Tuberculosis in the tropics.

Tropical countries bear the brunt of the global TB burden. Young children are at high risk and suffer the most severe forms of TB; adults with pulmonary cavities are the main sources of transmission. The incidence in sub-Saharan Africa is increasing as a consequence of the HIV pandemic. Smear-negative TB, which is common in children and patients who have HIV infection, is becoming a major problem in resource-poor settings where access to mycobacterial culture and histopathology is limited. Clinical case definitions are being developed to address this problem. Short courses of rifampin-based therapy are not universally available, but access is increasing. DOTS is the main strategy that the WHO is promoting to improve TB control. This is particularly important for sputum smear-positive patients. Unfortunately, the DOTS targets set by the WHO have not yet been met. Innovative, low-cost ways of supervising therapy have been developed using family members or lay supervisors. Preventive therapy in tropical countries is limited to high-risk cases (young children and HIV-infected patients who are tuberculin skin test-positive). An improved TB vaccine would dramatically improve TB control.