Pinworm

Alternative names:

enterobiasis Enterobius vermicularis; Enterobius vermicularis ovum or ova; oxyuriasis; pinworm infection; seatworm; threadworm

Definition:

A contagious intestinal parasite infestation that occurs commonly in children.

Causes, incidence, and risk factors:

The organism causing pinworm infection is a small whitish worm called Enterobius vermicularis. It is visible to the naked eye. E. vermicularis is found throughout the United States. The incidence varies and is higher in urban areas and crowded settings. The parasite is easily spread. Pinworm infections appear to come in cycles with years when very few infections are seen and then years when a high infection rate is seen.

Adult pinworms live in the large intestine (cecum and colon). Eggs are laid outside the anus during the night and are spread from person to person from contaminated clothing, articles, and hands. Eggs can also drift through the air where they are inhaled or swallowed. The eggs hatch in the small intestine and travel to the large intestine where they mature. Institutionalized children, large groups of children as in schools, and children with poor personal hygiene are at risk for contracting an infestation. The incidence is about 20 percent of children in the U.S., with a higher incidence in institutional settings.