En Español (Spanish Version)

Ascariasis is an infection with a nematode (worm) parasite known as ascaris lumbricoides .

This round worm can reach up to 40 cm (15.7 inches) in length. Their eggs hatch in the stomach and travel to the heart and lungs. This causes a type of pneumonia. They travel to the throat where they are swallowed and enter the stomach again and develop into adult worms. Each 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

Copyright © Nucleus Medical Media, Inc.

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. Risk factors that increase your chances of developing ascariasis include:

  • Travel to developing countries
  • Living in southern states of the US
  • Eating unsanitary food
  • Drinking unclean water
Most people will have no symptoms. Symptoms of ascariasis may include:

  • Dry cough and fever—when traveling through the lungs
  • Wheezing
  • Abdominal cramps
  • Vomiting
  • Poor nutrition, especially in children
  • Passing a worm either by mouth, nose, or rectum
  • Diseases caused by the Ascaris worm

Copyright © Nucleus Medical Media, Inc.

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:

  • X-ray
  • Ultrasound
It is common to have more than one intestinal parasite. You may need to be 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
Take these steps to reduce your chances of getting ascariasis:

  • Avoid foods prepared without proper sanitation, such as 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.

Center for Disease Control (CDC)

World Health Organization


Public Health Agency of Canada

Ascariasis. EBSCO DynaMed website. Available at: Updated April 29, 2013. Accessed July 19, 2014.

Parasites—ascariasis. Centers for Disease Control and Prevention website. Available at: Updated January 10, 2013. Accessed July 19, 2014.

Last Reviewed July 2014

Health Information Library content is provided by EBSCO Publishing, fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.


This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.


To send comments or feedback to EBSCO's Editorial Team regarding the content please e-mail