Data for Field Surveys and Experiments-Sack&Selland.xlsm

Schistosomiasis is a devastating parasitic disease in which the infectious stage to humans is released by intermediate host snails. The Senegal River Basin (SRB) is a high-risk area for both urogenital and fecal human schistosomiasis and has extensive rice cultivation. However, occupational risk of schistosomiasis to people working in irrigated rice fields is not well established. We performed intermediate host snail surveys from 2022-2023 in rice fields and irrigation canals throughout the SRB. We discovered human schistosome-shedding snails in rice fields and adjacent irrigation canals during the rice growing and non-growing seasons, establishing a clear occupational exposure risk to rice farmers. Relative to the non-growing season, this risk was higher in the rice growing and harvest season when more people are in the rice fields. Rice-fish co-culturing might reduce this occupational risk to rice farmers if local fish species consume enough snail intermediate hosts to reduce Schistosoma transmission. Our predation trials revealed that local Heterotis niloticus and Hemichromis spp. fish consumed significant numbers of Biomphalaria pfeifferi and Bulinus spp. snails, and separate trials revealed that these same snail species exhibited only moderate avoidance and refuge use responses to fish chemical cues. These results indicate that there is exposure to Schistosoma parasites in rice fields in the SRB and introducing local fish to rice fields has promise for reducing this exposure as well as providing a protein source to rice farming families. We encourage future studies to more fully explore the benefits of rice-fish co-culturing in the West Africa.

血吸虫病（Schistosomiasis）是一种极具破坏性的寄生虫病，其可感染人类的发育阶段由中间宿主螺类（intermediate host snails）释放。塞内加尔河流域（Senegal River Basin, SRB）是泌尿生殖道型与消化道型人血吸虫病的高风险区域，同时拥有大面积水稻种植区。然而，灌溉稻田务工人群所面临的血吸虫病职业暴露风险尚未得到充分阐明。本研究于2022至2023年间，对塞内加尔河流域全境的稻田与灌溉渠开展了中间宿主螺类调查。在水稻种植季与休耕季的稻田及邻近灌溉渠中，我们均发现了可排放人血吸虫尾蚴的螺类，明确了稻农面临的职业暴露风险。相较于休耕季，该风险在水稻种植与收获季更高——此时有更多人员进入稻田作业。若本地鱼类能够捕食足量的中间宿主螺类以阻断血吸虫传播，稻渔综合种养（rice-fish co-culturing）或可降低稻农面临的此类职业风险。捕食实验结果显示，本地的尼罗异耳骨舌鱼（Heterotis niloticus）与半攀鲈属（Hemichromis spp.）物种可捕食大量费氏双脐螺（Biomphalaria pfeifferi）及截口螺属（Bulinus spp.）物种；另有独立实验表明，上述螺类仅会对鱼类的化学信号产生中等程度的躲避与庇护行为响应。上述结果证实，塞内加尔河流域的稻田中存在血吸虫寄生虫暴露风险，而在稻田中引入本地鱼类，不仅有望降低此类暴露风险，还可为稻农家庭提供蛋白质来源。我们鼓励未来开展更多研究，以全面探索西非地区稻渔综合种养的益处。