Trichostrongylus spp.
- Parasite
- For completeness
A small roundworm of sheep, goats and cattle. People swallow its larvae on raw vegetables; its eggs look like hookworm eggs.
Also called: Trichostrongylus colubriformis, Trichostrongylus orientalis, Trichostrongylus axei, trichostrongylosis
Quick facts
- Type
- Parasite · Nematodes
- Gram / shape
- Thin
- Spread
- Vegetable gardens fertilised · Unlike hookworm
- Causes
- Trichostrongylosis
- Treatment
- Benzimidazoles
At a glance
- Shape
- Thin, thin-shelled colourless egg, tapering at one end, often already segmented
- Family
- Trichostrongylidae
- Type
- Strongylid nematode of herbivores; humans are incidental hosts
- Size
- Eggs 75–95 × 40–50 µm, longer and narrower than hookworm eggs (60–75 × 35–40 µm)
Morphology
- Egg larger than a hookworm egg, with one or both ends more pointed.
- The inner membrane may look wrinkled.
- Adults are small, slender worms of the small intestine.
Transmission
- Swallowing infective larvae on raw vegetables or water contaminated with herbivore manure.
- Vegetable gardens fertilised with sheep or goat manure are a classic source.
- Unlike hookworm, larvae do not need to penetrate the skin to infect.
Reservoir: Sheep, goats, cattle and other herbivores; Soil and vegetation contaminated with their faeces
Isolation precautions
What the care team adds to standard precautions.
- Standard
Life cycle
- Eggs leave in the faeces of a herbivore, usually a sheep, goat or cow.
- In warm, moist, shaded soil the larvae hatch within days.
- After two moults (5–10 days) they become infective third-stage larvae on soil and plants.
- A person swallows larvae on raw vegetables or in water.
- The worms mature in the small intestine, attach to the mucosa and lay eggs.
Virulence factors
- Adults embed their front end in the small-intestine mucosa, causing local inflammation.
- Heavy burdens cause blood loss and anaemia.
- The tissue phase drives eosinophilia, sometimes very high.
Diseases it causes
- Trichostrongylosis: usually silent; heavy infection causes abdominal pain, diarrhoea and anaemia
Clinical picture
- Most infections are light and asymptomatic.
- Epigastric pain, diarrhoea, loss of appetite, fatigue, headache.
- Unexplained eosinophilia in several members of a household who share a vegetable garden.
- Has been misdiagnosed as acute fascioliasis when eosinophilia and diet suggest it.
Diagnosis
- Eggs in stool; concentration or flotation methods help in light infections.
- Measure eggs carefully to separate them from hookworm; mixed infections occur.
- Stool larval culture can tell larvae apart from hookworm larvae.
- Adult worms may be recovered in stool after treatment.
Treatment
Benzimidazoles (albendazole or mebendazole); pyrantel pamoate is an alternative. Anthelmintic resistance is common in livestock strains.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Do not fertilise vegetable gardens with fresh animal manure.
- Wash and disinfect raw vegetables; safe drinking water.
- Hand hygiene after contact with soil and livestock.
Test yourself
Think of the answer, then tap the question to see it.
How do humans acquire Trichostrongylus?
By swallowing infective larvae on raw vegetables or in water contaminated with herbivore manure.
Which helminth egg is most easily confused with a Trichostrongylus egg?
The hookworm egg; Trichostrongylus eggs are longer, narrower and more pointed at one end.
Which laboratory clue often leads to the diagnosis in a family cluster?
Eosinophilia, sometimes marked, in several people who eat vegetables from the same garden.
Connections
← Back to the group: Nematodes
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: CDC - DPDx - Trichostrongylosis (CDC, 2017); Familial Trichostrongylus Infection Misdiagnosed as Acute Fascioliasis (Emerging Infectious Diseases (CDC), 2015).
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Representative model, for educational purposes only.