The spatio-temporal distribution of Oncomelania hupensis along Yangtze river in Jiangsu Province, China after implementation of a new, integrated schistosomiasis control strategy

This study concerns an integrated strategy of schistosomiasis control, focusing on the management and elimination of the main transmission cycles and reservoirs along Yangtze river, Jiangsu Province (China), instituted in 2004. Our analysis, including mapping, spatial autocorrelation and spatio-temporal scanning, was implemented between 2001 and 2013 to explore the changes in the distribution of Oncomelania hupensis, the intermediate host of Schistosoma japonicum. Two high-density snail locations in the upper and middle reaches of the river were observed along with one high-risk area due to infected snails in the upper reaches at the beginning of the study period. The number of high-density snail habitats declined sharply after 2004 and infected snails disappeared completely by 2010. Global spatial autocorrelation showed spatial clustering of snails in general, as well as of infected ones when snail densities were relatively high, while local spatial autocorrelation showed the number of specific clusters declining and switching spatially from the upper to the middle reaches of the Yangtze river in Jiangsu Province during the study period. The integrated snail control strategy was found to be effective, but the middle reaches of the river will require continued strong control resources.