The Effect of Treating Sexually Transmitted Diseases on the Transmission of HIV in Dually Infected Persons

Abstract

The effect of sexually transmitted disease (STD) treatment on HIV transmission is a topic of considerable current interest and controversy. To assess the potential effect of STD treatment on HIV transmission in persons who are dually infected with STD and HIV. Using data from eight STD clinic sites in the United States, the authors estimate the actual achievable reduction in HIV transmission by multiplying the prevented fraction associated with treatment of STDs (set at an average of 0.8) by the maximum potential reduction in HIV transmission achieved by treating STDs (using an average relative risk of 3.0 for increased HIV transmission in the presence of STDs). Subgroup analysis assessed infection proportions for genital ulcer disease, nonulcerative STDs, and any STD by sex, ethnicity, age, and sexual orientation. The maximum achievable reduction in HIV transmission from dually infected persons to their partners is approximately 33%. The actual achievable reduction is approximately 27% (range, 10.0-38.1%) at the eight clinic sites. If each of the 4,516 dually infected persons in this cohort experienced a single sexual exposure with an uninfected person, 28 HIV infections would occur in the absence of STD treatment whereas 16 infections would occur with STD treatment. The estimate of a 27% reduction provides a qualitative assessment of the potential impact of STD treatment on HIV transmission in the absence of any other behavioral intervention. Identification of dually infected persons in STD clinics is an important mechanism for targeting interventions to a social milieu with high risk for HIV infection and other STDs.