Prevalence and control of sexually transmitted infections in sub-Saharan Africa

Sexually transmitted infections (STIs) are a major yet often overlooked public health challenge in sub-Saharan Africa (SSA), associated with severe reproductive and neonatal sequelae, chronic complications, and an increased risk of HIV acquisition in the presence of co-infection. The WHO has set ambitious global incidence reduction targets for 2030, but progress in SSA is hindered by high rates of asymptomatic infection, limited diagnostic capacity, weak surveillance infrastructure, and fragmented health systems. This thesis combines systematic reviews, data synthesis, and mathematical modelling to generate evidence that strengthens STI surveillance and control in SSA. It estimates sub-regional trends in the prevalence of curable STIs among general populations, and characterises the evolving aetiologies of vaginal discharge, urethral discharge, and genital ulcer syndromes. It then investigates the utility of self-reported symptoms and treatment-seeking behaviours from population-representative surveys for quantifying the relative STI burden and trends, and monitoring treatment coverage. This includes assessing the consistency of these survey measures with national aetiologic prevalence estimates across SSA and with sub-national syndromic case diagnoses from health facility surveillance in Malawi. Finally, it evaluates how a limited supply of gonorrhoea point-of-care tests could be allocated across different testing strategies and target populations to maximise reductions in population-level incidence and morbidity in Kenya. Taken together, the findings highlight persistent surveillance gaps that undermine burden estimation and progress monitoring against global targets, identify considerable epidemiologic heterogeneity requiring more targeted programme strategies, and demonstrate that novel diagnostic technologies have potential to mitigate the high burden despite resource constraints.