Tuberculosis is an infection caused by Mycobacterium tuberculosis, which usually affects the lungs but can also affect the kidneys, lymph nodes, spine, intestinal tract and brain.

TB spreads through the air when an infected person coughs or sneezes, shouts, spreading germs in the air. Inhaling other people infected.

One of the reasons why TB has spread so fast lately is the largest number of patients infected with HIV. HIV leads to a weakened immune system, and thus, tuberculosis has a free way to grow, and passes rapidly concentrated primarily in the secondary phase.
The germ can be reactivated if a person has a weakened immune system, as in the case of AIDS, after surgery, after other infections in miners and smelter workers, and those who have scars of TB cured.

In addition, the risk of contracting TB increases with the frequency of contact of infected people with poor living conditions with poor nutrition.

Another factor that contributes to TB from spreading is the fact that some patients do not finish their antibiotic treatment. This treatment should be followed by a long period of time (6 to 9 months) and often, if patients feel better they stopped treatment, believing they are healed, but it is an illusion because the TB germ is still alive, can instantly activate and spread to other healthy people. This could also lead to the mutation of the germ that becomes resistant to several drugs, and do not respond properly to known treatments, therefore, scientists must find new effective drugs.