Ascariasis occurs when worm eggs of the parasite Ascaris lumbricoides (commonly found in soil and human feces) are swallowed. This can happen from contaminated food, drink, or soil. The roundworms range in size from 5.9 to 9.8 inches for adult males and 9.8 to 13.8 inches for adult females. The worms can grow to be as thick as a pencil and can live for 1 to 2 years.

Ascariasis is often found in developing countries with poor sanitary conditions or in areas where human stool is used as fertilizer. After the eggs are swallowed, they pass into the intestines, where 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.

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.

Signs and Symptoms
Kids are more likely than adults to develop gastrointestinal symptoms with an ascariasis infection because their smaller intestines are at greater risk for intestinal blockage. The greater the number of worms involved, the more severe the symptoms are likely to be. Symptoms seen with mild infestation include:
-- worms in stool (poop)
-- coughing up worms
-- loss of appetite
-- fever
-- wheezing

More severe infestations can cause more serious signs and symptoms, including:
-- 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)