Ascariasis is infection with the parasitic roundworm Ascaris lumbricoides.
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 small intestine. Within a few days, 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 reach the small intestine.
During movement through the lungs the larvae may produce an uncommon form of pneumonia called eosinophilic pneumonia. Once they are back in the small intestine, the larvae mature into adult roundworms. Adult worms live in the small intestine where they lay eggs that are present in feces. They can live 10 – 24 months.
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.
Kazura JW. Nematode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 378.
Maguire JH. Intestinal nematodes (roundworms). In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Orlando, FL. Saunders Elsevier; 2009:chap 287.
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