Climate change is already reshaping schistosomiasis transmission across Africa

Climate change is shifting infectious disease burdens ^1–6 , but attributing transmission changes remains difficult where interventions and socioeconomic development interact with temperature-dependent signals ^7–11 . Mechanistic models can isolate temperature-dependent signals from non-climatic influences ^5,12–16 but are often not tested against independent data. Here, we present a validation-first framework using a temperature-dependent R₀ transmission model ¹⁷ 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°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 R₀ 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.