Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis. It most commonly affects the lungs but can affect other parts of the body. The disease spreads through airborne droplets when infected people cough, sneeze or speak. Diagnosis involves medical history, physical exam, tuberculin skin test, chest x-ray and microbiological tests. Treatment requires a combination of antibiotics taken for at least 6-12 months to prevent drug resistance from developing. Prevention strategies include identifying infected individuals and their contacts, testing high-risk groups, and immunizing infants with the BCG vaccine.