GAO

United States General Accounting Office

Report to Congressional Requesters

September 2000 WEST NILE VIRUS

OUTBREAK

Lessons for Public

Health Preparedness

GAO/HEHS-00-180

Page 1 GAO/HEHS-00-180 West Nile Virus Outbreak

Contents

Letter 3

Appendixes Appendix I: Methodology 38

Appendix II: Timeline of Key Dates and Events in the West Nile Virus

Outbreak, 1999 40

Appendix III: Related Publications 59

Appendix IV: Comments From the Centers for Disease Control and

Prevention 63

Appendix V: Comments From the New York City Department

of Health 65

Tables Table 1: Examples of Surveillance and Laboratory Workload

Experienced by Selected Involved Agencies During and

Since the West Nile Outbreak 13

Table 2: Detailed Chronology of Events in the West Nile Virus

Outbreak, 1999 40

Figures Figure 1: Transmission of St. Louis and West Nile Viruses 6

Figure 2: Timeline of 1999 West Nile Virus Outbreak 9

Figure 3: Examples of Migratory Patterns of Three Bird Species

Susceptible to West Nile 16
Contents

Page 2 GAO/HEHS-00-180 West Nile Virus Outbreak

Abbreviations

APHIS Animal and Plant Health Inspection Service

CDC Centers for Disease Control and Prevention

DNA deoxyribonucleic acid

ELISA enzyme-linked immunoabsorbent assay

E. coli Escherichia coli

FBI Federal Bureau of Investigation

HHS Department of Health and Human Services

NYC New York City

NYS New York State

PCR polymerase chain reaction

ProMED Program for Monitoring Emerging Diseases

RNA ribonucleic acid

USDA U.S. Department of Agriculture

USGS U.S. Geological Survey
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United States General Accounting Office

Washington, D.C. 20548

Health, Education,

and Human Services Division

B-285899 Letr

September 11, 2000

The Honorable Daniel Patrick Moynihan

The Honorable Charles E. Schumer

United States Senate

The Honorable Gary L. Ackerman

The Honorable Joseph Crowley

The Honorable Eliot L. Engel

The Honorable Vito J. Fossella, Jr.

The Honorable Carolyn B. Maloney

The Honorable Jerrold L. Nadler

The Honorable Major R. Owens

The Honorable Charles B. Rangel

The Honorable Jose E. Serrano

The Honorable Edolphus Towns

The Honorable Anthony D. Weiner

House of Representatives

In the fall of 1999 the mosquito-borne West Nile virus—a virus never before

seen in this hemisphere—killed seven people in the New York City area and

made dozens more very sick. It was initially misidentified as a different,

related mosquito-borne virus often found in the United States. The

incorrect diagnosis did not significantly affect the appropriateness of

spraying and other mosquito control steps quickly begun in response. Even

so, the outbreak can serve as a source of lessons about how public health

officials can be better prepared in responding to potential crises involving

uncertain causes. And although the outbreak is considered to have been a

natural occurrence—possibly introduced by international travelers,

migrating birds, or mosquitoes accidentally brought from abroad—it can

also provide lessons about detecting and responding to an act of biological

terrorism.

You asked us to review this outbreak and the response to it. We focused our

efforts on the following:

• establishing a thorough chronological account of the significant events

and communications that occurred, from doctors and others who first

saw the symptoms and from the officials mounting a response, and
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• identifying lessons learned for public health and bioterrorism

preparedness.

We interviewed key officials, reviewed existing studies and reports,

assembled a detailed chronology of what occurred, and discussed the

implications of our findings with a wide range of agency and area officials.

We asked officials to provide documentation to the extent possible for key

decisions or events; however, to some extent the chronology of events is

based on officials’ recollections of the dates that particular events

occurred. Appendix I describes our methodology in more detail. We

conducted our work from May through August 2000 in accordance with

generally accepted government auditing standards.

Results in Brief The analysis of the West Nile virus outbreak began—and for several weeks

continued—as two separate investigations: one of sick people, the other of

dying birds. On the human side, the investigation began quickly after a

physician at a local hospital reported the first cases, and the original

diagnosis, while incorrect, led to prompt mosquito control actions by New

York City officials. The ongoing investigation involved the combined efforts

of many people in public health agencies and research laboratories at all

levels of government. A consensus that the bird and human outbreaks were

linked, which was a key to identifying the correct source, took time to

develop and was initially dismissed by many involved in the investigation.

When the bird and human investigations converged several weeks after the

initial diagnosis, and after laboratory research was launched independently

by several of the participants to explore other possible causes, the link was

made and the virus was correctly identified.

Key lessons that emerge from the investigation and response to this

outbreak are as follows:

• The local disease surveillance and response system is critical. In public

health, surveillance is the ongoing collection, analysis, and

interpretation of health-related data. In this outbreak, many aspects of

the local surveillance system worked well, in that the outbreak was

quickly spotted and immediately investigated. Assessments of the

infrastructure for responding to outbreaks suggest that surveillance

networks in many other locations may not be as well prepared.

• Better communication is needed among public health agencies. As the

investigation grew, lines of communication and decision-making were

often unclear, and efforts to keep everyone informed were awkward
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(such as conference calls that lasted for hours and involved dozens of

people). Many officials reported problems in this area.

• Links between public and animal health agencies are becoming more

important. Many emerging diseases, including West Nile, affect both

animals and humans. So do many viruses or other disease-causing

agents that might be used in bioterrorist attacks. The length of time it

took to connect the bird and human outbreaks of the West Nile virus

signals a need for better coordination among public and animal health

agencies.

• Ensuring adequate laboratory capabilities is essential. Even though this

was a relatively small outbreak, it strained resources for several months.

Officials said there is a need for broadening laboratory capabilities,

ensuring adequate staffing and expertise, and improving the ability to

deal with surges in testing needs. These concerns point out the

importance of ensuring adequate networks between public health and

other types of laboratories, and of completing assessments of what

laboratory capacity is needed and what capacity is available.

• Because a bioterrorist event could look like a natural outbreak,

bioterrorism preparedness rests in large part on public health

preparedness. While the West Nile virus outbreak is considered by the

Centers for Disease Control and Prevention (CDC) and others to have

been a naturally occurring event, at one point there was speculation that

it might have had an unnatural (bioterrorist) origin. The ensuing

investigation and post-outbreak assessments illustrate the challenges in

identifying the source of an outbreak, supporting public health officials’

views that public health preparedness is a key element of bioterrorism

preparedness.

Background

The Viruses: West Nile and

St. Louis Encephalitis

Identified in 1937 and named after the Ugandan province where its

discovery took place, West Nile virus has a widespread distribution in

Africa, West Asia, and the Middle East, occasionally causing epidemics also

in Europe. Many people infected with the virus do not become ill or show

symptoms, and even when they do, symptoms may be limited to a

headache, sore throat, backache, or fatigue. Because no effective antiviral

drugs have been discovered, treatment for those who do become seriously

ill can only attempt to address symptoms such as swelling of the brain

(encephalitis) and other complications such as bacterial pneumonia.
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Fatality rates—the percentage of people with confirmed infections who

have died—have ranged from 3 to 15 percent for West Nile and are highest

in the elderly.

The virus that was originally misidentified as the cause of the New York

outbreak is called St. Louis virus. Both West Nile and St. Louis encephalitis

viruses are in a group called “flaviviruses,” and can be spread when

mosquitoes bite birds (often a natural host for the virus), acquire the virus,

and then pass it on to humans (see fig. 1). St. Louis encephalitis is found in

nature through much of the lower 48 states and is the most common

mosquito-borne virus causing outbreaks of human disease in the United

States. About 30 confirmed cases occur on average each year during nonoutbreak years. St. Louis encephalitis is also similar to West Nile in that

most people infected with it show no symptoms, but for those who become

seriously ill, no effective antiviral drugs are available. St. Louis encephalitis

has a slightly higher fatality rate than West Nile, ranging from 3 to 30

percent of confirmed cases.

Figure 1: Transmission of St. Louis and West Nile Viruses

Overview of the Public

Health Response Network

Rapid and accurate diagnosis of disease outbreaks is essential for many

reasons. It can help contain an outbreak quickly by allowing health officials

to implement appropriate control or prevention measures and provide the

most effective treatment for those who are affected. Rapid and accurate

diagnosis is essential not only for the public at large, but also for health

care workers and others who work with patients and laboratory samples.

Accurate diagnosis is also important in providing information that could
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help determine whether the outbreak could have been deliberate—an act

of bioterrorism. Public health officials use the term “surveillance” to

denote the ongoing effort to collect, analyze, and interpret health-related

data so that public health actions can be planned, implemented, and

evaluated.

Local health personnel are likely to be the front line of response. Local and

state health departments might be the first to recognize unusual patterns of

illnesses. For example, an epidemiologist (a health official trained to

investigate diseases of unknown origin) in a city health department might

receive phone calls from nurses, doctors, or emergency room personnel

about increasing numbers of patients with similar symptoms. If the

problem is thought to be widespread or suspicious in origin, the local

health department is likely to involve the state health department, which is

responsible for statewide surveillance and investigations involving multiple

locations. The local and state response may also involve emergency

management personnel. Current protocols recommend that law

enforcement officials be notified if a case or series of cases have a

suspicious origin.

Local, state, and federal laboratories also play a vital role. Initially, this role

may be to determine whether the unusual cases have the same pathogen

(the specific causative agent for the disease), and if so, to identify it. Once

an outbreak is established, laboratories may be called upon to test samples

such as blood or spinal fluid from persons with similar symptoms, to

determine who has the illness and the extent of the problem.

At the federal level, CDC, an agency of the Department of Health and

Human Services (HHS), is available upon request to help state and local

officials investigate the nature and origin of disease outbreaks. For

example, CDC maintains several laboratories that identify unusual or

exotic viruses and other pathogens when other laboratories are unable to

do so. One such laboratory, at the Division of Vector-Borne Infectious

Diseases in Fort Collins, Colorado, deals with viral and bacterial diseases

transmitted by vectors such as mosquitoes and ticks. It is part of CDC’s

National Center for Infectious Diseases. Besides providing laboratory

services, this division also develops ways to diagnose vector-borne

pathogens more quickly and helps develop and evaluate approaches to

preventing and controlling outbreaks.
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CDC is also the lead agency in HHS for bioterrorism preparedness. In

recent years, the President and Congress have been increasingly concerned

about the threat of terrorists using weapons of mass destruction, including

biological agents.1 Part of CDC’s National Center for Infectious Diseases,

the Bioterrorism Preparedness and Response Program is responsible for

public health preparedness for potential acts of bioterrorism. In fiscal year

2000, HHS received $278 million of the $10.2 billion in counterterrorism

monies allocated to federal agencies. Of the HHS funding, CDC received

approximately $155 million for bioterrorism preparedness programs in

fiscal year 2000, approximately $40 million of which is to be awarded to

state and local health departments for surveillance, epidemiology,

laboratory, and communications.

West Nile Identified

After Separate

Investigations

Converge

During the first recognized outbreak of West Nile virus in the United States,

infection of animals preceded the first human cases by at least 1 to 2

months. Large numbers of dying birds and an unusual cluster of human

cases were at first viewed as separate events. Gradually, as an increasing

number of laboratories became involved to conduct further testing on

human, animal, and mosquito samples, the linkages became clear, resulting

in the identification of the West Nile virus (see fig. 2). The scale of these

efforts was substantial, involving participants around the country. Since the

end of the outbreak, various local, state, and federal agencies have taken

actions to address the potential ongoing consequences of the virus’s

introduction into North America.

1

Although the chance that terrorists may use biological materials may increase over the next

decade, conventional explosives and firearms continue to be the weapons of choice for

terrorists. Terrorists face considerable obstacles in developing biological weapons. See

Combating Terrorism: Need for Comprehensive Threat and Risk Assessments of Chemical

and Biological Attacks (GAO/NSIAD-99-163, Sept. 1999) and Combating Terrorism:

Observations on the Threat of Chemical and Biological Terrorism (GAO/T-NSIAD-00-50, Oct.

20, 1999).
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Figure 2: Timeline of 1999 West Nile Virus Outbreak

Detecting West Nile: An

Overview

The identification of a newly emerging infectious disease2 within a few

months was due to the combined, considerable efforts of scores of

individuals and several agencies in the animal and the human public health

fields and in academia. Here is an overview of the key events that occurred.

Appendix II contains a more detailed chronology.

The Animal Outbreak No one is sure exactly when or how birds became infected. By late June a

veterinarian at an animal health clinic in the New York City borough of

2

Emerging infectious diseases include those whose incidence in humans has increased

within the past two decades or threatens to increase in the near future.
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Queens had examined and treated several birds that appeared to have

nervous system disorders, releasing those that survived. Reports of dead

birds increased through July and into August. By mid-August, dead birds

were being sent to the wildlife pathologist at the New York State

Department of Environmental Conservation. The wildlife pathologist was

able to determine that the birds were not dying from any of several

common problems, but he could not identify a clear cause. By late August,

veterinarians at the Bronx and Queens zoos had joined the effort to identify

the disease, after several wild and caged birds died on zoo property.

The Human Outbreak Meanwhile, near the end of August, a specialist in infectious diseases in a

community hospital in Queens noticed that the hospital had an abnormally

large number of suspected cases of encephalitis or meningitis (diseases

involving inflammation of the brain or spinal cord) and that several of the

patients had developed an unusual pattern of muscle weakness. When the

hospital’s doctors were unable to find a clear cause or an effective

treatment, the specialist called the Bureau of Communicable Disease

within the New York City Department of Health.3 After a quick but careful

investigation, city health officials contacted the state health department

and CDC for additional help. Blood and spinal fluid specimens from

hospital patients were rapidly tested at state and CDC laboratories. On

September 3, CDC announced that the test results were positive for St.

Louis encephalitis, a virus known in the United States but never before

known to occur in New York City. That same day, the city, assisted by the

state and CDC, launched a massive campaign to prevent people from being

bitten by mosquitoes and to determine the extent of the St. Louis

encephalitis outbreak.

Within the next week, however, the State Department of Health obtained

what appeared to be conflicting test results for St. Louis encephalitis,

raising doubts among some health officials about whether the exact cause

of the outbreak in humans had been determined. In addition, CDC officials

were questioned by city and state health workers and the public as to

whether the deaths of large numbers of birds and the human encephalitis

cases might be connected. Because St. Louis encephalitis had not been

known to kill its bird hosts, CDC officials said they considered the two

3

According to a New York City Department of Health official, these patients were initially

seen by different physicians, as commonly occurs in any hospital, and it was not until a

single infectious disease consultant reviewed their cases that the opportunity to see these

patients as part of a cluster presented itself.
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outbreaks to be unrelated. The cause of the outbreak in birds remained

unidentified, and, to help identify it, the zoo veterinarians and the state

wildlife pathologist enlisted the help of federal veterinary laboratories at

the U.S. Department of Agriculture (USDA) and the U.S. Geological Survey

(USGS). By mid-September, both laboratories concluded that the bird

disease was caused by a virus, that it did not appear to be any strain of St.

Louis encephalitis or other avian virus they had previously tested, and that

they had insufficient laboratory capabilities to identify it more specifically.

The USDA veterinary laboratory sent its virus samples to the CDC

laboratory for further analysis.

The Two Responses Converge

and More Laboratories Become

Involved

The test results in birds, along with repeated negative test results in human

samples in the state health department laboratory, increased the doubts of

some state health officials about whether the human disease agent had

been correctly identified as St. Louis encephalitis. On September 15, they

invited a visiting academic researcher from California to try out some new

testing methods on tissue specimens from human patients. The following

week, a Connecticut agricultural laboratory involved in that state’s routine

mosquito surveillance reported isolating St. Louis encephalitis virus from

both a dead bird and mosquitoes collected near the outbreak area. This

finding was significant in implying that, if the virus was St. Louis

encephalitis, it was killing birds and possibly could be connected to the

human outbreak.

At about the same time, CDC had begun testing and retesting mosquito,

bird, and human specimens against a wider variety of flaviviruses in order

to rule out the possibility of another closely related virus. Independently,

the head pathologist at the Bronx Zoo gained agreement from the U.S.

Army Medical Research Institute of Infectious Diseases to attempt to

identify the virus in birds.

Beginning on September 23, the academic researcher and CDC came to the

same general conclusion: the virus causing the outbreak was not St. Louis

encephalitis but, rather, a virus that had never before appeared in the

United States. By the week of September 27, CDC had confirmed that a

“West Nile-like” virus was responsible for both the animal and the human

outbreaks.
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Workload Was Significant The effort involved in addressing these outbreaks and identifying the cause

was concentrated and considerable. Hundreds of reported potential human

cases were investigated to determine whether West Nile was the infecting

virus. By the end of the investigation, health officials confirmed 62 cases of

West Nile virus, including 7 people who died. Thousands of bird deaths

were similarly investigated by several state and federal laboratories and

agencies, to determine how far the virus had spread. In addition to the

laboratory investigations, state and local emergency management teams

were mobilized to respond to public health concerns. They managed the

coordination of conference calls and other communications, the

establishment of hotlines to address the general public’s concerns, and the

procurement, distribution, and application of pesticides. The New York

City and State Departments of Health also developed fact sheets for the

public on each of the pesticides in 1999, and in 2000 they implemented a

surveillance system for health effects from pesticides.4 Table 1 shows some

specific examples of the case surveillance and laboratory workload

experienced by some of the involved agencies during and since the

outbreak. Not all of the agencies involved have developed cost estimates

for their efforts. As one indication of the cost, however, New York State

officials estimated that the state, city, and four counties in the area spent

more than $14 million on protective measures such as mosquito control

from late August through October.

4

The City Department of Health conducts surveillance for pesticide-related morbidity by

monitoring calls to the Department’s Poison Control Center.
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Table 1: Examples of Surveillance and Laboratory Workload Experienced by Selected Involved Agencies During and Since the

West Nile Outbreak

Note: Several other state and private agencies experienced significant workloads. These examples

represent New York City and State as well as federal government activities.

a

PCR is a laboratory process in which a particular ribonucleic acid (RNA) or deoxyribonucleic acid

(DNA) segment is rapidly replicated, producing a large, readily analyzed sample of a piece of RNA or

DNA.

Agency Time frame Example of workload experienced during and since the outbreak

New York City

Department of Health,

New York City

August to

December

1999

Human case surveillance: The city health department investigated 622 suspect hospitalized

cases and 88 suspect outpatient cases that were reported. Case investigation included

contacting physicians and hospitals, interviewing patients, and coordinating specimen

collection and transport.

Animal and mosquito surveillance: The city set up and maintained mosquito traps, established

a hotline to receive dead bird reports, and triaged the collection of specimens and submission

for testing to appropriate laboratories.

New York State Health

Department (including

counties outside of New

York City and New York

State Department of

Agriculture and Markets)

August to

December

1999

Human case surveillance: The state and local health departments (outside of NYC)

investigated 229 suspect cases, of which 196 were hospitalized.

Human sample testing workload: Polymerase chain reaction (PCR) tests for 13 viruses were

performed on 198 specimens from 190 patients.a Serology tests were performed on almost

600 specimens. A laboratory official indicated that before the outbreak, the average number of

requests for arbovirus tests was 40 to 50 per year.

Animal and mosquito surveillanceb

: As many as 17,000 dead birds were reported by local

health departments to the state (one-third were crows). The state health department

coordinated submissions for testing, with 130 dead birds confirmed positive (at federal

laboratories). Twenty-five horse cases were reported. Over 25,000 mosquitoes (in more than

1,500 pools) were collected, with 15 pools testing positive (at CDC).

New York Department of

Environmental

Conservation, Albany,

N.Y.

1999 to

June 2000c

Avian sample preparation and pathology investigations: The department received, catalogued,

and performed necropsies (postmortem examinations) on 880 dead birds submitted from

various parties across the state; prepared and mailed samples to various laboratories for

testing.

CDC’s Division of

Vector-Borne Infectious

Diseases,

Fort Collins, Colo.

1999 Human sample testing workload: In 1999, CDC-Fort Collins received over 1,200 samples from

New York alone for testing, representing more than 700 patients. In past years, CDC has

received 10 to 20 specimens per year from the state.

Avian sample testing workload: CDC tested approximately 1,000 avian tissue samples and

3,000 serum samples from all locations.

U.S. Geological Survey,

National Wildlife Health

Center, Madison, Wisc.

Fall 1999 to

June 2000

Avian sample testing workload: The Center received almost 1,200 specimens from 22 states

and local jurisdictions, including nearly 500 animal carcasses for necropsy and testing and

699 tissues for testing for West Nile virus from states such as New York and New Jersey.

Live bird surveillance: The Center received almost 1,500 serum samples for West Nile testing

from collaborative surveillance activities with USDA in 10 states and from zoos and

endangered species in captivity. Collected over 1,000 blood samples from wild birds in New

York City in October 1999 for expanded surveillance.

USDA National

Veterinary Services

Laboratories, Ames,

Iowa

Fall 1999 to

July 2000

Animal sample testing workload: The laboratory performed almost 120 virus isolation attempts

and 640 serum sample tests.
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b

In addition to laboratory testing, a large number of staff are involved for surveillance and control and to

respond to public inquiries, set up mosquito traps, collect birds and mosquitoes for shipment, collect

blood samples from horses, establish computerized databases, complete specimen and summary

reports, prepare public information and maps, organize prevention and response programs, and so

forth.

c

Specimens from almost 20 crows stored in 1998 were sent for West Nile testing in the fall of 1999.

Many Federal, State, and

Local Activities Have

Continued Since the Initial

Outbreak

While the first frost of the season signaled the end to the initial outbreak in

1999, activities at the national, state, and local levels have continued. In the

first week of October 1999 the New York City Department of Health and

CDC conducted a random survey of Queens residents to assess the overall

infection rate associated with the outbreak. The results of this serosurvey

(in which a blood test for West Nile antibodies is performed) revealed that

between 1.2 and 4.1 percent of the population in the area surveyed had

been infected with West Nile virus.

The change in diagnosis from St. Louis encephalitis to West Nile also

caused public health agencies to evaluate whether aspects of their

intervention response should be changed. While the West Nile and St. Louis

encephalitis viruses are closely related and mosquito-borne, the change in

diagnosis had some implications for the intervention approach. For

example, past research had shown that different types of mosquitoes might

carry the viruses. Both West Nile and St. Louis encephalitis are carried by a

certain species of mosquito, Culex pipiens. However, West Nile is also

carried by other species, including Aedes vexans and Anopheles. Some of

these species have different habitat and activity patterns. For example,

Culex pipiens breeds in polluted water and is active at night, while A.

vexans has been found in natural areas and is active during the day.5 Once

the distinction between the viruses was made, the public health

interventions were changed accordingly to reflect the other types of

mosquitoes potentially carrying the West Nile. For example, local public

health notices stated that the public should also avoid contact with

mosquitoes active during the day. While these differences are not

considered significant since the public health recommendations for

mosquito control are appropriate in either case, they illustrate the potential

significance of an accurate diagnosis in that even closely related viruses

might require different responses.

5

Due to increased surveillance since the initial outbreak, a new species of mosquito, Aedes

japonicus, has been found to carry the virus.
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Some of the activity since the initial outbreak has involved learning more

about where the virus came from and when it arrived. Research into the

origins of the virus found that it is most closely related to a strain isolated

in a goose found in Israel in 1998. Testing of previously stored bird tissue

samples at the Bronx Zoo was negative for West Nile virus, suggesting the

virus was introduced in 1999.

Much of the ongoing effort has been applied to determining whether West

Nile will be an ongoing threat to animal and human health. The West Nile

outbreak represents a potential problem stretching well beyond New York

City, because the virus can spread through bird migrations. In fiscal year

2000, HHS and CDC will provide approximately $10 million for West Nile

virus activities. This amount includes grants totaling $4.5 million available

to 19 state and local health departments6 along the Atlantic flyway of

migratory birds for West Nile virus surveillance in humans, mosquitoes, and

birds. An additional $2.7 million of the $10 million has been made available

to 31 other state health departments to expand surveillance capabilities. As

of August 2000, communities in at least seven eastern states7 had

undertaken active mosquito control programs, such as spraying, as well as

public education campaigns and surveillance activities.

Surveillance activities have already produced evidence that West Nile has

spread to other areas. In October 1999 a dead crow carrying the virus was

found in Baltimore, Maryland. In 2000, as of August, West Nile virus had

been detected in birds in nearly all New York counties as well as in

Massachusetts, Connecticut, Rhode Island, and New Jersey and in

mosquito pools in several states. If West Nile is carried further south along

bird migratory routes (see fig. 3 for examples), it could become

permanently established in the Western Hemisphere.

6

Massachusetts, Rhode Island, Connecticut, New York State, New York City, Pennsylvania,

New Jersey, Delaware, Maryland, the District of Columbia, Virginia, North Carolina, South

Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and Texas.

7

Connecticut, Delaware, Maryland, Massachusetts, New York, New Jersey, and Rhode

Island.
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Figure 3: Examples of Migratory Patterns of Three Bird Species Susceptible to West Nile

UNITED STATES

CANADA

BRAZIL

Migration Routes

Starling

Herring Gull

Common Tern

Miami

New York

Gulf

of

Mexico
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Source: New Scientist, http://www.newscientist.com/nl/0708/birds.html.

The spread of the virus by birds and mosquitoes has significant

implications for animal health as well. Animal health officials are

concerned about the potential effects on wildlife and other animals,

particularly those birds that are susceptible to fatal illness from the virus.

The USGS, which conducts surveillance of wildlife health, has helped

develop and maintain national maps showing the current wildlife

surveillance data now submitted by states.8 Economic concerns also have

been raised. While wild birds were the primary carrier of West Nile in last

year’s outbreak, the disease was also detected in domestic livestock.

Twenty-five cases were identified in horses on Long Island, nine of which

died or were euthanized. Although there is no evidence that the virus can

spread from infected horses to uninfected horses or other animals,

countries from Argentina to the United Arab Emirates placed import

restrictions on horses from affected areas.9 In addition, the role of

commercial poultry in maintaining or transmitting the virus is not

thoroughly understood. CDC research has found that chickens can develop

a short-lived infection without clinical signs.10

Several organizations, including CDC, USDA, the Wildlife Conservation

Society, and Flushing Hospital, have organized conferences and workshops

to review the West Nile virus outbreak. In December 1999, CDC issued

guidelines for West Nile virus surveillance, prevention, and control. In the

spring of 2000, HHS and USDA appointed West Nile coordinators to

oversee efforts against the virus. See appendix III for a list of some key

publications about or related to the virus outbreak.

8

Developed in partnership with National Atlas of the United States,

http://www.nationalatlas.gov.

9

Horses are thought to be terminal or “dead-end” hosts, in that they can be infected with the

virus, but the virus does not develop in their blood at sufficient quantities to reinfect

mosquitoes.

10As of August 2000, no clinical signs of the virus had been reported in poultry in the United

States, according to USDA.
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Lessons Learned

Center on

Infrastructure and

Communication

While many officials and experts we contacted believe aspects of the

outbreak investigation went quickly and well, nearly all of them also

believe there were lessons to be learned. These lessons may be especially

relevant for acts of bioterrorism, where the outbreak of cases may be much

more rapid and law enforcement agencies may need to be involved to

prevent terrorists from releasing additional biological agents. The time

available for decision-making and response may be compressed from days

or weeks to a matter of hours. The lessons we identified related primarily

to addressing possible needs in five areas:

• local surveillance and response capabilities,

• communication among public health agencies,

• coordination between public health and animal health efforts,

• capabilities of laboratories, and

• efforts to distinguish between natural and unnatural events.

The Local Disease

Surveillance and Response

System Is Critical

The West Nile outbreak provided a number of lessons about surveillance.

We learned that many aspects of the surveillance network worked well,

speeding the response to the outbreak. These positive lessons can serve as

models for other communities that may have less substantial surveillance

networks. However, while several of the lessons are positive, the outbreak

also exposed some weaknesses.

Many Aspects of Surveillance

and Response Worked Quickly

and Well

The human outbreak of West Nile began with a few unusual cases. The

potential that one or two persons’ medical conditions could be an

indication of some larger concern, such as an emerging infectious disease,

may not be readily apparent to the health professionals involved. In many

cases, such events might not be noticed until a number of physicians have

reported the cases and the local health department identifies a cluster, or a

number of victims seek care for similar conditions at the same location.

Alert responses by the doctors and nurses who first see such victims are

particularly crucial in alerting the public health community to the

possibility of a wider problem.

In the West Nile outbreak, several actions were particularly important in

providing this early alert, as well as in providing valuable evidence for the

investigation. Among these actions are the following:

• The physician who encountered the first human cases at the local

hospital in Queens reported the unusual cluster of illnesses to local
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public health officials. Such occurrences could easily go unreported, if,

for example, the physician does not consider the circumstances to be

unusual enough to report or does not recognize a rare disease.

• Epidemiologists and staff at the New York City Department of Health

took a number of actions that were essential to containing the outbreak.

They quickly investigated and recognized the potential significance of

the initial case reports. Their interviews with patients and families

identified common features in how the patients were exposed out of

doors, suggesting that a mosquito-borne disease might be involved. They

canvassed all New York City area hospitals to identify potential cases,

and throughout their investigation, they remained in daily touch with the

many local, state, and federal officials who had quickly become

involved. These staff members said previous planning for bioterrorism

response in place at the city health department was key to the success

of the Department’s response.11

• Autopsies were performed on the victims. The New York City

Department of Health and Office of Chief Medical Examiner worked

together to ensure that autopsies were performed on any fatal case of

encephalitis. Autopsies were performed on over 25 fatal cases who were

initially suspected as having viral encephalitis, including all 4 fatal cases

of West Nile encephalitis that occurred among city residents. According

to one assessment of the response, information obtained from the

autopsies pointed to a flavivirus as the cause and helped guide

subsequent laboratory testing.12 Autopsy rates nationally have been

decreasing, at a time when public health officials believe they should

increase to help detect infectious diseases. The decline has been

influenced by such factors as costs and jurisdictional and authorization

uncertainties.

11Officials indicated that most critical was the collaborative relationship in place between

the health department and the Office of Emergency Management due to the bioterrorism

planning efforts. This collaboration helped facilitate the rapid mobilization of emergency

control measures, establishment of the public hotline, and rapid mobilization of staff over

the holiday weekend to assist in canvassing local neighborhoods with educational materials.

12Wun-Ju Shieh, Jeannette Guarner, Marci Layton, Annie Fine, James Miller, Denis Nash,

Grant L. Campbell, John T. Roehrig, Duane J. Gubler, and Sherif R. Zaki, “The Role of

Pathology in an Investigation of an Outbreak of West Nile Encephalitis in New York, 1999,”

Emerging Infectious Diseases, Vol. 6, No. 4 (May-June 2000).
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Uncertainty Exists About

What to Report, When, and

to Whom

While the West Nile outbreak was identified more quickly than otherwise

might have been expected because an astute physician reported two

unusual cases, it still provides evidence that the reporting system could be

improved. The virus might have been identified earlier—perhaps by a week

according to an involved official—if case reporting had been better and if

good baseline data showing past trends of encephalitis and related diseases

had been available. Similarly, a physician we interviewed who had treated

West Nile patients said clinicians often do not know whom to call when a

cluster of patients with a disease of unknown origin is noticed. Wildlife and

zoo officials also indicated that within their fields there is a need for better

information and guidance about whom to contact in the public health

community when an outbreak is suspected.

These problems have been noted in other instances besides the West Nile

outbreak. For example, a November 1998 workshop on public health

systems and emerging infections sponsored by the Institute of Medicine—

an organization chartered by the National Academy of Sciences to examine

public health policy matters—reported that physicians are not sure when

or where to report suspicious cases of infection. The workshop also

reported that physicians are unaware of the need to collect and forward

clinical specimens for laboratory analysis and may not be educated

regarding the criteria used to launch a public health investigation. Unlike

the case in New York City, where the health department had been actively

communicating with physicians, the workshop found that there is often a

lack of communication between public health agencies and community

physicians.13

A 1999 assessment by the Institute found that disease surveillance systems

in place at local, state, and federal levels rely on systems of disease

reporting from health providers that are notorious for their poor sensitivity,

lack of timeliness, and minimal coverage.14 Because an effective medical

response to a bioterrorist event would depend in part on the ability of

individual clinicians to identify, accurately diagnose, and effectively treat

diseases (including many that may be uncommon), the Institute reported

13Institute of Medicine, Public Health Systems and Emerging Infections: Assessing the

Capabilities of the Public and Private Sectors, Workshop Summary (Washington D.C.:

National Academy Press, November 2000), p. 5.

14Institute of Medicine and National Research Council, Chemical and Biological Terrorism:

Research and Development to Improve Civilian Medical Response (Washington D.C.:

National Academy Press, 1999), p. 66.
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that education about the threat posed by bioterrorism and about the

diagnosis and treatment of various agents deserves priority.

Some Inadequacies in Resources

for Surveillance Were Exposed

Although this outbreak was relatively small in terms of the number of

human cases, it taxed the resources of one of the nation’s largest local

health departments. The strain on resources is particularly noteworthy

because local health departments in the United States have initiated nearly

all the investigations that led to the recognition of infectious disease

outbreaks. At the time of the West Nile outbreak, the New York City

Department of Health had a unit of about eight people responsible for

surveillance and case investigations related to over 50 reportable infectious

diseases. Officials told us that having even this small number of trained

staff available was critical to the quick response to the initial outbreak.

Once the outbreak was identified, these and other staff assigned to help

from other agencies and departments worked long hours, seven days a

week.

We reported in 1999 that surveillance for important emerging infectious

diseases is not comprehensive in all states, leaving gaps in the nation’s

surveillance network.15 Many state epidemiologists reported inadequate

staffing for generating and using laboratory data—often considered more

reliable for case investigation purposes than physician-reported data—for

performing infectious disease surveillance. The Institute of Medicine

workshop reported that, in general, epidemiological investigations and

surveillance efforts are challenged by a variety of factors. These include

changes in the health care system and the continuing use of paper-based

disease-reporting systems in many locations, where surveillance is

consequently sporadic and inadequate.16

Better Communication Is

Needed Among Public

Health Agencies

Experts consider rapid and reliable communication among public health

agencies to be essential to bioterrorism preparedness and coordination.

Timely dissemination of information allows public health officials to make

decisions with the most current information available. During the West Nile

outbreak, however, officials indicated that the lack of leadership in the

initial stages of the outbreak and the lack of sufficient and secure channels

15Emerging Infectious Diseases: Consensus on Needed Laboratory Capacity Could

Strengthen Surveillance (GAO/HEHS-99-26, Feb. 1999), p. 2.

16Public Health Systems and Emerging Infections, p. 4.
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for communication among the large number of agencies involved

prevented them from sharing information efficiently.

Many officials interviewed pointed to the lack of clear reporting guidelines

as one source of confusion. Knowing who was in charge or could act as an

agency spokesperson, and which agency was responsible for what, would

have allowed each agency to operate more effectively. Some officials

suggested that each agency should have one “point person” overseeing

operations and the flow of information.

During the outbreak, local, state, and federal officials held daily conference

calls coordinated by the City or State Department of Health, or CDC.

During these calls, officials received up-to-date information on such topics

as the human and animal surveillance systems, test results from each

laboratory, and schedules for mosquito spraying. While these calls were

considered necessary to ensure that all parties heard the same information,

they sometimes involved over 100 people and lasted 2 hours or more.17 As a

result, key officials had less time to investigate the outbreak in the

laboratory and in the field. Additionally, veterinary health officials were

concerned because they were not always included in these calls.

While a secure electronic communication network was in place at the time

of the initial outbreak, not all involved agencies and officials were using it

at the time. For example, because CDC’s laboratory was not linked to the

New York State network, the New York State Department of Health had to

act as an intermediary in sharing CDC’s laboratory test results with local

health departments. CDC and the New York State Department of Health

laboratory databases were not linked to the database in New York City, and

laboratory results consequently had to be manually entered there.

Physicians, local health departments, and laboratory officials indicated that

during the outbreak, it was sometimes difficult to determine the status of

patients’ samples and of the laboratory results. During and since the

outbreak, however, officials indicated that the use and utility of the

network have improved for West Nile surveillance and information sharing.

Using the network, the state has put together an interactive surveillance

system for mosquito, bird, and human disease reports. Since the fall of

1999, access to the network has been provided to more health officials,

including animal health agencies, for tracking West Nile in animals and

17An involved official indicated that these problems were improved with the implementation

of a standard format and agenda for each call.
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humans. The communication limitations during the outbreak, the resulting

changes to the electronic network capabilities, and the increased reliance

on the network for sharing information have increased awareness of the

need for established electronic data-sharing mechanisms.

New York State officials told us that the state has invested heavily in its

communication infrastructure and has created an advanced information

system, but at a national level some local health departments still do not

have access to modern communication technologies. A 1999 survey by the

National Association of County and City Health Officials found that onethird of health departments serving fewer than 25,000 people did not have

access to the Internet or electronic mail. Similarly, more than half the

agencies surveyed had neither continuous, high-speed access to the

Internet nor broadcast facsimile transmission capabilities.

Links Between Public and

Animal Health Agencies Are

Becoming More Important

The West Nile events illustrate the value of communication between public

and animal health communities, the latter including those dealing with

domestic animals, wildlife, and other animals such as zoo animals. Many

infectious diseases, including West Nile, are zoonotic, that is, capable of

infecting both animals and people. According to recent research,

approximately three of every four emerging infectious diseases reach

humans through animals.18 Of over 1,700 known pathogens affecting

humans, including viruses and bacteria, 49 percent are zoonotic. Of the 156

pathogens associated with emerging diseases, 73 percent are zoonotic.

Many of the viruses or other pathogens considered most likely by CDC to

be used in a bioterrorist incident are zoonotic, such as anthrax, plague,

brucellosis, tularemia, and the equine encephalitic viruses. An official of

the USGS National Wildlife Center noted that many zoonotic pathogens

become established in wildlife before they are transmitted to humans and

domestic animals. The November 1998 Institute of Medicine workshop

reported that, because of their familiarity with a number of these biological

agents, the veterinary medicine community should not be overlooked in

surveillance efforts.19 Moreover, veterinarians and veterinary laboratory

workers are likely to have been vaccinated against many zoonotic diseases

and are used to working with zoonotic pathogens.

18M. Enserink, “Origins of New, Booming Diseases,”

http://sciencenow.sciencemag.org/cgi/content/full/2000/717/1 (cited July 17, 2000).

19Chemical and Biological Terrorism, p. 68.
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The West Nile outbreak shows how domestic, wild, and zoo animals can be

considered “sentinels,” providing an early warning device for diseases that

can harm people. Even for a deliberate biological attack, animals may be

the first victims, unintentionally or as part of an effort to avoid discovery,

according to the Institute of Medicine and National Research Council.20 In

the case of the West Nile outbreak, USDA and USGS National Wildlife

Center laboratories were involved in early or mid-September in testing bird

samples prior to the identification of the West Nile virus. However, because

these laboratories lacked reagents21 for the virus, they were unable at the

time to specifically identify it.

Experience with the West Nile outbreak also illustrates how links between

the animal and public health communities were missing. For example,

• Some key public health officials, such as the city health department’s

Director of the Bureau of Communicable Disease, indicated that they

were not aware of the similarities in the clinical symptoms occurring in

the birds and humans until many days or weeks after the human

outbreak began. Officials said they believe that communication was

hindered even further because, even within the animal health

community, there is fragmentation at the state and federal level in what

agencies are responsible for different types of animals. For example,

domestic animals, such as cats and dogs, are usually the responsibility

of state and local health departments. Livestock, such as cattle and

swine, are often the responsibility of state agricultural agencies.

Wildlife, such as birds, are under the state environmental or wildlife

agencies.

• When wildlife health officials approached the state public health

laboratory to test the bird samples, they were told their samples should

be tested at another laboratory, because the state laboratory did not

have the reagents to perform animal (bird) testing. According to a New

York State animal health official, not having adequate capacity within

the state laboratory to test animal samples can create administrative

and cost barriers to getting samples tested. For example, many

veterinary laboratories will test samples only on a fee basis and not for

public health purposes. In some areas of the country, such as the

20Chemical and Biological Terrorism, p. 72.

21Reagents are chemicals used in laboratory tests to indicate the presence of a virus or other

substance.
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Southwest, where zoonotic diseases such as hantavirus are endemic in

the animal population, integration of the animal and public health

communities is considered to be better.

• Several persons involved in the outbreak commented that the zoo

community is currently left out of the animal and public health

paradigm, even though zoo animals may be useful sentinels. Zoo animals

generally receive close attention from veterinarians, and in some cases

pathologists track health care and disease causes, creating detailed

health records and storing tissue samples for future analysis. Officials

indicated that because zoo animals are not considered to be wildlife or

domestic animals, they do not fall within the jurisdiction of animal

health agencies such as the USGS, which tracks wildlife issues, or the

USDA, which tracks concerns related to domestic animals. The Bronx

Zoo pathologist tried many different channels in order to find

laboratories willing to prioritize performing additional tests on the bird

samples and to provide advice on needed safety precautions for zoo

laboratory personnel working with the bird samples.22

Many officials provided other examples of where communication between

public and animal health communities had not worked well and indicated

that the West Nile events pointed to a need for better partnership between

these communities. This opinion was voiced even by those who at first

disregarded animal health officials’ views and questions about the potential

links between the animal and the human outbreaks. For example, in its

own internal assessment of the West Nile events, CDC concluded that the

relationships between public health agencies at the federal, state, and local

levels and their counterparts in public and private agencies that monitor

veterinary health should be strengthened. There are indications that some

of this greater collaboration has begun. Since the outbreak, archived blood

samples from zoo animals drawn in past years have been analyzed as part

22During the outbreak, one of the biggest concerns of the veterinary pathologist at the Bronx

Zoo was the safety of laboratory workers at the zoo who were handling sick or dead birds.

At one point before the virus was identified, a veterinarian who was euthanizing a dying

flamingo stuck himself with a needle. Because the pathologist surmised that the animal and

human outbreaks were related, this event heightened her concerns about identifying the

virus.
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of the ongoing investigation to determine when and how West Nile was

introduced.23

Assessment of Laboratory

Capacity and Improvement

of Linkages Among

Laboratories Are Needed

Another frequently cited lesson was the need for improved laboratory

infrastructure and technologies for responding to outbreaks and newly

emerging viruses. While the concerns were wide-ranging, three common

themes emerged: broadening laboratory capabilities, ensuring adequate

staffing and expertise, and improving ability to deal with work surges in

testing needs. Since the extent to which public health and other

laboratories across the country are capable of safely testing dangerous

pathogens is unknown, a first step in addressing these concerns may be to

complete assessments of inventory and core capacity needs. At the same

time, lessons from the West Nile outbreak point to the need to improve

current linkages among laboratories.

Broadening Laboratory

Capabilities

The need for enhanced laboratory capabilities was frequently mentioned by

officials involved in the West Nile outbreak, as well as in various

assessments. Officials pointed out the need for more laboratory capacity

for identifying and handling infectious agents of high concern to human

health, particularly emerging or exotic ones. For example, they said that at

the time of the outbreak, only two or three laboratories in the country had

the reagents necessary to identify the West Nile virus. One of these was

CDC’s laboratory in Fort Collins, which did not initially use this reagent

since the first test it had performed was consistent with the related St.

Louis encephalitis virus.24 Because New York State’s laboratory was

considered less equipped to perform the diagnostic testing on the human

samples once the outbreak was identified, CDC performed the bulk of

these tests. In this regard, the need to “expect the unexpected,” a phrase

frequently quoted in outbreak assessments, expresses the importance of

developing a broader awareness within the laboratories of the potential for

23Specifically, according to information provided by a Wildlife Health Sciences, Wildlife

Conservation Society researcher, a serologic survey of the Wildlife Conservation

Society/Bronx Zoo collection was performed to confirm infection of clinical cases, assess

the extent of West Nile exposure, and investigate when the virus was introduced to the

collection.

24According to CDC, West Nile virus was not included in the original battery of antigens in

the tests performed at this point because there are 30 possible antigens to include and West

Nile had never before been seen in the Western Hemisphere. Other experts indicated that

this was a reasonable conclusion at the time.
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new agents to appear and, concurrent with such awareness, developing

broader testing capacity. One federal laboratory official suggested, for

example, that federal policy should consider a broader dissemination of

methods for identifying more exotic pathogens—perhaps those pathogens

that are more likely to be introduced to the country through international

travel or otherwise.
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Some bioterrorism and public health officials noted that, while expansion

of laboratory capacity is vital to preparedness, efforts to identify more

exotic agents may be beyond the scope of all but the largest health

departments and therefore should be a regional or state-based activity.

Consequently, some experts have suggested research into determining the

utility of developing a network of regional laboratories capable of rapid

diagnostic testing.25 Determining current capacity will be a key first step in

assessing the need for a regional network. Currently, the number of public

health and other laboratories that can handle those viruses considered

most harmful (those classified as requiring Biosafety Level-3 or Biosafety

Level-4 equipment, trained staff, and safety procedures in place) is

unknown.26 CDC information indicates that most states lack the public

health laboratory capacity to handle many of those viruses that CDC has

classified as dangerous and identified as high priority because of risk to

national security and public health. Specifically, in fiscal year 1999, less

than half of the over 40 states and localities receiving funding for

laboratory capacity through CDC’s bioterrorism preparedness grant

program reported having advanced capacity for rapid testing for at least

four critical biologic agents.27 Within the veterinary community, a USDA

official told us that probably fewer than 20 veterinary laboratories across

the country have the capacity to test for Biosafety Level-3 pathogens, and

no veterinary laboratories have Biosafety Level-4 capacity.28

25Chemical and Biological Terrorism, p. 73.

26Biosafety Level-3 pathogens are considered serious or lethal with the potential for aerosol

transmission. Biosafety Level-4 pathogens are dangerous, exotic agents posing high risk of

life-threatening disease that also are transmitted through the air and with an unknown risk

of transmission; Biosafety Level-4 pathogens have no vaccines or drugs available for

treatment. Officials told us that three federal laboratories have Biosafety Level-4 capacity

and that an inventory of Biosafety Level-3 laboratories is currently under way.

27Critical biologic agents are those considered by CDC to be of potential concern for

bioterrorism and which must be registered with CDC when acquired or transported. CDC

has classified laboratories based on their biosafety and containment capacities and other

factors, level A, for example, representing those with low-level biosafety facilities and level

D representing those with the highest-level containment and expertise in the diagnosis of

rare and dangerous biological agents. CDC reported that in fiscal year 1999, 19 of 43 funded

states or localities self-reported a level C laboratory capability for at least four of the critical

biologic agents. According to CDC, level C capability requires a Biosafety Level-3 facility.

28Specifically, this official indicated that there are 9 Biosafety Level-3 veterinary laboratories

that can study Biosafety Level-3 pathogen-infected animals, and fewer than 10 additional

veterinary laboratories that have Biosafety Level-3 facilities for doing diagnostics or other

nonanimal work.
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Ensuring Adequate Staffing and

Expertise

Several officials commented on the declining capacity and expertise within

the federal and state public health laboratory infrastructure, particularly as

it relates to zoonotic and vector-borne diseases. At the time of the outbreak

the Fort Collins laboratory capacity was considered to be low, and many

needed specialist positions had been eliminated or left vacant as

experienced staff had left. Similarly, CDC reported that only a few states

and even fewer local health departments have trained personnel or the

resources to adequately address vector-borne diseases. According to CDC

and other officials, the infrastructure of laboratories with the capacity to

handle such diseases has deteriorated in recent decades. The number of

laboratories and extent of capacity have dropped, and the staffing, physical

plant, and financial support of many remaining laboratories have also been

affected.

New York State, prior to the outbreak, lacked the capacity to address

vector-borne diseases. A New York State laboratory official indicated that

at one time the state had 5 or 6 staff to perform mosquito surveillance to

track viruses. In recent years the laboratory’s staff had been cut back as

funding was diverted to other public health priorities. By contrast,

Connecticut officials indicated that they had—after a similar encounter

with eastern equine encephalitis, another mosquito-borne virus—instituted

mosquito surveillance in 1997, at a cost of about $200,000.29 Because of its

ongoing surveillance program, the state was able to quickly respond to the

outbreak, placing mosquito-monitoring devices in potentially infected

areas and identifying the appropriate places to spray. According to a

program official, having baseline data—for example, data on where most

mosquitoes of concern resided in previous years—allowed the state to

make informed decisions about where to spray.

29Officials told us that since the West Nile outbreak last fall, funding for these efforts in the

state has increased.
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Improving Ability to Deal With

Surges in Testing Needs

Testing for West Nile taxed those parts of the laboratory system that were

dealing with the outbreak—and in some ways, affected what some of these

laboratories were normally expected to do. The New York laboratory that

was testing samples for St. Louis encephalitis was also dealing with an

outbreak of Escherichia coli O157:H7 at the same time.30 Both the New

York State and CDC Division of Vector-Borne Infectious Disease

laboratories were quickly inundated with requests for tests, and because of

the limited capacity at the New York laboratories, the CDC laboratory

handled the bulk of the testing. CDC officials reported that nearly all the

Fort Collins Arbovirus Disease Branch laboratory staff at one point was

working on the response to the virus. Normally, the CDC laboratory

functions as a reference laboratory for arboviruses, maintaining the

technology and capability to accurately diagnose viruses of this type.31 In

this case, it was acting largely as a diagnostic laboratory, testing patient

samples to determine who had the virus and who did not. Officials

indicated that the CDC laboratory would have been unable to respond to

another outbreak, had one occurred at the same time. Some officials also

described what were considered to be unfortunate aspects of CDC’s taking

on the role of the diagnostic laboratory. Typically, the CDC laboratory’s role

would be to confirm test results rather than to perform diagnostic testing.

In this case, in assisting the state in performing the diagnostic testing, CDC

focused on determining whether individual patients had St. Louis

encephalitis (and then West Nile) rather than identifying other possible

causes of illness. This was considered by some to be unfortunate from the

standpoint of the individual patients, whose diagnoses could therefore be

delayed. Testing at the state laboratory from 95 patients with suspect viral

infections found 16, or about 17 percent, of the patients positive for viruses

other than West Nile.

30E. coli are normal bacterial inhabitants of the intestines of most animals, including

humans, where they suppress the growth of harmful bacteria and synthesize vitamins.

However, a minority of strains cause illness in humans. E. coli O157:H7, first identified as a

human pathogen in 1982, is a strain that causes severe abdominal cramping and diarrhea

that can become heavily bloody. Although people usually get well without treatment, the

illness can be fatal.

31CDC’s Division of Vector-Borne Infectious Diseases, Arbovirus Disease Branch, functions

as a World Health Organization Collaborating Center for Reference and Research on

Arboviruses.
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Improving the laboratory network is key to improving the laboratory

capacity to respond to surges in workload and to provide the new

technologies, staff, and expertise to respond to outbreaks. Networks or

linkages among federal, state, academic, and possibly private sector

laboratories may also be needed, in part to clarify responsibilities for

involved laboratories for providing surge capacity, diagnostic testing, and

other critical roles in emergency situations. CDC’s internal investigation

concluded that the agency should enlist help from academic laboratories.

The California researcher who conducted some of the diagnostic

laboratory work on the West Nile outbreak was brought in by officials at

New York State’s Department of Health because they learned of the

innovative research his laboratory was developing to quickly and

accurately identify the viral causes of unexplained deaths from

encephalitis.32 Some involved officials indicated that the California

laboratory’s involvement was fortuitous in allowing a laboratory not

consumed with diagnostic testing for the outbreak to focus on performing

the types of tests required to eventually identify the virus. On the other

hand, some officials also indicated that this laboratory’s unplanned

involvement contributed to confusion about which laboratories were

performing tests and the types of tests being performed.

Those involved in responding to the West Nile outbreak have concluded

that with a more formal network and clearer roles,

• necessary tests to accurately identify the virus could have been started

sooner, and

• the resulting confusion about which federal and other laboratories were

involved in the process and the tests each laboratory was performing

could have been avoided or minimized.

32CDC officials from Atlanta were also involved in the discussion regarding involving the

researcher. Because tests can take a considerable amount of time, a key state official

involved in the decision indicated that test results were not expected for weeks or months.

Consequently, officials did not inform the Fort Collins laboratory scientists that samples had

been given to the California laboratory.
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However, while many agree that more should be done to develop the

laboratory network, the plans for such a network are still being developed.

CDC’s planned laboratory response network for bioterrorism—linking

public health laboratories at the local, state, and federal levels—is still

under development.33 Private, veterinary, and USDA laboratories are not

yet part of the network.

Assessment of the public health infrastructure by public health experts,

and CDC’s strategic plan for preventing emerging infectious diseases, also

point out the need for defining and building the laboratory network. The

Institute of Medicine workshop that assessed the capabilities of the public

and private sectors for identifying emerging infections reported that surge

capacity in response to an outbreak is an area in which the public health

laboratory should define its core capability and standards, including the

unique and complementary roles of the public and private sector

laboratories.34 CDC’s strategic plan has a goal to strengthen the public

health infrastructure in part by strengthening CDC’s capacity to serve as

the national and international reference laboratory for the diagnosis of

infectious diseases.35

33The laboratory response network, which would link clinical laboratories to public health

agencies, is discussed in a report containing recommendations of a CDC workgroup. See

Centers for Disease Control and Prevention, “Biological and Chemical Terrorism: Strategic

Plan for Preparedness and Response: Recommendations of the CDC Strategic Planning

Workgroup,” Morbidity and Mortality Weekly, Vol. 49, No. RR-4 (April 21, 2000).

34The workshop also concluded that specialized laboratory techniques in modern biology

and the skilled personnel needed to perform those tests are usually too costly for most

laboratories but could be obtained through the use of a regional system and private-public

partnership. See Public Health Systems and Emerging Infections, p. 21.

35The plan similarly addresses goals and strategies related to other lessons learned

discussed in this report, including improving disease surveillance and outbreak response;

applied research to develop diagnostic tests, drugs, vaccines, and surveillance tools; public

health infrastructure and training; and disease prevention and control. See Centers for

Disease Control and Prevention, Preventing Emerging Infectious Diseases: A Strategy for

the 21st Century (Atlanta, Ga.: U.S. Department of Health and Human Services, 1998).
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Challenges in Distinguishing

Between Natural and

Unnatural Events Show

Common Elements of

Preparedness

Finally, the outbreak and surrounding events illustrate the challenges

inherent in recognizing a bioterrorist event versus a natural outbreak. In

October 1999 a media report suggested that the outbreak could have had an

unnatural origin.36 The Central Intelligence Agency examined the

allegations and concluded that there was no evidence indicating that the

outbreak was caused intentionally.

The report of the possibility of a bioterrorist event, and the difficulties in

correctly identifying the virus and its source, highlight how hard it can be

to determine whether an outbreak has an unnatural origin. While the actual

response to the West Nile virus outbreak might not have been significantly

different had it been considered a potential bioterrorist act, such an event

would require the involvement of additional organizations to carry out a

criminal investigation. CDC’s current recommended protocols are to notify

the Federal Bureau of Investigation and law enforcement officials, who

would also seek to determine whether terrorists had targeted additional

locations for release of the pathogen. The need to involve these agencies

may not be evident at the start. An HHS Office of Emergency Preparedness

official indicated that an investigation of a real bioterrorism attack may

start as an emerging infectious disease outbreak investigation that finds

that the cause was terrorism. It is difficult to establish specific criteria for

reporting an outbreak as suspicious, but officials indicated that improved

reporting criteria may be needed.

The West Nile investigation is not the only incident that has illustrated the

difficulties of determining whether an outbreak was intentionally caused.

According to the Federal Bureau of Investigation, there has been only one

act of terrorism in the United States in which a biological agent was used,

and in this case the deliberate cause was not known until long after the

outbreak had passed. The event occurred in September 1984, when 751

persons in Oregon became ill with gastroenteritis, an inflammation of the

stomach and intestines. The local health department, with assistance from

CDC, discovered that food at salad bars had been contaminated with

Salmonella typhimurium. More than a year later, the Federal Bureau of

36The New Yorker (Oct. 18 and 25, 1999), pp. 90-107.
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Investigation learned through a former member of a religious cult that the

cult had used the Salmonella to contaminate the food.37

The West Nile outbreak may also illustrate the importance of improving our

understanding of the causes of unexplained deaths of previously healthy

people. Currently, much is unknown about the specific pathogens that

cause the deaths of Americans from suspected infectious diseases. Most of

the specific causes of encephalitis are undiagnosed. From the point of view

of improving surveillance for acts of bioterrorism, a key may be in

improving the ability to identify the causative agent in any case where the

disease is serious and unusual. One effort toward this end is CDC’s

unexplained death project. The project—the focus of the Albany

conference at which the academic laboratory at the University of California

at Irvine was asked to use innovative techniques to test the human

samples—aims to improve CDC’s capacity to rapidly identify the cause of

unexplained deaths or critical illness, and to improve understanding of the

causes of specific infectious disease syndromes for which a cause is often

not found.38

37The cult’s intent was to incapacitate people so they would be unable to vote in a local

election. Because the crime was politically motivated, the Federal Bureau of Investigation

subsequently considered the incident to be an act of terrorism. Two former members

pleaded guilty to tampering with consumer products under the Federal Anti-Tampering Act

of 1983. They were each sentenced to 4-1/2 years in prison. See Food Safety: Agencies

Should Further Test Plans for Responding to Deliberate Contamination (GAO/RCED-00-3,

Oct. 1999), pp. 3-4.

38In part, this project was initiated when researchers realized that what were thought to be

new diseases or pathogens had actually been causing illness and deaths in past years. For

example, after the serious outbreak of Legionnaire’s disease in 1976 in Philadelphia, in

which 221 people fell ill and 34 died, investigations identified cases in 1947 and an outbreak

in 1957 that were previously unrecognized. Starting in 1995, under this project, surveillance

for unexplained deaths and critical illnesses occurred first in four, and now in six states.

This surveillance is considered to serve as an early warning system for dangerous microbes

as well as a focal point for research on new tests.
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Finally, the outbreak and surrounding events support public health

officials’ views that bioterrorism preparedness rests in large part on the

soundness and preparedness of the public health infrastructure for

detecting any disease and the causes of disease outbreaks. An important

public health responsibility in any disease outbreak is to identify the agent

and source of the disease as part of the process to determine how to

prevent it from spreading further. From the public health standpoint,

whether an outbreak is natural or artificial may be of little significance,

although the political or legal ramifications may be large.39 Bioterrorism

preparedness officials aware of the West Nile outbreak and investigation

indicated that because the local public health officials were taking

appropriate steps to identify the spread and source of the disease, the

proper steps were under way for determining whether the source or origin

should be considered suspicious.

Appendix III contains a bibliography of selected assessments and reports

that relate to the public health infrastructure and bioterrorism

preparedness.

Conclusions The sudden appearance of West Nile virus in this hemisphere is a clear

illustration of the often-repeated need to “expect the unexpected.” Much of

the initial response was based on typical steps for identifying and

responding to diseases that occasionally break out in the United States.

From that standpoint, the correct public health agencies were involved and

the response was timely and appropriate. But in this case, critical

information and clues pointing to a newly emerging virus were discounted

early on, but reemerged later. Persistence, coupled with the significant

contributions of additional laboratories, investigators, and researchers,

produced the additional evidence leading to the final identification of West

Nile as the cause of the outbreak. However, as more agencies became

involved, coordination with those already involved in the investigation was

not always effective, and communication became more difficult.

39This point was emphasized in the report of the CDC Strategic Planning Workgroup. The

report states that the epidemiologic skills, surveillance methods, diagnostic techniques, and

physical resources required to detect and investigate unusual or unknown diseases are

similar to those needed to identify and respond to an attack with a biological agent. See

Centers for Disease Control and Prevention, “Biological and Chemical Terrorism,” p. 4.
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How can this incident be translated into increasing the likelihood that the

public health network can detect similar threats and then identify and

contain them more effectively in the future? The public health community

is doing a great deal to respond—both to this particular outbreak, which

continues to unfold, and to the larger set of concerns it raised. The lessons

we identified are, to some extent, already part of that ongoing effort.

These lessons support the view of many that “an outbreak is an outbreak is

an outbreak”—that is, whether an outbreak is intentional or natural, the

public health response of determining the causes and containing its spread

will be the same. Thus, policies and actions that improve the capabilities of

the public health infrastructure—including those that improve the animal

health infrastructure—do more than help the nation better prepare for a

potential bioterrorist event. These same improvements will also increase

our ability to detect and contain the more likely sort of outbreak that starts

with a global traveler, a wayward mosquito, or a migrating bird.

We provided a copy of the draft report to CDC, USDA, and New York City

and State Department of Health officials for comment. CDC and the New

York City Department of Health provided written comments, which are

provided in Appendices IV and V. USDA and the New York State

Department of Health also provided comments, which are summarized

below.

Generally, officials agreed with the lessons and conclusions drawn from

experience that are presented in the report. The commenting agencies also

offered several observations on various aspects of the report draft. CDC

said that its strategic plans for emerging infectious diseases and

bioterrorism should be mentioned in the report, and we have done so. CDC

expressed a concern with the emphasis in the draft on those aspects that

did not go as well as others. Because this report was designed to analyze

the events of the fall of 1999 and identify lessons learned for the nation’s

preparedness, it necessarily focused on those things that were perceived as

problems at that time. CDC also expressed a concern that the report

overemphasized the role of the convergence of the human and animal

investigations, because laboratory tests conducted by the California

researcher and others on the human side were also showing that the virus

was not the one initially identified as the cause at the same time as the

animal tests. We agree that these contributions were significant, and we

made clarifications to the text to recognize them. Nonetheless, we continue
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to believe that the information from the animal investigations was critical

to the timing of the final accurate diagnosis.

New York City Department of Health officials highlighted as important the

points in the draft discussing the importance of effective disease

surveillance, the need for better communication among public health

agencies, and particularly the need for better communication within and

among public and animal health communities.

USDA officials indicated that increased emphasis is warranted on the

importance not only of public health preparedness, but also of animal

health preparedness. Several New York State Department of Health

officials and all of the agencies mentioned above provided technical

comments, which were incorporated where appropriate.

We also provided relevant excerpts of the draft report to officials from the

Bronx Zoo, State of Connecticut, New York State Department of

Environmental Conservation, USGS, and University of California at Irvine

for technical review, and their comments were incorporated in the draft

where appropriate.

We are sending copies of this letter to Donna E. Shalala, Secretary of Health

and Human Services; Daniel R. Glickman, Secretary of Agriculture; Jeffrey

Koplan, M.D., Director of CDC; and other interested officials.

This work was performed under the direction of Marcia Crosse, Assistant

Director. Other major contributors are Rob Ball, Katherine Iritani, Anita

Kay, Deborah Miller, and Stan Stenerson. Please contact me at (202) 512-

7119 if you or your staff have any questions.

Sincerely yours,

Janet Heinrich

Associate Director, Health Financing

and Public Health Issues
Page 38 GAO/HEHS-00-180 West Nile Virus Outbreak

Appendix I

Methodology ApApenednxidexiIs

We interviewed officials in the public and private sectors at the national,

state, and local levels, and, to the extent it was made available to us, we

obtained relevant documentation from them. With this information, we

developed a chronology and compiled a list of lessons learned from the

West Nile virus outbreak. To some extent, the chronology was based on

officials’ recollections of the specific events occurring on particular dates.

When information provided by agencies or officials was inconsistent, we

assessed its relevance to our reporting objectives, sought any needed

corroboration from other involved officials, and incorporated the

information accordingly. Officials and agencies contacted included the

following:

• U.S. Department of Health and Human Services, Office of Emergency

Preparedness

• Centers for Disease Control and Prevention, National Center for

Infectious Diseases, Division of Vector-Borne Infectious Diseases,

Division of Viral and Rickettsial Diseases, Division of Bacterial and

Mycotic Diseases

• Central Intelligence Agency

• U.S. Department of Agriculture, Animal and Plant Health Inspection

Service

• U.S. Geological Survey, National Wildlife Health Center

• U.S. Army Medical Research Institute of Infectious Diseases

• New York State Department of Health

• New York State Department of Environmental Conservation

• New York City Department of Health

• New York City Commissioner’s Office of Emergency Management

• Wildlife Conservation Society/Bronx Zoo

• Flushing Hospital Medical Center

• Connecticut Agricultural Experiment Station

• University of California at Irvine

• Association of Public Health Laboratories

• National Association of County and City Health Officials

• a ProMED moderator active during the initial outbreak

To gather background information and relevant literature on the West Nile

outbreak, West Nile virus, and surveillance activities put in place since the

outbreak, we searched academic journals and news media and performed

an extensive review of publications related to the virus. We performed a

similar review to identify reports and literature related to the preparedness

of the public health infrastructure for a bioterrorist event.
Appendix I

Methodology

Page 39 GAO/HEHS-00-180 West Nile Virus Outbreak

We also reviewed assessments of the response to the West Nile outbreak

prepared by various agencies. These assessments both describe the views

of these agencies on lessons learned and outline the steps they have taken

and policies they have implemented since the initial outbreak.
Page 40 GAO/HEHS-00-180 West Nile Virus Outbreak

Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999 ApendxiI

Time is of the essence in responding to an outbreak of an infectious

disease. When the cause of an outbreak is unknown, it is much more

difficult to respond quickly and effectively. As can be seen in the following

chronological table of events, the key to rapidly identifying and responding

to the West Nile virus outbreak lay in merging efforts and information from

separate investigations of outbreaks in animals and humans. At the same

time, as the number of participants increased, so did the complexity and

difficulty of communication and coordination. Looking back on the

outbreak of the fall of 1999 provides an opportunity not only to review the

significant investigative and laboratory work of a myriad of participants

and the contributions of each toward the final diagnosis of the virus, but

also to analyze the communications and actions of the responding

government agencies in order to improve the nation’s preparedness for

future outbreaks, including ones not due to natural causes. Table 2

provides a detailed chronology of significant actions and events.

Table 2: Detailed Chronology of Events in the West Nile Virus Outbreak, 1999

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak

Tuesday, 6/1/99 (Approx. date) Connecticut Agricultural Experiment

Station begins annual mosquito surveillance.

Mid-June to late July

1999

(Approx. dates) Veterinarian at Bayside veterinary clinic

finds crows with signs of nervous system disorders,

treats birds, and releases those that survive.

Tuesday,

8/1/99 to

Friday, 8/13/99

(Approx. date) New York State (NYS) Department of

Environmental Conservation investigates bird poisonings

in New York City (NYC) parks, obtains many reports and

samples of dead birds, especially crows.

(Approx. date) Veterinarian at Wildlife Conservation

Center, Queens, treats several sick wild birds and

releases those that survive; sends specimens to NYS

Department of Environmental Conservation.

(Approx. date) Zookeeper at Bronx Zoo tells zoo

veterinarians he has heard reports about dead crows.

8/2/99: Earliest case of human infection with West Nile

virus identified in retrospective study. Case was

unreported and unknown until after identification of

West Nile virus in late September.

Thursday, 8/12/99 Queens branch of Wildlife Conservation Society reports

dead wild birds to the Bronx Zoo branch.

Bronx Zoo branch of Wildlife Conservation Society sends

dead bird samples to wildlife pathologist at NYS

Department of Environmental Conservation.

Flushing Hospital in Queens admits an elderly patient

who, after a few days, develops serious neurologic

symptoms, including unusual pattern of muscle

weakness.
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 41 GAO/HEHS-00-180 West Nile Virus Outbreak

Sunday, 8/15/99 (Approx. date) Nassau County, N.Y., highway crew brings

in a bag of dead crows to NYS Department of

Environmental Conservation.

Flushing Hospital admits an elderly patient with heart

failure; after a few days he develops neurologic

symptoms, including muscle weakness.

Monday, 8/16/99 ProMED (Internet bulletin board posting news of

infectious disease outbreaks) posts news about bird

poisonings in NYC, says NYS Department of

Environmental Conservation is investigating.

Tuesday, 8/17/99 (Approx. date) Wildlife pathologist at NYS Department of

Environmental Conservation performs necropsies

(postmortem examinations, or autopsies) of dead birds,

examines for aspergillosis (fungal infection), poison,

bacteria.

Wednesday, 8/18/99 Flushing Hospital admits another elderly patient with

symptoms similar to those of the 8/12/99 admission.

Thursday, 8/19/99 Article in local Queens newspaper quotes NYS

Department of Environmental Conservation wildlife

pathologist as saying he has received many dead bird

reports from NYC and Buffalo; reports are being

investigated intensively.

Veterinary assistant from Bronx Zoo phones NYS

Department of Environmental Conservation requesting

laboratory results on zoo samples; informed that NYS

Department of Environmental Conservation wildlife

pathologist is finding several causes but “no common

thread.”

Friday, 8/20/99 Flushing Hospital admits a fourth elderly patient with

possible viral symptoms, who, after a few days,

develops neurologic symptoms.

Flushing Hospital’s chief of infectious diseases

recognizes that in the past 1 to 2 weeks, an unusually

large number of spinal fluid samples have been drawn

to test for meningitis or encephalitis (usually only two or

three per year). Patients’ advanced age and pattern of

muscle weakness also do not fit disease profile

commonly seen at the hospital.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 42 GAO/HEHS-00-180 West Nile Virus Outbreak

Monday, 8/23/99 (Approx. date) NYS agricultural veterinarian informs

state public health veterinarian that dead birds are

being reported in the state. They discuss need for

diagnostic laboratory testing and agree samples

should be sent to the National Veterinary Services

Laboratories in Ames, Iowa, operated by Animal and

Plant Health Inspection Service (APHIS) of U.S.

Department of Agriculture (USDA).

Chief of infectious disease at Flushing Hospital phones

director of Bureau of Communicable Disease, NYC

Department of Health. Requests assistance in

identifying disease causing encephalitis in elderly

patients, discusses possible need to rule out botulism.

Health bureau director does not think described

symptoms fit botulism. She sends an epidemiologist to

Flushing Hospital to review patient records and advises

the chief of infectious disease to send cerebrospinal

fluid samples to the virology laboratory at NYS

Department of Health.

Flushing Hospital admits a fifth patient with neurological

and possible viral symptoms.

Wednesday, 8/25/99 Several birds in outdoor cage at Bronx Zoo die;

necropsies performed in Bronx Zoo pathology laboratory.

Friday, 8/27/99 Chief of infectious disease, Flushing Hospital, again

phones director of NYC Department of Health, Bureau

of Communicable Disease, discusses whether to try

botulism antitoxin because patients are not responding

to any other treatments. Flushing Hospital is having

problems preparing and sending samples to NYS

Department of Health; specimens need to be sent on

dry ice, which hospital does not have. Flushing Hospital

neurologist reports seeing another similar case during a

visit to NYC Hospital−Queens.

To address the Flushing physicians’ concerns about

botulism, the director of the city bureau of

communicable disease contacts Centers for Disease

Control and Prevention (CDC) Foodborne and Diarrheal

Disease Program in Atlanta (oversees botulism

surveillance). CDC experts agree that botulism is

unlikely but that Flushing patients are unusual. Director

of the city Bureau of Communicable Disease decides to

visit Flushing Hospital the next day to gather more

information.

Sixth patient, elderly, admitted at Flushing Hospital with

viral and possible encephalitis symptoms.

Saturday, 8/28/99 Director and epidemiologist from Bureau of

Communicable Disease, NYC Department of Health,

visit Flushing Hospital to review patients and patient

records; they learn another patient with neurologic

symptoms has just been admitted.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 43 GAO/HEHS-00-180 West Nile Virus Outbreak

Sunday, 8/29/99 Epidemiologists from NYC Department of Health

continue interviewing patients and families. They call

hospitals in Queens and nearby Brooklyn and find three

more suspected cases of encephalitis, in addition to five

patients at Flushing Hospital and NYC Hospital,

Queens.

Director of city Bureau of Communicable Disease

begins contacting health officials within CDC’s

Arboviral, Enteroviral, and Viral Special Pathogens

Branches to request assistance with investigating a

possible outbreak of unknown infectious disease in

NYC. Also sends e-mail to NYS Department of Health,

Connecticut Department of Health, and departments of

health in surrounding counties.

Monday, 8/30/99

(approx.)

Wildlife pathologist at NYS Department of

Environmental Conservation contacts chief of

virology laboratory for NYS Department of Health,

requests testing of bird samples. State laboratory

does not have reagents to test for bird viruses.

Laboratory chief suggests sending to Cornell University

veterinary laboratory, who refers the wildlife pathologist

to USDA/APHIS National Veterinary Services

Laboratories.

Conference call between NYC Department of Health,

NYS Department of Health, and individuals in CDC’s

Division of Vector-Borne Infectious Diseases,

Bioterrorism Preparedness and Response Project, and

Division of Viral and Rickettsial Disease. Decision is

made to send patient specimens to NYS Department of

Health for testing. State health department issues

official invitation for CDC to assist with outbreak

investigation. CDC Epidemic Intelligence Service officer

already assigned to New York joins epidemiological

investigation.

NYC Department of Health begins active surveillance

for patients with encephalitis at hospitals throughout the

NYC area. Broadcast fax also is sent to alert NYC

physicians about the Queens disease cluster and to ask

that patients with similar symptoms be reported

immediately.

One of the elderly patients with serious neurologic

symptoms dies at Flushing Hospital; autopsy is

performed.

Tuesday, 8/31/99 Another elderly patient dies at Flushing Hospital of

encephalitis; autopsy is performed. A seventh patient

(young adult) is admitted with viral symptoms, rash,

muscle weakness.

(Approx. date) Human samples from Flushing Hospital

are received by NYS Department of Health virology

laboratory by way of NYC Department of Health.

CDC Epidemic Intelligence Service officer from Atlanta

joins epidemiological investigation in NYC. Evidence

from the environmental field investigation suggests

mosquito-borne disease as possible cause after

numerous mosquito-breeding sites and mosquito larvae

are found in patients’ backyards and neighborhood.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 44 GAO/HEHS-00-180 West Nile Virus Outbreak

Wednesday, 9/1/99 Head of pathology, Bronx Zoo, phones wildlife pathologist

at NYS Department of Environmental Conservation, who

says he has examined about 400 dead birds in August

and is sending samples to the laboratory at USGS

National Wildlife Health Center in Wisconsin.

State health department laboratory reports positive test

results for flavivirus, further evidence of mosquito-borne

disease agent.

NYS Department of Health ships blood and spinal fluid

samples from patients at Flushing Hospital to CDC

Division of Vector-Borne Infectious Diseases, and

informs CDC laboratory by e-mail of negative results for

St. Louis encephalitis by polymerase chain reaction

(PCR, or molecular biological) testing on the previous

day.

CDC Infectious Disease Pathology Activity laboratory

(Atlanta) receives human brain tissue sample from

autopsy of a Flushing patient.

Thursday, 9/2/99 NYS Department of Environmental Conservation wildlife

pathologist contacts the USGS National Wildlife Health

Center laboratory in Wisconsin to request help in testing

bird samples. Instructed to wait until Tuesday, 9/7, to

avoid having samples in transit over the long holiday

weekend.

State health department laboratory reports to NYC

health department that it has a strong reaction for St.

Louis encephalitis in human specimens, using

serological tests known to cross-react with similar

viruses. NYC has never before had a documented,

locally acquired human case of St. Louis encephalitis.

NYC Department of Health has received reports of 30

to 40 suspected human cases in response to its health

alerts and contacting infectious disease and neurology

departments in local hospitals.

CDC Division of Vector-Borne Infectious Diseases

receives samples of Flushing Hospital patients from

NYS Department of Health.

Director of NYC Office of Emergency Management

receives a call in late afternoon from head of NYC

Department of Health, requesting assistance with

cleanup of suspected mosquito-breeding site in Queens

area and preparation for rapid implementation of

mosquito control if CDC confirms mosquito-borne

disease outbreak.

Flushing Hospital admits eighth patient with possible

viral symptoms, muscle weakness, rash.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 45 GAO/HEHS-00-180 West Nile Virus Outbreak

Friday, 9/3/99 CDC Division of Vector-Borne Infectious Diseases

announces it has positive results for St. Louis

encephalitis in human samples by enzyme-linked

immunoabsorbent assay testing (ELISA, a rapid test for

virus antibodies), and it has ruled out several other

viruses.

NYC publishes news releases reporting that CDC has

announced an outbreak of St. Louis encephalitis in New

York City.

CDC Division of Vector-Borne Infectious Diseases

sends a third Epidemic Intelligence Service officer to

NYC to assist.

City Office of Emergency Management and NYC health

department initiate mosquito control activities and start

a public information hotline. Health department

disseminates public information materials and sends

sanitarians to assist with mosquito control and cleanup

in Queens area. Office of Emergency Management

provides interagency coordination and arranges

emergency contracts for mosquito control.

NYC Office of Emergency Management and city health

department begin spraying for mosquitoes in nonresidential areas.

Commissioner of NYC Office of Emergency

Management touches base with Federal Bureau of

Investigation (FBI) about outbreak of unusual infectious

disease in NYC so it can possibly evaluate for criminal

(bioterrorist) involvement. City health officials also in

contact with FBI.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 46 GAO/HEHS-00-180 West Nile Virus Outbreak

Saturday, 9/4/99 Over Labor Day weekend: Animal health officials

become aware of human outbreak of St. Louis

encephalitis through news releases, begin

considering the possibility that outbreak of unknown

infectious disease in birds might be linked.

Connecticut Agricultural Experiment Station

continues to trap mosquitoes and responds to

announcement of St. Louis encephalitis in NYC by

moving mosquito traps to areas near the NYC

outbreak area.

Epidemiologist at NYC health department finds out

about large numbers of dead birds from calls to

public hotline and public comments at a news

conference, considers possible connection

between bird deaths and human outbreak of St.

Louis encephalitis. She informs officials of the

Office of Emergency Management, NYS health

department, and CDC.

Director of NYS arthropod-borne disease program joins

outbreak team in NYC.

At a mobile command unit, a member of the public

brings in a dead bird. Director of NYS arthropodborne disease program advises sending the bird to

the wildlife pathologist at NYS Department of

Environmental Conservation.

Researchers at CDC Infectious Disease Pathology

Activity laboratory in Atlanta examine human

specimens from NYC, observe evidence of viral

encephalitis, obtain positive results for flavivirus in

human brain sample by immunohistochemical testing

(testing for chemical evidence of infection and immune

system response).

Sunday, 9/5/99 (Labor Day weekend) Response to large outbreak of

Escherichia coli O157:H7 at Washington County fair

places large demand on NYS Department of Health

resources.

City health department begins daily alerts to area

health officials.

ProMED electronic mailing list posts announcement of

outbreak of St. Louis encephalitis in NYC.

Monday, 9/6/99 Over Labor Day weekend, several more birds die at

Bronx Zoo.

NYC Office of Emergency Management and health

department do aerial survey, identifying stagnant water

in swimming pools as possible mosquito-breeding sites.

They begin door-to-door and call-in response to get

pools drained.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 47 GAO/HEHS-00-180 West Nile Virus Outbreak

Tuesday, 9/7/99 Wildlife pathologist at NYS Department of Environmental

Conservation sends bird samples to USGS National

Wildlife Health Center laboratory. In cover letter

requesting bird testing, he indicates NYC is

experiencing the highly unusual event of a human

outbreak of St. Louis encephalitis.

(Approx. date) NYS public health veterinarian e-mails

colleagues in other areas where St. Louis

encephalitis has occurred to see if bird die-offs have

been involved. All responses indicate bird die-offs

have not been involved. NYS public health

veterinarian reviews information on Rocio virus,

known to cause bird die-offs along with human

encephalitis outbreak in South America, but it does

not seem a likely cause of the New York outbreak.

City and state departments of health, NYC Office of

Emergency Management, and CDC continue outbreak

response, including telephone surveillance of hospitals

for meningitis and encephalitis cases, weekly fax alerts

to New York City medical community, daily public

communication and response activities, and mosquito

control.

Wednesday, 9/8/99 Wildlife pathologist at NYS Department of Environmental

Conservation sends bird samples to USDA/APHIS

National Veterinary Services Laboratories. Indicates

there is an outbreak of St. Louis encephalitis in

humans in the same area where crows are dying.

Bronx Zoo head pathologist receives and examines

slides from zoo birds that died in late August, compares

to samples from birds that died over the holiday

weekend, finds they have similar lesions indicating

possible encephalitis.

The National Wildlife Health Center laboratory in

Wisconsin receives birds from NYS Department of

Environmental Conservation.

ProMED posts news that Connecticut Agricultural

Experiment Station is testing mosquitoes trapped

near NYC area for both St. Louis encephalitis and

eastern equine encephalitis, and it will be 5 or 6 days

before test results are available.

Entomologist from CDC Division of Vector-Borne

Infectious Diseases arrives in NYC. Begins mosquito

collection in Queens area to study extent of outbreak.

Health officials confirm first positive human case in

Brooklyn (outside of Queens area). Based on this case

and increasing reports of suspected cases throughout

the city, the city health department and Office of

Emergency Management begin citywide mosquito

control.

Laboratory at CDC Division of Vector-Borne Infectious

Diseases begins testing serum samples from New York

patients using virus-specific neutralization assays (tests

used to detect parts of a specific virus) for St. Louis

encephalitis.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 48 GAO/HEHS-00-180 West Nile Virus Outbreak

Thursday, 9/9/99 Wildlife pathologist at NYS Department of Environmental

Conservation sends more crow samples to USGS

National Wildlife Health Center laboratory in Wisconsin,

indicates he has observed “gliosis” in brain tissue

(evidence of degenerative lesion, possible encephalitis).

USDA National Veterinary Services Laboratories in Iowa

receives samples sent on 9/8/99 by NYS Department of

Environmental Conservation.

Bronx Zoo head pathologist starts doing necropsies on

all birds that have died, preserving samples. She calls

CDC in Atlanta; referred to CDC Division of VectorBorne Infectious Diseases in Fort Collins, Colo.

Bronx Zoo head pathologist phones chief of the

epidemiology and ecology section at Division of

Vector-Borne Infectious Diseases, who says the

division’s laboratory is not the appropriate one to

test exotic bird specimens. Suggests specimens be

sent to USDA/APHIS National Veterinary Services

Laboratories for testing. They also discuss possible

human exposure at the Bronx Zoo (needle-stick

injury of veterinary assistant). Bronx Zoo head

pathologist makes a second phone call to Division of

Vector-Borne Infectious Diseases, speaks to the

secretary and requests forms for submitting

samples.

Secretary sends e-mail to chief of epidemiology and

ecology section and to section medical officer regarding

contact from the Bronx Zoo and asking whether approval

is given for sending samples. Medical officer forwards

the e-mail to vertebrate ecologist, who responds he

is willing to look at the bird samples.

Bronx Zoo head pathologist prepares and ships bird

tissue samples to National Veterinary Services

Laboratories; in a cover letter, she indicates possible

connection with St. Louis encephalitis outbreak in

humans and her concern about needle-stick injuries

among laboratory workers. She also sends a serum

specimen from a Bronx Zoo employee who suffered a

needle-stick injury and a plasma specimen from a

flamingo to CDC Division of Vector-Borne Infectious

Diseases.

Meeting held at Bronx Zoo, update on bird deaths and

possible diseases. Zoo officials decide to get an outside

consultant to help with mosquito control.

Third patient dies from viral encephalitis.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 49 GAO/HEHS-00-180 West Nile Virus Outbreak

Friday, 9/10/99 Medical officer, CDC Division of Vector-Borne Infectious

Diseases, responds to vertebrate ecologist by e-mail that

he talked to the head pathologist at Bronx Zoo this

morning, learned that the chief of epidemiology and

ecology section had already told her that the Division of

Vector-Borne Infectious Diseases was not the right place

to send bird specimens. The medical officer advised the

vertebrate ecologist to talk with the section chief before

proceeding further.

National Veterinary Services Laboratories in Iowa

receives Guanay cormorant, bald eagle, flamingo, and

tragopan (pheasant) samples from Bronx Zoo.

Head pathologist at Bronx Zoo is still concerned

about human safety in the laboratory while

performing bird necropsies. Contacts the NYS

agricultural veterinarian to get permission to send

samples to National Veterinary Services Laboratories.

Calls Cornell veterinary college; they suggest National

Veterinary Services Laboratories. Calls head veterinary

medical officer, National Veterinary Services

Laboratories, asks if he would look at samples sent

directly from the Bronx Zoo. Head veterinary medical

officer says he has ruled out Newcastle disease in

samples already received through NYS Department of

Environmental Conservation; preparing to test for avian

influenza.

Assistant to NYC health department

epidemiologists sends an e-mail to the team of

epidemiologists investigating the outbreak. E-mail

indicates receiving a call from the head veterinarian

at the Bronx Zoo saying that many birds are dying

and they have not been able to determine the cause.

NYC health department also has been contacted by

Bayside Historical Society in Queens about dead birds.

Assistant suggests passing the information on to the

CDC Epidemic Intelligence Service veterinarian, who

should let the CDC vertebrate ecologist know when he

arrives, because he “may want to contact the zoo for

samples and perform a battery of tests for

alphaviruses, and perhaps even St. Louis

encephalitis, on these birds.”

NYC Department of Health epidemiologists ask

CDC vertebrate ecologist if bird deaths and human

disease could be related. He responds that bird dieoffs can be caused by many things and the two

outbreaks probably are coincidental.

Saturday, 9/11/99 Head veterinary medical officer for National Veterinary

Services Laboratories phones Bronx Zoo head

pathologist. Results of serology testing are negative for

eastern, western, and Venezuelan equine encephalitis.

Now waiting for virus isolation.

Vertebrate ecologist from CDC Division of Vector-Borne

Infectious Diseases arrives in NYC to conduct the bird

serosurvey (taking and testing samples of blood from

live birds).

Sunday, 9/12/99 NYC Department of Health e-mails message about

Bronx Zoo’s request to look at bird die-offs to CDC

vertebrate ecologist. He responds that he hopes to

meet with head veterinarian of the Bronx Zoo the

next day.

(Approx. date) In the past 1 to 2 weeks, NYS

Department of Health’s virology laboratory has

conducted numerous tests for St. Louis encephalitis

using PCR, all with negative results.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 50 GAO/HEHS-00-180 West Nile Virus Outbreak

Monday, 9/13/99 Connecticut Agricultural Experiment Station obtains

an encephalitic dead crow from Westport area (near

NYC outbreak area), will attempt to isolate virus from

its brain tissue.

CDC vertebrate ecologist visits head veterinarian,

Bronx Zoo, and asks to gather blood samples from

live birds in the zoo. Bronx Zoo head veterinarian

refuses because birds have been dying in the zoo

and they do not want to expose them to additional

stress or infection. Asks if the CDC vertebrate

ecologist would like to test samples from dead

birds and he responds that he is unable to because

he is currently doing live-bird testing in

investigating the human outbreak.

In Albany, NYS Department of Health and CDC are

hosting a meeting of a work group on encephalitis

cases of unknown etiology, associated with CDC’s

unexplained deaths project. Includes researchers from

CDC Atlanta, NYS health department, and academic

researchers, including one from University of California

at Irvine.

Tuesday, 9/14/99 National Veterinary Services Laboratories isolates a

virus from bird samples from Bronx Zoo and NYS

Department of Environmental Conservation and begins

attempting to identify it.

Bronx Zoo head pathologist attempts to phone CDC

Division of Vector-Borne Infectious Diseases to ask

about results on specimens she has sent directly to

them.

(Approx. date) National Wildlife Health Center laboratory

in Wisconsin isolates virus from bird samples, obtains

negative results in testing for St. Louis encephalitis and

eastern equine encephalitis using reagents they have on

hand. National Wildlife Health Center virologists

discuss the possibility of a new strain of St. Louis

encephalitis or an exotic disease.

NYS Department of Health/CDC conference continues

on encephalitis cases of unknown etiology.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 51 GAO/HEHS-00-180 West Nile Virus Outbreak

Wednesday, 9/15/99 National Veterinary Services Laboratories observes, by

electron microscopy, a “flavi/toga-like virus, 40

nanometers in diameter.” Serum-based tests indicated

negative results for eastern, western, or Venezuelan

equine encephalitis viruses, or St. Louis encephalitis

virus. Researchers consider possibility of a new

strain or virus.

National Veterinary Services Laboratories informs head

pathologist at Bronx Zoo about latest test results. Bronx

Zoo head pathologist sends paired plasma samples (well

and sick) from birds to National Veterinary Services

Laboratories.

(Approx. date) Director of National Wildlife Health Center

talks with CDC Division of Vector-Borne Infectious

Diseases, branch chief of arbovirus diseases. They

discuss what virus could be killing birds in New York.

NYS Department of Health’s E. coli outbreak response

is gearing down.

Participants in the conference on encephalitis cases

(including officials from CDC Atlanta) hear that USDA

National Veterinary Services Laboratories isolated a

virus it is unable to identify, from dead birds from New

York. Conference participants suggest sending

human tissue samples to the University of

California researcher’s laboratory so he can attempt

to identify virus with rapid PCR testing methods.

State health officials decide to do so both to test

the California researcher’s testing methods and

also because, although CDC is reporting positive

serologies on human samples, the NYS Department

of Health has failed to obtain positive results for St.

Louis encephalitis by PCR testing after many

attempts.

Thursday, 9/16/99 CDC Division of Vector-Borne Infectious Diseases

medical officer calls back Bronx Zoo head

pathologist, suggests discontinuing bird necropsies

until human safety factors are determined. Suggests

sending existing samples to NYS Department of

Health’s laboratory for faster testing than Division of

Vector-Borne Infectious Diseases would do at this

time on animal samples.

USDA National Veterinary Services Laboratories

contacts the CDC liaison officer at Veterinary

Services at USDA/APHIS because of unusual

properties of the virus it has isolated and its lack of

reagents to identify whether the virus could be a

human pathogen. Liaison officer contacts CDC. CDC

contacts head veterinary medical officer at National

Veterinary Services Laboratories and asks for virus

isolate to be sent to the Division of Vector-Borne

Infectious Diseases in Fort Collins. CDC recommends

waiting until Monday, 9/20/99, to ship the isolate to avoid

having it in transit over the weekend.

Staff of virology laboratory, NYS Department of Health,

sends human brain tissue samples from several

patients to researcher at University of California at

Irvine.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 52 GAO/HEHS-00-180 West Nile Virus Outbreak

Friday, 9/17/99 Bronx Zoo head pathologist phones NYS Department of

Environmental Conservation wildlife pathologist, who

reports having sent bird samples to USGS National

Wildlife Health Center laboratory.

Bronx Zoo head pathologist leaves message for and

receives message from acting section chief of Diagnostic

and Reference, CDC Division of Vector-Borne Infectious

Diseases. He expects Bronx Zoo samples from National

Veterinary Services Laboratories to arrive on 9/21/99.

Bronx Zoo head pathologist attempts to establish contact

with the U.S. Army Medical Research Institute of

Infectious Diseases.

Bronx Zoo head pathologist calls chief of the

virology laboratory for the NYS Department of

Health. The laboratory chief requests samples of

virus isolates from National Veterinary Services

Laboratories and advises on use of laboratory hoods

for increasing human safety in the zoo pathology

laboratory.

University of California researcher receives brain

samples sent the previous day by NYS Department of

Health. He contacts officials at CDC’s Division of Viral

and Rickettsial Disease in Atlanta, informs them he has

been invited by NYS health department to assist in

testing human samples. He obtains information from

chief of the CDC Infectious Disease Pathology Activity

laboratory about his previous findings from

immunohistochemical testing of brain tissue from NY

patient.

At CDC Division of Vector-Borne Infectious Diseases,

results of testing for St. Louis encephalitis in human

serum specimens are inconclusive.

Saturday, 9/18/99 CDC entomologist returns to CDC Division of VectorBorne Infectious Diseases from NYC, begins

assembling data from mosquito survey.

Monday, 9/20/99 Bronx Zoo head pathologist contacts National

Veterinary Services Laboratories, provides address

for the virology laboratory at the NYS Department of

Health, requests that virus isolate samples of Bronx

Zoo birds be sent there.

National Veterinary Services Laboratories ships virus

isolates to the Division of Vector-Borne Infectious

Diseases. Virus isolates shipped were made from tissues

of birds originally submitted by NYS Department of

Environmental Conservation and the Bronx Zoo.

University of California researcher’s laboratory purifies

RNA from human brain samples and synthesizes

reagents in preparation for PCR testing.

(Continued From Previous Page)

Date Phase 1: Animal Outbreak Phase 2: Human Outbreak
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 53 GAO/HEHS-00-180 West Nile Virus Outbreak

Date Phase 3: Convergence

Tuesday, 9/21/99 Connecticut Agricultural Experiment Station reports isolating virus from brain tissue of a dead crow and from

mosquitoes; they appear to be the same virus. Possible implication: If the virus is St. Louis encephalitis, it can kill

and is killing birds; human and bird outbreaks may be related.

Chief of arbovirus diseases branch at CDC Division of Vector-Borne Infectious Diseases contacts Connecticut

Agricultural Experiment Station, determines testing protocols were not specific for St. Louis encephalitis. CDC

requests that Connecticut Agricultural Experiment Station send virus isolates to the laboratory at CDC Division of

Vector-Borne Infectious Diseases for confirmation.

Vertebrate ecologist, CDC Division of Vector-Borne Infectious Diseases, returns to Fort Collins laboratory from

NYC.

CDC Division of Vector-Borne Infectious Diseases receives virus isolates from head veterinary medical officer at

National Veterinary Services Laboratories and begins testing for several related viruses.

Veterinary pathologists at U.S. Army Medical Research Institute of Infectious Diseases respond to contact from the

head pathologist at the Bronx Zoo, agree to test bird samples.

University of California researcher initiates genomic sequence studies on human brain samples.

Wednesday, 9/22/99 Director of Bureau of Communicable Disease, NYC Department of Health, hears for the first time that the wildlife

pathologist at NYS Department of Environmental Conservation had been finding encephalitis in dead birds. Calls

CDC. The city health department begins helping to collect dead birds. NYS public health veterinarian establishes

surveillance system and database for ill and dead birds.

Vertebrate ecologist at CDC Division of Vector-Borne Infectious Diseases begins testing samples obtained through

bird serosurvey, hears about news from Connecticut Agricultural Experiment Station, sets up tests for other

flaviviruses besides St. Louis encephalitis.

CDC Division of Vector-Borne Infectious Diseases obtains positive test result for flavivirus in bird specimens from

National Veterinary Services Laboratories.

Bronx Zoo head pathologist phones U.S. Army Medical Research Institute of Infectious Diseases, learns that it has

negative test results on Bronx Zoo bird samples for eastern, western, and Venezuelan equine encephalitis. Bronx

Zoo head pathologist ships more samples to U.S. Army Medical Research Institute of Infectious Diseases. Bronx

Zoo head pathologist talks with director of virology laboratory at NYS Department of Health, learns Connecticut

Agricultural Experiment Station laboratory has isolated virus in both birds and mosquitoes. Bronx Zoo head

pathologist contacts CDC Division of Vector-Borne Infectious Diseases, informs them of results from U.S. Army

Medical Research Institute of Infectious Diseases.

Late evening: Using PCR technique, University of California researcher finds genetic patterns of a flavivirus in

brain samples of three New York patients.
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 54 GAO/HEHS-00-180 West Nile Virus Outbreak

Thursday, 9/23/99 University of California researcher phones virologist at NYS Department of Health laboratory, reports he has found

genetic evidence of flavivirus in brain samples of three human patients. Begins comparing flavivirus genomes from

two patients to genome patterns available in GenBank (a national database of genetic information on disease

agents).

CDC Division of Vector-Borne Diseases again contacts Connecticut Agricultural Experiment Station. The Station is

shipping virus isolates.

CDC Division of Vector-Borne Infectious Diseases completes retesting of four human specimens previously tested

for St. Louis encephalitis. Now testing for St. Louis encephalitis, West Nile, Japanese encephalitis, Powassan,

dengue, and yellow fever viruses to rule out possibility of infection by a closely related virus. Retesting produces

high reactivity with West Nile virus. Retesting commences on 24 more specimens. Strong reaction for West Nile

virus in human body fluid samples using enzyme-linked immunoabsorbent assay (ELISA). Informs CDC Atlanta.

CDC laboratory designs PCR test for West Nile virus and identifies “West Nile-like” virus in birds from virus isolates

from USDA/APHIS National Veterinary Services Laboratories.

Bronx Zoo head pathologist hears from veterinary pathologists at U.S. Army Medical Research Institute of

Infectious Diseases that they have preliminary identification of St. Louis encephalitis or a related virus; requesting

normal control samples for flamingo and tragopan.

Bronx Zoo head pathologist phones head veterinary medical officer at National Veterinary Services Laboratories,

asks why virus isolate samples were not sent to the NYS Department of Health laboratory as requested. National

Veterinary Services Laboratories will ship isolates to NYS Department of Health on September 27 because of the

need to send samples with adequate virus titer and to avoid shipping over the weekend.

Mid-afternoon: Teleconference between Bronx Zoo head pathologist and Division of Vector-Borne Infectious

Diseases, who report they have tested isolates from National Veterinary Services Laboratories and have obtained

positive results for flavivirus. Bronx Zoo head pathologist sends more samples to Division of Vector-Borne

Infectious Diseases.

(Continued From Previous Page)

Date Phase 3: Convergence
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 55 GAO/HEHS-00-180 West Nile Virus Outbreak

Friday, 9/24/99 NYS Department of Health gets phone and fax messages from University of California researcher. From samples

from NYS Department of Health, he has determined virus is not St. Louis encephalitis but appears most closely

related to Kunjin virus and West Nile virus. Researcher also informs others at University of California at Irvine.

Director of virology laboratory at NYS Department of Health calls chief of arbovirus diseases branch, CDC Division

of Vector-Borne Infectious Diseases; informs him of the University of California researcher’s results. State

laboratory officials inform NYS Health Commissioner.

Division of Vector-Borne Infectious Diseases completes retesting of 24 human specimens, results show high

reactivity with West Nile virus. Amplifies ribonucleic acid of virus from human brain tissue for PCR testing.

Conference call including officials from CDC Division of Vector-Borne Infectious Diseases, CDC Atlanta, NYS

Department of Health, NYC Department of Health, Connecticut Department of Health, and Connecticut

Agricultural Experiment Station, and Bronx Zoo head pathologist. CDC announces West Nile virus in birds, does

not want to announce publicly that West Nile virus has been found in humans until genome sequencing is

completed and diagnosis is confirmed, expected early the following week. CDC publishes news release on West

Nile virus found in birds.

Head veterinary medical officer at National Veterinary Services Laboratories contacts headquarters for Veterinary

Services at USDA Animal and Plant Health Inspection Service and also the office of the veterinarian-in-charge for

the New York area; informs them of CDC’s finding of West Nile-like virus in birds.

Friday evening: University of California researcher informs deputy director of Division of Viral and Rickettsial

Diseases, CDC Atlanta, of finding virus related to Kunjin virus or West Nile virus in humans by genomic

sequencing.

Saturday, 9/25/99 Partial genome sequencing of human specimens at CDC Division of Vector-Borne Infectious Diseases indicates

probable final diagnosis of West Nile virus in humans. Continuing analysis of samples from the bird serosurvey

produces evidence of West Nile virus-neutralizing antibodies in healthy birds. West Nile virus confirmed in

specimens obtained from the Connecticut Agricultural Experiment Station.

CDC Division of Vector-Borne Infectious Diseases contacts researcher at University of California at Irvine. They

compare their findings and discuss plans for public announcements and publications.

Connecticut Agricultural Experiment Station obtains a live Cooper’s hawk with neurologic symptoms; bird dies the

next day and is tested for viral identification.

News media breaks story, West Nile virus in birds and West Nile virus or Kunjin virus in people, explains CDC at

first misidentified the virus as St. Louis encephalitis.

ProMED reports a 75-year-old resident of Toronto, Canada, has St. Louis encephalitis after visiting New York City.

Sunday, 9/26/99 CDC Division of Vector-Borne Infectious Diseases expands dead bird surveillance, soliciting bird samples in

affected states and asking that samples be submitted through state wildlife pathologists.

(Continued From Previous Page)

Date Phase 3: Convergence
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 56 GAO/HEHS-00-180 West Nile Virus Outbreak

Monday, 9/27/99 Chief of epidemiology section, bacterial zoonoses branch, at CDC Division of Vector-Borne Infectious Diseases

goes to NYC to help the NYC health department conduct a human serosurvey (collection of blood samples from

random sample of humans in the outbreak area).

Researcher at Pasteur Institute, Paris, posts an offer on ProMED to assist scientists studying the New York

outbreak by providing West Nile virus genome sequence patterns that have not yet been published.

Researchers at CDC Division of Vector-Borne Infectious Diseases talk to foreign researchers to establish a

collaboration.

Evening: University of California researcher responds on ProMED to offer of assistance from researcher at Pasteur

Institute; gives detailed report on his work to date in identifying “Kunjin/West Nile virus” in humans.

USDA Animal and Plant Health Inspection Service is officially notified by CDC that “West Nile-like virus,” rather

than St. Louis encephalitis, is responsible for the human encephalitis outbreak in New York.

CDC announces it has established that human outbreak in New York is due to West Nile-like virus. Involved

agencies receive a large number of news media contacts and requests for information from the public.

Tuesday, 9/28/99 Human serosurvey (collection of blood samples) in NYC area begins, supported by six Epidemic Intelligence

Service (EIS) officers from CDC and over 100 personnel from the NYC health department.

(Approx. date) Preliminary results from bird serosurvey indicate an infection rate greater than 50 percent for birds

in northeast Queens, providing further evidence of where outbreak may have originated.

Daily conference calls are initiated among agencies participating in the outbreak response.

USDA/APHIS veterinary services headquarters notifies others in APHIS and the Secretary’s Advisory Committee

on Foreign Animal and Poultry Diseases about West Nile-like virus outbreak in NY area.

(Approx. date) CDC and international scientists find a link between the NYC strain of West Nile virus and a recent

strain from Israel.

Wednesday, 9/29/99 Briefing of staff for New York and Connecticut congressional representatives by CDC’s acting deputy director for

science and public health.

USDA Animal and Plant Health Inspection Service (APHIS) coordinates with state officials and cooperating federal

agencies to address impact of West Nile virus outbreak on agricultural industry.

Thursday, 9/30/99 USDA receives reports of a horse on Long Island possibly infected with West Nile virus.

Division of Vector-Borne Infectious Diseases isolates virus from Culex mosquitoes collected in Queens on

September 12 and 13, identifies West Nile virus.

Friday, 10/1/99 USDA Animal and Plant Health Inspection Service plans diagnostic testing, inoculation studies, surveillance.

Foreign animal disease diagnostician at USDA Animal and Plant Health Inspection Service investigates a

suspicious horse death on eastern Long Island and submits tissue samples to APHIS National Veterinary Services

Laboratories for diagnosis.

Saturday, 10/2/99 CDC identifies West Nile virus in infected birds submitted from New Jersey.

Sunday, 10/3/99 (Approx. date) Sixth human death from West Nile virus (Nassau County resident).

Tuesday, 10/5/99 National Veterinary Services Laboratories receives samples from Long Island horse; begins virus isolation.

ProMED posting: Birds found positive for West Nile virus in New Jersey.

(Continued From Previous Page)

Date Phase 3: Convergence
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 57 GAO/HEHS-00-180 West Nile Virus Outbreak

Wednesday, 10/6/99 (Approx. date) USGS National Wildlife Health Center laboratory in Wisconsin sends virus isolates from testing of

birds begun in early to mid-September to CDC Division of Vector-Borne Infectious Diseases. CDC laboratory

confirms West Nile virus in the samples.

The human serosurvey conducted by the NYC health department and CDC is completed.

Thursday, 10/7/99 USDA Animal and Plant Health Inspection Service distributes guidelines for investigating suspected West Nile

virus cases in livestock and poultry.

Saturday, 10/9/99 Tissues, including brain tissue, from a second horse from Long Island are received at National Veterinary Services

Laboratories, duplicates also sent to CDC.

Sunday, 10/10/99 CDC and other federal agencies provide information about West Nile virus outbreak in relation to bioterrorism, in

anticipation of a story to be released the following day in The New Yorker that indicates possible connection

between outbreak and bioterrorist activities by Iraq.

USDA Animal and Plant Health Inspection Service sends early response team, including veterinary pathologist,

epidemiologist, and foreign animal disease diagnostician, to investigate reports of several horse deaths on Long

Island. At the request of NYS animal health officials, the APHIS team works with state personnel, a local

veterinarian, and horse owners to conduct an epidemiological investigation and examine affected animals. Eight

horse deaths and 18 affected animals are identified.

Monday, 10/11/99 Article published in The New Yorker suggesting West Nile virus outbreak could have been deliberately introduced

by Iraq. More news media and public response.

Tuesday, 10/12/99 National Veterinary Services Laboratories isolates virus from horse samples from Long Island, sends to CDC

Division of Vector-Borne Infectious Diseases for identification.

Wednesday,

10/13/99

(Approx. date) USGS National Wildlife Health Center laboratory receives reagents from CDC so it can test for West

Nile virus in wildlife.

ProMED posting, University of California researcher responds to requests for West Nile virus primers and

protocols for RT-PCR test, publishes protocol on ProMED.

Thursday, 10/14/99 CDC examines isolates of West Nile virus from horse samples sent by National Veterinary Services Laboratories.

Initially obtains negative results by PCR testing but later confirms National Veterinary Services Laboratories’

isolation of virus.

Friday, 10/15/99 U.S. Army Medical Research Institute of Infectious Diseases agrees to provide laboratory support for National

Veterinary Services Laboratories and animal health investigations.

Saturday, 10/16/99 National Veterinary Services Laboratories completes PCR testing of virus isolated from two Long Island horses,

using genetic sequence provided by CDC. Both horses test positive for West Nile virus.

Monday, 10/18/99 U.S. Army Medical Research Institute of Infectious Diseases provides Vickers Unit (portable biosafety level 3

laboratory), requested and paid for by USDA Animal and Plant Health Inspection Service, to Bronx Zoo so it can

safely perform necropsies and prepare samples for testing.

Tuesday, 10/19/99 CDC Division of Vector-Borne Infectious Diseases reports serologic evidence of West Nile virus in horses.

NYS agricultural commissioner issues a press release reporting that horse deaths and illnesses in Long Island

area were likely due to West Nile-like virus.

Wednesday,

10/20/99

Memo from NYS agricultural veterinarian and NYS public health veterinarian summarizing confirmed cases of

West Nile virus in horses, birds, and humans (56 confirmed cases with seven deaths).

USDA Animal and Plant Health Inspection Service notifies agricultural commissioners and state veterinarians

along the East Coast that West Nile virus has been found in horses on Long Island, NY.

(Continued From Previous Page)

Date Phase 3: Convergence
Appendix II

Timeline of Key Dates and Events in the West

Nile Virus Outbreak, 1999

Page 58 GAO/HEHS-00-180 West Nile Virus Outbreak

Note: Events involving crossover between animal and health outbreaks before convergence phase are

represented in bold type.

Thursday, 10/21/99 USDA Animal and Plant Health Inspection Service notifies representatives of the horse industry that West Nile

virus has been found in Long Island horses, provides informational materials.

Many postings on ProMED about whether transcontinental airplanes are sprayed for mosquitoes.

Friday, 10/22/99 CDC Division of Vector-Borne Infectious Diseases and co-authors submit article for publication in Science, linking

NYC virus strain to a strain of West Nile virus from Israel. Later published in 12/17/99 issue, along with paper from

Connecticut Agricultural Experiment Station research group on its isolation of West Nile virus in Cooper’s hawk

and other species.

ProMED posts update from CDC, West Nile virus has been identified in a variety of birds, no human cases were

reported after 9/22/99. Posting stating that China has placed an import ban on U.S. horses.

Saturday, 10/23/99 (Approx. date) Researchers from USGS National Wildlife Health Center obtain a blood sample from a migrating

bird in the Bronx. CDC later isolates West Nile virus from this sample, providing evidence that migratory birds

might transport the virus.

Monday, 10/25/99 City department of health and Office of Emergency Management end the public hotline. Approximately 150,000

calls have been processed since it began on 9/3/99.

Thursday, 10/28/99 The Division of Vector-Borne Infectious Diseases reports that a dead crow infected with West Nile virus has been

collected from Baltimore, Md. (submitted by the Maryland Department of Health through the USGS National

Wildlife Health Center).

Friday, 10/29/99 European Union notifies USDA Animal and Plant Health Inspection Service of import restrictions on horses from

New York, New Jersey, and Connecticut.

USDA Animal and Plant Health Inspection Service notified that Mexico will not accept live poultry from areas

affected by West Nile virus.

Monday, 11/8/99 −

Tuesday, 11/9/99

Workshop co-sponsored by Department of Health and Human Services, CDC, and USDA held in Fort Collins,

Colo. Participants include most agencies and individuals involved in outbreak response.

(Continued From Previous Page)

Date Phase 3: Convergence
Page 59 GAO/HEHS-00-180 West Nile Virus Outbreak

Appendix III

Related Publications ApendxiI

West Nile Response

Summaries and Plans

Centers for Disease Control and Prevention. Expecting the Unexpected:

Lessons from the 1999 West Nile Encephalitis Outbreak. Atlanta, Ga.:

Centers for Disease Control and Prevention, July 2000.

-----. Epidemic/Epizootic West Nile Virus in the United States: Guidelines for

Surveillance, Prevention, and Control. Atlanta, Ga.: Centers for Disease

Control and Prevention, March 2000.

New York State Department of Health. New York State West Nile Virus

Response Plan. Albany, N.Y.: New York State Department of Health, May

2000.

Wildlife Conservation Society. Proceedings of the West Nile Virus Action

Workshop. New York, N.Y.: Wildlife Conservation Society, Jan. 19-21, 2000.

West Nile Virus

Veterinary/Animal Health Anderson, J.F., T.G. Andreadis, C.R. Vossbrinck, and others. “Isolation of

West Nile Virus From Mosquitoes, Crows, and a Cooper’s Hawk in

Connecticut.” Science, Vol. 286, No. 5448 (Dec. 17, 1999), p. 2331.

Nolen, R.S. “Veterinarians Key to Discovering Outbreak of Exotic

Encephalitis.” Journal of the American Veterinary Medical Association,

http://www.avma.org/onlnews/javma/nov99/s111599a.asp (cited Nov. 15,

1999).

Steele, K.E., M.J. Linn, R.J. Schoepp, N. Komar, T.W. Geisbert, R.M.

Manduca, P.P. Calle, B.L. Raphael, T.L Clippinger, T. Larsen, J. Smith, R.S.

Lanciotti, N.A. Panella, and T.S. McNamara. “Pathology of Fatal West Nile

Virus Infections in Native and Exotic Birds During the 1999 Outbreak in

New York City, New York.” Veterinary Pathology, Vol. 37 (May 3, 2000), pp.

208-24.

Medical/Public Health Asnis, D., R. Conetta, A. Teixeira, and others. “The West Nile Virus

Outbreak of 1999 in New York: The Flushing Hospital Experience.” Clinical

Infectious Diseases, Vol. 2000, No. 30 (Feb. 29, 2000), pp. 413-18.
Appendix III

Related Publications

Page 60 GAO/HEHS-00-180 West Nile Virus Outbreak

Centers for Disease Control and Prevention. “Outbreak of West Nile-Like

Viral Encephalitis—New York, 1999.” Morbidity and Mortality Weekly

Report, Vol. 48, No. 38 (Oct. 1, 1999), pp. 845-49.

-----. “Update: West Nile-like Viral Encephalitis—New York, 1999.” Morbidity

and Mortality Weekly Report, Vol. 48, No. 39 (Oct. 8, 1999), pp. 890-92.

Cheng, G.S. “West Nile Virus: Physician Reports Will Be Crucial.” Family

Practice News, Vol. 30, No. 1 (Jan. 1, 2000), p. 12.

“Exotic Diseases Close to Home.” Editorial, The Lancet, Vol. 354, No. 9186

(Oct. 9, 1999), p. 1221.

Research Briese, T., J. Xi-Yu, C. Huang, L.J. Grady, and I.W. Lipkin. “Identification of a

Kunjin/West Nile-like Flavivirus in Brains of Patients With New York

Encephalitis” (Letter). The Lancet, Vol. 354, No. 9186 (Oct. 9, 1999), pp.

1261-62.

Enserink, M. “Groups Race to Sequence and Identify New York Virus.”

Science, Vol. 286, No. 5438 (Oct. 8, 1999), p. 206.

-----. “New York’s Lethal Virus Comes From Middle East, DNA Suggests.”

Science, Vol. 286, No. 5444 (Nov. 19, 1999), p. 1450.

Lanciotti, R.S., J.T. Roehrig, V. Deubel, and others. “Origin of the West Nile

Virus Responsible for an Outbreak of Encephalitis in the Northeastern

United States.” Science, Vol. 286, No. 5448 (Dec. 17, 1999), p. 2333.

Shieh, W.J., J. Guarner, M. Layton, A. Fine, J. Miller, D. Nash, G.L. Campbell,

J.T. Roehrig, D. J. Gubler, and S.R. Zaki. “The Role of Pathology in an

Investigation of an Outbreak of West Nile Encephalitis in New York, 1999.”

Emerging Infectious Diseases, Vol. 6, No. 4 (May-June 2000), pp. 370-72.

Smithburn, K.C., T.P. Hughes, A.W. Burke, and J.H. Paul. “A Neurotropic

Virus Isolated From the Blood of a Native of Uganda.” American Journal of

Tropical Medicine and Hygiene, Vol. 20 (1940), p. 471.

Tsai, T.F., F. Popovici, G.L. Cernescu, and N.I. Nedelcu. “West Nile

Encephalitis Epidemic in Southeastern Romania.” The Lancet, Vol. 352

(Sep. 5, 1998), pp. 767-71.
Appendix III

Related Publications

Page 61 GAO/HEHS-00-180 West Nile Virus Outbreak

“West Nile Virus Similar to Israel ’98 Virus.” Family Practice News, Vol. 30,

No. 1 (Jan. 1, 2000), p. 12.

Reemergence Holloway, M. “Outbreak Not Contained.” Scientific American, Vol. 282

(April 2000), pp. 20-22.

Moran, M. “West Nile Outbreak Sends Wake-up Call for Surveillance.”

American Medical News, Vol. 43, No. 3 (Jan. 24, 2000), p. 1.

General Centers for Disease Control and Prevention. Preventing Emerging

Infectious Diseases: A Strategy for the 21st Century. Atlanta, Ga.: U.S.

Department of Health and Human Services, 1998.

Centers for Disease Control and Prevention, National Center for Infectious

Diseases, Division of Vector-Borne Infectious Diseases. Guidelines for

Arbovirus Surveillance Programs in the United States. Atlanta, Ga.: Centers

for Disease Control and Prevention, April 1993.

Public Health Service. Addressing Emerging Infectious Disease Threats: A

Prevention Strategy for the United States. Atlanta, Ga.: U.S. Department of

Health and Human Services, 1994.

Bioterrorism and

Public Health

West Nile Specific Schoch-Spana, M. “A West Nile Virus Post-Mortem.” Biodefense Quarterly,

Vol. 1, No. 3, www.hopkins-biodefense.org/pages/news/quarter1_3.html

(cited Dec. 1999).

General Advisory Panel to Assess Domestic Response Capabilities for Terrorism

Involving Weapons of Mass Destruction. “Excerpts, First Annual Report to

the President and the Congress.” ww.rand.org/organization/nsrd/terrpanel/

terror.pdf (cited Dec. 15, 1999).
Appendix III

Related Publications

Page 62 GAO/HEHS-00-180 West Nile Virus Outbreak

Centers for Disease Control and Prevention. “Biological and Chemical

Terrorism: Strategic Plan for Preparedness and Response:

Recommendations of the CDC Strategic Planning Workgroup.” Morbidity

and Mortality Weekly Report, Vol. 49, No. RR-4 (April 21, 2000).

Ember, L. “News Focus/Bioterrorism: Combating the Threat.” Chemical

and Engineering News, Vol. 77, No. 27 (July 5, 1999), pp. 8-17.

Institute of Medicine. Chemical and Biological Terrorism: Research and

Development to Improve Civilian and Medical Response. Washington, D.C.:

National Academy Press, 1999.

Lasker Charitable Trust. “Bioterrorism/Domestic Preparedness Suffers

From Neglect of Public Health Infrastructure.” www.laskerfoundation.org/

fundingfirst (cited Sept. 16, 1999).

McDade, J.E. “Addressing the Potential Threat of Bioterrorism—Value

Added to an Improved Public Health Infrastructure.” Emerging Infectious

Diseases, Vol. 5, No. 4, (July-Aug. 2000), pp. 591-92.

National Intelligence Council. “The Global Infectious Disease Threat and

Its Implications for the United States.” National Intelligence Estimate 99-

17D (Jan. 2000).

Novick, L. (ed.). Journal of Public Health and Management Practice (July

2000).
Page 63 GAO/HEHS-00-180 West Nile Virus Outbreak

Appendix IV

Comments From the Centers for Disease

Control and Prevention ApendxiIV
Appendix IV

Comments From the Centers for Disease

Control and Prevention

Page 64 GAO/HEHS-00-180 West Nile Virus Outbreak
Page 65 GAO/HEHS-00-180 West Nile Virus Outbreak

Appendix V

Comments From the New York City

Department of Health ApendxiV
Appendix V

Comments From the New York City

Department of Health

Page 66 GAO/HEHS-00-180 West Nile Virus Outbreak
Appendix V

Comments From the New York City

Department of Health

Page 67 GAO/HEHS-00-180 West Nile Virus Outbreak
Appendix V

Comments From the New York City

Department of Health

(201082) Letr Page 68 GAO/HEHS-00-180 West Nile Virus Outbreak
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