Threadworms

What are Threadworms?

Threadworms - named after their thread-like appearance - are parasitic worms which infect the large intestines of humans. Also known as pinworms, the parasite is common in the UK and particularly prevalent in children under 10.

Prevalence rates of threadworms among British children are believed to be as high as 50%.

While threadworms are often spread through a lack of good personal hygiene, it's important to be aware that they can affect anyone from any socio-economic community.

The eggs can survive for up to 2 weeks, residing under fingernails, on clothing articles, children's toys, in bedding or on pets - though it's important to note that threadworms do not infect pets. But pets can carry the eggs, which can then be transferred to human hands when stroked.

Eggs can also become airborne if infected clothes or bedding are shaken. Threadworm infections can also result from household dust.

Maintaining a high hygiene standard while treating threadworms is important, as it is very easy to infect other people or become reinfected by contaminated surfaces.

The life cycle of threadworms

Threadworm eggs are ingested through the mouth. They hatch in the small intestine, and the larvae which are spawned grow at an exponential rate. They migrate to the large intestine, undergoing a moulting process.

The parasites leech off of glucose (sugars) in the intestines.

Once they reach the ileum, the largest part of the small intestines, the male and female worms mate, after which the male worm die and are expelled from the bowels through defecation. The pregnant female worm travels through the large intestine towards the rectum.

The female worms leave the body through the anus to lay the eggs on the skin around the anus to provide the eggs with the oxygen they need to develop.

After laying the eggs, the female usually dies. Larvae can hatch on the anus and re-enter the host, causing further infection.

This process is repeated when the eggs are ingested.

Signs of a threadworm infection

It is not uncommon for a threadworm infection to go unnoticed, as it may not cause any symptoms (asymptomatic). Though there are some signs to look out for if you suspect you or your child are infected with threadworms:

• Changes in appetite
• Irritability in children
• Itching around the anus (especially at night)
• Itching around the vagina
• Restlessness or insomnia
• Small thread-like worms (approximately 1cm long) around the anus or in stools

A threadworm infestation can be confirmed through analysis of a provided sample. A piece of tape is placed over the skin around the anus to catch eggs. The strip of tape is then examined under a microscope to confirm the presence of threadworm eggs.

Alternatively, a swab from under the fingernails or around the back passage may be taken and examined to confirm the presence of threadworm eggs.

How is threadworm treated?

Fortunately, threadworm infections pose little long-term health threats and are simple to treat with over-the-counter medicines.

Threadworm infestations are typically treated with an anthelmintic (antiparasitic) medicine known as mebendazole.

Mebendazole, the active ingredient of Ovex and Vermox, works by preventing the worms' ability to absorb the sugars they need to survive. This starves the worms and causes them to die within approximately 3 days.

In most cases, only one dose of mebendazole is needed to clear the infection, though you may be advised to take a second dose two weeks later to ensure the worms are eradicated and prevent reinfection.

Everyone in the household will be required to take a single dose of mebendazole to ensure every person has been cleared of the worms. Mebendazole is available in flavoured tablets, which can be swallowed or chewed, and liquid suspension (syrup), suitable for children who cannot take tablets.

While the medicine kills the worms inside the intestines, Mebendazole does not kill the eggs which may have been laid. For this reason, a strict cleaning regime should be implemented to prevent further infections.

If, after two weeks, you or your child continues to experience symptoms of threadworms, you should seek advice from your doctor.

How to prevent threadworms?

Threadworms are very difficult to avoid, though there are a number of preventative measures you can take to protect yourself and your family.

Everyone in your household should be made aware of the risks of infection and uphold strong personal hygiene. You should avoid sharing towels and utensils until the infection has been cleared.

Hand hygiene

Encouraging children to wash their hands using anti-bacterial soap every time they go to the toilet and before they eat can help reduce the risk of further contamination in the home. You should also discourage children from biting their nails and sucking their thumbs, as these can spread eggs from their bottom to their mouth.

Showering and bathing

Showering or bathing in the morning will minimise the risk of spreading eggs. Each household member should refrain from sharing towels and flannels. Avoid co-bathing, as this can increase the risk of the infection spreading.

Clean bedrooms

Take care when cleaning bedrooms, as disturbing bedding by shaking them can cause the eggs to be spread to other surfaces. Bedrooms should be cleaned regularly - wipe down surfaces with a damp cloth and vacuum carpets regularly.

Wash fabrics

Bedding, towels, pyjamas, underwear and other surfaces which may be contaminated with eggs should be washed at a high temperature to prevent the spread of the infection.

Pets

Pets may also need to be washed to remove any eggs, which may have been transferred to their fur. No veterinary treatment will be required for pets because threadworms do not infect animals.

Buy threadworm treatment online

Threadworm treatments are available from our UK-registered pharmacy and eligible for a fast, next-day, discreet delivery service. Orders approved before 3pm on weekdays are dispatched the same day.

Our doctors are on hand to help you with any questions you have about your condition or the treatment.

Authored & Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist

This content has been written and checked for quality and accuracy by Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Published on: 19/09/2019 Reviewed on: 28/04/2023