Ascariasis is a roundworm infection of your intestines. It happens through hand-to-mouth contact with the eggs of the worm Ascaris lumbricoides. Ascariasis symptoms can include stomach pain. Providers can effectively treat ascariasis with medication.


What is ascariasis?

Ascariasis is a roundworm infection of your intestines. It’s common throughout the world in places where sanitation is poor. In these areas, people may be carrying the parasite that causes the infection.

Ascariasis, hookworm and whipworm are parasitic worms. They’re known as soil-transmitted helminths (STH) because the infection spreads through contaminated soil.

Ascaris, sometimes abbreviated as A., is the group of worms that cause ascariasis. The worm looks like the common earthworm. It’s about 6 to 13 inches long and about as thick as a pencil. Up to 100 worms could potentially infect a person.


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What is a parasite?

A parasite is a creature that needs to live on or in another creature to survive. Often, the parasite causes problems for its host (the creature it depends on). Roundworms need the body of a human or other animal to mature into egg-laying adults.

How common is ascariasis?

Ascariasis is one of the most common human parasitic infections. It infects more than 1 billion people worldwide.

Ascariasis is most common in children between 3 and 8 years old. It doesn’t occur frequently in the United States. But you may get ascariasis if you travel to an area of the world with poor sanitation.


Who is at risk for ascariasis?

People at risk for ascariasis live in or visit places:

  • With limited access to proper sanitation and hygiene.
  • Where people use human feces as fertilizer.
  • That are warm and humid, such as tropical and subtropical areas of Asia, sub-Saharan African and the Americas.

What is Ascaris suum?

Pig roundworm is called Ascaris suum. It’s similar to ascariasis. People who raise pigs or use pig manure for fertilizer are at higher risk for A. suum.


Is ascariasis contagious?

Yes. Anyone with live worms in their intestines can spread the infection to others.

Symptoms and Causes

What causes ascariasis?

Ascaris infection is caused by ingesting (swallowing) the eggs of the roundworm A. lumbricoides.

How is ascariasis transmitted?

Ascariasis spreads through hand-to-mouth contact — when a person touches and swallows fertilized Ascaris eggs.

In places that lack adequate sanitation, people infected with ascariasis may defecate (poop) outside. In some areas, people use human feces as fertilizer. Contaminated feces containing Ascaris eggs can lie in fields, streets and yards. The eggs can survive extreme temperature and humidity, often for years.

People may swallow the tiny eggs when they:

  • Touch contaminated soil and then put their hands in or near their mouths.
  • Eat fruits and vegetables grown in the infected soil without washing, peeling and cooking the produce.

How does ascariasis affect me?

After you swallow the eggs, they pass into your intestines. There, they hatch into larvae (immature form of worms) and begin to travel through your body:

  • From your intestines, they reach your lungs by traveling through your bloodstream or lymphatic system.
  • In your lungs, they pass through the air sacs and into your throat.
  • They travel to your throat, where you swallow them.
  • Back in your intestines, they grow, mature into adult worms and mate.
  • Fertilized eggs leave your body in your stool (poop), with the goal of infecting another host.

The whole process can take two to three months. The worms can live in your body for up to two years.

What are the symptoms of ascariasis?

If you only have a few roundworms, you may not have any symptoms. If you do have symptoms, you may experience abdominal pain that comes and goes.

The first sign of an infection might be seeing a live worm in your vomit or poop. If the larvae have traveled to your lungs, you may get a sickness similar to pneumonia, with:

At this early stage of the disease, the symptoms are challenging to diagnose. They’re similar to symptoms of many other illnesses.

Once the worms reach your intestines, you may experience more intense abdominal symptoms. The more worms you have, the more severe the symptoms will be. Symptoms may include:

In severe cases, the worms may partly or completely block your small intestine. You may get an inflamed pancreas. The infection can even be life-threatening.

Diagnosis and Tests

How is ascariasis diagnosed?

Once the infection has reached your intestines, your healthcare provider can diagnose the infection using a stool sample. The test involves looking for eggs or live worms in your poop.

If the infection is in your lungs, it can be more difficult to diagnose. Your provider can confirm a diagnosis by finding evidence of the larvae in your lungs or stomach fluids.

Sometimes people cough up a worm. In rare cases, you may even see one come out of your nose. If this happens, bring the worm to your healthcare provider so they can examine it.

Management and Treatment

How is ascariasis treated?

Medication is the primary treatment for ascariasis infection. Your provider will prescribe an anthelminthic medication. These medicines help the body get rid of parasitic worms:

  • Mebendazole (Vermox® or Emverm®).
  • Albendazole (Albenza®).
  • Pyrantel pamoate (Pin-X®).

Will I need surgery to treat ascariasis?

Rarely, Ascaris worms cause an intestinal blockage. In that case, you may need surgery or an endoscopic procedure to remove the worms.


Can I prevent ascariasis?

Take steps to prevent ascariasis:

  • Don’t touch soil that might be contaminated with human feces, including feces used to fertilize crops.
  • Wash hands with soap and water before preparing food.
  • Teach children to wash hands frequently.
  • Wash, peel and/or cook any raw vegetables and fruits, especially if they grew in manure-fertilized soil.
  • Don’t defecate outdoors except in latrines that have proper sewage disposal.

Outlook / Prognosis

How long does ascariasis treatment take to work?

The medicine takes about one to three days to be effective.

What’s the outlook for people with ascariasis infection?

Most ascariasis infections don’t cause long-term problems. Follow your provider’s instructions for taking your medicine. And take precautions to prevent an infection from happening again.

Living With

How should I take care of myself?

Take your medicine as prescribed. If you’re planning to travel to a high-risk area, talk to your provider about preventive steps you can take.

When should I call my healthcare provider?

Contact your provider if you:

  • · Have stomach problems that last longer than two weeks.
  • · Have unexplained weight loss.
  • · See a worm or piece of a worm in your poop.

What else should I ask my healthcare provider?

If you have an ascariasis infection, ask your provider:

  • Will I need medication?
  • How long should I take medication?
  • Will the infection come back?
  • Will there be long-term health problems from ascariasis?
  • What can I do to protect myself from ascariasis?

A note from Cleveland Clinic

Ascariasis is a common roundworm infection, though it’s not so common in the United States. You may not have any ascariasis symptoms at first. If you traveled to an area with poor sanitation and have stomach problems, see your healthcare provider. Medication can treat ascariasis effectively and the infection usually doesn’t cause any long-term health problems. Prevent ascariasis by washing your hands and any raw produce, especially if you travel to at-risk areas.

Medically Reviewed

Last reviewed on 04/30/2021.

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