Intestinal tuberculosis, gross specimen. Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis. In the majority of cases it affects the lungs, but it can affect any part of the body. In this case, it has led to the formation of a granuloma (oval, centre), a mass of white blood cells and bacteria. Tuberculosis is one of the world's most common fatal diseases, infecting up to a third of the world's population. It is dormant in most of those, however. It is responsible for around two million deaths each year. In the developed world, the BCG vaccine provides protection. Antibiotics can be used to treat it once contracted, but some strains are developing resistance to drugs.