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How can I recognize pinworm infection?

  Abdominal pain Anal itching
  Appetite loss Ear/nose itching or picking
  Irritability Pelvic pain
  Restlessness Sleeping disturbance
  Vaginal itching and or irritation Weight loss

Many infected people have no symptoms at all.

The tell-tale signs of itching and irritation are caused by egg-laden pinworm females exiting the body to lay their eggs around the anus or vagina. This irritation, often occurring at night, disturbs sleep and can cause fatigue-related irritability.

Who are at risk?

Pinworms affect people worldwide of all ages and walks of life. Socio-economic factors play no role in determining risk of pinworm infection.

Pinworms most commonly affect school-aged and preschool-aged children, institutionalized people, and household members and carers of infected persons. Cross-infection is common, with pinworm infection often occurring in more than one person in a household or institution.

Females appear to be more susceptible to pinworm infection between the ages of 5-14 years. Otherwise males are typically infected twice as often.

What is a pinworm?

Enterobius vermicularis (pinworms) are small, thin, white roundworms that live in the small intestine, colon and rectum of humans. Adult male worms are typically 3mm (0.12 inch), while females may grow to 10mm (0.39 inch) in length.

Female pinworms may often be observed at night exiting the body to deposit their eggs around the anus. They may also be detected on underclothing, pyjamas, or bed sheets a few hours after falling asleep.

Diagnosis can be made by applying clear adhesive tape to the skin around the anus, and then examining the tape for presence of eggs under a microscope. Symptoms such as anal itching are usually strong signs of infection without resorting to the tape test however.

Eggs may also be found under the fingernails, but are rarely identified in stool or urine samples.

Pinworms may complete the 3 stages of their lifecycle (egg, larva and adult) within the same human host within a 3 to 6 week period.

What caused the infection?

Infection of pinworms is spread by the ingestion of eggs. People become infected by swallowing eggs that are on their fingers, under their fingernails, or on clothing or bedding. Eggs may also survive on hard surfaces such as toys, doorknobs, furniture and faucets.

As pinworm eggs can survive for up to 3 weeks on such surfaces, cross-infestation amongst household members is extremely likely. Eggs may also become airborne and ingested while breathing. Larvae that hatch around the anus or vagina may also migrate back into the body causing re-infection.

Pinworms are prolific breeders, with one female able to lay thousands of eggs per day.


As the most common roundworm parasite of humans in North America and Europe, pinworms infect over 400 million people worldwide. Pinworms thrive in temperate climates, even in areas†that adhere†to good†sanitation practices.

In the United States up to 20% of all children may be infected at any one time. Prevalence in institutionalized persons is reported to be between 50 and 100%. Similar incidence of pinworm infection is reported in other lands, including European countries.

Is pinworm infestation dangerous?

Pinworm infection is rarely fatal. However infestation may cause other complications, including:

  • Appendicitis (increased risk for appendicitis from pinworm infestation is reported between 28 and 68%)
  • Endometritis%)
  • Impetigo (bacterial skin infection that causes red open sores that ooze fluid and develop a yellow-brown crust)%)
  • Salpingitis (infection and inflammation of the fallopian tubes)%)
  • Urethritis%)
  • Urinary tract infection%)
  • Vaginitis%)


Can I prevent pinworm infestation?

Pinworm infestation depends upon factors that are often out of the immediate control of the infected person (or their parent or carer). Eggs are easily passed from person to person even through casual contact. Day care centers, schools and nursing home facilities provide perfect environments for cross-infection.

Basic hygiene does inhibit the spread of pinworm infection, so washing of hands and regular bathing and grooming are essential practices. Changing of clothes and bed linen and regular laundering in hot water helps kill pinworm eggs.

Washing (and even cooking) of fruit and vegetables before eating further minimizes the risk of pinworm infection, as does the drinking of clean water.

There is no sure way of guaranteeing a total absence of pinworm infection.

Can pinworms be safely eradicated?

Treating pinworm infestation can be frustrating. Parents often complain that they give their children worming medicine, only for the children to show signs of infection weeks later.

What goes wrong? Have the worms been properly eradicated in the first place?

The important factors to address in treating a pinworm infection are:

    1. Pinworms lay their eggs outside of the body
    2. Eggs can contaminate any surface and remain fertile for up to 3 weeks
    3. Pinworms can complete all 3 stages of their lifecycle within the one human host

Thus pinworm treatments must demonstrate effectiveness against all 3 stages of the worm lifecycle, including egg, larval and adult stages.

A prolonged course is also required to halt cross-infestation amongst household members, and re-infection of the host by eggs or larvae following treatment. This may involve ongoing administration for 30 days or more depending on the severity of the infection in the household.

Common drugs prescribed or available over the counter for pinworms involve once-off treatments, sometimes with a second treatment given 2 weeks later. This follow-up treatment is given in the hope that it will catch up with the worm eggs and larvae that have found their way back into the system from the environment.

Unfortunately this incomplete approach does little to combat the comprehensive breeding patterns of the pinworm, or the hardy nature of its eggs. Eggs that are laid prior to the treatment remain unaffected and may re-infect after the initial treatment within hours. Other eggs may stay alive on surfaces outside the body for up to 3 weeks. The worm infestation has not been comprehensively addressed.

Over thousands of years herbal treatments have been used successfully to clear humans of pinworm eggs, larvae and adults. During this time various traditions have studied and recorded the safety of using herbs under controlled conditions over extended courses to break the worm infestation cycle. Some herbal treatments for pinworms are safe to take on a daily basis so as eliminate pinworm eggs or larvae that re-infest.

Black walnut, clove, garlic, gentian, thyme and wormwood are all herbs with a long tradition of use in combating intestinal worms, with garlic being particularly noted for its action against pinworm infestation.

Alternative: Drugs such as Albendazole and Mebendazole are administered to prevent larvae and adult worms from absorbing glucose. Due to diminished energy production, the parasite is immobilized and eventually dies. Pyrantel is a drug that paralyzes adult worms so that they "lose their grip" inside the human host and are eliminated.

Regardless of the method used to eliminate pinworms, all members of the household should be treated simultaneously to eliminate cross-infection.

As re-infection can easily occur, particular observance of good hygiene is essential. Washing of hands, keeping fingernails clean and trimmed, daily bathing and regular changing and laundering of underclothes, pyjamas, towels and bedding are important.

This page is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care professional. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care professional.


Center for Disease Control, Division of Parasitic Diseases Pinworm Infection
National Library of Medicine Medical Encyclopedia Pinworms
National Institute of Allergy and Infectious Diseases - Pinworms
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