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Filovirus Infection Associated with Contact with Nonhuman Primates or Their Tissues

 
Since November 1989, outbreaks of filovirus infection have been
described among cynomolgus monkeys (Macaca fascicularis) imported from
the Philippines into quarantine facilities in Virginia, Pennsylvania,
and Texas (1-3). Serologic evidence of filovirus infection, including
three seroconversions. among workers in these facilities (4) confirms
that virus can be transmitted to humans during care and management of
quarantined animals. 

To further assess the health risk to humans posed by the presence of
filoviruses in animals in facilities for nonhuman primates in the
United States, 550 persons with varying levels of exposure to monkeys
(or monkey body fluids or tissues) were tested by an indirect
immunofluorescence assay (IFA) and a confirmatory Western blot 
assay. Of these persons, 42 (7.6%), including seven reported previously
(4,5), were positive (IFA titer >=16, Western blot confirmed) to one
or more of the four filovirus test antigens used (Ebola-Zaire,
Ebola-Sudan, Filovirus-Reston, Marburg) as of June 18, 1990.
Seropositivity was not evenly distributed: 26 (9.8%) of 266 import 
quarantine facility staff members were seropositive, and 1 6 (5.6%) of
284 other persons having contact with monkeys (or with monkey body
fluids or tissues) outside of import quarantine facilities were
seropositive. None of the 42 seropositive persons reported having had
an illness considered to be caused by a filovirus. 

To provide a perspective for interpreting antibody seropositivity rates
for persons having contact with monkeys (or monkey body fluids or
tissues), serum specimens from 449 persons from throughout the United
States randomly selected from a cross-sectional adult primary-care
outpatient population were tested by the same IFA and Western blot
assays. Of these, 12 (2.7%) were positive. 

Reported by: Special Pathogens Br and Epidemiology Activity, Div of
Viral and Rickettsial Diseases, Center for Infectious Diseases, CDC. 

Editorial Note: The filoviruses isolated in 1989 and 1990 from
cynomolgus monkeys in Virginia and Pennsylvania are morphologically
identical but antigenically and genetically distinct from Marburg virus
isolated in Europe in 1967 (6) and Ebola virus isolated during human
epidemics in Africa in the 1970s (7-10). Severe hemorrhagic fever and
hisn death rates marked the European outbreak and the African
epidemics, but human illness has not been documented in association
with the recent occupationally acquired infections in the United
States. Serologic data confirm that routinecontact with and handling
of nonhuman primates (or their body fluids or tissues) in 
quarantine facilities increase the risk for infection of workers.
Recent actions have been taken to increase the level of worker
protection during importation and import quarantine (2,11). 

The background seropositivity rate for persons from throughout the
United States chosen randomly from an adult primary-care outpatient
population remains unexplained. One possibility is antigenic
crossreactivity between the known fiioviruses and another, as yet
undetermined, antigen. Further investigations are in progress to 
clarify this. Investigations are also in progress to define risk
factors for occupationally acquired infection and to assess the risk
for infection of household contacts of infected persons. 
 
References 
1. CDC. Ebola virus infection in imported primates--Virginia, 1989.
MMWR 1989;38:831-2, 837-8. 
2. CDC. Update: Ebola-related filovirus infection in nonhuman primates
and interim guidelines for handling nonhuman primates during transit
and quarantine. MMWR 1990;39:22 4, 29-30. 
3. Jahrling PB, Geisbert TW, Dalgard DW, et al Preliminary report:
isolation of Ebola virus from monkeys imported into the USA. Lancet
1990;335:502-5. 
4. CDC. Update: filovirus infections among persons with occupational
exposure to nonhuman primates. MMWR 1990;39:266-7,273. 
5. CDC. Update: evidence of filovirus infection in an animal caretaker
in a research/service facility. MMWR 1990;39:296-7. 
6. Martini GA. Siegert R, eds. Marburg virus disease. Berlin:
Springer-Verlag, 1971. 
7. World Health Organization. Ebola haemorrhagic fever in Sudan, 1976:
report of a WHO/International Study Team. Bull WHO 1978;56:247-70. 
8. World Health Organization. Ebola haemorrhagic fever in Zaire, 1976:
report of an International Commission. Bull WHO 1978;56:271-93. 
9. Baron RC, McCormick JB, Zubeir OA. Ebola virus disease in southern
Sudan: hospital dissemination and intrafamilial spread. Bull WHO
1983;61:997-1003. 
10. Gear JSS, Cassel GA, Gear AJ, et al. Outbreak of Marburg virus
disease in Johannesburg. Br Med J 1975;4:489-93. 
11. CDC. Requirement for a special permit to import cynomolgus, African
green, or rhesus monkeys into the United States. Federal Register
1990;55:15210-1.