Disease-Carrying Parasite May Have Achilles Heel

Researchers exploring the use of river prawns as a natural solution for a parasite-spread disease have found evidence the crustaceans are more effective than initially thought.

The team, which received early funding through Woods’ Environmental Venture Projects seed grant program, works in Senegal, West Africa, where people who live and work by riverways are at risk of contracting schistosomiasis, a potentially deadly parasitic disease that infects about 230 million people worldwide. The researchers, including Woods Senior Fellow Giulio De Leo (Biology) and Hopkins Marine Station Research Associate Susanne Sokolow, study how reintroduced native prawns prey on snails infected with a parasite that carries schistosomiasis, while providing a source of marketable protein-rich food. De Leo and Sokolow are both senior fellows at Stanford’s Center for Innovation in Global Health.

The team’s latest study, published in the Journal of Experimental Biology, finds that the prawns are twice as likely to devour infected snails as parasite-free snails.

“Once we discovered that native African river prawns would voraciously eat the right species of snails, the next big question was: would they eat the schistosome-infected snails or avoid them?” Sokolow said.

Infected snails were slower and less cautious than uninfected snails, often failing to make evasive manoeuvres such as avoiding open water and seeking shelter. This, in turn, made them easy meals for the prawns.

Sokolow and her colleagues speculate that the infection may alter snails’ behaviour in order to improve chances of transmission to humans who enter the water. The team is working on an experiment to test whether re-introduction of the prawns in small pens along the shore of the Senegal River can deliver on the promise of reducing schistosomiasis transmission to the area residents.

Other co-authors of “Infection with Schistosome Parasites in Snails Leads to Increased Predation by Prawns: Implications for Human Schistosomiasis Control,” include Stanford biology graduate student Scott Swartz (lead author) and Chelsea Wood of the University of Michigan.

While the prawn research has shown the effectiveness of natural solutions at small scales, the researchers plan to explore whether such approaches can be viable and sustainable on larger scales. They recently received a grant from the Stanford Institute for Innovation in Developing Economies (SEED) to establish a center on disease, ecology, health and development in collaboration with Woods and Stanford’s Center for Innovation in Global Health. Read more.

By Rob Jordan, Stanford Woods Institute for the Environment