Tuberculosis (TB) is caused by germs that are spread through the air when a person with infectious TB coughs or sneezes. Anybody nearby is at risk of breathing these air-borne TB germs into their lungs.
When these TB germs attack the lungs and grow, they cause damage to the lungs, and can spread these germs to other people. TB can also affect other parts of the body like glands, bones, joints, kidneys and reproductive organs. TB is not likely to be spread to others from these areas of the body.