- Helminthic parasite, common worldwide but especially in warmer climes.
- S. stercoralis is the major human pathogen.
- S. fuelleborni occasional human pathogen, described in Papua New Guinea and Africa.
- Larvae live in soil. Human infection by contact with contaminated soil.
- Filariform larvae penetrate the skin and enter lymphatics → can go to lung alveoli or straight to the small intestine.
- Adult female deposits eggs in the intestinal mucosa, larvae hatch and excreted in stool OR may become filariform (infective) in the large intestine and cause auto-infection.
- Cycle yields long-term infection in humans (years-decades, may be considered lifelong).
- Immunosuppression can yield increased organisms as a result of auto-infection → hyperinfection [see life cycle Fig. 1], a potentially fatal condition.
- Larvae are typically seen ~1 month after exposure.
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