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Karin Leder, MBBS, FRACP, PhD, MPH, DTMH
Peter F Weller, MD, MACP
Section Editor
Edward T Ryan, MD, DTMH
Deputy Editor
Elinor L Baron, MD, DTMH


Ascaris lumbricoides is the largest intestinal nematode (roundworm) parasitizing the human intestine and is one of the most common helminthic human infections worldwide [1]. Ascaris suum is a roundworm intestinal parasite of pigs and can also cause human infection [2-4]. A. lumbricoides and A. suum are genetically very closely related [5-11].

Transmission of ascariasis occurs primarily via ingestion of water or food contaminated with Ascaris eggs. Most patients with A. lumbricoides or A. suum infection are asymptomatic. When symptoms do occur, they occur most often during the adult worm intestinal stage (as intestinal, hepatobiliary, or pancreatic manifestations) but may also occur during the larval migration stage (as pulmonary manifestations).

The epidemiology, clinical manifestations, diagnosis, treatment, and prevention of ascariasis are reviewed here.


Human acquisition of Ascaris infection can occur via the following mechanisms:

Ingestion of eggs secreted in the feces of humans (A. lumbricoides) or pigs (A. suum). Eggs must embryonate in soil to become infectious. (See 'Life cycle' below.)

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Literature review current through: Nov 2017. | This topic last updated: Nov 06, 2017.
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