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What Is Ascariasis?

Ascariasis (as-keh-RYE-eh-sis) is an intestinal infection caused by a worm called Ascaris lumbricoides.

Treatment with prescription anti-parasite drugs usually clears up the infection within a week.

What Causes Ascariasis?

Ascaris eggs are found in soil and human feces (poop). They get into the body when someone eats or drinks something contaminated with the eggs.

Most people with ascariasis got it by:

  • putting dirty hands in their mouth
  • eating fruits or vegetables that weren't peeled, washed, or cooked

Globally, ascariasis is the most common human worm infection. Infections are more common in warmer or tropical climates, especially in areas with poor sanitation or crowded living conditions. They're rare in the U.S. due to strict sanitation practices.

Children are more likely to get ascariasis. They tend to put things in their mouths, including dirt, and often have poorer hygiene habits than adults.

What Happens in Ascariasis?

Swallowed eggs pass into the intestines, where they hatch into larvae. The larvae go through the intestinal wall and enter the bloodstream. Then, they travel to different organs, such as the liver, lungs, brain, or kidneys. Larvae in the lungs can climb up the airways to the throat, where they are swallowed. The swallowed larvae return to the small intestine and grow and mature into adults. This happens about 2 months after the egg was swallowed.

Adult worms can live in the small intestine for up to 1 to 2 years. They can be as thick as a pencil and can measure from 5 to 14 inches long. A person can have many worms at the same time if many eggs hatch. And each female worm can produce over 200,000 eggs per day. When they come out in the poop, they start the life cycle all over again.

What Are the Signs & Symptoms of Ascariasis?

Most people with ascariasis don't have any symptoms. Those who do can have symptoms that range from mild to severe depending on how many worms are in the intestines. Symptoms also depend on which part of the body is affected. They include:

  • wheezing or trouble breathing
  • worms in stool (poop)
  • loss of appetite and poor growth
  • fever
  • nausea and vomiting
  • diarrhea
  • belly pain or bloating
  • rarely, coughing up a worm

Kids are more likely than adults to complain of gastrointestinal symptoms. That's because their intestines are smaller and more likely to get blocked by the worms. A large mass of worms in the intestines can lead to malnutrition and poor growth. It can also block the appendix and other organs, leading to appendicitis or problems with the liver, pancreas, or gallbladder.

Is Ascariasis Contagious?

Ascariasis doesn't spread from one person to another. A person can only get infected by swallowing the worm's eggs.

How Is Ascariasis Diagnosed?

Doctors can diagnose ascariasis by looking at a worm that comes out when someone coughs or poops. They can also test stool samples for eggs.

Sometimes, imaging tests (like an X-ray, ultrasound, or CT scan) can show the worms in the belly or chest.

How Is Ascariasis Treated?

Doctors treat ascariasis with prescription anti-parasite drugs. Symptoms usually stop within 1 week of starting treatment.

Very rarely, doctors do surgery to remove the worms. This usually happens only if they block the intestines or cause problems with the liver, pancreas, or gallbladder.

Can Ascariasis Be Prevented?

Good sanitation is the best way to prevent ascariasis.

Children adopted from developing nations may be tested for worms even if they have no symptoms. Kids who live in areas where ascariasis is common might be treated for it even if they haven't been diagnosed with an infection.

It's also important to:

  • Teach kids to wash their hands well and often, especially after using the bathroom and before eating.
  • Keep kids from putting things in their mouths, especially if they're around soil that may be contaminated with poop.
  • Wash, peel, or cook all fruits and vegetables before eating them.

When Should I Call the Doctor?

Call your doctor right away if your child has any symptoms of ascariasis. This is especially important if you adopted your child from a developing country or you traveled to areas where ascariasis is common.

Also call the doctor if your child's symptoms don't get better with treatment or if new symptoms start.

Reviewed by: Yamini Durani, MD
Date Reviewed: Mar 5, 2023

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