Diseases & Conditions

Ascariasis - Roundworm Infection


Overview, Causes, & Risk Factors

A roundworm infection is caused by Ascaris lumbricoides, an intestinal roundworm. It is the largest intestinal parasite in humans. An estimated 1 billion people are infected worldwide.

What is going on in the body?

A person is infected by eating the eggs of the roundworm. In the small intestine, larvae hatch from the eggs and penetrate the intestine. They travel in the blood stream to the liver and then the lungs. The larvae rise up the airways and into the mouth. They are swallowed and proceed to mature into adults in the small intestine.

The adult worms live in the small intestine, where the females produce about 200,000 eggs a day. These eggs are excreted in the stool. After incubating for 2 to 3 weeks outside the human body, the eggs become infectious.

What are the causes and risks of the infection?

Roundworm infections are widely found in tropical and humid areas, including the southeastern United States. Infection usually occurs through contact with contaminated soil. The cause is often a lack of sanitation, or the use of human manure as fertilizer. A person can also be infected by eating foods that are contaminated with the cysts of the roundworm.


Symptoms & Signs

What are the signs and symptoms of the infection?

The symptoms of a roundworm infection may include:

  • fever
  • cough
  • wheezing
  • abdominal distress, including cramps
  • flatulence, or excess gas
  • bloating
  • vomiting

  • Diagnosis & Tests

    How is the infection diagnosed?

    Infection with the adult roundworm is usually diagnosed by identifying eggs in a sample of stool. Sometimes adult worms are found in the stool or vomit. A chest x-ray may detect signs of the migration into the lungs. Blood tests, such as a complete blood count or CBC, may show higher levels of some kinds of white blood cells.


    Prevention & Expectations

    What can be done to prevent the infection?

    Roundworm infections can be prevented by using good sanitation and avoiding unclean vegetables.

    What are the long-term effects of the infection?

    A child infested with roundworm may suffer from malnutrition, and may have growth problems if the infection is not effectively treated.

    What are the risks to others?

    If a person who excrete eggs does not properly dispose of his or her stool, the contaminated stool puts others at risk for infection.


    Treatment & Monitoring

    What are the treatments for the infection?

    Roundworm infections should always be treated in order to prevent serious complications. Medications such as mebendazole or albendazole may be used.

    What are the side effects of the treatments?

    Side effects of mebendazole or albendazole include mild diarrhea and abdominal distress.

    What happens after treatment for the infection?

    After the roundworm is out of the person's body, he or she can return to normal activities.

    How is the infection monitored?

    Any new or worsening symptoms should be reported to the healthcare provider. Another stool sample will be checked for signs of roundworm infection.


    Attribution

    Author:Danielle Zerr, MD
    Date Written:
    Editor:Duff, Ellen, BA
    Edit Date:08/25/00
    Reviewer:Gail Hendrickson, RN, BS
    Date Reviewed:06/11/01

    Sources

    Harrison's Principles of Internal Medicine, Fauci et al, 1998

    Current Medical Diagnosis and Treatment, 39th ed., Tierney, 2000

    The Merck Manual of Medical Information, 1997