Ascariasis is an infection caused by a parasitic roundworm, Ascaris lumbricoides.

Causes, incidence, and risk factors

Ascariasis is the most common intestinal worm infection. It is found in association with poor personal hygiene, poor sanitation, and in places where human feces are used as fertilizer. Intake of food or drink contaminated with roundworm eggs causes infection.

The eggs hatch and release larvae within the intestine. The larvae then move through the bloodstream to the lungs, exit up through the large airways of the lungs, and are swallowed back into the stomach and intestines.

During movement through the lungs the larvae may produce an uncommon form of pneumonia called eosinophilic pneumonia. Once back in the intestines, they mature into adult roundworms. Adult worms live in the intestine where they lay eggs that are present in feces.

It is estimated that 1 billion people are infected worldwide. Ascariasis occurs in all ages, though children seem to be affected more severely than adults.


  • Passing worms in stool  
  • Vomiting up worms  
  • Worms exiting through the nose or mouth  
  • Low-grade fever  
  • Cough  
  • Bloody sputum  
  • Wheezing  
  • Shortness of breath  
  • Skin rash  
  • Vomiting  
  • Stomach pain

Note: There may be no symptoms.

Signs and tests

  • Stool ova and parasites exam  
  • An abdominal x-ray  
  • Routine blood counts (may show anemia)  
  • Malnutrition

Treatment includes medications that kill intestinal parasitic worms such as albendazole or mebendazole. If there is a blockage of the intestine caused by a large number of worms, another medication can make the worms relax and pass through the intestine. This will relieve the obstruction.

Expectations (prognosis)
Most people recover from the infection, even without treatment. However, complications may be caused by adult worms that move to certain organs or multiply and cause a blockage in the intestine.


  • Biliary (liver secretion) tract obstruction  
  • Perforation (hole) in gut  
  • Blockage in the intestine  
  • Abscesses throughout the body

Calling your health care provider
Call your health care provider if you have symptoms suggestive of this disease, particularly if you have traveled to areas which may be affected. Also call if symptoms worsen, do not improve with treatment or if new symptoms occur.

Improved sanitation and hygiene in developing countries will reduce the risk in those areas. In areas where this disorder is common, routine or preventive (prophylactic) treatment with deworming medications may be advised.

Johns Hopkins patient information

Last revised: December 4, 2012
by Amalia K. Gagarina, M.S., R.D.

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