Tuberculosis (TB) is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attacks the lungs, but TB can attack any part of the body, including the kidneys, spine and brain. Not everyone with TB becomes sick. As a result, two TB-related conditions exist: latent TB infection (LTBI) and TB disease. If not treated properly, TB can be fatal.
TB can be spread through the air to people in close contact with someone who is ill with active pulmonary disease. This results in an infection that is not contagious, unless it later develops into an active disease.