Hydrological studies of schistosomiasis transport in Sichuan Province, China.

Schistosomiasis is a water-bourne parasitic disease endemic to Sichuan Province of China. Long-term studies of infection and disease ecology in catchments in Sichuan have been supplemented by detailed hydrometric measurements to produce a model of water velocity and flow in an irrigation system. The model provides a means of estimating travel times of two infectious stages of the parasite from source sites to water contact exposure sites for individuals of both the human population and the intermediate vector snail populations. The hydrological transport model will be part of an overall model of schistosomiasis transmission in the catchments. A GIS system is used to manage spatial data of the drainage network, land use, infection sources and population centres. The development of the Three Gorges Dam in China will increase marshlands and irrigation in areas currently free of schistosomiasis. The potential for the spread of schistosomiasis into these new areas is a major concern. Hydrological models can be of particular importance in assessing future environmental risk.