Tuberculosis TB is a disease that can cause a serious illness and can damage a person's organs. Every year more than 25,000 people in the U.S. are diagnosed with TB disease. That's only a fraction of the amount of people who carry the Mycobacterium tuberculosis. Mycobacterium tuberculosis is a rod-shaped bacterium. TB is spread through the air by carriers of the germ. People who breathe the same air can become infected with the TB germ. People who do work around or with people with the TB disease should take medicine. TB infection means that the person has the TB germs but they are in an inactive state. Wh