Bovine tuberculosis (bTB) is an important bacterial disease caused by Mycobacterium bovis. It occurs worldwide and affects a wide range of wild and domestic animals. Bovine tuberculosis is a zoonotic disease: man can become infected via milk, aerosols, consumption of infected meat and accidental laboratory exposure. M. bovis is responsible for 5–10 % of all human tuberculosis cases but the infection rate varies widely from country to country. After exposure to infection, animals respond by activating both cellular and humoral immunity. M. bovis moves via the lymphatic system within cells to regional lymph nodes similar to other mycobacterial infections, and delayed hypersensitivity reactions typically commence between 30 and 50 days after the establishment of infection. Tuberculosis is typically a chronic infection. Many infected animals in the herd remain undetected for a long time but they can shed the bacteria by aerosol, via milk, urine and faeces. Consequently, the infection spreads from chronically infected carrier animals to susceptible animals.