Risk Prediction of Emerging Sites Infested with Schistosome-Transmitting Oncomelania hupensis in Shanghai, China

Oncomelania hupensis, the sole intermediate host of Schistosoma japonicum, plays an essential role in the transmission of schistosomiasis. In 1985, snails were eliminated throughout Shanghai city. However, snail-infested sites have continuously emerged since the 1990s. The resurgence of snail habitats may signal the recurrence of schistosomiasis. Therefore, implementing continuous monitoring measures for snails is crucial, and predicting potential habitats for snails in Shanghai is essential for enhancing surveillance effectiveness, providing early warnings to health authorities, optimizing resource allocation, maintaining the elimination status of schistosomiasis in Shanghai, and ultimately, advancing the goal of eliminating schistosomiasis in China. Our research developed an ensemble model to predict the current and future distributions of snails in Shanghai by collecting emerging snail-infested records from 1991 to 2020 and integrating them with 19 environmental variables, including climate, geography, and socioeconomics. The ensemble model identified the annual average surface temperature as the most significant factor influencing snail occurrence. The highly suitable areas were primarily located in the northwestern part of Jinshan District and the southern part of Songjiang District. In the future, the southwestern part of Shanghai will continue to provide suitable habitats for snails in the long term. Therefore, even in areas where schistosomiasis has been eliminated, surveillance of snails and the disease should not be relaxed, and ongoing monitoring in these areas is necessary.