Ascariasis
Ascariasis is an intestinal infection caused by the parasitic roundworm Ascaris lumbricoides. While it is the most common human infection caused by worms in the world, ascariasis is not common in the United States. It occurs in varying prevalence worldwide, with far greater frequency in areas with poor sanitation or crowded living conditions.
Ascariasis occurs when worm eggs commonly found in soil and human feces are ingested. The eggs can be transmitted from contaminated food, drink, or soil. The roundworms range in size from 5.9 to 9.8 inches (15 to 25 centimeters) for adult males and 9.8 to 13.8 inches (25 to 35 centimeters) for adult females. The worms can grow to be as thick as a pencil and can live for 1 to 2 years.
Signs and Symptoms
Although no symptoms may occur, the greater the number of worms involved in the infestation, the more severe a child's symptoms are likely to be. Children are more likely than adults to develop gastrointestinal symptoms because they have smaller intestines and are at greater risk of developing intestinal obstruction. The following symptoms may be seen with mild infestation:
- worms in stool
- coughing up worms
- loss of appetite
- vomiting
- shortness of breath
- abdominal distention (swelling of the abdomen)
- severe stomach or abdominal pain
- intestinal blockage
- biliary tract blockage (includes the liver and gallbladder)
Description
Ascariasis is frequently found in developing countries where sanitary conditions are poor or in areas where human feces are used as fertilizer. When the eggs are swallowed and passed into the intestine, they hatch into larvae. The larvae then begin to move through the body.
Once they get through the intestinal wall, the larvae travel from the liver to the lungs through the bloodstream. During this stage, pulmonary symptoms such as coughing (even coughing up worms) may occur. In the lungs, the larvae climb up through the bronchial tubes to the throat, where they are swallowed. The larvae then return to the small intestine where they grow, mature, mate, and lay eggs. The worms reach maturity about 2 months after an egg is ingested from the soil.
Adult worms live and remain in the small intestine. A female worm can produce up to 240,000 eggs in a day, which are then discharged into the feces and incubate in the soil for weeks. Children are particularly susceptible to ascariasis because they tend to put things in their mouths, including dirt, and they often have poorer hygiene habits than adults.
Ascariasis is common in warmer or tropical climates, particularly in developing nations, where it can affect large segments of the population. Ascariasis is rare in the United States, due to strict sanitation rules and regulations.
Duration
Typically, symptoms usually disappear within 1 week of starting treatment.
Contagiousness
Ascariasis is not spread directly from one person to another. To become infected, an individual has to consume the worm's eggs.
Prevention
The most important measure of protection against ascariasis is the safe and sanitary disposal of human waste, which can transmit eggs. Areas of the world that use human feces as fertilizer must thoroughly cook all foods or clean them with a proper iodine solution (particularly fruits and vegetables).
Children who are adopted from developing nations are frequently screened for worms as a precautionary measure. Children who live in underdeveloped areas of the world may be prescribed a preventive deworming medication. The following practices are recommended for all children:
When to Call Your Child's Doctor
If your child has any of the symptoms of ascariasis, you should contact your child's doctor right away. Barbara P. Homeier, MD
Date reviewed: June 2005
Originally reviewed by:
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