Tuberculosis (TB) is an infectious disease usually caused by Mycobacterium tuberculosis (MTB) bacteria. Tuberculosis generally affects the lungs, but can also affect other parts of the body. TB is a severe infection caused by bacteria called Mycobacterium tuberculosis. TB usually starts in the lungs. The bacteria are easily spread from one person to another through the air. They can live in your body a long time without making you sick. This is called latent TB. Latent means you do not have symptoms, but you may develop them later. Latent TB can develop into active TB if it is not treated.
As of 2018 one quarter of the world’s population is thought to have latent infection with TB. New infections occur in about 1% of the population each year. In 2018, there were more than 10 million cases of active TB which resulted in 1.5 million deaths. This makes it the number one cause of death from an infectious disease. As of 2018, most TB cases occurred in the regions of South-East Asia (44%), Africa (24%) and the Western Pacific (18%), with more than 50% of cases being diagnosed in eight countries: India (27%), China (9%), Indonesia (8%), the Philippines (6%), Pakistan (6%), Nigeria (4%) and Bangladesh (4%)