Tuberculosis, or TB, is a disease (usually of the lungs) caused by Mycobacterium tuberculosis (M. tuberculosis) and is easily transmitted through the air when an infected person speaks, sneezes, laughs, sings, or coughs. The airborne particles then get inhaled and enter the exposed person’s lungs, where they multiply. Although TB is rare and highly treatable in the US, you will still need to take measures to prevent tuberculosis in certain situations, especially if you have already tested positive for latent TB ( an inactive form of TB which affects approximately 1/3 of the world's population).