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Ascariasis is an infection with the parasitic roundworm Ascaris lumbricoides.
People get ascariasis by consuming food or drink that is contaminated with roundworm eggs. Ascariasis is the most common intestinal worm infection. It is related to poor personal hygiene and poor sanitation. People who live in places where human feces (stool) are used as fertilizer are also at risk for this disease.
Once consumed, the eggs hatch and release immature roundworms called larvae inside the small intestine. Within a few days, the larvae 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 small intestine.
As the larvae move through the lungs they may cause an uncommon form of pneumonia called eosinophilic pneumonia. Eosinophils are a type of white blood cell. Once the larvae are back in the small intestine, they mature into adult roundworms. Adult worms live in the small intestine, where they lay eggs that are present in feces. They can live 10 to 24 months.
An estimated 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:
Exams and Tests
The infected person may show signs of malnutrition. Tests to diagnose this condition include:
- Abdominal x-ray or other imaging tests
- Complete blood count
- Eosinophil count
- Stool exam to look for worms and worm eggs
Treatment includes medicines that paralyze or kill intestinal parasitic worms.
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.
People who are treated for roundworms should be checked again in 3 months. This involves examining the stools to check for eggs of the worm. If eggs are present, treatment should be given again.
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
If the worms multiply, they can block the intestine.
These complications may occur:
- Blockage in the bile ducts of the liver
- Blockage in the intestine
- Hole in the gut
When to Contact a Medical Professional
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
- If symptoms do not improve with treatment
- 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 treatment with deworming medicicines may be advised.
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. 8th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014:chap 288.
- Last reviewed on 12/7/2014
- Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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This page was last updated: May 4, 2015