An understanding of the epidemiology of Mycobacterium tuberculosis is critical for effective control. The global burden of tuberculosis (TB), risk factors for transmission, and the epidemiology of TB in the United States will be reviewed here. The epidemiology of drug-resistant TB is discussed separately. (See "Epidemiology and molecular mechanisms of drug-resistant tuberculosis".)
M. TUBERCULOSIS COMPLEX
M. tuberculosis is a member of the Mycobacterium tuberculosis complex; other members include Mycobacterium africanum and Mycobacterium bovis.
M. africanum is most commonly found in West African countries; it causes up to a quarter of cases of tuberculosis (TB) in the Gambia . The symptoms of infection resemble those of M. tuberculosis. The infectivity is similar to M. tuberculosis, and it is an important opportunistic pathogen in the setting of advanced immunosuppression due to HIV or other causes. Management is identical to management for disease due to M. tuberculosis.
M. bovis is discussed in detail separately. (See "Mycobacterium bovis".)
More than two billion people (about one-third of the world population) are estimated to be infected with Mycobacterium tuberculosis . The global incidence of tuberculosis (TB) peaked around 2003 and appears to be declining slowly . According to the World Health Organization (WHO), in 2012, 8.6 million individuals became ill with TB and 1.4 million died . Both these statistics reflect a decline compared with prior years. The number of individuals infected with TB peaked in 2005, when nine million individuals became ill. The death peaked at 1.8 million in 2003.