Bovine brucellosis, caused by the bacterium Brucella abortus, is an economically important cause of abortions in cattle. B. abortus also affects other species including bison, buffalo and elk; some species are maintenance hosts for this organism. Infections in wildlife can hinder eradication efforts in cattle. In addition, B. abortus is a human pathogen. In humans, brucellosis can be a serious, debilitating and sometimes chronic disease that may affect a variety of organs. Most cases are the result of occupational exposure to infected animals, but infections can also occur from ingesting contaminated dairy products. In addition, B. abortus could be used in a bioterrorist attack.