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Ascariasis

Definition

Ascariasis is infection with the parasitic roundworm Ascaris lumbricoides.

Causes, incidence, and risk factors

People get ascariasis by consuming food or drink contaminated with roundworm eggs. Ascariasis is the most common intestinal worm infection. It is related to poor personal hygiene and poor sanitation. Persons who live in places where human feces are used as fertilizer are also at risk of this disease.

Once consumed, the eggs hatch and release immature roundworms called larvae within the small intestine. Within a few days, the larvae then move through the bloodstream to the lungs. They travel up through the large airways of the lungs, and are swallowed back into the stomach and reach the small intestine.

As the larvae move through the lungs they may cause an uncommon form of pneumonia called eosinophilic pneumonia. Once they are back in the small intestine, the larvae mature into adult roundworms. Adult worms live in the small intestine where they lay eggs that are present in feces. They can live 10 – 24 months.

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

Symptoms

Most of the time, there are no symptoms. If there are symptoms, they may include:

Signs and tests

The infected person may show signs of malnutrition. Tests to diagnose this condition include:

Treatment

Treatment includes medicines that paralyze or kill intestinal parasitic worms, such as albendazole or mebendazole. These medicines should not be used for pregnant patients. Pyrantel pamoate is the preferred medication for pregnant patients.

If there is a blockage of the intestine caused by a large number of worms, endoscopy may be used to remove the worms. In rare cases, surgery is needed.

Patients should be checked again in 3 months. This involves examining the stools to check for worm eggs. If eggs are present, treatment should be given again.

Expectations (prognosis)

Most people recover from symptoms of the infection, even without treatment. But they may continue to carry the worms in their body.

Complications can be caused by adult worms that move to certain organs such as the bile duct, pancreas, or appendix. If the worms multiply, they can block the intestine.

Complications

  • Liver secretion (biliary tract) obstruction
  • Blockage in the intestine
  • Hole (perforation) in the gut

Calling your health care provider

Call your health care provider if you have symptoms of ascariasis, particularly if you have traveled to a high-risk area. Also call if symptoms get worse, do not improve with treatment, or if new symptoms occur.

Prevention

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.

References

Diemert DJ. Intestinal nematode infections. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011: chap 365.

Maguire JH. Intestinal nematodes (roundworms). In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Churchill-Livingstone; 2009:chap 287.


Review Date: 11/10/2012
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.
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