Ebola virus outbreak among wild chimpanzees living in a rain forest of Cote d'Ivoire

An outbreak of Ebola in nature is described for the first time. During a fe w weeks in November 1994, similar to 25% of 43 members of a wild chimpanzee community disappeared or were found dead in the Tdi National Park, Cote d' Ivoire. A retrospective cohort study was done on the chimpanzee community. Laboratory procedures included histology, immunohistochemistry, bacteriolog y, and serology. Ebola-specific immunohistochemical staining was positive f or autopsy tissue sections from 1 chimpanzee. Demographic, epidemiologic, a nd ecologic investigations were compatible with a point-source epidemic. Co ntact activities associated with a case (e.g., touching dead bodies or groo ming) did not constitute significant risk factors, whereas consumption of m eat did. The relative risk of meat consumption was 5.2 (95% confidence inte rval, 1.3-21.1), A similar outbreak occurred in November 1992 among the sam e community. A high mortality rate among apes tends to indicate that they a re not the reservoir for the disease causing the illness. These points will have to be investigated by additional studies.