CD4 and tuberculosis: Patients from the rural setting were older (median age 37 years vs. 34 years, P = 0.003), had a lower median body mass index (17.5 kg/m2 vs. 18.5 kg/m2, P <  0.001), a higher proportion of recurrent TB cases (9% vs. 1%, P <  0.001), and in HIV/TB co-infected patients a lower median CD4 cell counts (147 cells/μl vs. 249 cells/μl, P = 0.02) compared to those from urban Tanzania.