Roundworm (ascariasis)

Published by Bupa's Health Information Team, October 2010.

This factsheet is for people who have roundworm, or who would like information about it.

Ascariasis is an infection caused by the worm Ascaris lumbricoides, which is more commonly known as roundworm. It's very common in tropical and subtropical areas of the world and occurs most often in children. Roundworm can affect people from the UK who travel to, or who are living or working in, countries where sanitation and hygiene are poor.

About roundworm

Roundworm is the most common type of worm infection that affects humans. It's thought to affect up to a quarter of the world's population. Anyone can become infected, but it mostly affects children between the ages of two and 10. Roundworm infection is most common in Africa, Central and South-East Asia and South America.

Roundworm is a type of parasite. A parasite is something that grows, feeds off and lives on, or in an animal (the host). Roundworm is well adapted to living in the human body. You can become infected with roundworm when you swallow roundworm eggs in contaminated food or soil.

The worms are white in colour, have a similar appearance to an earthworm and can grow to 35cm long. Roundworm eggs are too small for you to see.

Symptoms of roundworm

Roundworm infection doesn't usually cause any symptoms. However, if you're infected with lots of worms, you may:

• cough and wheeze (when a coarse, whistling sound is heard when you breathe)
• have difficulty breathing and chest pain
• have a fever
• have abdominal (tummy) pain
• feel sick or vomit
• lose your appetite
• have diarrhoea

If your baby or child has roundworm, you may notice other symptoms. For example, babies may have colic (inconsolable crying with bouts of fussiness and irritability).

Generally, the more worms you're infected with, the worse these symptoms are likely to be. These symptoms aren't always caused by roundworm but if you have them, see your GP.

Complications of roundworm

People who get severely infected may have hundreds, even thousands of adult worms living inside them. If this happens, the worms may block your small intestine completely, causing pain and tenderness in your abdomen (tummy). Depending on how severe your condition is, you may need an operation to clear the blockage, but this is very rare.

Roundworm can also enter and block the bile duct from your liver, causing you to become jaundiced (which makes your skin and the whites of your eyes yellow). The worms may block your pancreatic duct, causing your pancreas to become inflamed (pancreatitis) - you may have pain around the upper part of your abdomen.

If the roundworm larvae reach your central nervous system, you may have fits and find it hard to get to sleep or stay asleep (insomnia), but this is very rare. You must seek urgent medical attention if you develop symptoms of meningitis, such as headache, fever, or feel sick.

Children with severe roundworm may have vitamin A and vitamin C deficiencies and become malnourished, grow more slowly and find it hard to put on weight.

Causes of roundworm

You can become infected with roundworm if you come into contact with food or soil that is contaminated with A. lumbricoides eggs. The eggs can live in soil for up to a year and a half and can be transferred to fruit and vegetables that you may then eat. If you accidentally swallow A. lumbricoides eggs, they pass from your stomach and into your small intestine. Here, they hatch and develop into larvae. The larvae then travel through the wall of your intestine and enter your blood stream. After one to seven days, the larvae reach your lungs. From here, they travel up your windpipe, to the back of your throat. You then swallow the larvae, which pass through your stomach and into your small intestine, where they develop into adult worms. The adult female worms produce eggs that are passed out in your faeces, and the cycle begins again.

Rarely, in developing countries, people can get roundworm from infected pig faeces that have been used as fertiliser for crops.

Diagnosis of roundworm

Your GP will ask about your symptoms and examine you. If, in the last two years, you have been to an area where roundworm is common, your GP may ask you to give a sample of faeces (stool sample), which will be sent to a laboratory for testing. He or she may also ask you to have a chest or abdominal X-ray.

Roundworm is diagnosed by the presence of A. lumbricoides eggs or worms in your faeces.

Treatment of roundworm

Medicines

Roundworm can be treated effectively with medicines. The medicines work best against the adult worms. Your GP may prescribe you:

• mebendazole - you take this as a tablet either once, or twice a day for three days
• levamisole - this is an alternative tablet to mebendazole, which you take in a single dose
• piperazine - this medicine comes as a sachet of powder that you stir into milk or water

Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

If your breathing is affected by A. lumbricoides larvae in your lungs, your GP may prescribe a drug called prednisolone to control the inflammation. The adult worm infection can then be treated two to three weeks later.

Hospital treatment

Rarely, if the roundworm infection is very severe and your intestines become blocked, you may need to go to hospital. Your doctor will try to clear the blockage using liquid paraffin and the drug piperazine, which kills the worms. You may also be given fluids through a tube into your veins to keep you hydrated. If the treatment doesn't work, you may need surgery to clear the blockage, but this is very rare.

Prevention of roundworm

There are a number of precautions you can take to help reduce your risk of getting roundworm if you're planning to travel to, or live or work in, an affected area. You should:

• avoid touching or eating foods that may have come into contact with human faeces
• only eat freshly prepared foods that have been cooked thoroughly
• always wash your hands after going to the toilet and before preparing food

These measures can also help prevent you from becoming infected with roundworm and stop it spreading to other people.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.