Parasite
Strongyloides stercoralis
Threadworm with autoinfection cycle
stron-jih-LOY-deez ster-koh-RAL-iss
High-yield clue
Autoinfection lets it persist for years, and stool shows rhabditiform larvae (not eggs) - the defining teaching distinction.
Overview
An intestinal nematode capable of completing its cycle within a single host through autoinfection, the key concept that allows decades-long persistence and severe hyperinfection in immunocompromised study cases.
Classification
- Nematode (roundworm)
- Filariform larvae penetrate skin
- Rhabditiform larvae passed in stool
- Free-living and parasitic cycles
Lab & identification clues
- Rhabditiform larvae in stool (eggs rarely seen)
- Larvae distinguished from hookworm by short buccal cavity vocabulary
- Serology and repeated stool concentration concepts
Associations
- Filariform larvae penetrate skin from soil
- Autoinfection and hyperinfection syndrome vocabulary
- Risk with corticosteroids/immunosuppression
- Larva currens migratory rash association
Commonly confused with
- Hookworm (Ancylostoma/Necator)
- Enterobius vermicularis
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.