Strongyloides stercoralis

Valeria Fabre, M.D., Paul G. Auwaerter, M.D.


  • 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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Last updated: October 10, 2021