Roundworm (Ascaris) infection: symptoms, causes and treatment in the UK

Roundworms are parasites that can live in the human gut, where they feed and reproduce. nidirect explains that the condition is also sometimes known as ascariasis or Ascaris, and describes it as usually easy to treat. The NHS describes roundworms as looking more like earthworms than the tiny white threadworms that are common in the UK.

The distinction matters because threadworms, which the NHS says cause extreme itching around the anus, particularly at night, and are common in the UK, are a different infection. The NHS says a pharmacist can help with small white thread-like worms in the poo or extreme itching around the anus, while larger worms or worm eggs in the poo should be seen by a GP.

Soil-transmitted worm infections, including roundworm, are among the most common infections worldwide according to nidirect. They affect communities where there is overcrowding and poor sanitation, and are common in tropical and sub-tropical regions such as sub-Saharan Africa, the Americas, China and East Asia.

According to the NHS, worms are mainly spread in small bits of poo from people with a worm infection, and some are caught from food. Infection can follow touching objects or surfaces with worm eggs on them, or touching soil or swallowing water or food containing eggs, which is mainly a risk in parts of the world without modern toilets or sewage systems.

nidirect describes the cycle: eggs present in human faeces are picked up from contaminated soil, food or water, and after the eggs mature into adult worms the worms produce more eggs, which leave the body through the bowel and can then infect other people. Most recorded cases in Northern Ireland are contracted abroad, by travellers or by migrants from parts of the world where roundworm is present.

This is why the questions a GP asks are about where you have been. A person who has not travelled to a high-risk area is unlikely to have roundworm, while the NHS points out that these infections can take a long time to cause symptoms.

nidirect says a roundworm infection often does not cause any noticeable symptoms, although symptoms are more likely when there are large numbers of worms. You should suspect it if you have been abroad within the last two years to a region where roundworm is common and you have one of the following.

• Unexplained asthma-like symptoms, such as wheeze or shortness of breath.

• Persistent symptoms such as vomiting or diarrhoea.

• A worm passed in your poo, which has a distinct appearance.

• Less commonly, a high temperature and dry cough four to 16 days after swallowing the eggs.

The NHS advises seeing a GP if you find a large worm, a piece of worm or worm eggs in your poo, have a red, itchy worm-shaped rash on your skin, have sickness, diarrhoea or stomach ache for longer than 2 weeks, or are losing weight for no reason. These could be symptoms of roundworm, hookworm or tapeworm.

nidirect adds that you should see your GP if you notice a roundworm in your poo or have unexplained symptoms after visiting a tropical or sub-tropical country. nidirect names bowel obstruction as a possible serious complication when many eggs are swallowed, so severe tummy pain with repeated vomiting should be assessed urgently through NHS 111 or emergency care.

The NHS says you might be asked to provide a sample of poo so it can be tested for worm eggs. nidirect says the infection can be diagnosed by examining a small sample of poo under a microscope and is confirmed by the presence of eggs or a worm in the sample.

A GP will also ask about your travel history over the last two years, as advised by the NHS.

nidirect says roundworm infections can usually be successfully treated with medication and that your GP will discuss options with you. The NHS says it does not matter which type of worm you have, as all worm infections are treated in a similar way: a GP prescribes medicine to kill the worms, which you take for 1 to 3 days.

The NHS adds that the people you live with may also need to be treated, and that any worms in your gut will eventually pass out in your poo, which you may not notice. During the weeks after starting treatment, it is very important to wash your hands after going to the toilet, before eating or preparing food and regularly during the day, to avoid becoming infected again or infecting others.

The NHS asks you to go back to the GP if symptoms do not get better in 2 weeks or you keep passing live worms in your poo.

The NHS recommends washing your hands before eating or preparing food and after touching soil or using the toilet, thoroughly washing garden-grown fruit and vegetables, and only drinking bottled or boiled water in high-risk areas. In those areas it also advises not eating raw fruit and vegetables and not walking barefoot.

nidirect gives similar advice: regular handwashing, and extra precautions when travelling to a part of the world where roundworm is common, such as only drinking bottled water and avoiding raw fruit and vegetables. These are the same precautions that help prevent many other infections linked to poor sanitation.

On the NHS, worm infections are assessed by a GP, who may send a stool sample to the laboratory and prescribe treatment. If you are unwell after travel, or the picture is unclear, a GP can refer you to an infectious diseases or tropical medicine service.

Some people choose to see a private travel medicine or infectious diseases clinic for convenience or a quicker appointment. The stool tests and the medicines are the same, and the main differences are speed and choice of clinician. Tell any clinician where and when you travelled.