Points in question. The  origin of Oesophagostomum columbianum.
D000818:Animals; D000866:Antelopes / Q000469:parasitology*; D001188:Artiodactyla / Q000469:parasitology*; D006790:Host-Parasite Interactions; D009815:Oesophagostomum / Q000254:growth & development*; D012756:Sheep / Q000469:parasitology*