Ascaris is a round worm that lives in the small intestine. Infection with Ascaris is called ascariasis (ass-kuh-rye-uh-sis). Adult female worms can grow to over 12 inches in length - adult males are smaller.

Ascariasis is the most common human worm infection - children are infected more often than adults.

Most people have no symptoms that are noticeable, but infection may cause slower growth and slower weight gain. If you are heavily infected, you may have abdominal pain. Sometimes, while the immature worms migrate through the lungs, you may cough and have difficulty breathing. If you have a very heavy worm infection, your intestines may become blocked. You may cough up an ascaris larvae or pass an adult worm in your stool.

Ascaris eggs are found in human feces. After feces contaminates the soil, the eggs become infectious after a few weeks. Infection occurs when a person accidentally ingests (swallows) infectious microscopic Ascaris eggs. Once in the stomach, immature worms hatch from the eggs. The larvae are carried through the lungs and then to the throat where they are swallowed. Once swallowed, they reach the intestines and develop into adult worms. Adult female worms lay eggs that are then passed in feces; this cycle will take between 2-3 months.

Pigs can be infected with another species of Ascaris. Occasionally, a pig Ascaris infection can be spread to humans - this occurs when infective eggs, found in the soil and manure, are ingested. Infection is more likely if pig feces is used as fertilizer in the garden - crops then become contaminated with Ascaris eggs.

You or your children can become infected after touching your mouth with your hands that have become contaminated with eggs from soil or other contaminated surfaces or by ingesting contaminated food or water.

To prevent infection with Ascaris:
Avoid contacting soil that may be contaminated with human feces.
Do not defecate outdoors.
Dispose of diapers properly.
Wash hands with soap and water before handling food.
When traveling to countries where sanitation and hygiene are poor, avoid water or food that may be contaminated.
Wash, peel or cook all raw vegetables and fruits before eating.