Describe the cutaneous manifestations of schistosomiasis as they relate to the parasite’s life cycle. Schistosomiasis is a trematode (fluke) infection produced by one of three species of the genus Schistosoma. Schistosomes have a complex life cycle that involves development in freshwater snails (intermediate host) and the release of free-swimming cercariae that penetrate the human skin. Penetration produces a transient pruritus and burning followed by blisters, bruising, and crusted papules over the next few days. As the worm reaches maturity in the portal or caval venous system, the ova are released by the adult female and passed into the feces or urine. Some ova are deposited in the skin and may produce nodules, ulcers, and warty tumors. The anogenital region is most often involved through direct extension from the bladder or rectum, but spread through the bloodstream and lymphatics may produce lesions at other sites. |
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