One quarter of the world’s population is infected with tuberculosis (TB), which is among the deadliest diseases in the world. In 2017 alone, there were 1.3 million deaths related to the disease and 10 million new cases of it. But what causes this lethal illness?
The UK National Health Service explains that a bacteria known as Mycobacterium tuberculosis causes TB; a person contracts the disease when someone with an active form of the illness in their lungs sneezes or coughs and someone else, in turn, inhales the droplets expelled from the infected individual.
It may be encouraging to note, however, that while TB is spread in a way akin to the flu or cold, it isn’t as infectious: one would have to spend several hours in close proximity with someone sick with TB in order to contract it. Furthermore, not everyone who has TB can spread it. Those with extrapulmonary TB–or TB that occurs outside the lungs–and children with the disease cannot spread it.
Most healthy individuals are able to harness their immune systems in order to destroy the Mycobacterium tuberculosis before it infects them.