Tuberculosis in sub-Saharan Africa: a regional assessment of the impact of the human immunodeficiency virus and National Tuberculosis Control Program quality

Abstract

Background: The effect of the human immunodeficiency virus (HIV) epidemic on tuberculosis (TB) has been evaluated for certain countries in sub-Saharan Africa. However, no multi-country comparisons have been performed of the magnitude of the changes in TB case rates and the roles of the HIV epidemic and national TB control program (NTP) quality in these changes.

Methods: We examined trends in TB case rates after 1985 for 20 sub-Saharan African countries, and also from 1975-1984 for 10 of these countries (core countries). Average annual changes in TB case rates after 1985 were stratified by 1992 urban low-risk HIV seroprevalence and by NTP quality, as determined by a survey of international TB experts.

Results: Case rates in the core countries decreased by an average of -1.6% per year prior to 1985, but increased by an average of +7.0% per year after 1985 (+7.7% per year after 1985 in all 20 countries). Average annual case rates after 1985 increased approximately twice as fast in countries with high vs low or intermediate HIV seroprevalence ratings. In both the core countries and all 20 countries, the average annual rate of rise in case rates after 1985 decreased as NTP quality rating increased. This relationship persisted even after stratification by HIV seroprevalence rating.

Conclusions: TB case rates have increased in sub-Saharan Africa since 1985. These increases were relatively greater as HIV seroprevalence increased, and relatively lower as NTP quality increased. Improving NTP quality is essential to mitigate the resurgence of TB in the HIV era.

PIP: Specialists in tuberculosis (TB) prevention and control examined trends in TB case rates after 1985 for 20 sub-Saharan African countries and these trends during 1975-84 for 10 of the countries (core countries). They aimed to determine the effect of the HIV epidemic on TB. The 20 countries accounted for 50% of the total population of sub-Saharan Africa and 85% of TB cases. The figures for the core countries were 19% and 27%, respectively. In the core countries, TB case rates fell on average by 1.6% (range, -12.7% to 4.6%) annually before 1985, but increased on average by 7% (range, -2.6% to 18%) thereafter. The TB case rate increased by 7.7% (range, -4.5% to 14.5%) after 1985 in the 20 countries. TB case rates after 1985 increased almost twice as fast in countries with high HIV prevalence ratings when compared to those with low or intermediate HIV prevalence ratings (12.7% vs. 4.6% and 4.5% in core countries and 7.8% and 5.1% in the 20 countries, respectively). In both the core countries and the 20 countries, the annual rate of increase in TB case rates fell as the quality of the national TB control program increased. This held true when the researchers stratified by HIV prevalence. Improving quality had the least impact on the rate of increase in TB case rates in countries with a high HIV seroprevalence. These findings suggest that sub-Saharan African countries should invest in improving the quality of the national TB control program to effect reductions in TB morbidity, even in the face of the HIV epidemic.