Tuberculosis is caused by bacteria, the most common of which is the pathogen called Mycobacterium tuberculosis. It is a communicable air-borne disease that is transmitted in the form of droplets from one person to another. The mechanisms of transmission are therefore similar to those of a cold: a cough, a contaminated doorknob, or being seated next to an infected person are enough to contract the disease.

As previously mentioned, an infection with the pathogen does not automatically result in a breakout of the disease. Instead, a latent, non-contagious TB infection (LTBI) develops. The WHO estimates that about one-third of the world is infected with the TB bacteria. This latent infection means that there is a constant struggle in the human body between the pathogen and the immune system, in which the immune system usually emerges as the victor. However, when the body’s defense mechanism is weakened or exposed, the active disease may develop.

Move on to the next section to read more about the different types of TB and parts of the body the bacteria infects.

>> Types of TB