Brucellosis is a severe acute febrile disease caused by bacteria of the genus Brucella. These bacteria cause diseases primarily in domestic, feral and some wild animals, and most of them are also pathogenic for humans. In animals, brucellae typically affect the reproductive organs, and abortion is often the only sign of the disorder. Human brucellosis is either an acute febrile disease or a persistent disease with a wide variety of symptoms. It is a true zoonosis in that virtually all human infections are acquired from animals. The disease is controlled by the routine practice of pasteurizing milk and milk products, and through comprehensive campaigns to eradicate the disease by destroying domestic animals that exhibit positive serologic reactions to brucellae. Vaccines providing some protection to cattle, sheep and goats are available.