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Genome of Schistosomiasis Parasite Sequenced

Scientists have sequenced the genome of the parasitic flatworm (Schistosoma mansoni) that causes intestinal schistosomiasis (also called snail fever), a devastating tropical disease that afflicts more than 200 million people in the developing world. "We have used state-of-the-art genetic and computational approaches to decipher the genome of this pathogen and to facilitate drug discovery," said Dr. Najib El-Sayed, senior author of the paper. "Many promising leads for drug development targets have emerged." Schistosomiasis is one of several neglected tropical diseases prevalent across much of Africa, Asia, and South America and affects mainly poor populations living in areas where water is unsafe, sanitation inadequate, and basic health care unavailable. It impacts adults’ and children's capacity to work and learn, and often leads to death. With knowledge of this parasite's genome sequence, scientists will now possibly be able to develop much-needed new treatments for schistosomiasis, for which a vaccine does not yet exist. The drug commonly used to treat this parasitic infection does not prevent re-infection, and there are growing reports of drug resistance and treatment failures. The term “snail fever” comes from part of the S. mansoni parasite’s complex life cycle. The parasite's eggs hatch in water, enter into snail hosts, and then travel to human hosts through contaminated water sources, such as bathing and swimming areas. The mature worm grows in the human blood vessel system, depositing eggs around the bladder or intestines, which triggers the formation of excess connective tissue in those regions. The parasite's eggs are passed to the liver or exit through the urine or feces, continuing the cycle of infection. The genome sequencing of S. mansoni is described in the July 16 issue of Nature and is featured as that issue’s cover article. [Press release] [Nature abstract]