Enterobius vermicularis (Pinworms)
Epidemiology and Etiology:
- Nematode family
- One of the most common human parasites
- Worldwide
- Cold or temperate climates more common
- Developed countries more common
- US and northwestern Europe extremely common
- Infective egg resides in dust and soil
- Fecal-oral transmission
- Female migrates to the anus to lay eggs and die
Common sites:
- Ileum
- Cecum
- Proximal colon
- appendix
Gross features:
- 2-5 mm
- Mucosa normal often
- Hemorrhage and ulceration maybe
Histologic features:
- Cross section:
- Cuticle
- Lateral ala
- Numerous eggs
- Often little or no inflammatory reaction, even
if invasive
- Inflammatory infiltrate comprised of
neutrophils and eosinophils occurs uncommonly
- Granulomas, sometimes with necrosis maybe
around degenerating worms or eggs
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- Pruritis
ani
- Many infections are asymptomatic
- Appendicitis, colitis, vulvovaginitis,
and peritoneal involvement have been described
References: