B virus, or Cercopithecine herpesvirus 1, is an infectious agent that is commonly found among macaque monkeys, including rhesus macaques, pig-tailed macaques, and cynomolgus monkeys. Monkeys infected with this virus usually have no or mild symptoms. In humans, however, B virus infection can result in a fatal encephalomyelitis. B virus disease in humans is extremely rare, but often fatal -- an estimated 80% of untreated patients die of complications associated with the infection.

Persons at greatest risk for B virus infection include veterinarians, laboratory workers, and others who have close contact with Old World macaques or monkey cell cultures. Infection is typically caused by animal bites, scratches, or exposure to the tissues or secretions of macaques. In late 1997, a worker at a primate center died from B virus infection that developed after biologic material from a monkey was splashed into the patient's eye. In response to this case, CDC formed a working group to reassess the existing recommendations for the prevention, evaluation, and treatment of B virus infection in humans.

References:

Holmes GP, Chapman LE, Stewart JA, Straus SE, Hilliard JK, Davenport DS, The B Virus Working Group. Guidelines for the prevention and treatment of B-virus infections in exposed persons. Clin Infect Dis 1995;20:421-39