Environmental Factors Influencing the Distribution of Oncomelania hupensis in Central Region, China

Schistosomiasis, caused by the snail-borne parasite Schistosoma japonicum, remains highly prevalent in Hubei, China, especially the central region (Jianghan Plain). Because the control of S. japonica primarily depends on the rapid discovery and elimination of its intermediate host Oncomelania hupensis snails, the spatio-temporal distribution of snails and the environmental factors influencing it warrant clarification. We used geographic information system technology to investigate the spatial dynamics of snail distribution in Jianghan Plain from 2008 to 2012. A generalized linear-mixed model, with time as a random effect, was applied to characterize the relationship between snail density at the village level and the associated environmental factors. The percentage of villages in which the frequency of areas with <50% snail occurrence was 71.74-82.67%, which was much higher than that for villages where snail occurrence was >50% (17.33-28.26%). Precipitation, daylight hours, land surface temperatures, wetness index, and proportion of silt were positively associated with snail density, with precipitation having the greatest effect. Normalized difference vegetation index and elevation were negatively associated with snail density. Our findings can be used as a theoretical basis to develop models predicting outbreaks of snail occurrence in the Jianghan Plain and for preventing and controlling schistosomiasis.