Parasitology Training Manual

Enterobius vermicularis

• Abbreviation: Ev
• A nematode
• Egg size: 50 - 60 microns
• Adult size:8 - 13 mm
• Common name: pinworm
• Method of choice for recovery is "Pinworm Paddle" or a properly prepared scotch tape preparation.
• Anterior end of adult female worm has typical cephalic inflations.
• The eggs are generally flat on one side and rounded on the other.
• When seen in a smear that has been stained with a modified Kinyoun Acid Fast and Haematoxylin stain they may appear red.

Click on the image below to enlarge.

E. vermicularis Life Cycle

Adult worms are found in the cecum, appendix and colon. The female migrates to the perianal area at night where eggs are released. Embyonated eggs become infective in 4 - 6 hours. Once ingested the larva hatch in the small intestine and mature. Time between ingestion of egg and perianal migration is about 2 - 4 weeks.

Return to Helminth Introduction

The material on this site is owned by Scientific Image and Consulting
David M. Raymondo
MLT, CLS(m)
Professional Affiliation: Gamma-Dynacare Medical Laboratories, Ottawa, Ontario, Canada
Gamma-Dynacare is a Division of the Dynacare Health Group