Public Health Fact Sheet

What are Pinworms?
Pinworm disease is a condition caused by parasitic worms that invade and live in the intestine. The disease is very common and can affect anyone. A Pinworm ("threadworm") is a small, thin, white roundworm (nematode) called Enterobius vermicularis that sometimes lives in the colon and rectum of humans.  Pinworms are about the length of a staple. While an infected person sleeps, female pinworms leave the intestine through the anus and deposit their eggs on the surrounding  skin.

How are Pinworms spread?
Pinworm infection is spread by the fecal-oral route, that is by the transfer of infective Pinworm eggs from the anus to someone's mouth, either directly by hand or indirectly through contaminated clothing, bedding, food, or other articles.

How are Pinworms treated?
Treatment involves two doses of medication with the second dose being given 2 weeks after the first dose.  All household contacts and caretakers of the infected person should be treated at the same time.  Reinfection can occur easily so strict observance of good hand hygiene is important.  Daily morning showering and daily changing of underwear helps remove a large proportion of eggs.  Carefully handle and frequently change underclothing, pajamas, towels, and bedding.  Wash items in hot water, especially after each treatment of the infected person and after each usage of washcloths until infection is cleared.

How can we prevent Pinworms?
Keep nails clipped short.  Wash hands and nails often particularly before eating and after going to the toilet or after diaper changes.  Keep fingers out of mouth and discourage nail biting.  Avoid scratching the anal area.

Additional information is available on the CDC website at

  • Irritability
  • Anal and perianal itching
  • Difficulty sleeping at night

February 2020