One Health assessment of fascioliasis and schistosomiasis in humans, livestock, and snail vectors in peri-urban Rwanda

Background and Aim: Fascioliasis and schistosomiasis are significant snail-borne trematode infections that affect humans and livestock in tropical regions, leading to notable public health and economic impacts. In Rwanda, previous studies have examined these diseases separately in humans or animals, but integrated surveillance encompassing humans, livestock, and snail vectors is missing. This study aimed to assess the prevalence, transmission patterns, and related risk factors of fascioliasis and schistosomiasis in humans, livestock, and freshwater snails, using a One Health approach in peri-urban districts of Kigali City, Rwanda. Materials and Methods: A cross-sectional One Health study was conducted from November 2023 to July 2024 in Gasabo and Kicukiro districts. Fecal samples were collected from livestock at farms (n = 120) and at the Nyabugogo abattoir (n = 150), and examined using sedimentation and postmortem inspection techniques. Human samples (n = 120) were analyzed with the Flukefinder® technique and direct microscopy. Freshwater snails (n = 222) were collected from 15 wetlands and rivers using a 500 μm mesh kick-net, identified morphologically, and examined for cercarial shedding. Water physicochemical parameters were measured at each sampling site. Logistic regression and descriptive statistics were employed to evaluate prevalence and risk factors. Results: The prevalence of fascioliasis in farm livestock was 40.8%, whereas schistosomiasis prevalence was 7.5%. At the abattoir, fascioliasis prevalence was 33.3%, and no schistosomiasis lesions were detected. Animals with lower body condition scores had significantly higher odds of Fasciola infection (OR = 43.33, p = 0.002). All Schistosoma-positive animals originated from Masaka sector (p < 0.0001). Among 222 snails collected, 1.4% shed cercariae, including Biomphalaria pfeifferi, Biomphalaria sudanica, and Lymnaea natalensis. Environmental parameters were generally favorable for snail survival, although only temperature showed significant association with cercarial shedding. No human infections were detected, likely due to low egg shedding or sampling limitations. Conclusion: This initial integrated One Health study in peri-urban Rwanda reveals active transmission of fascioliasis and schistosomiasis in livestock and snail vectors, suggesting a potential risk for human infection despite no current human cases. The detection of infected snails near livestock farms and wetlands indicates transmission hotspots that call for coordinated control efforts. Recommendations include regular livestock deworming, snail control, environmental management, and community education programs. Further longitudinal and molecular studies are necessary to better understand transmission dynamics and to support national One Health surveillance for neglected tropical diseases. Keywords: fascioliasis, livestock, One Health, peri-urban Rwanda, schistosomiasis, snail vectors, trematode infections, wetlands.