The impact of concurrent partnerships on HIV transmission dynamics
Many societies have monogamous partnerships as a social norm, with most individuals having at most one partner at a time. If, instead, a society has concurrent partnerships as a social norm, so that many individuals have multiple partners at a time, does this enhance the spreading of sexually transmitted infections such as HIV? So far, opinions expressed on this point in the literature differ. The posed question is particularly pertinent with regard to the HIV epidemic in sub-Saharan Africa. In this region, HIV is widespread among heterosexual populations, which is very different from the rest of the world, where HIV remains concentrated in specific high-risk groups, such as injecting drug users. If concurrent partnerships are driving the HIV epidemic in sub-Saharan Africa, then prevention and intervention programs will need to account for their epidemiological implications. Therefore, we need to understand how concurrent partnerships actually impact the spreading of HIV. In previous work, I have already developed a mathematical framework for dynamic sexual networks that incorporates demography and allows for concurrent partnerships. For these networks, I defined two measures of partnership concurrency. In this project, I will analyze how initial disease spread and eventual endemic level are related to these two concurrency indices. Likewise, I will use the modeling framework to investigate how other concurrency measures proposed in the empirical literature relate to the disease dynamics. The anticipated improved understanding of the role of concurrent partnerships will facilitate the design of better HIV-prevention strategies and provide guidance for which observables should be monitored in the field.