Schistosomiasis Outbreak Driven by River Water Contact Among Children in Petauke District, Eastern Province, Zambia, May 2026

Background: Schistosomiasis (bilharzia) is a water-borne parasitic disease that remains endemic in Petauke District, Eastern Province, Zambia. In 2025, Petauke Urban Health Centre recorded 98 suspected and 50 laboratory-confirmed cases, compared with 38 suspected and one confirmed case in 2024, exceeding the epidemic threshold of 53.2 cases (mean + 2 SD, 2021–2024) by 84.2%. We investigated to determine the magnitude of the outbreak, describe cases by person, place and time, identify independent risk factors and recommend control measures.
Methods: We conducted a descriptive analysis of surveillance data and an unmatched case-control study (1:2) in the Petauke Urban Health Centre catchment area. Cases were residents with schistosome eggs detected on urine microscopy between September 2025 and January 2026; controls were residents aged five years and above from the same catchment who tested negative on urine microscopy. Data were collected using structured KoboToolbox questionnaires and analysed in R (version 4.5.3) using univariable and multivariable logistic regression, with sex included a priori in the adjusted model.
Results: We enrolled 117 participants (39 cases, 78 controls). Median age of cases was 13 years (IQR 11.0–14.5); 97.4% of cases were male and 59.5% were aged 10–14 years. Haematuria was universal (100%), followed by dysuria (76.9%). Chimate (n=12) and Stambuli (n=11) villages accounted for 59.0% of cases. River water contact was reported by 89.7% of cases versus 10.3% of controls. In multivariable analysis adjusted for sex, river water contact (aOR 43.71; 95% CI 8.80–217.20) and children swimming and urinating in water bodies (aOR 6.24; 95% CI 1.42–27.43) were independently associated with infection. No participant had received praziquantel through mass drug administration (MDA), median care-seeking delay was 44 days, and 23.1% of confirmed cases had not been treated.
Conclusion: This was a true outbreak of urogenital schistosomiasis, consistent with S. haematobium infection on urine microscopy, associated with recreational river contact among school-age boys in a setting with no preventive chemotherapy coverage. Emergency praziquantel MDA, treatment of all untreated cases, malacological surveys to guide any focal snail control at implicated river sites, targeted risk communication and improved access to safe water are recommended.

Schistosomiasis, bilharzia, Schistosoma haematobium, outbreak investigation, case-control study, water contact, Petauke District, Zambia.

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