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Brucellosis is a bacterial infection that causes disease in mammals, especially sheep, goats, and cattle. Humans become infected by exposure to the tissues, blood, urine, vaginal discharge, aborted fetuses, and placentas of infected animals. Contaminated animal products (e.g., raw milk and dairy products) can also transmit the disease.

Farmers, ranchers, and veterinarians, as well as slaughterhouse workers, meat inspectors, and laboratory personnel are at increased risk for brucellosis. In the United States, 100 to 200 brucellosis cases are reported each year. Most cases result from travel outside the United States and ingestion of unpasteurized milk products. Person-to-person transmission rarely has been documented. Because small amounts of aerosolized bacteria can cause disease, Brucella is considered a potential agent of bioterrorism.

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