CD4 and tuberculosis: Figure 1 shows the study recruitment flow chart including the patient numbers stratified by patient subgroups, smear microscopy, HIV status and CD4 T cell count. The demographic and clinical characteristics of the cohort, stratified by HIV status, are shown in Table 1. The predominant male and Black African population reflects the prevailing demography of TB in South Africa. The prevalence of HIV in the cohort was 31% and the median CD4 count in the HIV-infected population was 177 cells/mm3.