Threadworm, also known as pinworm, is a small parasite that commonly take their refuge to humans intestines. The parasite is often found in children, but can also affect adults. The infestation starts trough ingesting the eggs that are then transported to the intestines. This might sound alarming, but the worms are rarely causing any trouble except from itching around the anus and it can easily be treated.

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What is a threadworm?

A threadworm’s life starts with the ingestion by a human. The eggs then hatch in the small intestine and there grows to larvae than then move toward the rectum. In the intestines, the worms consume the contents of the intestine. After about five weeks after ingesting the first eggs, the female worms are starting to lay eggs around the anus area.

The eggs can survive up to three weeks outside a body if a moist environment allows it. These are not visible to the naked eye, but adult worms can be seen in stools or around the anus as light yellow, thread-like worms.

Who is affected?

The parasite is transferred from person to person and can affect anyone. The eggs can be ingested through the hands, contaminated food or other things that are in contact with your mouth. Since the eggs are very small, they can sometimes be airborne and be inhaled and later swallowed.

Children are more likely to be affected, but it can also be spread to adults. Since the eggs enter the body through ingestion, you can run a greater risk of being affected if you or your children are sucking your fingers or is biting your nails. Living closely to other people can also put you at higher risk, such as if you go to school, live in health care institution or prison. If someone in your household is affected, you should too take measures and medication for the condition.

A study conducted in the UK could confirm that approximately 50% of children experience threadworms at some point1, and this is a worldwide phenomenon and has been with mankind for thousands of years. This is the most common worm infection in western countries. Symptoms & diagnosis

The only symptom that is experienced by the threadworms is an itch around the anus, especially at night2. Except this, the worms are not causing any trouble, except perhaps psychological such. The itching at night can lead to secondary symptoms such as insomnia or restlessness. For women, the worms can move to the vagina and thus cause problems there as well as urinary tract infections.

The eggs can be seen through a microscope and can be extracted through what is called the tape test. For this test, you put adhesive tape on the anus and then looked at through a microscope. This test should be done in the morning, and preferably three times in a row to be sure not to miss any eggs since the worms lay eggs inconsistently.

Diagnosis of this disease is mainly done by the itching as well as sightings of the worms when passing stools. Many people affected do not see them, but can mainly confirm the presence of the worms through the itching.


Treatment for these parasites is mainly done by medicines containing the active substances mebendazole (with brands such as Ovex, Vermox, Antiox and Pripsen), pyrantel pamoate or albendazole (Albenza, Eskazole, Zentel and Andazol). These are often taken as two doses, one or two weeks apart. They work through starving the worms of their vital nourishment, either food or oxygen. These medications do have some side effect, where some may experience diarrhoea, stomach pain, flatulence and other stomach discomforts.

These are often very effective (mebendazole, for example, has a success rate of 96%), so some medical experts find hygienic measures to be redundant. It is still highly recommended that you take these measures since the medication only kills the adult worms and not the eggs. Since the period for an egg to become a full adult is up to three weeks, it can work as a reinfection pool, and more treatments may be needed. Reinfection is very common and it can take many treatments to fully eliminate the parasite from your home.

You should wash your bed linen and other personal belongings in hot water to prevent reinfection. Wash your hands properly, shower in the morning to remove any possible new eggs and change underwear often.


It is thought that keeping a good hygiene is a measure to prevent the worms, but it is no guarantee. Some things you can do to avoid reinfection of threadworms is:

  • Keep fingernails short
  • Wash hands thoroughly after defecation and before eating
  • Change bed linen and hand towels frequently
  • Do not shake bed linen or clothes, this can make the eggs airborne
  • Shower in the morning to remove eggs laid overnight
  • Avoid scratching the area around the rectum
  • Change undergarments often

Detergents for cleaning have little effect on the eggs, and will thus not help to eliminate the threadworm eggs.


  1. Pinworms report – Burkheart & Burkheart
  2. More about the condition – NHS inform