Ascaris lumbricoides

Ascaris lumbricoides is a large parasitic roundworm of the genus Ascaris. It is the most common parasitic worm in humans. An estimated 807 million–1.2 billion people are infected with Ascaris lumbricoides worldwide. People living in tropical and subtropical countries are at greater risk of infection. Infection by Ascaris lumbricoides is known as ascariasis.

It has been proposed that Ascaris lumbricoides and Ascaris suum (pig roundworm) are the same species.