Microbiology, parasitology & COVID-19

Parasites-gastrointestinal (not liver)


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Last staff update: 24 December 2020

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PubMed Search: Strongyloides

Nat Pernick, M.D.
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Cite this page: Pernick N. Strongyloides. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/parasitologystrongyloides.html. Accessed June 5th, 2023.
Definition / general
  • Nematode whose larvae buries into the mucosa of the duodenum and jejunum where they mature into adults
  • Females then lay eggs which develop into larvae that pass into the stool, where they mature and become infective
  • Infective larvae penetrate intact skin, usually through the feet
  • Larvae enter the circulatory system, are transported to the lungs and enter the alveolar spaces
  • Larvae are carried to the trachea and pharynx, are swallowed and enter the intestinal tract, where the process is repeated
  • If the larvae become infective before leaving the body, they may invade the intestinal mucosa or perianal skin, causing autoinfection
Diagrams / tables

Images hosted on other servers:

Life cycle

Clinical features
  • Most patients suffer diarrhea, malabsorption or no symptoms
  • Immunocompromised individuals can acquire disseminated strongyloidiasis; a possibly fatal condition in which worms move into other organs (WormBook 2015:1)
  • Prevention is by wearing shoes in endemic areas
  • Stool exam looking for larvae or biopsy of small intestinal mucosa looking for the adult female or eggs
Case reports
  • 43 year old Honduran man with diarrhea, abdominal pain and duodenal biopsy (Case #133)
Microscopic (histologic) description
  • Larvae, adult female or eggs
  • In female worms, the intestine or ovaries may be prominent
  • In gravid females, an egg may be identified within the uterus
  • There is often granulomatous or eosinophilic inflammation
Microscopic (histologic) images

Contributed by Bobbi Pritt, M.D.

Adult female and larvae

Prominent genital primordium

Case #133

Duodenal biopsies of a 43 year old Honduran man


Contributed by Bobbi Pritt, M.D.

Endodoscopy of elderly woman with hematemesis (parasite case #499)

Differential diagnosis
  • Capillaria philippinensis:
    • May present similar to S. stercoralis with intestinal adults and larvae
    • However, Capillaria is an obligate parasite and usually does not survive in viral culture media for very long
    • In wet preparations Capillaria adults have a prominent stichosome but Strongyloides adults do not
    • Capillaria rhabditiform larvae lack the prominent genital primordium and clavate eosphagus of Strongyloides
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