In a clinical study in 1999 in Malawi 7.5% of patients registered with new tuberculosis were found to have had previous tuberculosis, with recurrence due to reactivation or reinfection [4]. Tuberculosis patients infected with HIV are significantly more likely to relapse compared with patients uninfected with HIV [5]. Specifically, it is reported that with HIV disease, individuals exposed to tuberculosis can reactivate as frequently as 10% per year, as compared with 10% per lifetime without HIV disease [6].