Pinworms are common parasites that live in the intestine.

The Intestine
The Intestines
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Pinworms are most active at night, 2 to 3 hours after bedtime. The female worm comes out through the anus and deposits eggs in the perineal area. This area is between the anus and genitals.

Pinworms are visible to the naked eye. They are about the size of a staple, yellow-white in color, and look like a fine piece of thread, which moves actively.

A small white worm called Enterobius vermicularis causes pinworm infection. A separate species also causing infection (E. gregorii) has been reported in England.

Pinworms are spread by accidentally eating the eggs of the worm, which can be found on infected clothing, bedding, toys, or in the stool of an infected person.