strongyloidiasis

Infection with soil-borne nematodes of the genus Strongyloides, considered to be a parthenogenetic parasitic female. Larvae passed to the soil develop through four larval instars to form free-living adults or develop from first and second free-living stages into infective third-stage strongyliform or filariform larvae, which penetrate the skin or enter the buccal mucosa via drinking water. Infection can occur by larvae of a new generation developed in the soil (indirect cycle), by infective larvae developed without an intervening adult stage (direct cycle), or by larvae that develop directly in the feces within the intestine of the host, penetrate the mucosa, and pass by blood/lung sputum migration back to the intestine (autoreinfection); most serious human infections and nearly all fatalities result from autoreinfection and subsequent disseminated infection, which commonly follow immunosuppression by steroids, ACTH, or other immunosuppressive agents. Autoreinfection also may develop in patients with AIDS. SYN: strongyloidosis.

* * *

stron·gy·loi·di·a·sis -.lȯi-'dī-ə-səs n, pl -a·ses -ə-.sēz infestation with or disease caused by nematodes of the genus Strongyloides

* * *

(strongyloidosis)

n.

an infestation of the small intestine with the parasitic nematode worm Strongyloides stercoralis, common in humid tropical regions. Larvae, present in soil contaminated with human faeces, penetrate the skin of a human host and may produce an itching rash. They migrate to the lungs, where they cause tissue destruction and bleeding, and then via the windpipe and gullet to the intestine. Adult worms burrow into the intestinal wall and may cause ulceration, diarrhoea, abdominal pain, nausea, anaemia, and weakness. Treatment involves use of the drug tiabendazole.

* * *

stron·gy·loi·di·a·sis (stron″jə-loi-diґə-sis) infection with Strongyloides stercoralis. Adult female worms and larvae inhabit the mucosa and submucosa of the small intestine, and the larvae expelled in the feces develop in the soil and can penetrate skin on contact. They later are carried in the bloodstream to the lungs, and from there they travel to the intestine via the trachea and esophagus. Massive infection (hyperinfection) is occasionally seen in immunocompromised patients and those treated with corticosteroids or certain other agents. An endogenous cycle of development (autoinfection) may occur, allowing infections to persist for many years.