Parasite-carrying snails can travel long distances, spreading a deadly disease along the way, according to new research led by UC Berkeley. The study is the first to find genetic evidence for long-distance movements — as far as 30 miles—among snails that pose an important public health threat.

Schistosoma japonicum/CDC
Schistosoma japonicum/CDC

Where and how snails move is of concern in many developing countries because freshwater snails transmit schistosomiasis, a parasitic disease that affects more than 240 million people worldwide. Each snail can contaminate the water that people work, swim or wash in with many parasites, so movement of just one snail to a new area could introduce the disease in a previously healthy population. The study found that the way humans manage the land and waterways that snails traverse could be enabling their spread.

“We don’t think of snails as particularly mobile, but the genetic evidence we found — that snails can traverse substantial distances — is a reminder of just how difficult it is to contain and control infectious diseases carried by animals and insects,” said Justin Remais, an associate professor of environmental health sciences at UC Berkeley, who led the study.

The study was published Dec. 15 in the journal PLoS Neglected Tropical Diseases.

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