Strongyloides stercoralis Flashcards
What is the common name for Strongyloides stercoralis?
Thread worm
What is unique about Strongyloides stercoralis among nematodes infecting humans?
It is the smallest nematode infecting man.
What type of nematode is Strongyloides stercoralis?
Facultative nematode.
What are the stages of Strongyloides stercoralis?
It has free-living rhabditiform and parasitic filariform stages.
Is Strongyloides stercoralis pathogenic to humans?
Yes, it is the only species of this genus that is naturally pathogenic to humans.
What is the diagnostic stage of the life cycle?
Egg (heavy infections) / Larva
What is the infective stage?
L3 / Filariform (Unsheathed)
What is the mode of transmission (MOT)?
Skin Penetration (Swamp itch)
What are the three ways of transmission?
- Direct
- Indirect
- Autoinfection (internal)
How does the adult worm mimic the hookworm life cycle?
Rhabditiform larvae are usually passed in the stool; eggs are only occasionally found in such samples.
What happens to rhabditiform larvae in the outside environment?
They mature into free living adults that are non-parasitic and may initiate a new indirect cycle.
Where do rhabditiform larvae develop and where do they enter?
They develop inside human intestines, enter lymphatics or bloodstream, and initiate a new cycle.
Where are these infections predominantly found?
Tropical and subtropical regions of the world and areas of poor sanitation.
Which regions in the U.S. are affected?
Areas of the South and Appalachian Mountain region.
What are some clinical symptoms of strongyloidiasis?
Asymptomatic (chronic), Diarrhea, Abdominal pain, Urticaria with eosinophilia, Vomiting, Constipation, Weight loss, Variable anemia, Death, Pulmonary symptoms possible during parasite migration (Löffler syndrome), Hyperinfection is possible.
What laboratory diagnosis methods are used?
Diagnostic eggs may be present in diarrhea, Baermann Funnel Technique, Harada-Mori Culture Method, Zinc sulfate concentration, Diagnostic rhabditiform larvae recovered in fresh stool samples and duodenal aspirates.
What are some additional diagnostic methods?
Beale’s string test, duodenal aspiration, small bowel biopsy, Serologic tests including ELISA tests available.
What are the treatment options?
Ivermectin, Albendazole, Thiabendazole (contraindicated for pregnant women).
What are some prevention and control measures?
Exercising proper sanitation and personal hygiene practices, Avoidance of defecating directly into the soil, Avoidance of using feces as fertilizer, Covering of bare feet and skin from contaminated soil.
