[Effect of water conservancy schistosomiasis control projects in rivers and estuaries connecting with the Yangtze River on Oncomelania snail control].

Objective: To evaluate the effect of the water conservancy schistosomiasis control projects in rivers and estuaries connecting with the Yangtze River on Oncomelania snail control.

Methods: Three water conservancy schistosomiasis control projects of Laobianmin River, Panjia River and Bianmin River were chosen for the objects of the study. The concrete slope protection and the overflow dam, the concrete slope protection and the check sluice, and the simple concrete slope protection were built respectively in above mentioned three rivers. The changes of the area with snails and density of snails were investigated before and after the interventions, and the results were compared among the three projects.

Results: In the condition of the routine snail control with the molluscicide, the snails were eliminated in the main riverway of the Laobianmin River, but the snails still existed in the target protected area (tributaries of the river and irrigation areas); the snails were eliminated in the Panjia River and its irrigation areas; in the Bianmin River, the areas with snails dropped by 89.22% in the main river and still remained in the tributaries and irrigation areas after the project implementation.

Conclusions: The sluice and overflow dam more contribute to control and eliminate snails in the project areas and the target protected areas in the rivers and estuaries connecting with the Yangtze River. The priority of consideration should be given to the water level control and prevention of snail spreading in the water level instability rivers connecting with the Yangtze River.