Curable Sexually Transmitted Infection Treatment Interventions to Prevent HIV Transmission in Sub-Saharan Africa

Introduction: Sub-Saharan Africa (Africa) remains the most severely HIV affected region in the world. As there will not be a cure or vaccine against HIV for many years, primary HIV prevention remains key to HIV control. Primary prevention currently includes treatment of curable sexually transmitted infections (STIs). Here, the evidence for curable STI treatment as an HIV prevention strategy in Africa is reviewed. Results: Despite data on the plausible biological mechanisms from laboratory studies and the relative risks from epidemiological studies suggesting that classical STIs do increase the risk of HIV acquisition and transmission, the impact of curable STI treatment on HIV transmission measured in RCTs has varied markedly. Syndromic STI treatment was shown to be an effective strategy in a population with an early HIV epidemic, but neither syndromic STI treatment, nor mass STI treatment were effective in mature HIV epidemics. Among sex workers with relatively low rates of STI, presumptive STI treatment also failed to reduce HIV incidence. Discussion: Rational health policy requires that scarce resources be allocated to interventions with the best costeffectiveness even if relative impact at population level is modest. Curable STI treatment is likely to prevent a decreasing fraction of new HIV infections as the HIV epidemic expands, but, because of increasing HIV incidence it may remain cost-effective for HIV prevention in many African countries.