The following are pre-publication drafts of articles from the
Morbidity and Mortality Weekly Report dated September 8, 1995.
Late-breaking articles, and final editorial revisions are not
included; therefore, these articles should be considered
preliminary, and not to be released to the public. --CDC
--------------------------------------------------------------
Arboviral Disease -- United States, 1994
     Arboviruses are mosquitoborne and tickborne agents that
persist in nature in complex cycles involving birds and mammals,
including humans. Characteristics of arboviral infection include
fever, headache, encephalitis, and sometimes death. In 1994, health
departments in 20 states reported 100 presumptive or confirmed
human cases of arboviral disease* to CDC. Of these, 76 were
California (CAL) serogroup encephalitis; 20, St. Louis encephalitis
(SLE); two, western equine encephalomyelitis (WEE); one, eastern
equine encephalomyelitis (EEE); and one, Powassan encephalitis
(POW). This report summarizes information about arboviral disease
in the United States during 1994.
Powassan Encephalitis
     POW was serologically confirmed in a 49-year-old female
resident of Massachusetts who had onset of illness May 24. She
reported removing an engorged tick from her abdomen approximately
2 weeks before onset of symptoms. She was admitted to the hospital
on May 25 with a diagnosis of meningoencephalitis, which progressed
during the following 72 hours to encephalitis involving the brain
stem and basal ganglia. During hospitalization, the patient was
comatose for 3 days and required mechanical ventilation. On June
16, she was discharged to a rehabilitation center and, on July 25,
was transferred to a resident health-care facility. On examination
in August 1995, she had residual weakness in her right leg
requiring a brace. The patient's prolonged convalescence is
consistent with that reported for POW encephalitis.
California Serogroup Encephalitis
     During 1994, a total of 76 human CAL serogroup encephalitis
cases were reported from 13 states: West Virginia (32 cases), Ohio
(14), Wisconsin (seven), Illinois (six), Minnesota (four), Indiana
and North Carolina (three each), Alabama (two), and Iowa, Kentucky,
Michigan, Rhode Island, and Virginia (one each). Patients ranged in
age from 6 months to 26 years (mean: 7 years). A total of 57 cases
(75%) occurred among males. Onsets of illness occurred in May (one
case), June (one), July (12), August (35), September (22), and
October (five).
St. Louis Encephalitis
     During 1994, a total of 20 human cases of SLE were reported
from five states. Sixteen cases were reported in Louisiana; most
(14) occurred in urban New Orleans (Orleans and Jefferson
parishes). Three cases (in 44- and 60-year-old men and a
63-year-old woman) were fatal. Patients ranged in age from 12 to 78
years (mean: 46 years). Of the 16 cases, nine (56%) occurred among
males. SLE cases also were reported in residents of Riverside
County, California; Charlotte County, Florida; Forrest County,
Mississippi; and Harris County, Texas (one each). For the 20 total
cases, onsets of illness occurred in July (one case), August
(nine), September (nine), and October (one).
Western and Eastern Equine Encephalomyelitis
     During 1994, two human cases of WEE were reported from Goshen
County in southeastern Wyoming; the cases occurred in a 40-year-old
woman and a 42-year-old man. One human case of EEE in a 67-year-old
man was reported from Iberville Parish, Louisiana.
Western and Eastern Equine Encephalomyelitis in Animals
     Surveillance for arboviral disease includes cases in
susceptible animals because, during previous outbreaks, animal
cases preceded human cases by 2-3 weeks. During 1994, a total of
five WEE cases among horses were reported from three states: Idaho
(two cases), Wyoming (two), and Texas (one). WEE was isolated from
emus in Boulder County, Colorado (one), and Lancaster County,
Nebraska (one), and from a symptomatic pigeon in Stanislaus County,
California.
     A total of 133 cases of EEE among horses were reported from 11
states: Florida (54 cases), South Carolina (20), North Carolina
(15), Michigan (12), Georgia (nine), Alabama and New Jersey (seven
each), Indiana and Louisiana (three each), Ohio (two), and Virginia
(one). In addition, EEE virus was isolated from other species in
five states. In Michigan, virus was isolated from two pheasant
flocks. In Florida, EEE virus was isolated from specimens of
viscera from a symptomatic duck and from 1-4-week-old piglets
during an epizootic in the Florida panhandle in which 50 of 90
piglets observed had objective central nervous system signs; the
number of deaths is unknown. In Georgia, EEE virus was recovered
from a litter of 3-week-old boxer puppies; three of five puppies in
the litter died. EEE cases in emus were reported from New Jersey
(10 cases), Florida (three), Georgia (two), and North Carolina
(one).
Reported by: State health depts. D Jacoby, MD, Massachusetts
General Hospital, Boston. M McGuilf, DVM, Epidemiology Div, J
Fontana, MS, B Werner, PhD, Virology Div, Massachusetts Dept of
Public Health State Laboratory. L McFarland, DrPH, S Wilson, M
Kohn, MD, H Bradford, PhD, Louisiana Dept Health and Hospitals; E
Bordes, New Orleans Mosquito Control Board, New Orleans. D Alstad,
DVM, National Veterinary Svcs Laboratories, Animal Plant and Health
Inspection Svc, US Dept of Agriculture, Ames, Iowa. H Rubin, DVM,
Bur of Diagnostic Laboratories, Florida Dept of Agriculture and
Consumer Svcs, Kissimmee. S Baldwin, DVM, Veterinary Diagnostic and
Investigation Laboratory, Univ of Georgia, Tifton. Epidemiology and
Ecology Section, Div of Vector-Borne Infectious Diseases, National
Center for Infectious Diseases, CDC.
Editorial Note: The findings in this report indicate that CAL
serogroup encephalitis remains the most frequently reported
arbovirus infection in the United States. Although the number of
CAL serogroup encephalitis cases has remained relatively constant
since the 1970s and was reported primarily from the Midwest, the
number of cases reported from the South has increased. For example,
in 1994, Alabama for the first time reported CAL serogroup
encephalitis cases, and Kentucky and Virginia--which previously had
reported a total of only six cases since 1964--each reported one in
1994.
     In general, SLE occurs as periodic focal outbreaks followed by
years of sporadic cases. In 1994, a small focal outbreak of SLE
occurred in urban New Orleans. Evaluation of case-patients by date
of illness onset and location suggests that the earliest cases
occurred among persons living within or in proximity to urban
public housing projects. Subsequent cases followed a pattern of
radial spread from the central urban area, although the small
number of cases preclude a definitive analysis. An investigation by
New Orleans Mosquito Control Board personnel found large
populations of immature and adult Culex pipiens quinquefasciatus
mosquitoes under housing units. Leaking sewer lines located in the
crawl space beneath these housing units provided an extensive and
ideal habitat for the SLE virus vector mosquito.
     The POW case in Massachusetts in 1994 was the first reported
from that state. Previously, the most recent POW case in the United
States occurred in New York in 1978. POW virus is a tickborne
flavivirus most closely related to Russian spring summer and
Central European encephalitis viruses. Although understanding of
the epidemiology of POW virus in the United States is limited, the
virus appears to be widely distributed. In North America, Ixodes
cookei has been implicated as the principal tick vector, and virus
has been recovered from several rodent and carnivore species,
including the red squirrel, woodchucks, striped and spotted skunks,
foxes, short- and long-tailed weasels, and the white-footed deer
mouse.**
     Human infections with POW virus occur infrequently, with
seroprevalence rates of 0.5%-4.0% in areas where the virus is
endemic (1). During 1958-1981, a total of 19 confirmed POW cases
among humans were reported in North America, primarily from the
northeastern United States and eastern Canada. Since 1981, five
additional confirmed cases have been reported from Canada: Quebec
(two, one fatal) (H. Artsob, Quebec Laboratory Center for Disease
Control, personal communication, 1995); New Brunswick (one) (2);
Ontario (one); and Nova Scotia (one) (M. Mahdy, Ontario Ministry of
Health Laboratory Services, personal communication, 1995). Based on
evaluation of the 24 total POW cases that occurred in North America
during 1958-1994, risk for infection may be highest in wooded areas
where potential contact with infected rodent or carnivore hosts or
tick vectors is greatest. Of the 24 cases, 21 occurred in persons
aged less than 20 years. Four of the acute infections were fatal,
and two patients died 1 and 3 years after onset as a result of
sequelae reported to be directly related to the disease.
     Health-care providers should consider arboviruses in the
differential diagnosis of aseptic meningitis and encephalitis cases
during the summer months. Early identification of arboviral cases
is important to implement risk-reduction strategies (i.e., use of
vector-control practices, repellents, and changes in human activity
patterns). Serum (acute and convalescent) and cerebrospinal fluid
samples should be obtained for serologic testing, and cases should
be promptly reported to state health departments. New rapid
diagnostic techniques, including detection of immunoglobulin M
antibody in acute serum or cerebrospinal fluids, have facilitated
confirmation of arbovirus infections.
References
1. Artsob H. Powassan encephalitis. In: TP Monath, ed. The
arboviruses: epidemiology and ecology. Vol IV. Boca Raton, Florida:
CRC Press, Inc, 1988:29-49.
2. Fitch W, Artsob H. Powassan encephalitis in New Brunswick. Can
Fam Physician 1990;33:1289-90.

* At CDC, a confirmed case is defined as febrile illness with mild
neurologic symptoms, aseptic meningitis, or encephalitis with onset
during a period when arbovirus transmission is likely to occur,
plus at least one of the following criteria: 1) fourfold or greater
rise in serum antibody titer, 2) viral isolation from tissue,
blood, or cerebrospinal fluid; or 3) specific immunoglobulin M
(IgM) antibody in cerebrospinal fluid. A presumptive case is
defined as compatible illness, plus either a stable elevated
antibody titer to an arbovirus ( greater than or equal to 320 by
hemagglutination inhibition, greater than or equal to 128 by
complement fixation, greater than or equal to 256 by
immunofluorescent assay, or greater than or equal to 160 by
plaque-reduction neutralization test) or specific IgM antibody in
serum by enzyme immunoassay.
** Tamiasciurus hudsonicus, Marmota monax and Mephitis mephitis,
Spilogale putorius, Vulpes sp. Urocyon Cinereoargenteus (gray fox),
Mustella erminea and Mustella frenata, and Peromyscus maniculatus,
respectively.

Update: Influenza Activity -- Worldwide, 1995
     From October 1994 through August 1995, influenza activity
occurred at low to moderate levels in most parts of the world.
Influenza activity usually was associated with the cocirculation of
influenza types A and B viruses. Overall, influenza A(H3N2) was the
predominant influenza A subtype, but isolation of influenza A(H1N1)
viruses increased during this period and was the most frequently
isolated influenza virus in Australia from March through August.
This report summarizes influenza activity worldwide from March
through August 1995.
     Africa. In Madagascar, circulation of influenza A(H3N2) began
during January and continued through April; during April, influenza
A(H1N1) was isolated in Madagascar. In South Africa, influenza
A(H1N1) and influenza A(H3N2) viruses were isolated from samples
collected for respiratory virus isolation during May-July.
Influenza B viruses also were detected in South Africa during July.
Influenza A(H3N2) was isolated in Zambia during June.
     Asia. Influenza A(H1N1), A(H3N2), and influenza B viruses were
isolated during every month from March through June in Asia.
Influenza A(H1N1) viruses were isolated in Guam during May, in Hong
Kong during March and April, and in Thailand during April, May, and
July. Influenza A(H1N1) and influenza B viruses were isolated
during outbreak-level activity in Taiwan during April-June. Other
countries reporting influenza B activity associated with sporadic
cases or outbreaks included China, Hong Kong, Japan, Korea,
Singapore, and Thailand. Influenza A(H3N2) viruses were isolated in
China in association with sporadic and outbreak activity during
April and from sporadic cases during June. Influenza A(H3N2)
viruses also were isolated in Korea and Thailand during March, in
Guam during March and May, in Hong Kong during March and July, and
in Japan during April. Singapore reported influenza A activity
every month from March through June; influenza A (H3N2) isolates
were subtyped during March, May, and June. Additional influenza A
viruses, subtype unknown, were identified by antigen-detection
methods in Malaysia during March.
     Europe. Activity in Europe began with an outbreak of influenza
B virus in Portugal during October 1994 and continued from March
through June. Influenza A(H3N2), A(H1N1), and influenza B viruses
were isolated during this period. Outbreak activity was last
reported from Romania and Bulgaria during May. Circulation of
influenza A(H1N1) viruses increased from March through May and was
associated with an outbreak in members of a military unit in   
Bulgaria. Detection of both influenza A and influenza B viruses
continued in France during June.
     North America. Influenza A(H3N2) viruses predominated during
the 1994-95 season, but influenza B and A(H1N1) viruses also were
isolated. Following peak activity during February through early
March in the United States, influenza A(H3N2), A(H1N1), and
influenza B viruses continued to be isolated every month during
March-June. Influenza A(H1N1) was isolated from one patient in
Arizona during July. The number of influenza A(H1N1) isolates
increased during February-May; most were collected during May.
Late-season influenza activity also occurred in Canada. The most
recent detection of influenza B virus was reported during the week
ending June 3, and reports of influenza A virus isolation or
detection continued during July and August. As in the United
States, influenza A(H1N1) viruses were reported in Canada during
the latter part of the influenza season.
     Central and South America. Influenza A and influenza B viruses
were detected during the 1994-95 influenza season in South America
with influenza A predominating. Brazil reported detection of
influenza A from February through April. In Chile, outbreaks of
influenza were detected during May-July; influenza A predominated,
but influenza B also was detected. In Argentina, the first case of
influenza A was diagnosed in late May and outbreaks were reported
during June and July; influenza A predominated, but influenza B
also was detected. Reports of influenza-like illness increased in
Uruguay during May-July, and influenza A virus was identified by
antigen-detection methods. Influenza A virus was detected in one
patient in Panama during June, followed by a single detection of
influenza B virus during July. All influenza A viruses from
Argentina, Brazil, and Chile subtyped or further identified by
serologic testing were influenza A(H3N2). No influenza A(H1N1)
isolates were reported from Central or South America.
     Oceania. The influenza season began early in Australia with
outbreaks in the Northern Territory at the end of March. Both
influenza A(H1N1) and influenza B viruses were isolated during the
outbreak, with influenza A(H1N1) viruses predominating.
Influenza-like illness, as reported by general practitioners,
increased through the beginning of July and remained stable during
mid-July through the beginning of August. As the season progressed,
the number of influenza B isolates increased; however, influenza
A(H1N1) viruses remained more prevalent. Influenza A(H3N2) viruses
were rarely isolated. In contrast, influenza B predominated in New
Zealand through July, but the proportion of influenza A(H3N2)
viruses isolated increased during July. Both influenza A(H3N2) and
influenza B viruses were associated with outbreaks at the end of
July.
     Characterization of influenza virus isolates. From October 1,
1994, through August 15, 1995, a total of 760 influenza isolates
collected worldwide were antigenically characterized by the World
Health Organization Collaborating Center for Surveillance,
Epidemiology, and Control of Influenza at CDC. Of these, 535 (70%)
were from North America, 76 (10%) from Europe, 130 (17%) from Asia,
and 19 (3%) from South America and Oceania. Of the viruses
subtyped, 396 (52%) were influenza A(H3N2), 91 (12%) A(H1N1), and
273 (36%) influenza B. Of the 396 influenza A(H3N2) isolates
characterized, 227 (57%) were antigenically related to
A/Shangdong/09/93, the 1994-95 vaccine strain, and 164 (41%) were
more closely related to A/Johannesburg/33/94, the A(H3N2) component
of the 1995-96 influenza vaccine. Of the 273 influenza B viruses,
66 (24%) were similar to B/Panama/45/90, the 1994-95 vaccine
component, and 202 (74%) were similar to B/Beijing/184/93, the
1995-96 vaccine component. Of the 91 influenza A(H1N1) viruses, 12
(13%) were A/Texas/36/91-like, and 79 (87%) were more closely
related to the antigenically similar A/Taiwan/01/86-like viruses
(1,2). The influenza A(H1N1) component of the 1995-96 vaccine is
A/Texas/36/91.
Reported by: World Health Organization National Influenza Centers,
Communicable Disease Div, World Health Organization, Geneva. World
Health Organization Collaborating Center for Surveillance,
Epidemiology, and Control of Influenza. Influenza Br, Div of Viral
and Rickettsial Diseases, National Center for Infectious Diseases,
CDC.
Editorial Note: Based on recent patterns of worldwide influenza
activity, the 1995-96 influenza season in the United States may be
characterized by cocirculation of influenza type A(H3N2), type
A(H1N1) and type B. However, because specific patterns of influenza
activity cannot be predicted with certainty, the extent of virus
circulation and the relative prevalence of the different influenza
virus strains is unknown. Therefore, influenza vaccination should
be offered each fall to persons at high risk for influenza-related
complications and their close contacts and to health-care
providers.
     The influenza vaccine is updated annually to include viruses
that are antigenically similar to the strains of the three distinct
groups of influenza viruses that have been in worldwide
circulation. Most of the influenza viruses isolated since March
1995 are antigenically similar to the 1995-96 influenza vaccine
strains (CDC, unpublished data, 1995).
     Vaccination against influenza is recommended by the Advisory
Committee on Immunization Practices for 1) persons aged greater
than or equal to 65 years; 2) persons who reside in nursing homes
or chronic-care facilities; 3) persons with chronic cardiovascular
or pulmonary disorders, including children with asthma; 4) persons
who required medical follow-up or hospitalization during the
previous year because of diabetes and other chronic metabolic
diseases, renal dysfunction, hemoglobinopathies, or
immunosuppression; and 5) children and adolescents who are
receiving long-term aspirin therapy and who therefore may be at
risk for developing Reye syndrome after influenza. Vaccination also
is recommended for health-care workers and other persons who are in
close contact with persons in high-risk groups, including household
members. Women who will be in the third trimester of pregnancy
during the influenza season may be at increased risk for medical
complications following influenza infection and should consult with
their health-care providers about receiving the vaccine. Influenza
vaccine also can be administered to anyone who wants to reduce the
likelihood of acquiring influenza.
     Beginning in September, persons at high risk who are seen by
health-care providers for routine care or as a result of
hospitalization should be offered influenza vaccine. The optimal
time for organized vaccination campaigns is mid-October through
mid-November. Health-care providers should continue to offer
vaccine to high-risk persons up to and even after influenza
activity is documented in a community.
     Information about influenza surveillance is available through
the CDC Voice Information System (influenza update) by telephone
([404] 332-4555) or fax ([404] 332-4565) (document number 361100)
or through the CDC Information Service on the Public Health Network
electronic bulletin board. From October through May, the
information is updated weekly. Periodic updates about influenza are
published in MMWR, and information on local influenza activity is
available through county and state health departments.
References
1. CDC. Update: influenza activity--United States and worldwide,
1993-94 season, and composition of the 1994-95 vaccine. MMWR
1994;44:179-83.
2. CDC. Update: influenza activity--United States and worldwide,
1994-95 season, and composition of the 1995-96 vaccine. MMWR
1995;44:292-5.

Notice to Readers
NIOSH Alert: Request for Assistance in Preventing Deaths and
Injuries of Adolescent Workers
     CDC's National Institute for Occupational Safety and Health
(NIOSH) periodically issues alerts about workplace hazards that
have caused death, serious injury, or illness in workers. One such
alert, Request for Assistance in Preventing Deaths and Injuries of
Adolescent Workers (1), was recently published and is available to
the public.* This alert summarizes information about work-related
injuries and deaths among adolescents, identifies work that is
especially hazardous, and offers recommendations for prevention.
This information can help employers, parents, educators, and
adolescent workers make informed decisions about safe work and
recognize hazards in the workplace.
     Each year, approximately 70 adolescents die from injuries at
work. Hundreds more are hospitalized, and tens of thousands require
treatment in hospital emergency departments. For example, 68
adolescents aged less than 18 years died from work-related injuries
in 1993 (2), and an estimated 64,000 adolescents had work-related
injuries that required treatment in hospital emergency departments
in 1992 (3). Compared with adults, adolescents have a higher risk
for work-related injury (4) and a similar risk for fatal
occupational injury (5). During 1980-1989, the risk for fatal
injury among workers aged 16 and 17 years was 5.1 per 100,000
full-time equivalent workers, compared with 6.0 for adult workers--even though adolescents are employed less frequently in especially
hazardous jobs.
     Agricultural businesses and retail trade accounted for the
most work-related deaths among adolescents, and many deaths of
workers aged less than 16 years occurred in family-owned businesses
(1). Types of work associated with large numbers of deaths and
serious injuries included the following: working in or around motor
vehicles, operating tractors and other heavy equipment, working
near electrical hazards, working in retail and service businesses
with a risk for robbery-related homicide, working with fall hazards
such as ladders and scaffolds, working around cooking appliances,
and performing hazardous manual lifting.
To reduce the potential for serious injuries and deaths of
adolescent workers, NIOSH recommends:
1. Employers should know and comply with child labor laws and
should evaluate workplace hazards for adolescent workers.
2. Parents should participate in their children's employment
decisions and should discuss the types of work, training, and
supervision provided by the employer.
3. Educators should know child labor laws, provide work experience
programs with safe and healthful work environments, and incorporate
occupational safety and health information in the general
curriculum.
4. Adolescents should know their rights and responsibilities as
workers and should seek training and information about safe work
practices.
References
1. NIOSH. Request for assistance in preventing deaths and injuries
of adolescent workers. Cincinnati: US Department of Health and
Human Services, Public Health Service, CDC, 1995; DHHS publication
no. (NIOSH)95-125.
2. Toscano G, Windau J. The changing character of fatal work
injuries. Monthly Labor Review 1994;118:17-28.
3. Layne LA, Castillo DN, Stout N, Cutlip P. Adolescent
occupational injuries requiring hospital emergency department
treatment: a nationally representative sample. Am J Public Health
1994;84:657-60.
4. CDC. Surveillance of occupational injuries treated in hospital
emergency departments. MMWR 1983;32 (no. 2SS):31SS-37SS.
5. Castillo DN, Landen DD, Layne LA. Occupational injury deaths of
16- and 17-year-olds in the United States. Am J Public Health
1994;84:646-9.

* Single copies of this document are available without charge from
the Publications Office, NIOSH, CDC, Mailstop C-13, 4676 Columbia
Parkway, Cincinnati, OH 45226-1998; telephone (800) 356-4674 ([513]
533-8328 for persons outside the United States); fax (513)
533-8573.

Errata: Vol. 44, No. 32
     In the article, "Human Granulocytic Ehrlichiosis--New York,
1995," references 4,5, and 3 at the end of the second and third
sentences of the Editorial Note on page 594 should be renumbered
(3,4) and (5), respectively; however, the numbers were attributed
to the correct references in the list on the following page.
     The fourth and new fifth sentences of the first paragraph of
the Editorial Note should read: "E. chaffeensis has most commonly
been identified in the Lone Star tick (Amblyomma americanum) (6)."
HGE patients reported having been bitten by "deer ticks" and "wood
ticks" (possibly I. scapularis and Dermacentor variabilis,
respectively) (2)." The new reference 6 is: Anderson BE, Sims KG,
Olson JG, et al. Amblyomma americanum: a potential vector of human
ehrlichiosis. Am J Trop Med Hyg 1993;49:239-44.

Erratum: Vol. 44, No. 34
     In the article "Hypertension Among Mexican Americans--United
States, 1982-1984 and 1988-1991," the last sentence on page 635
should read: "Analysis of characteristics of persons with
hypertension included awareness (being told by a health
professional of having hypertension), treatment (taking
antihypertension medication),and control (taking antihypertension
medication and having blood pressure less than 140/90 mm/Hg)."

Erratum: Vol. 43, No. 38
     On page 702 of the article "Health Status of Displaced Persons
Following Civil War--Burundi, December 1993-January 1994," in the
"Reported by:" section, S Nkurikiye should be listed first, and the
affiliation of JS Kidasi should be U.S. Agency for International
Development.