5. Study Outcome The primary endpoint of this study will be the development of recurrent TB. TB recurrence as a result of relapse will be defined as isolates of M. tuberculosis from the first and second episodes of TB which cluster in Restriction Fragment Length Polymerization (RFLP) analysis. TB recurrence as a result of re-infection will be defined as isolates from the first and second episode of TB which differ on RFLP analysis. Each study participant who has recurrent TB will be assessed by Interferon (IFN) gamma ELISPOT assay to compare cytotoxic lymphocyte (CTL)immune responses in TB relapse and re-infection.