Impact of HIV on tuberculosis in sub-Saharan Africa: a regional perspective.

SETTING

The relative magnitude of the recent rise in tuberculosis (TB) in sub-Saharan Africa and the proportion of excess TB cases attributable to the human immunodeficiency virus (HIV) have not been evaluated from a regional perspective.

METHODS

For each of 10 countries in mainland sub-Saharan Africa, we used reported TB case data from 1975-1993 to calculate annual excess TB cases after 1985, by subtracting the number of TB cases that would have been expected had pre-1985 trends continued from the number of reported cases for each year from 1985-1993. Using HIV seroprevalence rates from the literature for TB patients and the general population, we estimated the number of HIV-attributable TB cases in each country from 1985-1994.

RESULTS

Excess TB cases accounted for a mean of 34% (range, 0-72%) of reported cases post-1985. HIV seropositivity in TB patients was a mean of 3.5 times (range, 1.8-6.1 times) higher than in the general population. The percentage of excess TB cases attributable to HIV increased as the HIV seroprevalence among TB patients increased, with HIV-attributable cases equalling or exceeding the number of excess TB cases in four of the six countries where > or = 50% of TB patients were estimated to be seropositive in 1992.

CONCLUSION

Approximately one-third of TB cases in sub-Saharan Africa after 1985 would not have occurred had pre-1985 trends continued. The dramatic interaction of HIV and TB in the region was underscored by the high rates of HIV infection among TB patients and the high proportion of excess TB morbidity attributable to HIV.