What Is Ascariasis?

Ascariasis is a kind of roundworm infection you get in your intestines. It’s spread through contact with the worm’s eggs in contaminated food, soil, or water. You can't get it from another person.

Ascariasis is more common in warm and humid climates, in areas where poop is used as fertilizer, or where poor sanitation allows poop to mix with the soil. It affects about 1 billion people worldwide, but it isn’t common in the United States.

Because they put objects in their mouths and often play in the dirt, children are most at risk. Most people who get the infection are under the age of 10.

How the Infection Happens

The life cycle of the worm begins when someone swallows a bit of infected soil or eats unwashed fruits or vegetables grown in that soil. After that:

  • The eggs travel to the intestines, where they hatch.
  • Larvae then go to the lungs through the bloodstream or the network of vessels in the lymphatic system.
  • After about a week, the larvae leave the lungs and make their way to the airway and throat, where the person coughs them up and swallows them.
  • The parasites grow into adult worms after they go back into the intestines (males can grow up to 9.8 inches and females up to 13.8 inches). Female worms can lay up to 200,000 eggs a day. The eggs leave the person's body when they poop.
  • If the poop mixes with soil, the eggs can live there for several years.

This cycle from egg to adult takes about 2 to 3 months. The adults can live up to 2 years in a person's intestines.

Signs of Ascariasis

In some cases, a mild infection won't cause any noticeable symptoms. Other times, it can lead to a little pain in the belly, nausea, and diarrhea. When the larvae travel from the intestines to the lungs, that can cause a cough or trouble breathing.

A large infestation of worms can lead to:

  • Severe stomach pain
  • Tiredness
  • Vomiting
  • Weight loss
  • A worm in poop or vomit
  • Blockages in the intestines
  • Duct blockages of the liver or pancreas

Heavy infestations can also keep children from growing at a normal rate if they don't get enough nutrients.



If a doctor thinks someone may have ascariasis, they'll send a sample of the person's poop to a lab, where technicians look for eggs or worms through a microscope. And imaging tests like an ultrasound or an MRI can sometimes show if there are worms.


Doctors use antiparasitic medications like albendazole or mebendazole to treat ascariasis. Symptoms usually go away in a week, then they check for eggs and worms again around 3 weeks later.

If there are any infestation-related blockages or infections, surgery may be recommended to take care of them.


Because ascariasis is spread through soil that’s been mixed with human waste, it's best to stay away from those areas and from food grown in contaminated dirt. If you travel to another country or to an area where there might be poor sanitation, it’s always a good idea to practice good hygiene:

  • Wash your hands often, especially when you prepare and eat food.
  • Thoroughly wash, peel, and cook all raw vegetables and fruits.
  • Drink bottled water.
  • Keep your fingernails trimmed.
  • Clean your clothing and bedding regularly.

WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on July 16, 2019



Kidshealth.org: “Ascariasis.”

CDC: “Parasites -- Ascariasis.”

Health Victoria (Australia): “Ascariasis (roundworm infection).”

Mayo Clinic: “Ascariasis.”

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