Definition of Ascariasis:

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 intestine. 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 intestines.

During movement through the lungs the larvae may produce an uncommon form of pneumonia called eosinophilic pneumonia. Once they are back in the intestines, the larvae mature into adult roundworms. Adult worms live in the intestine where they lay eggs that are present in feces.

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.