Ascaris's a genus of parasitic nematode worms known as the giant intestinal roundworms. One species, A. suum, typically infects pigs, while another, A. lumbricoides, affects human populations, typically in sub-tropical and tropical areas with poor sanitation. A. lumbricoides's the largest intestinal roundworm and's the most common helminth infection of humans worldwide, an infection known as ascariasis. Infestation can cause morbidity, and sometimes death, by compromising nutritional status, af… (More on Ascaris)