Epidemiology of tuberculosis

Globally, tuberculosis is one of the leading infectious causes of adult mortality. Most tuberculosis cases occur because of late reactivation of the vestigial lesions of primary infection in the lungs or in extrapulmonary sites. Rapid progression to overt disease occurs in a minority of newly infected persons who cannot mount sufficient immune responses. Groups at high risk include children from infancy through 4 years of age, the infirm elderly, and immunocompromised subjects, including patients with acquired immunodeficiency syndrome (AIDS), organ transplant recipients, and other patients who are immunosuppressed by malnutrition, illnesses, or chemotherapy. Recently, treatment of rheumatologic disease and inflammatory bowel disease with antitumor necrosis factor-α (anti–TNF-α) antibody therapy has been associated with reactivation tuberculosis.