THE PROPORTION OF TUBERCULOSIS CASES IN TANZANIA ATTRIBUTABLE TO HUMAN-IMMUNODEFICIENCY-VIRUS

Background. Routine data obtained from the National Tuberculosis end L eprosy Programme (NTLP) of Tanzania have shown a constant increase in the notified number of tuberculosis (TB) cases since 1982. Possible ca uses include an improved reporting system, improvement in health servi ces after the introduction of short course chemotherapy (SCC), and hum an immunodeficiency virus (HIV) infection. This paper examines to what extent the increased TB case detection rate can be attributed to HIV infection, by calculating the population attributable risk for various years. Method. The prevalence of HIV infection was obtained from data of the National AIDS Control Programme and the relative risk of HIV f or developing TB from a case-control study and the literature. Results . Between 1985 and 1989 the increase was the highest among women aged 15-24 years and men aged 25-34 years; age groups in which HIV prevalen ce is highest. In the case-control study HIV prevalence among blood do nors was 9.4% and among smear-positive pulmonary TB patients 51.6%, gi ving an odds ratio (OR) of 8.1 (95% confidence interval (CI):4.4-16.3) . For all TB cases the OR was 11.8. In a population with an HIV preval ence of 10%, about 40% of the smear-positive TB patients are attributa ble to HIV. The excess of TB cases in the entire country between 1982 and 1989 can be attributable to HIV infection. This has implications f or TB control and socioeconomic consequences in the country.