A deadly disease may have met its match: a bug-eyed, pint-sized crustacean. A Stanford-led study in Senegal, West Africa, finds that freshwater prawns can serve as an effective natural solution in the battle against schistosomiasis, a potentially deadly parasitic disease (image shows parasite) that infects approximately 230 million people. The prawns prey on parasite-infected snails, while also providing a source of marketable protein-rich food. Because prawns cannot support schistosomiasis' complex life cycle, they do not transmit the disease themselves. "The results of our study open the pathway to a novel approach for the control of schistosomiasis," said co-author Dr. Giulio De Leo, a biology professor at Stanford's Hopkins Marine Station and a senior fellow at the Stanford Woods Institute for the Environment. The new study, published online on July 20, 2015, tracked parasite-infected snails and people in two villages. In one village, the international research team and Senegalese partner Biomedical Research Center Espoir pour la Santé stocked a river access point with prawns. Over the course of 18 months, the researchers found 80 percent fewer infected snails and a 50 percent lower disease burden (the mean number of parasite eggs in a person's urine) in people living in the village neighboring the prawn-stocked river. The PNAS article is titled “Reduced Transmission of Human Schistosomiasis after Restoration of a Native River Prawn That Preys on the Snail Intermediate Host.” In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminated schistosomiasis in high-transmission sites. "Where drugs, alone, fail to control schistosomiasis due to rapid reinfection, prawns may offer a complementary strategy" for controlling the disease, the study's authors write.
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