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Pronounced: ASS-car-EYE-uh-sis


Ascariasis is an infection with a roundworm parasite.

This roundworm can grow to over 15 inches (40 centimeters) in length. Their eggs hatch in the stomach and the larvae travel to the liver and lungs. This causes a type of pneumonia. The larvae are coughed or travel to the throat where they are swallowed. They enter the stomach again and develop into adult worms. Each female worm lays 240,000 eggs per day. These eggs leave the body with bowel movements. The cycle begins again when contaminated food or water is eaten.

Digestive Tract and Lungs

Digestion tract and Lungs 3D

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Ascariasis is caused by swallowing food or water that is contaminated by feces containing eggs.

Risk Factors

Infestations are more common in preschool age or younger children because they are more likely to play in contaminated soil and are not so careful with fecal hygiene. Other factors that may increase the chance of ascariasis include:

  • Travel to developing countries
  • Living in the southern United States
  • Eating unsanitary food
  • Drinking unclean water

Most people will have no symptoms. If present, they may include:

  • Dry cough and fever
  • Wheezing
  • Abdominal cramps
  • Vomiting
  • Poor nutrition, especially in children
  • Passing a worm by mouth, nose, or rectum
  • Diseases caused by the Ascaris worm include:


Inflammed appendix

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Your doctor will ask about your symptoms, and your travel and medical history. A physical exam will be done. You may be referred to a gastroenterologist or a specialist in tropical diseases.

Your bodily fluids and waste may be tested. This can be done with:

  • Blood tests
  • Urine tests
  • Stool tests

Images may be taken to look for evidence of the worm. This can be done with:


It is common to have more than one intestinal parasite. You may need to be tested and treated for several. Talk with your doctor about the best treatment plan for you. Treatment options include the following:

  • Medications such as mebendazole, albendazole, ivermectin, and pyrantel pamoate
  • Endoscopy or surgery if you have an intestinal obstruction from a large number of worms

To reduce your chance of ascariasis:

  • Avoid foods prepared without proper sanitation, such as with unwashed hands.
  • Avoid water and other drinks that may be from contaminated sources.
  • Peel, cook, or wash vegetables if they may have been fertilized with human excrement.
  • Wash hands when leaving the bathroom.


Centers for Disease Control and Prevention

World Health Organization


Health Canada

Public Health Agency of Canada


Ascariasis. EBSCO DynaMed Plus website. Available at: Updated June 2, 2016. Accessed June 28, 2016.

Parasites—ascariasis. Centers for Disease Control and Prevention website. Available at: Updated January 10, 2013. Accessed June 28, 2016.

Last reviewed June 2016 by James Cornell, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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