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Threadworm can be an itchy subject

Almost half of children become infected with threadworms, yet little attention is given to this common infection. Treatments are available from the pharmacy, which, combined with good hygiene practices, make threadworm management both simple and effective

Sharon White
Professional Officer School and Public Health Nurses Association
Jane Stevenson
Medical Writer

It is estimated that 40% of children under the age of 10 will have been infected with threadworms (Enterobius
vermicularis) at some point in their lives.(1) Although treatment for threadworms or pinworms is effective, reinfection is common and hygiene measures are essential to break the cycle of infection and reinfection.(2) Fortunately, threadworm infection is easy to treat. However, it is not always easy for parents to talk about it and parents may be embarrassed discussing personal hygiene.

The most common symptom of threadworms is intense itching in the perianal area, particularly at night, and sometimes itching around the vaginal area in girls. This may be accompanied by other symptoms including irritability, abdominal pains and disturbed sleep.

Infection and reinfection
Eggs on the fingers and under the fingernails transfer between children in schools and nurseries, and to other members of the family. Eggs are transferred into the mouth and swallowed. After the eggs are ingested, they hatch in the duodenum and reproduce in the large intestine. The worm takes between one and two months to mature. At night, pregnant females migrate out of the anus and lay up to 15,000 eggs on the surrounding skin together with irritant mucus. 
This causes itching, which promotes scratching, causing the tiny eggs to get lodged under fingernails where they may be ingested, causing reinfection, or transferred onto door handles or other surfaces, putting friends and family members at risk of infection. Shaking contaminated articles spreads the eggs in dust, although less than 10% of eggs survive two days at room temperature.(3)

Taking an accurate patient history is usually the simplest way to diagnose threadworms. They may be seen in the stools and appear as thin white threads; however, they are tiny and can easily be missed. The adult males are 2-5 mm in length and females are between 8 and 13 mm long.

Over-the-counter treatment, available from the pharmacist, is effective in treating threadworms in about 90% of cases.(2)
Mebendazole tablets can be taken by both adults and children over two years of age and may treat the infection in a single dose, although a second dose may be recommended if reinfection occurs. An alternative treatment, piperazine combined with senna (available as tablets or sachets of powder which can be added to water or milk), paralyses the worms, which are expelled by the laxative effect of the senna. A second dose is usually required 14 days later to break the threadworm life cycle. Piperazine is suitable for children from the age of three months, but is contraindicated in patients with epilepsy, neurological disease or severe renal or hepatic impairment.
Usually the whole family should be treated at the same time to prevent infection and reinfection; however, pregnant women should not take either mebendazole or piperazine.

Meticulous attention to hygiene is essential to prevent both infection and reinfection. To prevent reinfection, the following hygiene measures should be recommended and practised for at least two weeks:

  • Wash hands and scrub fingernails regularly, keep fingernails short.
  • Wash thoroughly around the perianal area every morning.
  • Dust damp surfaces daily, washing the cloth frequently in hot water.
  • Disinfect door handles and light switches.
  • Vacuum carpets and wash towels, clothes and bed linen regularly.
  • Wear underwear in bed.
  • Do not share towels or nail brushes.
  • Small children can wear mittens at night to discourage scratching.

The community nurse is well placed to offer simple advice about good hand hygiene. Advise that handwashing should always take place:

  • After visiting the toilet.
  • Before eating or handling food.
  • After touching animals.
  • Whenever hands look dirty.

This basic information reinforced by a handwashing poster can be invaluable in preventing threadworms from spreading, particularly in places such as schools and nurseries. For more information about handwashing go to
Threadworm Action Week
Hand hygiene is a key factor in preventing threadworms, which is why it is the theme for this year's Threadworm Action Week from 5 to 11 November. A handwashing poster, classroom activity booklet, handwashing badges and star charts will all be available free of charge for healthcare professionals. Details are available at




  1. Royal College of General Practitioners. Fact sheet 32. London: RCGP; 1996.
  2. National Prescribing Centre. The management of scabies and threadworms. Prescribing Nurse Bull 1999;1:11-12.
  3. Kucik CJ, Martin GL, Sortor BV. Common intestinal parasites. Am Fam Physician 2004;69:1161-8.
  4. Herrström P, Friström A, Karlsson A, Högstedt B. Enterobius vermicularis and finger sucking in young Swedish children. Scand J Prim Health Care 1997;15:146-8.