Cause and Incidence

B virus infection is caused by the zoonotic agent Macacine herpesvirus (formerly Cercopithecine herpesvirus 1 [CHV-1], an alphaherpesvirus commonly found among macaques—a genus of Old World monkeys that serve as the natural host. B virus infection in macaques results in a disease similar to herpes simplex virus infection in humans.

B virus infection in macaques is usually symptom-free or causes only mild disease, but in humans the infection can be fatal.

Reported cases of infection in humans are very rare; since the identification of the virus in 1932, there have only been 31 documented human infections by B virus, 21 of which were fatal. Most of these infections have resulted from animal bites or scratches or from percutaneous inoculation with infectious materials. However, in 1997 a researcher died from B virus infection following a mucosal splash exposure (see Fatal Cercopithecine herpesvirus 1 (B virus) Infection Following a Mucocutaneous Exposure and Interim Recommendations for Worker Protection. Morbidity and Mortality Weekly Report 1998).