Climate change is already reshaping schistosomiasis transmission across Africa

Climate change is shifting infectious disease burdens1-6, but attributing transmission changes remains difficult where interventions and socioeconomic development interact with temperature-dependent signals7-11. Mechanistic models can isolate temperature-dependent signals from non-climatic influences5,12-16 but are often not tested against independent data. Here, we present a validation-first framework using a temperature-dependent R transmission model17 to detect and attribute temperature-mediated climate impacts on schistosomiasis transmission across Africa. First, semi-natural mesocosm experiments confirmed the model's biological constraints, with high temperatures suppressing the host-parasite system above ~33{degrees}C. Next, we established epidemiological relevance in the Lake Victoria Basin using 141,829 longitudinal infection records. Interannual temperature anomalies predicted infection risk, with anthropogenic warming accounting for 17.1% of observed infections relative to a natural-forcing-only counterfactual. Finally, across Africa, the mechanistic R predictor explained prevalence better than correlative climate metrics, even after accounting for intervention and socioeconomic covariates. Applying the validated framework to ensemble climate model simulations and a natural-forcing-only counterfactual (1984-2014) showed that anthropogenic warming increased transmission potential in cooler regions while suppressing it in hotter regions across Africa, a contrast projected to intensify under higher-emissions scenarios by mid-century. Climate impacts are not solely future threats, but present-day forces already reshaping transmission and disease burden.