Ascaris lumbricoides

Definition: a large roundworm of humans, one of the most common human parasites (20–25 cm in length); various symptoms such as restlessness, fever, and sometimes diarrhea are attributed to its presence, but usually it causes no definite symptoms; the similar species, Ascaris suum (or Ascaris lumbricoides suum) is common in swine but is not readily transmitted to humans; Ascaris lumbricoides and Ascaris suum are morphologically and immunologically similar but apparently are host adapted, considered distinct species.

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