Section VII Agent Summary Statements
Arboviruses and Arenaviruses Assigned to Biosafety Level 4

SALS recommends that work with the 11 arboviruses, arenaviruses, or filoviruses(1)included in Table 5 be conducted at the equivalent of Biosafety Level 4 practices, safety equipment, and facilities. These recommendations are based on documented cases of severe and frequently fatal naturally occurring human infections and aerosol-transmitted laboratory infections. SALS recommends that certain agents with a close antigenic relationship to Biosafety Level 4 agents (e.g., Russian Spring-Summer Encephalitis virus ) also be provisionally handled at this level until sufficient laboratory experience indicates their retention at this level or movement to work at a lower level. As noted above, with immunization, SALS recommends downgrading the biohazard classification of Junin virus and the Central European Tick-borne encephalitis virus complex viruses ( Absettarov, Hanzalova, Hypr, and Kumlinge) to BSL-3. Laboratory or laboratory animal-associated infections have been reported with the following agents:(2)(3)(4)(5)(6)(7)(8)

Virus	Cases (SALS)
Junin*	21 (1 death)
Marburg*	25 (5 deaths)
Russian Spring-Summer	8
Congo-Crimean hemorrhagic	8 (1 death)
Omsk hemorrhagic fever	5
Lassa*	2 (1 death)
Machupo*	1 (1 death)
Ebola*	1
Sabia*	3 (1 death)

* Export permit required by Department of Commerce.

Rodents are natural reservoirs of Lassa virus (Mastomys spp.), Junin, and Machupo viruses (Calomys spp.), Guanarito (Zygodontomys spp.), and perhaps other members of this group. Nonhuman primates were associated with the initial outbreaks of Kyasanur Forest disease (Presbytis spp.) and Marburg disease (Cercopithecus spp.). More recently, filoviruses related to Ebola were associated with Macaca spp. and chimpanzees (Pan troglodytes). Arthropods are the natural vectors of the tick-bome encephalitis complex agents. Work with or exposure to rodents, nonhuman primates, or vectors naturally or experimentally infected with these agents represents a potential source of human infection.

Laboratory Hazards. The infectious agents may be present in blood, urine, respiratory and throat secretions, semen, and tissues from human or animal hosts, and in arthropods, rodents, and nonhuman primates. Respiratory exposure to infectious aerosols, mucous membrane exposure to infectious droplets, and accidental parenteral inoculation are the primary hazards to laboratory or animal care personnel.(9)(10)

Recommended Precautions. Biosafety Level 4 practices and facilities are recommended for all activities utilizing known or potentially infectious materials of human, animal, or arthropod origin. Clinical specimens from persons suspected of being infected with one of the agents listed in this summary should be submitted to a laboratory with a Biosafety Level 4 maximum containment facility.(11)(12)

Transfer of Agent: For a permit to import these agents, contact CDC. Contact the Department of Commerce for a permit to export these agents. Laboratory registration with CDC is required before sending or receiving these select agents.

References

1. Kiley, M.P., et al. 1982. Filoviridae: a taxonomic home for Marburg and Ebola viruses? Intervirology 18:24-32.

2. Edmond, R.T.D., et al. 1977. A Case of Ebola virus infection. Br Med J 2:541-544.

3. Hanson, R.P., et al. 1967. (3)

4. Hennessen, W. 1971. Epidemiology of "Marburg Virus" disease. In: Martini, G.A., Siegert, R. eds., Marburg Virus Disease. New York: Springer-Verlag 161-165.

5. Leifer, E., Gocke, D.J., and Bourne, H. 1970. Lassa fever, a new virus disease of man from West Africa. II. Report of a laboratory-acquired infection treated with plasma from a person recently recovered from the disease. Am J Trop Med Hyg 19:677-9.

6. Pike, R.M. 1976 (4)

7. Subcommittee on Arbovirus Laboratory Safety for Arboviruses and Certain Other Viruses of Vertebrates. 1980. (2)

8. Weissenbacher, M.C., et al. 1978. Inapparent infections with Junin virus among laboratory workers. J Infect Dis 137:309-313.

9. Leifer, E., Gocke, D.J., and Bourne, H. 1970. (24)

10. Weissenbacher, M.C., et al. (27)

11. Centers for Disease Control, Office of Biosafety. 1974. Classification of Etiologic Agents on the Basis of Hazard, 4th Edition. U.S. Department of Health, Education and Welfare, Public Health Service.

12. Oliphant, J.W., et al. 1949. Q fever in laundry workers, presumably transmitted from contaminated clothing. Am J Hyg 49(1):76-82.