Monkeys could be reservoirs for human infection. These are probably the most dangerous diseases, because they are so difficult to diagnose and treat. A virus may be latent in one species of primate, with little or no symptoms, yet be fatal in another species of primate, including humans. May be spread by feeding pinkies. Parenteral inoculation or intimate contact required.
Infected monkeys can appear normal, showing no symptoms.
The virus remains latent and may reactivate spontaneously or in times of stress resulting in virus shedding Since there is a high percentage of infection in monkeys yet relatively few human cases, risk of acquiring infection appears to be low. A few other cases are attributed to B virus infection, but lack adequate documentation. Twenty of the 22 human patients developed encephalitis. Fifteen of these died. Monkeys may shed the virus infrequently.