River shrimp, like this Macrobrachium raised in a local hatchery in the Senegal River basin, can consume a dozen or more snails per day. A team led by University of California, Berkeley, scientists, has shown how communities can harness freshwater prawn's voracious appetite for snails to battle the parasite that causes schistosomiasis, while still making money selling the prawns for food. Credit: Hilary Duff of the Planetary Health Alliance