Ascaris lumbricoides
Ascaris lumbricoides is the "large roundworm" of humans, growing to a length of up to . It is one of several species of "Ascaris". An ascarid nematode of the phylum Nematoda, it is the most common parasitic worm in humans. This organism is responsible for the disease ascariasis, a type of helminthiasis and one of the group of neglected tropical diseases. An estimated one-sixth of the human population is infected by "A. lumbricoides" or another roundworm. Ascariasis is prevalent worldwide, especially in tropical and subtropical countries.