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Brucellosis Disease Information

Brucellosis is a bacterial disease primarily of Rocky Mountain elk and bison. The disease is limited to northwestern Wyoming and adjoining portions of Montana and Idaho. Cows often abort their first fetus after becoming infected. Abortions may occur in subsequent pregnancies but diminish over time. The disease does not affect bull reproduction; however infection may result in inflammation of the testes (orchitis). Brucellosis also infects domestic cattle. A state/federal eradication program has almost eliminated the disease in cattle, but infected elk and bison pose a continuing threat.

How Does Brucellosis Affect Me?

Brucellosis is a zoonotic disease. Humans, including hunters, usually become infected by handling the infected reproductive tract or fetus. Hunters should wear protective gloves when field dressing late season (January on) cow elk. Reproductive organs, placentae, or swollen testes or joints should not be opened. Symptoms include recurring (undulant) low-grade fever, joint or back aches, night sweats, and depression. Such symptoms can occur weeks or months after exposure and often are not related back to the handling of an infected animal. Symptoms can be successfully treated with a prolonged course of antibiotics. Failure to treat brucellosis can result in lifelong debilitation.

Brucellosis Impacts on Wildlife

The prevalance of brucellosis can be quite high (up to 75% in bison), yet there is no evidence that brucellosis has noticeable impacts on populations. The primary management concern is the possible transmission of brucellosis from elk or bison to domestic cattle. States having infected cattle herds suffer economic hardships. The threat to cattle results in ongoing friction among wildlife management agencies, ranchers, and federal agencies.