performed. Two independent
examinations were performed on each sample by clinical
parasitologists. After informed parental consent, a subsample of 83
children was enrolled into a prospective study to monitor episodes
of diarrhea following mebendazole de-worming. Stool samples
were collected weekly or during gastrointestinal illness or diarrhea
over 13 consecutive weeks of posttreatment observation (March to
June 1996). Specimens were screened for parasites and ova as
described above.

A hospital-based study to determine the causes of diarrhea among
Indonesian residents of Jakarta was initiated in July 1997 as a
collaborative study between the Departments of Microbiology and
Parasitology, the Health Research Branch of the Indonesian
Ministry of Health, and several participating Jakarta hospitals. A
single stool sample was collected for testing from study participants
who reported to the clinic with diarrhea lasting >72 hours.
Preliminary analysis for parasitic causes associated with diarrhea
was done in cases of children < 3 years old who were screened
during the first 12 months (July 1997 to June 1998) of this 3-year
study.

C. cayetanensis was the dominant pathogenic intestinal parasite,
present in 29 (11.5%) of 253 cases of gastrointestinal illness and
diarrhea among European expatriates who sought medical care
during January 1995 to January 1998 (Table). C. cayetanensis was
the most frequently identified pathogenic intestinal parasite each
year, accounting for 8.6% to 15.1% of the annual diagnoses. All
but one of these cases were in adults (30 years of age or older).
Cases were clustered during the wet season (November May),
suggesting a seasonality of risk (Figure).

Table. Parasites associated with self-reported gastrointestinal illness
or diarrhea, German Embassy Health Unit, Jakarta, Indonesia
-----------------------------------------------------------------------
                        Entamoeba                                Blasto
       No. Cyclospora histolytica/ Giardia Trichuris Ascarislum -cystis
       exa cayetanensis E. dispar  lamblia trichiura bricoides   hominis
Year -mined   No. (%)    No. (%)   No. (%)   No. (%)   No. (%)   No. (%)
-----------------------------------------------------------------------
1995   104     9 (8.6)    8 (7.7)   4 (3.8)   5 (4.8)   1 (1.0)  23 (22.1)

1996    96    12 (12.5)   4 (4.2)   2 (2.1)   2 (2.1)   0        10 (10.4)

1997   53(sup  8 (15.1)   4 (7.5)   1 (1.9)   2 (3.8)   1 (1.9)   5(9.4)
          a)
Total 253     29 (11.5)  16 (6.3)   7 (2.8)   9 (3.5)   2 (0.8)  38 (15)

-------------------------------------------------------------------------
(sup a)No laboratory diagnoses were performed during June and July 1997.

The second Jakarta-based laboratory that performed parasitologic
screening on predominantly American families identified C.
cayetanensis in 9 (9.1%) of 99 persons with gastrointestinal illness
or diarrhea who sought care during a 24-month period. Cyclospora
oocyst counts per gram of feces from these symptomatic C.
cayetanensis cases were 100 to 327,600/gm; the highest counts
were associated with early onset and acute symptoms. All nine C.
cayetanensis cases were in adults.

The U.S. Embassy Health Unit in Jakarta identified 28 C.
cayetanensis infections among 206 patients (13.6%) with
gastrointestinal illness or diarrhea who were examined during an
11-month period in 1998. Pediatric infections, seen only in
teenagers, accounted for 2 of the 28 cases. An apparent association
was found between expatriates' risk for infection and the cooler wet
season (October-May) (Figure).

[fig]

Figure. Monthly profiles of Cyclospora infection among
gastrointestinal illness/diarrhea cases at private health laboratories
serving expatriate populations of Jakarta, Indonesia.

A well population of 348 Indonesian schoolchildren was screened
for intestinal parasite infections. The prevalence of intestinal
helminth and protozoan infections among the children was 84% and
77%, respectively. Asymptomatic, low-density C. cayetanensis
infections were found in 2 (0.6%) children.

A prospective study of 83 of these children was performed for
1,006 weeks of follow-up (average 12.2 weeks per child). Single or
multiple samples of loose or watery stool (230 per 1,006 total
samples) were collected from 71 of the 83 children. Although
generally well and attending school, 26 (31.3%) of these 71
children had loose or watery stools at least four times during
follow-up. Low-density C. cayetanensis infections were identified in
two (2.4%) children, for an incidence of two infections per 19.3
person-years.

In the first year of the 3-year Jakarta diarrhea study, 263
Indonesians were screened for parasites; 170 (64.6%) of these were
children younger than 3 years of age (ave. = 10.9 months, SD = 7.5
months). No Cyclospora infections were found.

The relatively sudden appearance, since 1995, of C. cayetanensis
infections among long-term expatriate residents of Jakarta may
indicate either a new ability of local diagnostic laboratories to
recognize an established parasite or new establishment of this
pathogen in the urban environment of Indonesia. Recent
parasitologic surveys conducted throughout Indonesia may not
have been undertaken with sufficient sensitivity to detect C.
cayetanensis and may have been conducted during periods of low
transmission.

The high frequency with which C. cayetanensis infections were
found in expatriate patients cannot be attributed to new staining or
concentration methods. Three laboratories applied direct
wet-mount microscopy to identify this agent, and each laboratory
independently classified C. cayetanensis as the dominant pathogenic
parasite associated with diarrhea. Despite moderately enhanced
recovery of C. cayetanensis oocysts by formalin-ethyl acetate
sedimentation, virtually all diagnoses were made from the initial
findings of the direct wet-mount or the modified Kato thick smear
and were not dependent on the concentration step.

Cyclospora infections were identified in the cross-sectional
prevalence survey and the prospective study of rural schoolchildren
but not in the diarrhea specimens from Jakarta infants during the
year-long study. Unlike the C. cayetanensis infections among
foreign residents of Jakarta, infections by this parasite in rural
Indonesian children were rare and characterized by low parasite
density, absence of symptoms, and sporadic appearance.

These disparate findings suggest various possibilities: 1) The
absence of Cyclospora infection in young children with diarrhea,
both expatriate and native Indonesian, may result from their lack of
exposure to foods or other risk factors to which older children and
adults are exposed. Additionally, Indonesian infants may be
protected by maternally acquired passive immunity. 2) Fecal
contamination of food and water in rural Indonesia may be
sufficiently high that local children, by the age of 8 to 10 years,
have effective clinical and parasitologic immunity to Cyclospora
and other pathogens. Infection of Indonesian children by other
enteric pathogens may confer cross-protective immunity. 3) Urban
transmission of Cyclospora may predominate among expatriate
residents of Jakarta because of their atypical food preferences
(imported, varied, fresh fruit and vegetables, restaurant-prepared)
and preparations (prepared by servants, frequent use of raw garnish
and salads).

The paucity of Cyclospora infections associated with loose stool or
diarrhea in the rural and urban Indonesian children may not be
atypical for these age groups. Among children of Bangkok (<5)
who were screened for diarrheal causes during 1985 to 1986,
Cryptosporidium was the only protozoon associated with illness
(4). If Cyclospora was also present in this population but classified
as Cryptosporidium spp., these organisms collectively accounted
for only 1.8% of cases and 0.3% of controls.

Among nearly 900 Jakarta expatriates of all ages, we saw relatively
few pediatric cases of Cyclospora and suspect that infections in this
age group may also go undetected. Our methods may not have been
sufficiently sensitive to detect mild infections of Cyclospora in
highly susceptible young persons or in asymptomatic older persons
who have been sensitized, even without prior exposure to C.
cayetanensis, by repeated new contact and long-term maintenance
of other commensal and pathogenic parasite infections.

Despite the likelihood that pathogenic bacterial and viral agents are
the principal causes of gastrointestinal illness and diarrhea among
native and expatriate residents of Indonesia (5,6), our results clearly
identify C. cayetanensis as commonly associated with these health
problems.

Acknowledgments

The authors thank Aftab Ansari for critical review of the
manuscript. They also thank Wolfgang Benkel, Regional Medical
Officer of the German Embassy, Jakarta, Indonesia; Carol Francis,
Registered Medical Technologist, American Embassy, Jakarta,
Indonesia; and collaborating investigators of the Health Research
Branch of the Indonesian Ministry of Health (LITBANGKES),
Harapan Kita, Sumber Waras, and Persahabatan Public Hospitals of
Jakarta, Indonesia, for their contributions. This work was
conducted in accordance with U.S. Navy and Republic of Indonesia
regulations governing the protection of human subjects in medical
research.

Portions of this work were supported by U.S. Naval Medical
Research and Development Command work unit number 623002A.

 Dr. Fryauff heads the Parasitic Disease Program of the U.S. Navy
Medical Research Unit No. 2 in Jakarta, Indonesia. His principal
research interest is in malaria: drug trials for prevention and
treatment, monitoring drug resistance, evaluating rapid diagnostics,
and immunologic and epidemiologic studies.

 Address for correspondence: David J. Fryauff, U.S. NAMRU-2,
Box 3, APO AP 96520-8132; fax: 62-21-424-4507; e-mail:
fryauff@smtp.namru2.go.id.

References

  1. Ortega YR, Sterling CR, Gilman RH, Cama VA, Diaz F.
Cyclospora speciesa new protozoan pathogen of humans. N Engl J
Med 1993;328:1308-12.
  2. Mintz ED, Long EG. CLB: an emerging infectious cause of
chronic diarrhea. CDC/NCID report. Infect Dis Clin Pract
1994;3:315-20.
  3. Fryauff DJ, Krippner R, Purnomo, Ewald C, Echeverria P. Case
report of Cyclospora infection acquired in Indonesia and treated
with cotrimoxazole. Am J Trop Med Hyg 1996;55:584-5.
  4. Echeverria P, Taylor DN, Lexsomboon U, Bhaibulaya M,
Blacklow NR, Tamura K, et al. Case-control study of endemic
diarrheal disease in Thai children. J Infect Dis 1989;159:543-8.
  5. Subekti D, Lesmana M, Komalarini S, Tjaniadi P, Burr D,
Pazzaglia G. Enterotoxigenic Escherichia coli and other causes of
infectious pediatric diarrheas in Jakarta, Indonesia. SE Asian J Trop
Med Pub Hlth 1993;24:420-4.
  6. Richie E, Punjabi NH, Corwin A, Lesmana M, Rogayah I,
Lebron C, et al. Enterotoxigenic Escherichia coli diarrhea among
young children in Jakarta, Indonesia. Am J Trop Med Hyg
1997;57:85-90.
_______________________________________________________________________

Dispatches

The First Major Outbreak of Dengue Hemorrhagic Fever in Delhi,
India

L. Dar, S. Broor, S. Sengupta, I. Xess, and P. Seth
All India Institute of Medical Sciences, Ansari Nagar, New Delhi,
India

An outbreak of dengue hemorrhagic fever/dengue shock
syndrome (DHS/DSS) occurred in 1996 in India in and near Delhi.
The cause was confirmed as dengue virus type 2, by virus
cultivation and indirect immunofluorescence with type-specific
monoclonal antibodies. This is the largest such outbreak reported 
from India, indicating a serious resurgence of dengue virus
infection.

An outbreak of dengue hemorrhagic fever/dengue shock syndrome
(DHF/DSS) occurred in Delhi, India, and its adjoining areas, from
August through November 1996. We confirmed the etiologic agent
of this outbreak as dengue virus type 2 by virus cultivation and
indirect immunofluorescence with type-specific monoclonal
antibodies. This is the largest culture-confirmed outbreak of
DHF/DSS in India and indicates a serious resurgence of dengue
virus infection in this country.

Dengue fever occurs worldwide, in nearly all tropical and
subtropical countries (1). Dengue virus was first isolated in India in
1945 (2). All four virus types circulate and cause epidemics, but
only occasional cases of DHF/DSS have been reported in India (3).

Delhi, situated in the northern part of India, had outbreaks of
dengue virus infection due to different dengue virus types in 1967,
1970, 1982, and 1988, but no culture-confirmed cases of DHF/DSS
were reported during these epidemics (4-7). Some cases of DHF
were seen for the first time in 1988 (7). These were confirmed only
serologically, by the hemagglutination inhibition test.

Delhi had its largest outbreak of DHF/DSS in 1996. The outbreak
started the last week of August and continued until the end of
November, peaking in mid-October (8,9). A total of 8,900 cases
were reported, with a death rate of 4.2% (9). We report results of
virologic testing of samples received at the All India Institute of
Medical Sciences from patients with suspected dengue fever or
denguelike illness from Delhi and its adjoining areas, along with a
profile of the culture-confirmed cases.

Virus isolation was carried out on 149 samples received on ice from
patients with acute illness. Serum was separated aseptically and
stored at -70C. The standard method of virus cultivation, which
used the C6/36 clone of Aedes albopictus cell line, was followed
with some modifications (10).

On days 5 and 10, cells were tested by indirect immunofluorescence
assay (IFA) by using monoclonal antibodies to dengue virus types
1-4. If IFA was negative for dengue viruses on first passage, a
second passage was made, and cells were again harvested on days 5
and 10 for IFA. All four dengue virus types (from the National
Institute of Virology, Pune, India) were included as positive
controls, and uninfected C6/36 cells were kept as negative controls.

Dengue viruses were isolated in C6/36 cells from 27 (18.1%) of
149 samples processed for virus isolation. Of the 27 isolates, 26
were identified as dengue virus type 2 and one as dengue virus type
1. Sixteen of the 27 isolates were from patients with DHF/DSS,
while 11 were isolated from patients with uncomplicated dengue
fever. Of the 27 culture-positive patients, 11 (40.7%) were in the 5-
to 12-year age group (Table). However, the isolates were nearly
equally distributed among children (<12 years) and adults. The ratio
of male to female in these 27 cases was 12:15. The median duration
of fever at the time of viral isolation was 4 days, on the basis of 24
culture-positive cases for which the duration of fever was available.
After 5 days of fever, virus isolation was possible only from one
patient. The median duration of viremia in dengue type 2 infection
was also found to be 4 days in a detailed study on dengue viremia
from Jakarta, Indonesia (11). Testing for immunoglobulin (Ig) M
antibodies to dengue virus was performed on 270 serum samples by
MAC-ELISA according to a standard protocol (12). Of 270 sera
tested for antibodies to dengue virus by MAC-ELISA, 140 (51.9%)
showed anti-dengue IgM antibodies. All samples from patients with
a duration of fever > 5 days were tested for anti-dengue IgM
antibodies. In some samples, antibodies could be detected as early
as the fifth day of fever. Three of the culture-positive acute-phase
samples were also positive by MAC-ELISA.

Table. Age distribution of patients with culture-
positive dengue
-------------------------------------------------
Age (years)              No. of cases
-------------------------------------------------
 0-1                           2
 >1-5                          1
 >5-12                        11
 >12-20                        7
 >20-30                        4
 >30                           2
 -------------------------------------------------

 
Analysis of the outbreaks of dengue virus infection in Delhi
indicates a seasonal trend. All outbreaks (including the one reported
here) occurred during the monsoon (rainy) season (August to
November) and subsided with the onset of winter. Dengue virus
types 1, 2, and 3 have been isolated during dengue fever outbreaks
(without DHF/DSS) in Delhi. Serologic studies have also shown
that dengue infection has been endemic in this region (13). During
the 1996 outbreak of DHF/DSS, we were able to identify dengue
virus type 2 as the etiologic agent. This is the first
culture-confirmed outbreak of DHF/DSS from Delhi and its
adjoining areas and the largest reported outbreak of DHF/DSS
from India.

Acknowledgments

We thank Duane J. Gubler for supplying diagnostic reagents
and protocols for our work and the director, National Institute of
Virology, Pune, India, for providing known strains of all dengue
virus types. We also thank Milan Chakraborty and Raj Kumar for
excellent technical support.

Dr. Dar is associate professor in the virology section of the
Department of Microbiology at the All India Institute of Medical
Sciences, New Delhi, India. His interests include diagnostic
virology, viral immunology, and tuberculosis.

Address for correspondence: Shobha Broor, Department of
Microbiology, All India Institute of Medical Sciences, Ansari
Nagar, New Delhi-110 029, India; fax: 91-11-686-2663; e-mail:
broor@hotmail.com.

References

  1. Thongcharoen P, Jatanasen S. Dengue haemorrhagic fever and
dengue shock syndromeintroduction, historical and  
epidemiological background. In: Thongcharoen P, compiler.
Monograph on dengue haemorrhagic fever. WHO, Regional Office  
for South-East Asia; 1993. p. 1-8.
  2. Sabin AB. Research on dengue during World War II. Am J
Trop Med Hyg 1952;1:30-50.
  3. Rao CVRM. Dengue fever in India. Indian J Pediatr
1987;54:11-4.
  4. Balaya S, Paul SD, D'Lima LV, Pavri KM. Investigations on an
outbreak of dengue in Delhi in 1967. Indian J Med Res  
1969;57:767-74.
  5. Diesh P, Pattanayak S, Singha P, Arora DD, Mathur PS, Ghosh
TK, et al. An outbreak of dengue fever in Delhi1970. J Commun
Dis 1972;4:13-8.
  6. Rao CVRM, Bagchi SK, Pinto BD, Ilkal MA, Bharadwaj M,
Shaikh BH, et al. The 1982 epidemic of dengue fever in Delhi.     
Indian J Med Res 1985;82:271-5.
  7. Kabra SK, Verma IC, Arora NK, Jain Y, Kalra V. Dengue
haemorrhagic fever in children in Delhi. Bull WHO 1992;70:105-8.
  8. Broor S, Dar L, Sengupta S, Chakraborty M, Wali JP, Biswas
A, et al. Recent dengue epidemic in Delhi, India. In: Saluzzo JE,
Dodet B, editors. Factors in the emergence of arbovirus diseases.
Paris: Elsevier; 1997. p. 123-7.
  9. Sharma PL, Sood OP, editors. Round table conference
seriesdengue outbreak in Delhi: 1996. Gurgaon, India: Ranbaxy  
Science Foundation; 1996.
 10. Gubler DJ, Kuno G, Sather GE, Valez M, Oliver A. Mosquito
cell and specific monoclonal antibodies in surveillance for dengue
viruses. Am J Trop Med Hyg 1984;33:158-65.
 11. Gubler DJ, Suharyono W, Tan R, Abidin M, Sie A. Viraemia in
patients with naturally acquired dengue infection. Bull WHO
1981;59:623-30.
 12. Monath TP, Nystrom RR, Bailey RE, Calisher CH, Muth DJ.
Immunoglobulin M antibody capture enzyme linked immunosorbent 
 assay for the diagnosis of St Louis encephalitis. J Clin Microbiol
1984;20:784-90.
 13. Mathew T, Nayar M, Gupta JP, Suri NK, Bhola SR, Ghosh
TK, et al. Serological investigations on arbovirus activity in and
around Delhia five year study. Indian J Med Res 1979;69:557-66.

_______________________________________________________________________
COMMENTARY
_______________________________________________________________________

Commentary

Addressing the Potential Threat of BioterrorismValue Added to
an Improved Public Health Infrastructure

Joseph E. McDade
Centers for Disease Control and Prevention, Atlanta, Georgia, USA

The use of biological weapons was banned in 1972 by the
Convention on the Prohibition of the Deployment, Production, and
Stockpiling of Bacteriological and Toxin Weapons (1). Caches of
biological weapons still exist, however, and their illegal use in
military operations cannot be discounted entirely (2).

The threat of biological warfare seems remote to industrialized
nations, which have enjoyed decades of peace and prosperity. In
contrast, the threat of bioterrorism, in which biological agents are
used by extremists as weapons against civilian populations,
generates considerable anxiety. Although the likelihood of a
bioterrorist attack is difficult to predict, the consequences of a
successful attack could be devastating and cannot be ignored.
Unlike attacks involving conventional or even chemical weapons,
which could be readily detected and limited to a specific geographic
area, an attack with a biological agent (and the resulting symptoms
of exposed persons) could remain undetected for days, would be
widely scattered, and depending on the etiologic agent, might not
be identified immediately as a manmade event. Secondary cases
would confound epidemiologic investigations as well.

Regardless of the source, surveillance of infectious diseases,
detection and investigation of outbreaks, identification of etiologic
agents and their modes of transmission, and the development of
prevention and control strategies are responsibilities of public health
agencies. Acquiring and sustaining the capability for an adequate
response to bioterrorism requires thoughtful analysis and carefully
integrated planning by these agencies, as well as law enforcement
officials, emergency response physicians and other first responders,
the military, and others. New partnerships will need to be forged
and old ones strengthened.

Preliminary assessments of our nation's capabilities for responding
to possible bioterrorist attacks have identified many deficiencies.
From the public health perspective, these deficiencies include
inadequate surveillance systems; lack of rapid diagnostic
techniques; insufficient stockpiles and distribution systems of
antimicrobial agents and vaccines; inefficient communication
systems; and insufficient training of physicians, epidemiologists, and
laboratorians. The deficiencies may be more pressing in certain
disease areas than in others. Some diseases that are considered
bioterrorist threats, such as anthrax and plague, are no longer
important public health problems in most industrialized nations, so
the capabilities and capacities for responding to outbreaks of these
diseases may be at historic lows. These deficiencies in response
capacity can be traced to the 1960s and 1970s, when complacency
began to erode essential components of the public health
infrastructure. Since the early 1970s, at least 25 previously
unknown pathogenic agents and diseases have been identified, and
in recent years mounting resistance to antimicrobial agents has
confounded the treatment of many illnesses (3).

A strategic plan for reducing the consequences of new and
reemerging infectious diseases (4) proposes corrective measures for
addressing the infrastructure deficiencies: instituting better
surveillance systems, improving diagnostic techniques, developing
new vaccines and drugs, and conducting research and providing
training in several areas. The measures needed to prevent and
control emerging infections are strikingly similar to those needed to
check the threat of bioterrorism. Improving capabilities and
capacities for responding to one issue will almost certainly benefit
the other. For example, developing rapid diagnostic techniques that
would make it possible to quickly detect bioterrorist attacks
involving anthrax, plague, or Q fever would have considerable
usefulness in the routine clinical diagnosis of pneumonia.
Distribution systems set up to deliver antimicrobial agents and
vaccines after bioterrorist attacks would be indispensable in
delivering antiviral compounds and influenza vaccine during a large
pandemic. Surveillance and communication systems are
fundamental components of an adequate public health
infrastructure, so an electronic, integrated surveillance system based
on standard architecture and vocabulary would serve all needs.

A value-added approach to infrastructure development is not a new
concept in public health. In 1951, at the beginning of the cold war,
the Epidemic Intelligence Service (EIS) was founded at the Center
for Disease Control (CDC) (5,6). The EIS concept originated with
Joseph W. Mountin, founder of CDC, and was implemented by
Alexander D. Langmuir. Noting the "dearth of trained
epidemiologists," Langmuir proposed training a corps of young
physicians that could "investigate outbreaks of disease in strategic
areas." He also noted, "A broader but equally pressing need is to
make available competent epidemiologists to assist in the planning
and organization of the total civil defense program at all levels."
Langmuir also observed that while "this dearth exists even in
peacetime, defense needs exaggerate this deficiency."

In 1951, 22 young physicians and one sanitary engineer signed on
as EIS Officers at CDC, where they received several weeks of
instruction in epidemiology, biostatistics, and public health
administration and then served for 2 years as field epidemiologists,
either at CDC or in state health departments. EIS has been in
operation since then, and as the purview of CDC expanded beyond
infectious diseases, so have the size and composition of EIS and the
training of EIS Officers. Surveillance, outbreak investigations, and
research on the epidemiology of new diseases remain standard
activities, however. EIS has rarely had occasion to investigate
outbreaks caused by the intentional release of microorganisms
(7,8). However, as Langmuir predicted in 1951, the program has
increased public health preparedness and made important
contributions to the control of communicable diseases. EIS now has
more than 2,000 alumni, including nearly 200 scientists from
abroad. Many alumni have moved on to distinguished careers in
academia, industry, and clinical practice, but many others have filled
key positions at federal and state public health agencies. Trained to
consider diseases as problems of populations, EIS alumni remain a
valuable resource when disease outbreaks occur.

As in 1951, civil defense, and particularly the use of biological
agents against civilian populations, is of utmost concern. Efforts are
under way to improve the capabilities of the public health system
for detecting and responding to this threat. Also as in 1951, we
have an opportunity to ensure that improvements made in response
to the threat of bioterrorism have multiple uses and can be applied
to other public health emergencies. Planning efforts to date have
adopted this viewpoint. Developing a separate infrastructure for
responding to acts of bioterrorism would be poor use of scarce
resources, particularly if this infrastructure is never used. "Value
added" should be the watchwords of the current initiative.

References

  1. Smart JK. History of chemical and biological warfare: an
American perspective. In: Medical aspects of chemical and
biological warfare. Sidell FR, Takafuji ET, Franz DR, editors.
Washington: Office of the Surgeon General; 1997. p. 9-86. 
  2. Zilinskas RA. Iraq's biological weapons: the past as future?
JAMA 1997;278:418-24.
   3. McDade JE. Global infectious disease: surveillance and
response. Australian Journal of Medical Science 1997;18:2-9.
   4. Centers for Disease Control and Prevention. Preventing
emerging infectious diseases: a strategy for the 21st century.
Atlanta: U.S. Department of Health and Human Services; 1998.
   5. Langmuir AD, Andrews JM. Biological warfare defense. 2. the
Epidemic Intelligence Service of the Communicable Disease Center.
Am J Public Hlth 1952;42:235-8.
   6. Thacker SB, Goodman RA, Dicker RC. Training and service in
public health practice, 1951-90CDC's Epidemic Intelligence
Service. Public Health Rep 1990;105:599-604.
   7. Torok TJ, Tauxe RV, Wise RP, Livengood JR, Sokolow R,
Mauvais S, et al. A large community outbreak of salmonellosis
caused by intentional contamination of restaurant salad bars. JAMA
1997;278:389-95.
   8. Kloavic SA, Kimura A, Simons SL, Slutsker L, Barth S, Haley
CE. An outbreak of Shigella dysenteriae Type 2 among laboratory
workers due to intentional food contamination. JAMA
_______________________________________________________________________
LETTERS
_______________________________________________________________________

Letters             

Current Status of Smallpox Vaccine

To the Editor: The possible use of smallpox virus as a weapon by
terrorists has stimulated growing international concern and led to a
recent review by the World Health Organization of the global
availability of smallpox vaccine. This review found approximately
60 million doses worldwide, with little current vaccine manufacture,
although limited vaccine seed remains available (1). Ongoing
discussions in the United States suggest that the national stockpile
should contain at least 40 million doses to be held in reserve for
emergency use, including in case of a terrorist release of smallpox
virus (O'Toole, this issue, pp. 540-6).

The current U.S. stockpile contains approximately 15.4 million
doses of vaccinia vaccine (Dryvax) made from the New York City
Board of Health strain of vaccinia and was produced by Wyeth
Laboratories in 13 separate lots. The vaccine is lyophylized in glass
vials with rubber stoppers and sealed with a metal band. When
rehydrated, each vial contains 100 doses and has a potency of at
least 10(sup 8) plaque-forming units (pfu)/ml. Some vials of the 
vaccine stockpile have shown elevated moisture levels and thus failed
routine quality control testing; however, the vaccine in these vials
remains potent, and the failed lots have not been discarded.

The diluent used to rehydrate the vaccine contains brilliant green,
which makes the vaccine easier to visualize when administered with
bifurcated needles. Over time, the brilliant green has deteriorated,
and most of the available diluent does not pass quality control.
Discussions are under way with Wyeth to begin production of
sufficient new diluent for the entire stockpile.

The vaccine is administered by superficial inoculation (scarification)
with a bifurcated needle. Fewer than 1 million bifurcated needles
are held as part of the stockpile. As with the diluent, Wyeth has
been requested to produce additional bifurcated needles.

Vaccinia virus produces adverse reactions in a small percentage of
vaccinated persons. Adverse reactions are treated with vaccinia
immune globulin (VIG), currently only available from Baxter
Healthcare Corporation (5,400 vials of VIG in stock). Each vial
contains 5 ml of VIG; the recommended dose for postvaccine
complications is 0.6 ml per kg of body weight. This volume is
sufficient to treat adverse reactions in approximately 675 adults.
Further, the entire stockpile of VIG has been placed on hold while
the cause of a slight pink discoloration is investigated. Until the
cause of the discoloration is determined or another approved supply
of VIG is obtained, no vaccinia vaccine is being released. While
unknown, the rate of adverse reactions in today's population is
likely to be greater than seen during the global eradication
campaign because of recent increases in the number of
immunocompromised persons. The Department of Defense has
recently contracted the processing of new lots of VIG (to be
administered intravenously rather than by the intramuscular route
like existing VIG stocks); however, maintaining adequate stocks of
VIG will remain a challenge.

In the event of release of smallpox virus, persons at high risk and
persons exposed but not yet showing clinical illness would be
vaccinated immediately. Intensive case detection and vaccination of
contacts and other persons at risk would follow. All vaccine,
including lots retained after failed quality control tests, would be
made available for emergency use. Previous studies have found that
more than 90% of susceptible persons respond to vaccinia virus
with a titer of 10(sup 7) pocks/ml (2). In an emergency, consideration
would be given to diluting the existing vaccine as much as 10-fold,
so that each vial could conceivably contain 1,000 doses of vaccine,
rather than the current 100 doses. The present vaccine container is
sufficiently large to accommodate the added diluent. The absence of
sufficient quantities of VIG to protect against adverse reactions
during a mass immunization campaign would necessitate careful
screening of those receiving the vaccine; some persons with adverse
reactions would likely go untreated.

While the intentional release of smallpox virus would represent a
global emergency, the existing national stockpile could be
effectively used to limit the spread of disease and buy time while the
pharmaceutical industry begins emergency vaccine production.
 
James W. LeDuc and John Becher
Centers for Disease Control and Prevention, Atlanta, Georgia, USA

References

  1. World Health Organization. Report of the meeting of the ad
hoc committee on Orthopox virus infections. Department of
Communicable Disease Surveillance and Response. WHO, 14-15
January 1999.
  2. Cockburn WC, Cross RM, Downie AW, Dumbell KR, Kaplan
C, Mclean D, et al. Laboratory and vaccination studies with dried
smallpox vaccines. Bull World Health Organ 1957;16:63-77.

West Nile Fever in Czechland

To the Editor: After heavy rains in July 1997, extensive floods
occurred along the Morava River, Czech Republic. Populations of
Aedes mosquitoes increased rapidly in the flooded areas, prompting
surveillance for mosquito-borne virus infections in the Breclav area,
South Moravia. We collected 11,334 female mosquitoes (9,100
Aedes vexans, 917 Ae. cinereus, 11 Ae. cantans, 1,074 Ae.
sticticus, and 232 Culex p. pipiens) from July through September
1997 and tested them for virus in 117 monospecific pools by
intracranial inoculation of suckling mice. Seven virus isolates were
obtained and identified by complement-fixation and neutralization
tests. Six isolates (five from Ae. vexans, one from Ae. cinereus)
were identified as the bunyavirus Tahyna, California serogroup, and
one (strain 97-103 from 57 C. p. pipiens collected at Lanzhot,
48  40'N, 1656'E, on September 17) was identified as the flavivirus
West Nile (1). A crossed comparison of 97-103 and topotype
Eg-101 (2) West Nile virus strains and their antisera (prepared in
mice by three intraperitoneal doses at weekly intervals) by plaque
reduction neutralization (PRN) on XTC-2 cells (3,4) showed their
antigenic relationships: reciprocal titers of
homologous/heterologous sera were 512/512 in Eg-101 and 512/64
in 97-103. Strain 97-103 has lower virulence than Eg-101 in that it
does not kill adult ICR mice and may represent a subtype of West
Nile virus.

Blood samples were obtained from 619 persons seeking treatment
at hospital and outpatient clinics in the Breclav area from June 23
through September 29, 1997. Sera were inactivated at 56oC for 30
minutes, diluted 1:8, and assayed by PRN for antibodies against c.
30 plaque-forming units (PFU) per well of West Nile virus strains
Eg-101 and 97-103. All sera causing 90% reduction of PFU at 1:8
dilution were titrated, and the highest serum dilution showing 50%
PFU reduction was regarded as the titer. Antibodies neutralizing
West Nile virus were detected in 13 (2.1%) persons: 2.8% of 179
male and 1.8% of 440 female. Persons with detectable West Nile
virus antibody were questioned about their health history during the
previous 5 years, and their medical records were reviewed; none
recalled having had tickborne encephalitis (Central-European
encephalitis [CEE] virus is the only other flavivirus present in
Czechland) or having been vaccinated against CEE or yellow fever
virus. Titers of PRN antibodies to CEEV were all below 16. Two
of the seropositive persons had traveled abroad during the last 5
years: one to Croatia in 1996, and one to South Australia during
1951 to 1994.

Paired serum samples were obtained from 72 of the 619 persons
examined. A significant increase (>4 times) in antibody titer against
West Nile virus between the first (acute-phase) and second
(convalescent-phase) samples was detected four times: in 2 of 41
young persons (<16 years of age) and in 2 of 31 adults (>16 years
of age). Among the four seroconverting persons, only the two
children had clinical symptoms compatible with West Nile fever. A
9-year-old boy had fever (39C) for 4 days, sore throat, headache,
muscle ache, pronounced fatigue, and nausea lasting approximately
6 days, with recovery after 13 days. Neutralizing antibodies to West
Nile virus, Eg-101 and 97-103, were 64 and 32 on July 22 and 512
and 256 on August 4, respectively. A 9-year-old girl had fever
(38C-39C) for 3 days, sore throat, headache, muscle ache,
pronounced fatigue, nausea, vomiting, maculopapular rash
(including flushed face), and slightly enlarged inguinal lymph nodes.
The illness lasted approximately 7 days, with complete recovery
after 17 days. Neutralizing antibodies to West Nile virus, Eg-101
and 97-103, were 64 and 32 on August 6 and 256 and 128 on
August 20, respectively. Of the remaining nine seropositive persons
lacking paired serum samples, one had severe headache, muscle
ache, prolonged fatigue, nausea, pain on eye movement,
maculopapular rash, and insomnia in summer of 1997. Two other
persons had had "summer fever" (sore throat and lymphadenitis;
headache with pain on eye movement) in 1997. The other persons
who seroconverted did not report any substantial illness. In total,
clinical symptoms in five persons are compatible with West Nile
fever.

These are the first reported human cases of West Nile fever in
Central Europe (5); an extensive outbreak occurred in Romania in
1996, with approximately 500 patients hospitalized and a 4% to 8%
fatality rate (6,7). West Nile virus should be viewed as a potential
agent of local sporadic cases, clusters, or outbreaks, even in
temperate Europe. Environmental factors (including human
activities) that enhance vector population densities (heavy rains
followed by floods, irrigation, higher than usual temperatures due
to global warming) might produce an increased incidence of West
Nile fever and other new or reemerging mosquito-borne diseases.
Surveillance for West Nile fever should monitor population density
and infection rate of principal vectors, antibodies in vertebrates and
exposed human groups, and routine diagnosis of human infections.

Zdenek Hublek, Jir Halouzka, and Zina Juricov
Institute of Vertebrate Biology, Academy of Sciences, Brno, Czech
Republic

References

  1. Hublek Z, Halouzka J, Juricov Z, Sebesta O. First isolation of
mosquito-borne West-Nile virus in the Czech Republic. Acta Virol
1998;42:119-20.
   2. Melnick JL, Paul JR, Riordan JF, Barnett VHH, Goldblum N,
Zabin E. Isolation from human sera in Egypt of a virus apparently
identical to West Nile virus. Proc Soc Exp Biol Med
1951;77:661-5.
  3. de Madrid AT, Porterfield JS. The flaviviruses (group B
arboviruses): a cross-neutralization study. J Gen Virol
1974;23:91-6.
  4. Leake CJ, Varma MGR, Pudney M. Cytopathic effect and
plaque formation by arboviruses in a continuous cell line (XTC-2)
from the toad Xenopus laevis. J Gen Virol 1977;35:335-9.
  5. Hublek Z, Halouzka J. Arthropod-borne viruses of
verte-brates in Europe. Acta Scientiarum Naturalium Academiae
Scientiarum Bohemicae Brno 1996;30, no. 4-5:1-95.
  6. Le Guenno B, Bougermouh A, Azzam T, Bouakaz R. West
Nile: a deadly virus? Lancet 1996;348:1315.
   7. Tsai TF, Popovici F, Cernescu C, Campbell GL, Nedelcu NI.
West Nile encephalitis epidemic in southeastern Romania. Lancet
1998;352:767-71.

Ofloxacin-Resistant Vibrio cholerae O139 in Hong Kong

To the Editor: Unexpected outbreaks of cholera occurred in many
areas of the world in 1997-98, partly because of weather changes
associated with the El Nio phenomenon (1). Outbreaks caused by
antibiotic-resistant Vibrio cholerae O1 and O139 have been
documented in the Indian subcontinent (2-4), Africa (5), and
Ukraine (6).  In Hong Kong, nonduplicate bacterial strains of V.
cholerae O1 and O139 isolated from patients and environmental
sources and received in the Public Health Laboratory between
January 1, 1993, and June 30, 1998, were identified by
conventional biochemical tests (7,8) and API 20E (bioMerieux,
France); serotyped by slide agglutination with polyvalent O1 and
mono-specific Inaba and Ogawa antisera (Murex, Dartford, United
Kingdom); and checked with O139 antiserum (Denka Seiken,
Tokyo, Japan). Biotyped and antibiotic susceptibilities were
determined by the Kirby-Bauer disk-diffusion assay (8-10).
Antibiotics tested included chloramphenicol and tetracycline (from
1993 to 1996) and ofloxacin (added in routine testing from 1997).
V. cholerae isolates available for further study were tested with the
standard broth microdilution method (11) to measure minimum
inhibitory concentrations (MICs) of susceptibilities to
chloramphenicol, tetracycline, and ofloxacin.

No antibiotic resistance was seen in V. cholerae isolates in testing
conducted from 1969 to 1995. The first V. cholerae isolate with
reduced susceptibility to chloramphenicol but sensitive to
tetracycline was encountered in Hong Kong in 1996. This O1 El
Tor Ogawa strain was imported from Nepal. Since then, more O1
strains were isolated that exhibited reduced antibiotic
susceptibilities to chloramphenicol and tetracycline but not to
ofloxacin (12). In May 1998, seven V. cholerae O139 strains were
isolated that displayed patterns of antibiotic susceptibilities
strikingly different from those of O1 isolates; the former were all
sensitive to tetracycline but showed reduced susceptibilities to
chloramphenicol and ofloxacin. All V. cholerae O1 strains tested
have been susceptible to ofloxacin; O1 isolates falling into
intermediate categories for chloramphenicol and tetracycline
susceptibilities (31% and 27.6%, respectively) were common.

The first isolate of V. cholerae O139 in Hong Kong came from the
imported case of a patient who had traveled to other provinces of
China (13,14). Isolation of O139 continued sporadically since then,
with six cases between 1993 and the 1st quarter of 1998. In May
1998, a cluster of seven imported cases of V. cholerae O139 were
reported with strains isolated from seven persons who became ill
with severe diarrhea after visiting Zhuhai in Guangdong Province,
China. Of 13 V. cholerae O139 isolates tested, 7 showed
intermediate resistance to chloramphenicol and high-level resistance
to ofloxacin (MIC 1mg/ml) but no resistance to tetracycline (MIC
50s and MIC 90s were 0.25 mg/ml). This is the first evidence of a
quinolone-resistant strain of V. cholerae O139 in Hong Kong. Of
the O1 isolates, none were resistant to chloramphenicol and
ofloxacin, but six were resistant to tetracycline (MIC 50s and MIC
90s were 0.25 mg/ml and 8 mg/ml, respectively).

Although all O1 isolates were sensitive to chloramphenicol, there
was only a twofold difference in MIC 90 to chloramphenicol
between O1 and O139 isolates. MIC 90s of ofloxacin for O139
were nearly 10 times higher than those for O1 strains.

The novel appearance of O139 resistant to ofloxacin with MICs of
16 mg/ml from Guangdong Province, China, was of special concern.
Preliminary results using pulsed-field gel electrophoresis analysis of
chromosomal DNA showed that these ofloxacin-resistant O139
strains had identical fingerprint patterns and probably belonged to
the clone that had caused severe diarrheal disease in the region.
Two previous surveys of V. cholerae antibiotic susceptibilities had
not described any ofloxacin-resistant O139 strains (15,16). The
potential for rapid spread of these strains threatens cholera
prevention and control efforts that may still rely on chemotherapy.

Different antimicrobial resistance patterns of V. cholerae O1 and
O139 were noted. Among the resistant O1 isolates, four were local,
one was from other provinces of China, and one was from
Thailand. All the resistant O139 isolates were imported from
Guangdong Province, China. Antibiotic resistance was found in
strains from local isolates and from neighboring countries. The
unique patterns of antimicrobial resistance for the O1 and O139
isolates suggest different mechanisms of resistance. As quinolones
are used heavily in this region to treat cholera and other enteric
diseases, selective pressure could encourage emergence of
ofloxacin resistance. Prudent use of antibiotics should be exercised
during antimicrobial therapy and prophylaxis for cholera and other
enteric diseases to decrease the selection of more resistant clones in
our locality.

Kai Man Kam, Kit Yee Luey, Tze Leung Cheung, Kwan Yee Ho,
Kwok Hang Mak, and Paul Thian Aun Saw
Department of Health, Hong Kong SAR Government

References

  1. World Health Organization, Geneva. Cholera in 1997. Wkly
Epidemiol Rec 1998;73:201-8.
  2. Gharagozloo RA, Naficy K, Mouin M, Nassirzadeh MH, Yalda
R. Comparative trial of tetracycline, chloramphenicol, and
trimethoprim/sulphamethoxazole in eradication of Vibrio cholerae
El Tor. BMJ 1970;4:281-2.
  3. Glass RI, Huq I, Alim AR, Yunus M. Emergence of multiply
antibiotic-resistant Vibrio cholerae in Bangladesh. J Infect Dis
1980;142:939-42.
  4. Ramamurthy T, Garg S, Sharma R, Bhattacharya SK, Nair GB,
Shimada T, et al. Emergence of novel strain of Vibrio cholerae with
epidemic potential in southern and eastern India. Lancet
1993;341:703-4.
  5. Finch MJ, Morris JG Jr, Kaviti J, Kagwanja W, Levine MM.
Epidemiology of antimicrobial resistant cholera in Kenya and east
Africa. Am J Trop Med Hyg 1988;39:484-90.
  6. Clark CG, Kravetz AN, Alekseenko VV, Krendelev YuD,
Johnson WM. Microbiological and epidemiological investigation of
cholera epidemic in Ukraine during 1994 and 1995. Epidemiol
Infect 1998;121:1-13.
  7. Cowan ST, Steel KJ. Manual for the identification of medical
bacteria. 2nd ed. Cambridge: Cambridge University Press; 1974.
  8. Bradfold AK, Bopp CA, Wells JG. Isolation and identification
of Vibrio cholerae O1 from fecal specimens. In: Wachsmuth IK,
Blake AB, Olsvik  , editors. Vibrio cholerae and cholera:
molecular to global perspectives. Washington: American Society
for Microbiology; 1994. p. 3-26.
  9. National Committee for Clinical Laboratory Standards.
Performance standards for antimicrobial disk susceptibility tests
approved standard. NCCLS document M2-A6. Villanova (PA):
The Committee; 1997.
 10. National Committee for Clinical Laboratory Standards.
Performance standards for antimicrobial susceptibility testing;
NCCLS document M100-S8, 18(1). Villanova (PA): The
Committee; 8th information supplement, 1998.
 11. National Committee for Clinical Laboratory Standards.
Methods for dilution antimicrobial susceptibility tests for bacteria
that grow aerobically. 4th ed. NCCLS document M7-A4. Villanova
(PA): The Committee; 1997.
 12. Wong W, Ho YY. Imported cholera cases among tours
returning from Thailand. Public Health & Epidemiology Bulletin,
Department of Health, Hong Kong. 1998;7:21-4.
 13. Kam KM, Leung TH, Ho PYY, Ho KY, Saw TA. Outbreak of
Vibrio cholerae O1 in Hong Kong related to contaminated fish tank
water. Public Health 1995;109:389-95.
 14. Lee SH, Lai ST, Lai JY, Leung NK. Resurgence of cholera in
Hong Kong. Epidemiol Infect 1996;117:43-9.
 15. Yamamoto T, Nair GB, Albert MJ, Parodi CC, Takeda Y.
Survey of in vitro susceptibilities of Vibrio cholerae O1 and O139
to antimicrobial agents. Antimicrob Agents Chemother
1995;39:241-4.
 16. Sciortino CV, Johnson JA, Hamad A. Vitek system
antimicrobial susceptibility testing of O1, O139, and non-O1 Vibrio
cholerae. J Clin Microbiol 1996;34:897-900.

Plant Pathology and Public Health

The day will come when the sign of the plant pathologist will stand
forth in the street alongside that of the physician and surgeon. . . .
For what will it profit us if all the ills and diseases of the human
race be banished and we then face starvation because of diseases
and pests in our food (1).

To the Editor: Every year plant diseases affect human society,
resulting in inadequate nutrition and economic loss. The potato
famine in the mid-1800s is the best-known example of a fungal
plant pathogen's effect on history (2-4); Phytopthora infestans has
recently reemerged in the Americas (5). Among the silent problems
that have enormous effects on human society each year are crop
infections by geminiviruses and tomato spotted wilt virus (6). These
plant viruses are transmitted by whiteflies, leafhoppers, or thrips to
hundreds of species of plants. They cause diseases of crops and
ornamental plants around the world.

More obvious problems include ergotism, caused by the alkaloids
produced by the fungus Claviceps purpurea. Ergotism was
associated with the growth of rye, particularly in cool climates that
cannot support wheat, and was implicated in the aberrant human
behavior responsible at least in part for the Salem witch trials and
St. Anthony's fire (2,7). In the last 5 years, a new plant disease,
sorghum ergot (Claviceps africana), has spread north from Brazil
into the United States. This fungus also causes disease in Australia,
a sudden change from its known occurrence in Africa (8). Sorghum
is the fifth most important cereal crop in the world, with
approximately 45 million hectares under cultivation for food,
beverages, feed, and fodder (8). Ergot alkaloid toxicity has not yet
been demonstrated, but potential nutritional and economic losses
could have substantial impact on public health.

With our increased awareness of the fragility of the environment,
including the quality of our drinking water, opportunities may exist
for physicians to interact with plant pathologists. Concern is
growing about the use of Burkholderia cepacia, a bacterial
phytopathogen, for the biologic control of seedling diseases (9).
Although B. cepacia is effective for the biologic control of fungal
diseases in the agricultural environment (10), this bacterium could
contaminate the public water supply and subsequently influence the
health of the immunosuppressed or persons with cystic fibrosis
(9-11). This risk exemplifies the need to integrate plant health
measures with human and veterinary health guidelines.

Plant pathology and public health also intersect with post-harvest
fungal infections of seed and grain, particularly Aspergillus flavus
and Fusarium moniliforme (2), which produce aflatoxin and
fumonisin, respectively. During the past 2 drought years in Texas,
aflatoxin in contaminated corn and peanuts has become a public
health problem. In 1998, more than 50 pet dogs died of
aflatoxicosis, perhaps by eating aflatoxin B1-contaminated corn
used in dog food (12).  

Although the veterinary and medical communities are well aware of 
the risks associated with plant pathogens when they enter the animal 
or human food supply, more routine interactions with plant 
pathologists could benefit public health. For example, plant 
pathologists can often predict impending plant disease outbreaks. 
This information can be used by epidemiologists to sound a warning 
about impending food shortages or poor food quality, particularly 
in developing countries. Plant pathologists are also developing new 
types of resistance in host plants and alternative strategies for 
managing plant diseases. These measures should improve food quality 
and reduce the negative public health impact associated with 
plant diseases.

Karen-Beth G. Scholthof
Texas A&M University, College Station, Texas, USA

References

  1. Whetzel HH. The relation of plant pathology to human affairs.
Mayo Foundation Lectures 1926-1927. Philadelphia: W.B.
Saunders Co.; 1928. p. 151-78.
  2. Hudler GW. Magical mushrooms, mischievous molds.
Princeton: Princeton University Press; 1998.
  3. Woodham-Smith C. The great hunger: Ireland 1845-1849. New
York: Old Town Books; 1962.
  4. Schumann GL. Plant diseases: their biology and social impact.
St. Paul: American Phytopathological Society Press; 1993.
  5. Goodwin SB, Smart CD, Sandrock RW, Deahl KL, Punja ZK,
Fry WE. Genetic change within populations of Phytopthora
infestans in the United States and Canada during 1994 to
1996role of migration and recombination. Phytopathology
1998;88:939-49.
  6. Prins M, Goldbach R. The emerging problem of tospovirus
infection and nonconventional methods of control. Trends
Microbiol 1998;6:31-5.
  7. Matossian MK. Poisons of the past: molds, epidemics, and
history. New Haven: Yale University Press; 1989.
  8. Bandyopadhyay R, Frederickson DE, McLaren NW, Odvody
GN, Ryley MJ. Ergot: a new disease threat to sorghum in the
Americas and Australia. Plant Disease 1998;82:356-67.
  9. Holmes A, Govan J, Goldstein R. Agricultural use of
Burkholderia (Pseudomonas) cepacia: a threat to human health?
Emerg Infect Dis 1998;4:221-7.
 10. Park JL. Burkholderia cepacia: friend or foe? 1998. Available
from: URL: http://www.scisoc.org/feature/BurkholderiaCepacia/
 11. King EB, Parke JL. Population density of the biocontrol agent
Burkholderia cepacia AMMDR1 on four pea cultivars. Soil Biology
and Biochemistry 1996;28:307-12.
 12. Texas Veterinary Diagnostic Medical Laboratory. Epidemiol
Bull 1998. Available from: URL: http://www.tvmdl.tamu.edu/.

Pet-Associated Zoonoses

To the Editor: We read with interest the article by Grant and Olsen
on preventing zoonotic diseases in immunocompromised persons
(1). We completely agree with the benefits of communication
between physicians and veterinarians. However, we want to
emphasize that pet-associated illnesses are not limited to the
immunocompromised; pregnant women and young infants should
be included in this high-risk category. Our recently published survey
(2) reaffirms the need for education of the general public, parents,
andto a lesser extentpediatricians regarding pet-associated
hazards.

Leslie L. Barton,* Rodrigo G. Villar,  and Megan Connick 
*University of Arizona Health Sciences Center, Tucson, Arizona,
USA;  Indian Health Service, Gallup, New Mexico, USA; and
 Washington University School of Medicine, St. Louis, Missouri,
USA

References

  1. Grant S, Olsen CW. Preventing zoonotic diseases in
immunocompromised persons: the role of physicians and
veterinarians. Emerg Infect Dis 1999;5:159-63.
  2. Villar RG, Connick M, Barton LL. Parent and pediatrician
knowledge, attitudes, and practices regarding pet-associated
hazards. Arch Pediatr Adolesc Med 1998;152:1035-7.

_______________________________________________________________________
BOOK REVIEW
_______________________________________________________________________

Book Review

Clinical Infectious Diseases: A Practical Approach.

K.R. Root, F. Waldvolgel, L. Corey, W.E. Stamm, editors. Oxford
University Press, New York, 1999,1,013 pages.

This new text presents updated and valuable information to the
clinician and brings to the forefront issues important for diagnosing
and managing infectious diseases in an era of competing demands
on resources and rapidly evolving health-care delivery systems.
While other books on infectious diseases are available, the speed
with which new diagnostic methods are developed and the
unpredictable nature of microbial pathogens require that the clinical
and health-care community be kept informed of new approaches to
diagnosis. This is particularly true in today's medical environment,
where international travel and world events compel the local
medical community to broaden its scope beyond its former comfort
zone. The editors and contributors to this book have successfully
presented the diagnosis, management, and prevention of infectious
diseases in a context that promotes the best of patient care and
outcome.

The text has 1,013 pages of information, tables, charts, algorithms,
and photographs provided by 150 contributors representing a broad
array of internationally recognized expertise. The book's 103
chapters are logically divided into seven parts: Pathophysiology of
Infectious Diseases, Diagnostic Methods in Infectious Diseases,
Antimicrobial Drugs: Principles and Usage, Vaccines and
Immunomodulary Agents, Infectious Disease Syndromes, Infections
in Special Patient/Risk Groups, and Human Immunodeficiency
Virus and AIDS. The first four provide sufficient background for
focusing on the final three sections. The text includes 49 color
plates with 54 photos that are bright, colorful, descriptive, and large
enough for detail to be appreciated.

Specimen management is covered nicely in the chapters on bacteria,
viruses, parasites, and fungi, although the apparent assumption is
that the patient will usually be an adult. In some cases, specimens
from pediatric patients may require different approaches to
collection and to the amount of material to collect. In addition, the
role of the swab as a collection device is not detailed enough, since
there are so many types (e.g., Dacron-, rayon-, calcium alginate-,
and cotton-tipped swabs), some of which are specifically
recommended for use with certain agents or tests. More could have
been presented regarding specimen transport, in light of the
emergence of central core laboratory facilities for multihospital
health systems and the use of distant facilities for microbiology
analysis.

The 22 chapters on antimicrobial drugs and their appropriate use
are complete and up to date. For example, a brief discussion of the
recently emerged glycopeptide-intermediate Staphylococcus aureus
is presented, as is information on inappropriate use of antimicrobial
drugs, particularly vancomycin, and the emergence of
extended-spectrum beta-lactamases. Pharmacokinetics, clinical
indications and use, mode of action, clinical experience, adverse
reactions, mechanisms of resistance, and other useful information
are described, along with a generous array of very helpful summary
tables and charts.

The primary diagnostic portion of the text is presented by
syndrome, not by organism or individual disease. For example,
tuberculosis is covered in the chapter on "Cavitary Pulmonary
Disease," while varicella is discussed in "Infections with Rash." The
annotated bibliography at the end of each chapter is very helpful:
recent literature references are included where possible, along with
italicized notes about the content and value of each reference
selected. Pathogenesis is appropriately discussed in the section for
each disease or agent rather than in an introductory section. The
complexity of pathogenic mechanisms and host-parasite
relationships within the microbial groups makes this approach a
sound one. This section of the book is nicely introduced by valuable
discussions on fever that set the stage for the subsequent syndrome
presentations.

The section on infections in special patient populations and in
special groups at risk is appropriate and informative and recognizes
the unique needs and problems associated with these populations.
Infections in immunocompromised patients, postsurgical wound
infections, trauma, in-dwelling medical devices, transplantation,
travelers, and alcohol and drug abuse are some of the special risks
and groups presented. AIDS and HIV are considered separately in a
seven-chapter section.

There are few negatives about this book. For ease of use, it might
have been helpful for all information about specimen management
to be summarized in a single chapter. There were some
controversial recommendations for blood collection at 1-hour
intervals, and some may question the proposed use of direct antigen
tests in spinal fluid for pediatric patients. Today vaginosis is
recognized with more accuracy in the microbiology laboratory by
Gram stain evaluation rather than by culture (as recommended in
the book), which can often be inconclusive.

This book, while not inexpensive, will be an important addition to
the resources available to clinicians and laboratorians alike.

J. Michael Miller
Centers for Disease Control and Prevention, Atlanta, Georgia, USA

_______________________________________________________________________
NEWS and NOTES
_______________________________________________________________________

News and Notes

The Epidemiology and Control of Communicable Diseases

Surveillance and Investigating Outbreaks (November 2223)
Control of Communicable Diseases (November 2425)

Presented by the University of Western Australia (UWA),
Department of Public Health's Summer School Program 1999, this
interactive course will provide both an overview of com-municable
disease control and practical skills in surveillance, investigation,
health outcomes, role of government, policy development and
analysis, value, and limitations of legislation in the context of
infectious disease control.

The presenter, Dr. Aileen Plant, is a medical epidemiologist with
UWA and recently undertook a 6-month study leave with WHO,
working with a new international surveillance and investigative
network, TEPHINET.

Cost is $400 AUD per module with discounts for registration
before August 31. Participants may enrol in one or both modules.
Prior epidemiologic experience is not necessary. CME points for
general practioners have been applied for.

To register, contact Serena Angelo at serena@dph.uwa.edu.au.

For information on UWA's Summer School go to
http://www.publichealth.uwa.edu.au/events/summer/ or contact
Melodie Kevan, Dept. of Public Health, The University of Western
Australia Nedlands WA 6907; phone: 61-8-9380-1286; fax:
61-8-9380-1188; e-mail: melodie@dph.uwa.edu.au.

Antibiotic Resistance in Bacteria of Animal Origin

Institut Pasteur, Paris, France,
November 2930, 1999

This international symposium, organized as part of a European
Concerted Action, will gather scientists from diverse disciplines
(microbiology, epidemiology, ecology) to share data and actual
knowledge on antibiotic resistance, especially in the veterinary field.

Objectives of this congress are the presentation of current
recommendations of Concerted Action members, of current
knowledge on antibiotic resistance, and of existing monitoring
strategies, and the promotion of research funded by the European
Union.

Information on this program and the topic of antibiotic resistance in
bacteria of animal origin is available at
http://www.fougeres.afssa.fr/arbao.

To receive conference materials, please forward your name,
affiliation, postal address, phone and fax number, and e-mail
address to P. Sanders, AFSSA-Fougres, La Haute Marche-Javen,
BP 90203, 35302 Fougeres Cedex, France; phone:
33-29-994-7876; fax: 33-29-994-7877; e-mail:
arbao@fougeres.afssa.fr.

Keystone Symposia on Molecular and Cellular Biology

Genetics, Pathogenesis and Ecology of Emerging Viral Diseases
(J1)
Taos Civic Center, Taos, NM, January 2430, 2000
Organizers: Michael J. Buchmeier and Clarence J. Peters
Abstract Deadline: September 24, 1999
Early Registration: November 23, 1999

Pathogen Discovery: From Molecular Biology to Diseases (J2)
Taos Civic Center, Taos, NM, January 2430, 2000
Organizers: Georg Hess and Helen H. Lee
Sponsored by Roche Diagnostics
Abstract Deadline: September 24, 1999
Early Registration: November 23, 1999

Biological Threats and Emerging Diseases (F3)
Beaver Run Resort, Breckenridge, CO, April 813, 2000
Organizers: Gregory Milman, Joseph E. McDade and Gail H.
Cassell
Abstract Deadline: December 8, 1999
Early Registration: February 8, 2000
For information or registration visit Keystones's Web site:
http://www.symposia.com.

The 5th World Congress on Trauma, Shock, Inflammation and
Sepsis-Pathophysiology, Immune Consequences and Therapy

Munich, Germany, February 29March 4, 2000

Deadline for abstracts is October 30, 1999.
For further information contact: Eugen Faist, Dept. of Surgery,
Ludwig-Maximilians-University Munich, Klinikum Grosshadern,
Marchioninistrasse 15, 81377 Munich, Germany; phone:
49-89-7095-5461/2461; fax: 49-89-7095-2460; e-mail:
faist@gch.med.uni-muenchen.de.

ICEID 2000

Hold the dates of July 1619, 2000 for the International Conference
on Emerging Infectious Diseases, a meeting of 2,500 specialists in
infectious diseases. The program will include plenary sessions and
symposia with invited speakers, presentations on emerging
infections activities, and oral and poster presentations. Major topics
will include current work on surveillance, epidemiology, research,
communication and training, as well as prevention and control of
emerging infectious diseases, both in the United States and abroad.
Abstracts are invited and will be accepted beginning in September
1999.

The Call for Abstracts and Preliminary Program will be mailed in
August 1999.

For more information, call ICEID management at 202-942-9248,
e-mail meetinginfo@asmusa.org, or
www.cdc.gov/ncidod/iceid2k.htm.
_______________________________________________________________________

Emerging Infectious Diseases
National Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, GA

URL: ftp://ftp.cdc.gov/pub/EID/vol5no4/ascii/vol5no4.txt

Please note that figures and equations are not available in ASCII
format;  their placement within the text is noted by [fig] and [eq],
respectively.  Greek symbols are spelled out. The following codes
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subscript;  >/= for greater than or equal to.