We propose to conduct this study in Mali, West Africa and local clinics in the U.S. Tuberculosis affects 593/100,000(2) individuals in Mali and most have been exposed to the disease. Additionally it would be important to evaluate the same parameters locally as latent infection is one of the major factors for reactivation tuberculosis in this country. Patients would be enrolled in 4 major groups: HIV-/TST- (Group A), HIV-/TST+ (Group B), HIV+/TST+(G roup C) and HIV+/TST- (Group D).