Alphabetical Listing | Travel Pinworm Infection What is pinworm infection This infection is caused by a small, white intestinal worm called Enterobius vermicularis (EN-ter-O-be-us ver-MIK-u-lar-is). Pinworms are about the length of a staple and live in the rectum of humans. While an infected person sleeps, female pinworms leave the intestines through the anus and deposit eggs on the surrounding ...