Elaeophora elaphi is a nematode parasite found in the blood vessels of the liver in Red Deer (Cervus elaphus) in certain parts of Spain. The adult male measures 77 mm long and 549 µm wide, adult females are 91-109 mm long and 793-1049 µm wide, and microfilariae (in utero) are 225 µm long. Though adult E. elaphi induce lesions in the blood vessels, and appear to activate the local immune response, they seldom cause overt clinical symptoms in their hosts.