Tuberculosis and Mycobacteria

: Causes of Tuberculosis

The main cause of TB is Mycobacterium tuberculosis, a small, aerobic, nonmotile bacillus. TB is widespread, deadly and causes the highest number of deaths worldwide. One third of the global population has latent TB infection. The bacteria usually attack the lungs. But, TB bacteria can attack any part of the body such as the kidney, spine, and brain.

 The M. tuberculosis complex (MTBC) includes four other TB-causing mycobacteria:

·         M. bovis: It was once a common cause of tuberculosis, but the introduction of pasteurized milk has almost completely eliminated this as a public health problem in developed countries.

·          M. africanum: It is not widespread, but it is a significant cause of tuberculosis in parts of Africa. 

·         M. canetti: It is rare and seems to be limited to the Horn of Africa, although a few cases have been seen in African emigrants. 

·         M. microti.  It is also rare and is seen almost only in immunodeficient people, although its prevalence may be significantly underestimated.

Other known pathogenic mycobacteria include M. leprae, M. avium, and M. kansasii. The latter two species are classified as "nontuberculous mycobacteria" (NTM). NTM cause neither TB nor leprosy, but they do cause pulmonary diseases that resemble TB.