[The Changes of Hydrological Regime in Poyang Lake After Runs of Three Gorges Project and Its Impact on Prevalence of Schistosomiasis in the Lake Region]

Objective: To clarify new features of hydrological regime in the Poyang Lake after runs of the Three Gorges Project and its impact on the prevalence of schistosomiasis in this region.

Methods: It is collected information of Three Gorges Project, average daily water level from 2002 to 2012 at Duchang hydrological station in Poyang Lake and the data of prevalence and control of schistosomiasis in 12 endemic counties along the lake. It was analyzed the trends of prevalence of schistosomiasis under the changed condition of hydrologic situation.

Results: Effects of impoundment of Three Gorges reservoir running on water level of Poyang Lake are mainly shown in: Water levels of the lake are suppressed throughout the year which was characterized by high water level in flood season dropped, lower water level appeared in the spring, water withdrew earlier and quicker in the fall and to an even lower level in dry season. After impoundment of Three Gorges Project, infection rate of Schistosomajaponica in human and in bovine decreased by 92.65% and 76.37% respectively in endemic areas around the lake. The density of Oncomelania snails decreased by 94.21%. Prevalent of schistosomiasis in this region showed a significant downward trend.

Conclusions: After runs of the Three Gorges Project, regularized changes hydrologic conditions has taken place in Poyang Lake which is characterized by lower water level and thus might lead to lower density of Oncomelania snails on marshlands and reducing of prevalence of schistosomiasis. Significant strengthening of schistosomiasis control efforts might also contributed to the stable and low level of prevalence of schistosomiasis in the region.