The Proportion of Tuberculosis Cases in Tanzania Attributable to Human Immunodeficiency Virus

The increase seen in the incidence of tuberculosis (TB) in many developing countries in the early 1980s was at first through to be the result of better case detection but it soon became clear that HIV infections were influencing this increase. To determine the extent that HIV infection has increased TB case detection rates in Tanzania data were analyzed from the National TB and Leprosy Programme the National AIDS Control Programme and a case-control study conducted for three months in 1990. Cases were all 128 newly registered cases of TB in three districts. Controls were 1558 blood donors in these districts. HIV prevalence among the cases was 51.6% with no differences in sex residence or type of TB. HIV prevalence was highest among 25-34 year olds. HIV prevalence in controls was 9.4% with no variation by age or sex. The odds ratio for association between HIV infection and new smear-positive TB stratified by age was 8.1. The age-stratified offs ratio for HIV infection and any type of TB was 11.8. The population attributable risk for 1990 was in the order of 30% which means that without HIV the increase in TB cases seen after 1985 would not have occurred. It is essential to improve TB programs to minimize the looming increase in the annual risk of infection. Also HIV control programs will have a large effect on TB control programs and collaboration between the two should be encouraged.