bilharziasis

bilharziasis: see schistosomiasis.

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schistosomiasis

 or bilharziasis

Group of chronic disorders caused by parasitic flatworms of the genus Schistosoma (blood flukes). Depending on the infecting species, thousands of eggs released by the females reach either the intestine or the bladder, are excreted in feces or urine, and hatch on contact with fresh water. The larvae invade snails, develop to the next stage, emerge into the water, and invade mammals to feed and breed in the bloodstream. An initial allergic reaction (inflammation, cough, late-afternoon fever, hives, liver tenderness) and blood in the stools and urine give way to a chronic stage, in which eggs impacted in the walls of organs cause fibrous thickening (fibrosis). This condition can lead to serious liver damage in the intestinal types and to bladder stones, fibrosis of other pelvic organs, and urinary-tract bacterial infection. In most cases, early diagnosis and persistent treatment to kill the adult worms ensure recovery.