Ascaricides are drugs to treat ascariasis that is caused by infections with parasitic nematodes (roundworms) of the genus Ascaris (giant intestinal roundworms). The large roundworm of pigs (Ascaris suum) typically infects pigs while Ascaris lumbricoides affects human populations, typically in sub-tropical and tropical areas with poor sanitation. Ascaricides belong to the group of drugs collectively called anthelmintics which expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host.[citation needed]