Modelling the efficacy of prophylactic and curative therapies for preventing the spread of tuberculosis in Africa

Abstract

Concerns have been raised about whether the interaction between tuberculosis and human immunodeficiency virus (HIV) may lead worldwide to a recrudescent tuberculosis pandemic. These concerns are particularly grave in Africa which has a high prevalence of both tuberculosis and HIV. This study used a computer simulation model to examine the effect of tuberculosis-HIV interactions on tuberculosis prevalence and mortality in Africa. The model then assessed the impact of expanding treatment and chemoprophylaxis programmes on tuberculosis prevalence and mortality over the next decade. In communities where 20% of the population is infected with HIV and 25% receive treatment for tuberculosis, deaths from tuberculosis would be 100% higher than in communities where none of the population is HIV-infected. In a population the size of Uganda's, during one decade there would be approximately an additional 530,000 deaths from tuberculosis. When 50% of patients with active tuberculosis receive treatment, one death will be averted for every 2.5 people who receive treatment. The prevalence of active tuberculosis could be cut by over 90% in a decade by providing effective chemoprophylaxis to 30% of individuals with inactive TB. In conclusion, TB is only one example of a preventable and treatable infectious disease which can be spread through casual contact and which, because of its higher prevalence among the HIV positive population, may lead to a preventable increase in incidence of infection among the general population.