Tuberculosis is a potentially serious infectious bacterial disease caused by Mycobacterium tuberculosis. It mainly affects the lungs but other organs may also be involved.

TB is a contagious airborne disease. The germs spread through the air between the person with active Tb and everyone else, even if the TB positive person coughs, laughs, sneezes, or even talks to close. When a person breathes in TB bacteria, the bacteria settle in his/her lungs and multiply. The disease develops anywhere from a couple of days to a week after the infection is contracted.