Ascariasis is infection with the parasitic roundworm Ascaris lumbricoides.
Causes, incidence, and risk factors
Ascariasis is caused by consuming food or drink contaminated with roundworm eggs. 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.
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, exit up through the large airways of the lungs, and are swallowed back into the stomach and reach the small intestine.
During movement through the lungs the larvae may produce 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.
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 includes medications that paralyze or kill intestinal parasitic worms, such as albendazole or mebendazole. These drugs 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 to remove the worms or, rarely, surgery may be needed.
Most people recover from symptoms of the infection, even without treatment, although they may continue to carry the worms in their body.
Complications may be caused by adult worms that move to certain organs such as the bile duct, pancreas, or appendix, or multiply and cause a blockage in the intestine.
- 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.
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.
Kazura JW. Nematode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 378.
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. Orlando, FL. Saunders Elsevier; 2009:chap 287.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; 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 David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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