New Issue: Science’s Impossible Questions. Read Now

Breeding Snail Fever

Three Gorges Dam boosts parasitic infections

Join Our Community of Science Lovers!


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


High in the mountains of China's Sichuan Province, George Davis of George Washington University is collecting tiny, seemingly harmless snails from a muddy ditch that runs through terraced fields. As the evolutionary biologist wields his tweezers, he contemplates how massive disruptions of the environment produce widespread problems, including emerging epidemics. "Diseases like SARS can pop up because of the interference of man in the ecosystem," he explains. "And now we have one of the most dynamic ecosystem changes in history in the Three Gorges Dam."

His concern: infections by parasitic worms, producing the fast-spreading and potentially deadly schistosomiasis that infects his collected snails--and humans. Davis and his colleagues from China's Institute for Parasitic Diseases (IPD) in Shanghai are finding that the Three Gorges Dam--the world's largest--is driving an increase in schistosomiasis infection densities around China's greatest lake.

Subscribe to Support Independent Journalism

Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.

When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.

Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber

Thank you,

Jeanna Bryner, Editor in Chief, Scientific American

Subscribe