HIV and human papillomavirus (HPV) are two heavy hitting sexually transmitted infections (STIs). Meta-analyses of the association between HPV prevalence and HIV acquisition and the association between HIV prevalence and new HPV detection have estimated a two-fold increased risk in both directions, after adjusting for individual-level (sexual behavioural) factors. The studies argue that biological mechanisms may be responsible for these increased risks, but they also concur that residual confounding due to behaviour at the sexual network level cannot be ruled out. We used an individual based model to shed some light on the matter.
Sexually Transmitted Infections
Antiretroviral therapy (ART) markedly reduces the risk of sexual transmission of HIV. This inspired the idea of treatment as prevention (TasP) to reduce population HIV incidence, by reducing the infectiousness of HIV-infected individuals. However, increased infectiousness when treated individuals are co-infected with other sexually transmitted infections (STIs) could potentially undercut the effectiveness of TasP programs. As there is limited knowledge about the impact of STI co-infections on HIV shedding from individuals on ART, this study reviewed all published scientific evidence.