Two studies led by University of Texas (UT) Southwestern (UTSW) researchers have shed light on the biology and potential vulnerabilities of schistosomes – parasitic flatworms that cause the little-known tropical disease schistosomiasis. The findings, published in the Septembr 25, 2020 issue of Science, could change the course of this disease that kills up to 250,000 people a year. About 240 million people around the world have schistosomiasis – mostly children in Africa, Asia, and South America in populations that represent “the poorest of the poor,” says study leader James J. Collins (photo) (https://profiles.utsouthwestern.edu/profile/154775/james-collins.html), PhD, Associate Professor in UTSW’s Department of Pharmacology. Most of those infected survive, but those who die often suffer organ failure or parasite-induced cancer. Symptoms can be serious enough to keep people from living productive lives, Dr. Collins says. The parasite that causes this disease has a complicated life cycle that involves stages in both freshwater snails and mammals. Dwelling in mammalian hosts’ circulatory systems, schistosomes feed on blood and lay copious numbers of eggs, all while causing an array of symptoms including abdominal pain, diarrhea, bloody stool, or blood in the urine. Larval worms are released from snails into water, where the flatworms then may infect humans by penetrating the skin. Schistosomiasis may become a chronic disease that affects the person for years. Only one drug, praziquantel, is available to treat this condition. However, Dr. Collins explains, it is of limited use – it doesn’t kill all intramammalian stages of the schistosome life cycle, and it has a variable cure rate in some endemic settings. There’s been little interest by pharmaceutical companies in developing new drugs for this disease, he adds, because there is no monetary incentive to do so.
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