Sexual Age-Mixing and HIV Transmission in Rural Uganda

Abstract

HIV is a major threat to global health and equity, causing millions of deaths since the beginning of the pandemic in 1981 and disproportionately affecting regions of lower socioeconomic status, particularly sub-Saharan Africa. The creation of accurate mathematical models of infectious diseases and the identification of HIV risk factors are two important steps toward the goal of understanding and preventing the spread of HIV. This thesis characterizes sexual age-mixing patterns in Rakai, Uganda, including analyses through time and by relationship type. Sexual age-mixing patterns varied strongly with participant sex and age, as well as with the type of relationship reported. There were no general population-level changes in sexual contact age-assortativity from 1999 to 2013, though some age- and sex-based trends were identified. Further, this thesis evaluates age-disparate relationships as a potential risk factor for HIV infection, as existing studies have come to mixed conclusions about whether or not relationship age disparities elevate HIV risk. The relationship between age disparities and HIV infection was found to depend on age and sex, and age-disparate relationships were only found to be a potential HIV risk factor in women aged 15 to 19. In other subsections of the population, age-disparate relationships either had no significant association with HIV incidence or were found to be a potential protective factor against HIV infection. All of these findings contribute to our understanding of the transmission of HIV and other STIs through the Rakai population; this knowledge can inform targeted interventions for HIV prevention.