MONITORING PARASITIC DISEASE TRANSMISSION THROUGH MULTIPLE SPACEBORNE SENSORS: SCHISTOSOMIASIS IN POYANG LAKE, CHINA

Schistosomiasis is a water-dependent parasitic tropical disease involving an intermediate snail host in the transmission cycle. Second only to malaria in prevalence and over 200 million infections occur annually worldwide including areas in Africa, Southeastern Asia, and China. This chronic disease shortens average lifespans by ten years and leads to increased cancer risks. Hydrology plays a critical role in the snail ecology and thus affects the human disease burden. Our research focuses on the influence of hydrology on the schistosomiasis transmission cycle in the Poyang Lake region in southeastern China where health education and behavioral changes are insufficient to control the disease. Hydrological factors, such as the area of land covered by water and lake water dynamics, affect the snail populations, which influences disease transmission. In this study, we use multiple geodetic sensors, including Envisat dual-frequency radar altimeter and MODIS/Terra 8-day sun reflectance data to monitor water extent and water level variation in Poyang Lake. In the the preliminary results, the water area delineation using MODIS Modified Normal Difference Water Index shows Poyang Lake and surrounding basins have an annual variation of water extent in between 500 km² and 3400 km² since 2003, with a decreasing trend of both annual maximum water level and water extent. This corresponds well with previous studies observed by in situ gauge data, InSAR and other optical methods. This study shows that satellite-based observers and hydrological analyses could be well integrated as the first step to build a monitoring system for control and analysis of water-dependent parasitic disease transmission.