The Impact of HIV Infection on Tuberculosis in Africa

Abstract

Tuberculosis (TB) notification rates in Africa have doubled since the early 1980s, with the largest increases in countries most affected by the HIV epidemic. HIV increases the risk of TB in those latently infected with M tuberculosis and increases the risk of active disease soon after new infection or re-infection with M tuberculosis. Overall, the risk of TB in those with HIV infection is about 4-10 times that in those without HIV infection. The risk starts to rise soon after infection with HIV, and continues to increase with increasing immunosuppression. At a population level, the relative risk for the association of HIV and TB increases as the HIV epidemic progresses, and will continue to increase for some time after a fall in HIV incidence due to the long latent period of HIV. The proportion of TB currently directly attributable to TB in Africa has been estimated at 31%, but the true impact of HIV on TB will be even greater because of onward transmission from the extra TB cases. Antiretrovirals can decrease the risk of TB, but would have to be used early and extensively to have a large effect at the population level.