Threadworms (also known as pinworms) are tiny worm parasites which infect the large intestine (gut). Threadworms look like small thin white pieces of thread. This type of infection is common, particularly in young children.

Threadworms can live in the gut for around 6 weeks before dying. The female worms may also lay tiny eggs around the anus, which can result in itching around the anus.

Sometimes threadworm infection may not present with any particular symptoms and therefore may go unnoticed.

Common symptoms of threadworm infection include:

• Finding worms in your stools when going to the toilet or around the anal area. Worms may also sometimes be found on clothes worn at night or bedsheets.
• Intense itching around the anus (back passage) which gets worse at night – this is as the female threadworms lay their eggs around the anus at night
• Itching which keeps you up at night

You should see your GP if you develop other less common symptoms of threadworm infection, including:

• Finding large worms or large pieces of worm in your poo
• Red, itchy worm-shaped rash on your skin
• Sickness, vomiting, diarrhoea or a stomach ache for longer than 2 weeks
• Unexplained weight loss

Threadworm infection is spread when the eggs are swallowed by uninfected individuals. The threadworms lay eggs around the anus at night, which results in intense itching. When scratching the eggs can become stuck beneath the fingernails.

From there the eggs may be transferred upon touch to other surfaces including bedsheets, other peoples hands, food and clothing. As the eggs can stay alive for 2 weeks on other surfaces outside of the body they can easily be picked up by other individuals who then swallow them and become infected.

People can also get threadworms again after they have been treated if they scratch the anus and then transfer the eggs into their mouth. This is known as reinfection and is why it is very important to regularly wash hands following threadworm infection.

Taking medication will help kill threadworms, however it does not kill the eggs, which can stay alive for 2 weeks outside of the body. Therefore to it is important to follow strict hygiene measures during the infection and for a few weeks afterwards. This will reduce the chances of you other people in your household getting infected or you getting re-infected.

Self-help measures you can take to help clear threadworm infection and stop reinfection include:

• Washing hands regularly, including scrubbing under fingernails – particularly before eating, after using the toilet or changing nappies
• Cutting fingernails short – this will help stop eggs from being trapped underneath them upon scratching and will also prevent the skin being damaged when you itch
• Avoid biting nails or sucking on fingers or thumbs
• Bathing or showering every morning
• Thoroughly washing all clothing such as sleepwear, bedsheets and towels – you should avoid shaking the clothing or bedding when washing as this could result in eggs from being spread to other surfaces
• You should clean your household thoroughly ensuring all surfaces are disinfected and floors are mopped and vacuumed
• Ensuring children wear underwear at night, which should be changed in the morning
• Avoiding sharing towels or flannels

Mebendazole (brand name Ovex) is the most commonly used treatment for threadworms in the UK. It is available to purchase over the counter from the pharmacy or maybe prescribed by your GP. The treatment is available in tablet or liquid form.

Treatment involves taking only one single dose of Mebendazole (Ovex), which will work to kill the live worms. It is important to treat all household members at the same time, including those without symptoms.

In the event where reinfection occurs, a second dose of Mebendazole may need to be taken 2 weeks after the first dose. As the medication does not kill unhatched eggs, it is essential to follow good hygiene measures during the infection and for a few weeks afterwards. This will reduce the chances of anyone getting re-infected.

If you leave threadworm infection untreated it is unlikely to lead to any serious consequences. However, it may result in you developing more severe symptoms as such as sickness, diarrhoea, rashes and weight loss. Furthermore, the intense itching associated with the infection can result in sleep loss. Therefore it is advisable to treat threadworm infection without delay and avoid getting re-infected.

No. As threadworm infection is very common in young children it is not necessary to keep them home from school. However, it is important to make the school aware of the infection and they will then ensure the strict hygiene procedures are followed accordingly.