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Update: Filovirus Infections Among Persons with Occupational Exposure to Nonhuman Primates

Since November 1989, evidence of active filovirus infection has been detected in cynomolgus (Macaca fascicularis) monkeys imported from the Philippines to quarantine facilities in Virginia, Pennsylvania, and Texas (1-3). CDC has used an indirect immunofluorescent antibody assay (IFA) to examine approximately 2200 serum specimens from nonhuman primates (cynomolgus, rhesus, and African green monkeys) obtained from a variety of settings (including the quarantine facilities in which filovirus transmission has been documented). Approximately 10% of these specimens have been positive for antibody to at least one of four filovirus test antigens (Ebola-Zaire, Ebola-Sudan, Filovirus-Reston, and Marburg).

Filovirus-related illness has not been observed in any human who has been in contact with infected monkeys or their blood or tissues since November 1989. However, antibody to one or more filovirus antigens has been detected in six of the 178 persons tested as of April 23 (Table 1). Of the six persons, four--all animal handlers at one quarantine facility--had serologic evidence of recent infection (4). It is likely that one of the four was infected when he lacerated a finger while performing a necropsy on an infected animal (4); the mode of transmission for the other three is unknown. The other two persons were seropositive at low titer and had evidence of past infection; one of these persons, a worker at a facility that temporarily houses nonhuman primates before delivery to U.S. quarantine facilities, has had regular contact with quarantined monkeys for 3 years. The other person is employed as an animal handler at a second quarantine facility. Reported by: RK Miller, MD, Fairfax Health District; JY Baumgardner, MAS, CW Armstrong, MD, SR Jenkins, VMD, CD Woolard, MPH, GB Miller, Jr, MD, State Epidemiologist, Virginia State Dept of Health. LD Polk, MD, Bucks County Health Dept; DR Tavris, MD, State Epidemiologist, Pennsylvania State Dept of Health. KA Hendricks, MD, JP Taylor, MPH, DM Simpson, MD, State Epidemiologist, Texas Dept of Health. S Schultz, MD, City Epidemiologist, New York City Dept of Health; L Sturman, MD, JG Debbie, DVM, DL Morse, MD, State Epidemiologist, New York State Dept of Health. PE Rollin, MD, PB Jahrling, PhD, TG Ksiazek, DVM, CJ Peters, MD, US Army Medical Research Institute of Infectious Diseases, Frederick, Maryland. Office of the Director, National Institute for Occupational Safety and Health; Div of Quarantine, Center for Prevention Svcs; Scientific Resources Program, Div of Viral and Rickettsial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Epidemiologic and laboratory studies suggest that there is a risk of transmission of filoviruses to humans that is associated with routine handling and management of quarantined nonhuman primates. Studies are in progress to quantify and better define the risk for infection among persons working with nonhuman primates in U.S. quarantine facilities and among their household and sexual contacts. In addition, studies are under way to better define the frequency and duration of importation of these agents into the United States.

Serious health consequences, including hemorrhagic disease and death, have resulted from human filovirus infections in Europe (Marburg virus) (5), and in Africa (Ebola and Marburg viruses) (6-9). To minimize the health hazard from these agents and any potential hazard from the newly recognized filovirus strains, on April 17, 1990, CDC implemented a procedure (10), effective immediately, requiring the issuance of a special permit from the Director, CDC, before importation of individual shipments of cynomolgus, rhesus (M. mulatta), and African green (Cercopithecus aethiops) monkeys into the United States. Registered importers of nonhuman primates have been notified of the requirement to submit a detailed written plan that specifies steps that will be taken to prevent exposure of persons and animals to filoviruses during the entire importation and quarantine process for imported nonhuman primates. This plan, together with a request for a special permit, must be submitted to the CDC Director for consideration at least 30 days before the proposed importation of any of the three nonhuman primate species into the United States.


  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.(Continued on page 273)

4. CDC. Update: filovirus infection in animal handlers. MMWR 1990;39:221. 5. Martini GA, Siegert R, eds. Marburg virus disease. Berlin: Springer-Verlag, 1971.

6. World Health Organization. Ebola haemorrhagic fever in Sudan, 1976: report of a WHO/International Study Team. Bull WHO 1978;56:247-70.

7. World Health Organization. Ebola haemorrhagic fever in Zaire, 1976: report of an International Commission. Bull WHO 1978;56:271-93.

8. Baron RC, McCormick JB, Zubeir OA. Ebola virus disease in southern Sudan: hospital dissemination and intrafamilial spread. Bull WHO 1983;61:997-1003.

9. Gear JSS, Cassel GA, Gear AJ, et al. Outbreak of Marburg virus disease in Johannesburg. Br Med J 1975;4:489-93. 10. CDC. Requirement for a special permit to import cynomolgus, African green, or rhesus monkeys into the United States. Federal Register 1990;55:15210-1.

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