Parasite
Enterobius vermicularis
Pinworm with perianal tape-test clue
en-ter-OH-bee-us ver-mik-yoo-LAIR-iss
High-yield clue
Nocturnal perianal itching identified by the cellophane tape (Scotch-tape) test showing D-shaped eggs flattened on one side.
Overview
A small intestinal nematode (pinworm) whose gravid female migrates to the perianal skin at night to deposit eggs, a classic study model for fecal-oral and autoinfection transmission.
Classification
- Nematode (roundworm)
- Not a soil-transmitted helminth; directly egg-borne (eggs infective within about 4-6 hours)
- Small white pinworm
- Humans are the only host
Lab & identification clues
- Cellophane tape test of perianal skin vocabulary
- Eggs flattened on one side (asymmetric, D-shaped)
- Eggs usually absent from stool
- Adult worms may be seen grossly
Associations
- Perianal pruritus, especially at night
- Fecal-oral and autoinfection transmission vocabulary
- Common in young children and households
- Temperate-climate crowding association
Commonly confused with
- Ascaris lumbricoides
- Strongyloides stercoralis
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.