Ossiuriasis or enterobiasis (worms in children)




Oxyuriasis is the infestation of the intestine by some parasites, pinworms (nematodes of the genus enterobius), also called "worms of children"Due to their greater diffusion among children than adults.

Pinworms are intestinal parasites that are easily visible to the naked eye. They look like worms with a tapered shape, of a white-ivory color, about 1 centimeter long, if female, and 5 millimeters long, if male.

The infection is caused by the ingestion of the parasite's eggs (fecal-oral cycle); the eggs, in fact, are very resistant in the environment and survive even 2 or 3 weeks after being expelled. Ingestion can occur following contact (often with hands) with surfaces or objects contaminated by eggs, which are not visible to the naked eye, and subsequent ingestion of the eggs themselves ("putting their hands in their mouths" by children is therefore often a vehicle of contagion).

The entire life cycle of the parasite takes place inside the human intestine: the eggs, which have reached the small intestine, open and the larvae begin to move to the large intestine where, within 2-6 weeks, they mature up to to become adults.

The male is short-lived and dies after having fertilized the female. Female pinworms, on the other hand, survive in the colon for 5 to 13 weeks, adhere to the intestinal mucosa and feed on part of the food that reaches the intestine. They can contain from 11 to 16 thousand eggs. When the eggs are mature, the females detach from the intestine wall and move towards the anus, moving especially at night to lay the eggs in the folds of the skin. Then they die in less than half an hour.

The eggs contain worms which after 4-6 hours of laying become infesting, in other words, capable of infecting a person. At this stage, "self-contagion" is common, meaning that a person can become infected again by bringing their hands to their mouth after scratching to relieve itching, or having touched their clothing, linen and sheets contaminated by the eggs themselves. Itching is the main ailment these parasites cause.

The infestation is resolved with some drugs, thorough cleaning of the rooms and careful personal hygiene. It is a good idea, if a family member becomes infected, that everyone else gets treated as well because pinworm infestations are very contagious.



In most cases, pinworm infection does not cause disturbances (symptoms) but, generally, the greater the number of worms in the intestine, the greater the discomfort felt.

Disorders, when present, are due to the adhesion of pinworms to the intestinal wall and their movement along the intestine which occurs, above all, at night. They include:

  • itching in the anal area
  • irritation of the anal and perineal area, often as a result of scratching the area
  • abdominal pain

It is possible that in some cases they also occur:

  • easy irritability
  • insomnia
  • teeth grinding (bruxism)
  • convulsions

These disorders are partly due to the reduction of sleep and nocturnal awakenings caused by the migration of pinworms along the intestine.

In women, in extremely rare cases, parasites can migrate from the anus and perineum into the vagina, causing vaginitis.



Pinworm infection is caused by ingesting the parasite's eggs.

Usually, it occurs through hands that have previously touched contaminated objects. If the infected person touches dirty sheets, underwear, towels, toilet seats, toys or other objects with their hands, they transfer the eggs onto them which can then infect another person.

The eggs are particularly hardy: they survive 2-3 weeks.

Children are more easily infected because they often put infected toys or other objects directly into their mouths. The disease is very widespread in kindergartens and kindergartens precisely due to the ease of contagion that occurs in these environments.

Even for adults, however, it is not uncommon to ingest pinworm eggs. Contagion can also occur by inhalation when shaking contaminated sheets, towels or clothing, because the eggs are very small and light.

Hand hygiene is very important, especially in children who, scratching the perianal area due to intense itching, can transfer the eggs to their hands and under the nails and, therefore, contaminate the objects they come into contact with.

Transmission does not occur, however, through the faeces since the eggs are not eliminated with them.

Pinworm infestations are highly contagious. When a person in a family falls ill, it is necessary that all the others also undergo treatment and respect the rules of hygiene.



The detection of pinworm infection (diagnosis) can take place in different ways: by directly identifying the parasite or by collecting small amounts of material present in the perianal area to check for the presence of eggs. The parasite, in fact, is visible to the naked eye while the eggs are not.

Pinworms can be seen in stools, underpants or in the area around the anus (perianal). In children, if you look at the perianal area in the morning, you may be able to spot the parasite.

If, on the other hand, you cannot see it, you can perform a so-called exam "Scotch test" which allows you to collect the deposited eggs. The test consists in applying for a few seconds some common transparent adhesive tape on the skin around the anus to collect the eggs; the adhesive tape, then, must be glued on a slide supplied by an analysis laboratory. The test must be repeated for three consecutive days and then the slides must be delivered to the laboratory which will analyze them under the microscope.
The examination should be performed in the morning before washing, or washing the baby, so that it is easier to collect the eggs deposited by the worms that have moved during the night.

The classic stool test, on the other hand, is useless because it is positive only occasionally.



The treatment of oxyuriasis consists in "taking medications by mouth. The most common and effective medicines to treat the infection are:

  • mebendazole, prevents the use of glucose by pinworms which thus slowly go towards death
  • albedanzolo, acts in a similar way to mebedanzol
  • pyrantel pamoate, causes an irreversible motor paralysis of the parasites. This results in their detachment from the intestinal wall and their expulsion through the faeces

These drugs do not act on the eggs but on the larvae. It is therefore advisable to repeat the treatment after 2-3 weeks to eliminate any worms that may have hatched from eggs that have not yet been opened or ingested after administering the drug.

It is equally important that all family members are treated because oxyuriasis is very contagious.



The best way to prevent pinworm infection is to follow normal hygiene rules, so:

  • wash your hands thoroughly with soap and water, after going to the bathroom, before cooking and before eating
  • keep nails clean and short
  • avoid putting your hands, fingers or nails in your mouth
  • do not use the same towels and clothing

In the event that a family member has been infected, in addition to drug therapy it is good to:

  • change underwear and clothes daily
  • change the sheets frequently
  • wash clothes at least at 60 °
  • keep the rooms well lit during the day, because eggs are sensitive to sunlight

In addition, it has been noted that people with a diet rich in carbohydrates and sugar are more vulnerable to pinworm. Parasites, in fact, live better with sugars. Limiting their intake can help prevent infestation and eliminate it.



It is difficult for oxyuriasis to have serious consequences. However, very rarely, pinworms may travel to the appendix or vagina, causing genital problems.



Mayo clinic. Pinworm infection (English)

Bambino Gesù Pediatric Hospital. Ossiuriasis

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