Use of snail traps for surveillance of schistosome-shedding snails in rice fields and fragile ecosystems

Human schistosomiasis is a waterborne trematode disease that often affects communities already dealing with poverty and limited access to health care. Sampling to look for the snail intermediate host of schistosomiasis is often done in resource-poor settings with a sweep net, but this can be damaging to aquatic plants, such as rice. To address this issue, we tested a baited snail trap to use in fragile ecosystems and rice fields where sweep netting might not be advisable. The trap design and bait options were first tested in the laboratory with Biomphalaria glabrata and Bulinus truncatus before being tested in the Senegal River Basin in rice fields and canals. The best option was a funnel trap that was also environmentally friendly because it reuses a 1.0- to 1.5-L water bottle and includes mango as bait, a very common fruit in the region. This trap can be used by others looking to sample fragile ecosystems or rice fields for intermediate host snails of human schistosomiasis and the trematodes they harbor.