The impact of HIV infection on the global epidemiology of tuberculosis.

HIV is the strongest risk factor for tuberculous disease observed in the last 100 years in subjects infected with tubercle bacilli. Its impact upon tuberculosis incidence is so great that it has disrupted the balance between the tubercle bacillus and the community. The breakdown rate from tuberculous infection to active tuberculosis in persons infected dually is at least 30%. Although adequate chemoprophylaxis would prevent a considerable number of tuberculosis cases among these individuals, its application is not feasible in developing countries with a high prevalence of both tuberculous and HIV infections. Thus it seems that very little can be done against the increase in the incidence of tuberculosis caused by HIV. The only feasible measure to contain the transmission of tuberculous infection is to achieve a high cure rate and a high detection rate of smear-positive and other cases. This would enable us to contain-to an extent-the transmission of tuberculous infection. The results of IUATLD assisted National Tuberculosis Programmes in Tanzania and Malawi show that this can be achieved.