Burden of schistosomiasis in Ethiopia following 10 years of preventive chemotherapy: a national cross-sectional geostatistical survey.

BACKGROUND: Current strategies aim to eliminate schistosomiasis as a public health problem globally by 2030. As this target approaches, up-to-date knowledge of the burden and distribution of schistosomiasis is crucial. After a decade of control measures in Ethiopia, there are currently no high-resolution data with which to evaluate progress and guide interventions. Through a nationwide survey, we aimed to map the fine-scale distribution of schistosomiasis in Ethiopia to guide programmatic decision making at the kebele (subdistrict) level. METHODS: This cross-sectional geostatistical survey was conducted across ten regions of Ethiopia using spatially regulated sampling. Children aged 9-14 years were selected, using sex-stratified systematic random sampling, from schools or communities. Stool samples, collected from children in all ten regions, were assessed for Schistosoma mansoni using the Kato-Katz thick smear technique. Schistosoma haematobium infection was assessed by urine filtration and a urine dipstick test from samples obtained from children in three endemic regions. We fitted geostatistical models incorporating environmental covariates from five domains: sociodemographic, bioclimate, geology, land cover, and exposure to contaminated water. We generated 1 km2 prevalence maps and estimated the probability of exceeding WHO preventive chemotherapy thresholds at the kebele level. The primary outcomes were the prevalences of infection and heavy-intensity infection with S mansoni and S haematobium. FINDINGS: Between June 20, 2021, and Oct 22, 2024, 121 593 children were enrolled at 4258 sites. Complete datasets for S mansoni analysis were available from 119 559 children surveyed at 4100 sites, among whom 26 885 were also assessed for S haematobium. The mean age of the children was 11·4 years (SD 1·7), with 57 046 (47·7%) female and 62 513 (52·3%) male. The combined survey prevalence of both Schistosoma species analysed was 5·4% (95% CI 5·0-5·9): 5·2% (4·8-5·7) for S mansoni and 1·0% (0·8-1·3) for S haematobium. Compared with baseline defined woreda-level prevalence categories, areas with a prevalence of at least 10% have declined, reducing the number of people above the threshold for requiring annual preventive chemotherapy from 25·6 million to 10·8 million. 1622 (11·0%) of 14 763 assessed kebeles were above the threshold for annual preventive chemotherapy, and the predicted probability of correct classification was at least 70% for 11 600 (78·6%) of the 14 763 kebeles. The prevalence of heavy-intensity infection among the survey population was 0·2% (95% CI 0·2 to 0·3) overall (0·2% [0·2 to 0·3] for S mansoni and <0·1% [<0·1 to <0·1] for S haematobium), below the WHO elimination as a public health problem target of 1%. INTERPRETATION: This national, high-resolution map of schistosomiasis in Ethiopia shows marked progress towards elimination. The model-based geostatistical approach supports targeted, evidence-driven interventions and more efficient use of resources. FUNDING: END Fund's Deworming Innovation Fund, which receives funding from anchor partners including the ELMA Foundation, Delta Philanthropies, the Children's Investment Fund Foundation, the Wyss Medical Foundation, and Virgin Unite through an Audacious Project.