Ascaris suum, also known as large roundworm of pigs, is a parasitic nematode that causes ascariasis in pigs. While roundworms in pigs and humans are today considered as two species, A. suum and A. lumbricoides, with different hosts, cross infection between humans and pigs is possible, so researchers have argued they are the same species. Ascariasis is associated with contact to pigs and pig manure in Denmark.