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Nematode - Strongyloides stercoralis
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Nematode - Strongyloides stercoralis

Strongyloides stercoralis
  • Has both free-living and parasitic adult forms.
Life Cycle
  • Larva penetrates skin, travels to lungs in circulatory system
  • Coughed and swallowed
  • Transitions to adult form in small intestine
  • Adult females lay ~12 eggs/day
  • These eggs hatch in the small intestine, release rhabditiform larvae.
Two courses for rhabditiform larvae:
  • Leave host in feces – two options form here:
– Transition to filiaform larvae and infect new host (direct cycle) – Develop into free-living adults and mate (indirect cycle)
  • Or, Autoinfection:
– Rhabditiform larvae penetrate small intestine wall – Enter circulation, go thru lungs and return to gastrointestinal tract, become adults and produce more larvae. – This cycle can go on for years.
Clinical:
  • Otherwise healthy people are often asymptomatic or experience pulmonary or intestinal symptoms.
– When symptomatic, infection mimics peptic ulcers with inflammation, epigastric pain, vomiting, and diarrhea.
  • In immune compromised (esp. those on immunosuppressive therapies or transplant recipients), chronic infection can lead to hyperinfection and dissemination to other organs (abdominal organs, thyroid, heart, brain, meninges are common).
– Requires treatment.
Image Credits:
https://www.cdc.gov/dpdx/strongyloidiasis/index.html

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