Tuberculosis (TB) is a disease caused by bacteria called Mycobacterium tuberculosis. These bacteria usually attack the lungs but can attack any part of the body. Most tuberculosis disease is in the lungs and spreads through the air from one person to another. The bacteria are put in the air when a person with TB disease coughs, sneezes and speaks. People nearby may breathe in these bacteria and become infected.
However, not everyone who breathe in these bacteria become sick. Most people have what is called latent tuberculosis infection. They are not sick and cannot give these germs to anyone. A small percentage of those with latent tuberculosis infection may go on to develop tuberculosis disease. Most people with latent tuberculosis infection can take medicine so they won't develop tuberculosis disease.