A recent study published in Infectious Diseases of Poverty examines how climate warming affects the habitat risks of Oncomelania hupensis, the amphibious snail that acts as an intermediate host for Schistosoma japonicum worms in China. Schistosomiasis affects more than 240 million people globally, with over 800 million living in at-risk areas. Although China reached its criteria for transmission interruption by 2023, climate and land-use changes can create new or re-emerging habitats for the snails.
Climate Warming and Habitat Risks for Schistosomiasis-Transmitting Snails
Surveillance Data and Temperature Experiments Covering 34,554 Villages
Researchers combined a 45-day temperature-controlled experiment with surveillance data covering 34,554 villages across 12 provinces from 1990 to 2022. The findings showed that body size influences snail survival. Larger snails achieved the highest survival under low temperatures at 91.6%, compared with 64.3% for small snails, while high temperatures reduced small snail survival to 2.9%, compared with 45.7% for large snails. Across the dataset, 833 of 1,123 populations with sufficient records showed significant temperature responses, with 92.0% displaying positive temperature sensitivity.
Prof. Xu on Seasonal Temperature Exposure and Population Density
“Climate warming does not affect O. hupensis populations uniformly. Our findings show that seasonal temperature exposure, geography, and land use together determine where snail populations may expand or become vulnerable,” Prof. Xu noted. Higher latitude was associated with greater population density, whereas higher altitude corresponded to lower density. Furthermore, populations exposed to greater historical temperature variability demonstrated higher densities and growth rates.
Socioeconomic Pathways Projections for Regions Around Poyang Lake
Projections under different socioeconomic pathways (SSPs) indicated that populations benefiting from warming would decline to 24.6% under SSP1-2.6, 21.5% under SSP2-4.5, and 19.0% under SSP5-8.5 by the year 2100. Croplands accounted for 72.0% of populations benefiting from warming, followed by forests at 17.2% and impervious-dominated areas at 8.3%. Regions around Poyang Lake emerged as major hotspots, with waterbodies showing the highest predicted densities and impervious areas the lowest.
The study suggests that excessive warming could eventually suppress snail density. “Ours is the first study to examine the impacts of climate warming on O. hupensis using daily temperature variation,” according to researchers from the National Institute of Parasitic Diseases at China CDC. Investigators state that strengthening surveillance in vulnerable and expanding habitats—particularly around waterbodies and agricultural landscapes—may help anticipate changes in transmission risk and sustain elimination achievements.
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