Herpes B (also known as Macacine herpesvirus 1 or Cercopithecine herpesvirus 1) is a virus carried by certain monkeys called macaques. When the monkey gets herpes B virus, it makes a blister on or near the monkey's lips. After the blister heals, the virus hides inside the monkey and you would not know the monkey has had the virus. The virus may be in its mouth, hands or other body parts. When a monkey bites, scratches, or spits on a worker, the virus may pass to that worker. Herpes B virus does not make monkeys very sick but can make people very sick and even cause death.