Causes

Brucellosis affects many wild and domestic animals, including:

• Cattle
• Goats
• Sheep
• Pigs and wild hogs
• Dogs, especially those used in hunting
• Deer
• Elk
• Bison
• Caribou
• Moose
• Camels

A form of brucellosis also affects harbor seals, porpoises and certain whales.

The most common ways that bacteria spread from animals to people are by:

• Eating 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 of infected animals.
• Inhaling contaminated air. Brucella bacteria spread easily in the air. Farmers, hunters, laboratory technicians and slaughterhouse workers can inhale the bacteria.
• Touching blood and body fluids of infected animals. 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 who have weakened immune systems should avoid handling dogs that are 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 children during birth or through their breast milk. Rarely, brucellosis may spread through sexual activity or through contaminated blood or bone marrow transfusions.