Brucellosis is a bacterial infection that spreads from animals to people — most often via unpasteurized milk, cheese and other dairy products. More rarely, the bacteria that cause brucellosis can spread through the air or through direct contact with infected animals.
While brucellosis is uncommon in the United States, the disease affects hundreds of thousands of people and animals worldwide. Avoiding unpasteurized dairy products and taking precautions when working with animals or in a laboratory can help prevent brucellosis

Brucellosis affects many wild and domestic animals. Cattle, goats, sheep, pigs, dogs, camels, wild boar and reindeer are especially prone to the disease. A form of brucellosis also affects harbor seals, porpoises and certain whales. The bacteria may be spread from animals to people in three main ways: raw dairy products. Brucella bacteria in the milk of infected animals can spread to humans in unpasteurized milk, ice cream, butter and cheeses. The bacteria can also be transmitted in raw or undercooked meat from infected animals.
Brucella bacteria spread easily in the air. Farmers, laboratory technicians and slaughterhouse workers can inhale the bacteria. Bacteria in the blood, semen or placenta of an infected animal can enter your bloodstream through a cut or other wound. Because normal contact with animals — touching, brushing or playing — doesn’t cause infection, people rarely get brucellosis from their pets. Even so, people with weakened immune systems should avoid handling dogs known to have the disease.
Brucellosis normally doesn’t spread from person to person, but in a few cases, women have passed the disease to their infants during birth or through their breast milk. Rarely, brucellosis may spread through sexual activity or through contaminated blood or bone marrow transfusions.

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