<p>This article explores the history of Schistosomiasis in the Huangpu River basin, where Jiaxing and Qingpu were once among the most severely endemic counties in China. In this region, the occurrence and prevalence of Schistosomiasis depended on changes in the tidal zone, in contrast to many other epidemic regions in China. And its epidemic history is full of historical contingencies and chance occurrences. The Lijiahong and the Laoguanzui dikes, which acted as a sea wall, were washed out in storm surges in the 1580s and 1650s. As a result, the Huangpu tidal flow strengthened, and the strong muddy tide then brought soil to the upper stream of the Wusong and Huangpu Rivers and caused the sedimentation of channels and lakes. With the sedimentation, the river and lake beds around the Qingpu county rose and gradually emerged from the tidal region. Although this region had historically witnessed the cumulative effects of sporadic outbreaks of Schistosomiasis, a flood in 1931 further reduced the stream flow and fostered and greatly expanded habitat conducive to the snails that served as an intermediary host, invading a habitat that had long sustained the region’s prosperity.</p>