B virus is endemic in macaque monkeys, which are frequently used for research studies. B virus is a risk for every employee working with macaque monkeys, their tissues or cells. Although the risk for B virus infection is low, the risk of death or permanent neurological deficit is high if an exposure is not promptly evaluated and treated. Researcher training, routine use of personal protective equipment, first aid protocols, and prompt reporting to a provider knowledgeable about B virus treatment are essential to prevent this 70% lethal infection in untreated humans. This article presents the history and pathogenesis of B virus, first aid, treatment, and prevention.