The mother of a 5 year old boy brings her son to your office because the child has been having difficulty sleeping at night because of severe itching in the perineal area.


What advice would you give the mother?

  • Pinworm infection is caused by a small, thin, white roundworm called Enterobius vermicularis. Although pinworom infection can affect all people, it most commonly occurs among children, institutionalized persons, and household members of persons with pinworm infection. 
  • 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.
  • The life cycle of the pinworm begins after ingesting eggs that hatch in the stomach and duodenum. The larva migrate to the cecum where the male and females mate. The female then migrates to the perineal area and lays her eggs. The female dies after laying her eggs. The cycle is repeated by ingesting the eggs picked up after touching the perineal area. The entire cycle takes about 4-6 weeks. Infection may be spread by crowded conditions and close contact with infected individuals. Because of their small size, pinworm eggs sometimes can become airborne and ingested while breathing.

Enterobius vermicularis.png
Pinworm eggs (Enterobius vermicularis)


  • Pinworm infection is caused by infection with the nematode enterobias vermicularis. It is the most common helminthic infection in the United States, affecting approximately 40 million people. 
  • Humans are thought to be the only host organism for enterobias. 
  • Most commonly affected are children <18 years, caretakers of children, and institutionalized adults. Infection often occurs in families and among those living in crowded conditions

Enterobias Life Cycle 


  • Infection occurs through ingestion of eggs
  • Eggs hatch in the small intestine, and adult worms migrate to the cecum and appendix
  • Gravid females migrate to the perianal folds at night and deposit eggs. Eggs are infective for approximately 1-2 days
  • Hosts that scratch the area may accumulate eggs under their fingernails and proceed to auto-inoculate or infect others
  • Others can be infected by consuming food with eggs. Eggs can also become airborne and be inhaled or swallowed, for example, when handling linens


  1. Enterobiasis is often asymptomatic
  2. The presence of eggs in the perineal area causes itching that may interfere with sleep.
  3. May cause vaginal itching and vulvovaginitis when worms migrate into the vagina.
  4. May see the female worm with the naked eye. They are yellow-white thread like worms.
  5. There are no constitutional symptoms, diarrhea, bloody stools, nor eosinophilia.


  1. During the night when the child is scratching, may see the adult worms with a flashlight
  2. Apply scotch tape to the perineal area in the morning to pick up eggs and look at them under microscope.
  3. Symptoms of extreme itching and no other findings.


The medications used for the treatment of pinworm are mebendazole, pyrantel pamoate, and albendazole.

  • All three of these drugs are to be given in 1 dose at first and then another single dose 2 weeks later.
  • Pyrantel pamoate is available without prescription.
  • The second dose of medication is to eliminate possible re-infection since the first dose of medication.
  • Health practitioners and parents should weigh the health risks and benefits of these drugs for patients under 2 years of age.
  • Repeated infections should be treated by the same method as the first infection. In households where more than one member is infected or where repeated, symptomatic infections occur, it is recommended that all household members be treated at the same time.


  • Washing hands with soap and warm water after using the toilet, changing diapers, and before handling food is the most successful way to prevent pinworm infection.
  • People who are infected should bathe every morning to help remove a large amount of the eggs on the skin. Showering is a better method than taking a bath, because showering avoids potentially contaminating the bath water with pinworm eggs.
  • Infected people should not co-bathe with others during their time of infection.
  • Infected people should also cut fingernails regularly, and avoid biting the nails and scratching around the anus. Frequent changing of underclothes and bed linens first thing in the morning is a great way to prevent possible transmission of eggs in the environment and risk of reinfection. These items should not be shaken and carefully placed into a washer and laundered in hot water followed by a hot dryer to kill any eggs that may be there.
  • Reassurance very important and emphasis that this is not an invasive disease and only symptom is pruritis.


  1. Pediatrics in Review July 1995 page247
  2. Centers for Disease Control and Prevention. Enterobiasis (Enteroblus vermicularis) (Accessed on May 20, 2011)