Three Months of Weekly Rifapentine and Isoniazid for M. Tuberculosis Infection

The PRIMARY objective of this open-label Phase III clinical trial is to compare the effectiveness of a three-month (12-dose) regimen of weekly rifapentine and isoniazid (3RPT/INH) to the effectiveness of a nine-month (270-dose) regimen of daily isoniazid (9INH) to prevent tuberculosis (TB) among high-risk tuberculin skin-test reactors, including children and HIV-infected persons, who require treatment of latent TB infection (LTBI). The 3RPT/INH regimen will be given under direct observation and the 9INH regimen will be self-administered. SECONDARY Objectives: * Compare the rates of drug discontinuation due to adverse drug reactions associated with 3RPT/INH and 9INH. * Compare the rates of drug discontinuation for any reason associated with 3RPT/INH and 9INH. * Compare the rates of any grade 3, 4, or 5 drug toxicity associated with 3RPT/INH and 9INH. * Compare treatment completion rates of 3RPT/INH and 9INH. Compare the efficacy (i.e., among persons who complete study-phase therapy) of 3RPT/INH and 9INH. * Compare the effectiveness and tolerability of 3RPT/INH and 9INH in HIV-infected persons. * Compare the effectiveness and tolerability of 3RPT/INH and 9INH in children \< 18 years old. * Compare the rates of methadone withdrawal associated with 3RPT/INH and 9INH among persons concomitantly receiving methadone. * Describe patterns of antibiotic resistance among M. tuberculosis isolates in patients who develop TB despite treatment of latent infection. Amendment of the study protocol to allow extension of enrollment to children \< 12 years old and HIV-infected persons: For assessment of the primary outcome, development of TB, a sample size of approximately 4,000 persons per arm will be required. To assess tolerability (one of the secondary outcomes) in sub-groups, children less than 12 years old and HIV-infected persons, a sample size of 644 per strata will be required. A sample size of 8,053 patients for the primary outcome was reached on February 15, 2008 (with expected follow-up completion time in 2010), leaving approximately 454 additional young children and 200 HIV-infected persons to be enrolled to achieve the targets of 644 for each group. The additional data on tolerability in those sub-groups will available for analysis in 2013.