Fatal Herpesvirus Simiae (B Virus) Infection in a Patas Monkey (Erythrocebus Patas)

Abstract

Herpesvirus simiae (B virus) occurs naturally in Asian macaques, particularly rhesus, bonnet, and cynomolgus monkeys 7,8 The term B virus was coined after a physician (W.B.) died from encephalitis 3 days after being bitten by a clinically normal rhesus monkey. Herpesvirus simiae was isolated from the patient’s brain, medulla, spinal cord, and spleen. The B virus is well adapted to its natural simian host, frequently causing only transient, mild oral lesions. Like many herpesviruses, a latent form occurs in recovered animals, and the virus can be recovered from kidney, oral secretions, and the trigeminal ganglia in clinically normal monkeys. Infected animals may not show clinical signs or have detectable antibody to the B virus. Surveys of wild and captive monkeys reveal a high variability in B virus infection rates. Approximately 10% of young recently captured animals were seropositive for B virus, whereas 70-80% of adults had positive titers. In addition to age, population density also influenced the number of positive animals. In Indonesia, 77% of those monkeys tested had positive titers, in Malaysia, 64%, and in the Philippines, 28%. Sera obtained from various laboratories utilizing primates revealed approximately 19% of the animals tested had antibody titers to B virus. The major interest in B virus has been the disease it causes in humans. Infected individuals develop an almost invariably fatal ascending myelitis and encephalitis. Fatal disease suspected to be caused by B virus has been reported in patas and colobus monkeys. This report describes a case of fatal B virus infection in a pet patas monkey. An adult male patas monkey was submitted for necropsy following a brief illness. The monkey had been normal the previous morning, yet developed anorexia and lethargy the evening prior to its demise. The monkey had been purchased from an unknown dealer in Missouri 3 weeks previously. He had been housed in an outside enclosure until 1 week prior to his death, when he was moved into an 8x 12x 6-foot indoor cage located in the basement of a house. There were 2 pairs of rhesus monkeys also in the basement. Their cages were separated from the patas monkey’s cage by a solid partition. All cages were cleaned at 2-3-day intervals. The patas monkey’s cage had never been used for holding other primates. All monkeys were fed a commercial diet formulated for primates and supplemented with various fruits. The patas monkey was fed an all fruit diet for 1 week prior to his death.