LETHAL EXPERIMENTAL-INFECTION OF RHESUS-MONKEYS WITH EBOLA-ZAIRE (MAYINGA) VIRUS BY THE ORAL AND CONJUNCTIVAL ROUTE OF EXPOSURE

Objective.-The source of infection or mode of transmission of Ebola vi rus to human index cases of Ebola fever has not been established. Fiel d observations in outbreaks of Ebola fever indicate that secondary tra nsmission of Ebola virus is linked to improper needle hygiene, direct contact with infected tissue or fluid samples, and close contact with infected patients. While it is presumed that the virus infects through either breaks in the skin or contact with mucous membranes, the only two routes of exposure that have been experimentally validated are par enteral inoculation and aerosol inhalation. Epidemiologic evidence sug gests that aerosol exposure is not an important means of virus transmi ssion in natural outbreaks of human Ebola fever; this study was design ed to verify that Ebola virus could be effectively transmitted by oral or conjunctival exposure in nonhuman primates. Materials and Methods. -Adult rhesus monkeys (Macaca mulatta) were exposed to Ebola-Zaire (Ma yinga) virus orally (N = 4), conjunctivally (N = 4), or by intramuscul ar Inoculation (N = 1, virus-positive control). Results.-Four of four monkeys exposed by the conjunctival route, three of four monkeys expos ed by the oral route, and the intramuscularly inoculated positive cont rol monkey (one of one) were successfully infected with Elbola-Zaire ( Mayinga). Seven monkeys died of Ebola fever between days 7 and 8 poste xposure. One monkey was given aggressive supportive therapy and a plat elet transfusion; it lived until day 12 postexposure. Conclusions.-Fin dings in this study experimentally confirm that Ebola virus can be eff ectively transmitted via the oral or conjunctival route of exposure in nonhuman primates.