Zoonotic TB: Mode of transmission

People are most commonly infected with M. bovis by eating or drinking contaminated, unpasteurized dairy products. Infection can also occur from direct contact with a wound, such as what might occur during slaughter or hunting, or by inhaling the bacteria in air exhaled by animals infected with M. bovis. Direct transmission from animals to humans through the air is thought to be rare, but M. bovis can be spread directly from person to person when people with the disease in their lungs cough or sneeze.

People at higher risk include individuals who work with cattle or live stocks. Among other occupations, dairy farmers, people working in slaughterhouse are at increased risk of infection. People who drink raw milk (unpasteurized) or dairy products made from raw milk are also at a higher risk. The pasteurization process eliminates M. bovis from milk products.

Figure: Modes of transmission of Bovine TB