Threadworms, also known as pinworms, are the most common form of worm infection in the UK and are particularly common amongst young children under the age of 10. Threadworm infections are generally caused by poor hygiene – not washing your hands after using the toilet (or touching/scratching the anal area) results in threadworm eggs being stuck under the fingernails and being passed on to anything you touch.

These tiny parasitic worms infect and hatch eggs in the large intestine of humans. They resemble a tiny piece of white thread, approximately one centimetre in length and can be visible around the anus or vaginal area and also in the stools.

Threadworms are not harmful, however, they can be uncomfortable and also embarrassing for the sufferer due to the nature of the area they infect. They should be treated as soon as possible to relieve symptoms and prevent spread.

Threadworms do not always cause symptoms but the most common is itchiness around the bottom (or vaginal area in girls), especially at night. This can lead to interrupted sleep due to discomfort and irritability.

More severe threadworm infections can cause skin infections around the anus from where bacteria have been able to enter the raw, scratched skin. Loss of appetite and subsequently weight loss are also symptoms attributed to severe or persistent threadworm infections. In extreme and rare cases it has been known for threadworms to spread beyond the large intestine and nest in other places, such as the urinary tract, the liver and for women, in the vagina. If any of these symptoms are present you should see your GP for treatment.

Usually threadworm, or pinworm, can be diagnosed and treated at home without the need to see a doctor.

Diagnosis of a threadworm infection can normally be made with a combination of the symptoms detailed above and the presence of threadworms in the stools. Usually a diagnosis from a doctor is not necessary unless the sufferer is a child under 2 years old or is a woman who is pregnant or breastfeeding.

Treatment for threadworms will need to include everyone in your household. This is because the risk of the infection spreading is very high. This will also need to include people who aren’t currently presenting with any symptoms. The majority of cases of threadworm treatment will involve a single dose of Mebendazole, which is the drug contained in the branded medicine, Ovex. Mebendazole is 90-100% effective at killing the threadworms and normally does this within a couple of days, after which your symptoms should subside.

Ovex does not kill the eggs, which is why strict hygiene measures (outlined below) should be followed for six weeks after treatment. This will ensure the threadworm’s eggs aren’t spread and cause reinfection. A follow-up dose of Ovex can be taken after two weeks if required.

The threadworm treatment, Ovex, is available as a chewable tablet or banana-flavoured suspension that is suitable for children aged 2 years and over. Children under 2 years that are suffering with threadworm require attention from their GP. Ovex threadworm treatment is also not suitable for those who are pregnant or breastfeeding.

Threadworm treatment should always include preventative and hygiene measures for at least 6 weeks as detailed in ‘Prevention’ below.

It’s not always possible to prevent threadworm infection but by following common sense hygiene practice the risk of infection can be significantly reduced, such as:

• Washing hands regularly, particularly after going to the toilet and before eating food.
• Keeping fingernails short and clean, particularly underneath, as the fingernails can harbour and spread eggs from person to person.
• Washing night clothes, bed linen, towels and soft toys.
• Avoid shaking any material that may be contaminated with eggs, such as quilts and clothing. This can make the threadworm eggs airborne, allowing them to be breathed in resulting in infection.
• Keeping surfaces clean, particularly kitchens and bathrooms and regular vacuuming of floors will all help prevent infection. Threadworm eggs can survive for up to three weeks on surfaces making thorough cleaning vital.
• If already infected then avoid scratching the affected area will help to prevent reinfection and also reduce the risk of spreading the infection to other people.

Treatments include over-the-counter anti-parasitic medications and strict hygiene measures to prevent reinfection.