Elaeophora schneideri

Elaeophora schneideri (arterial worm; cause of elaeophorosis, aka "filarial dermatitis" or "sorehead" in sheep; or "clear-eyed" blindness in elk) is a nematode which infests several mammalian hosts in North America. It is transmitted by horse-flies. Infection in the normal definitive hosts, Mule deer or Black-tailed deer, seldom produces clinical symptoms. In other hosts, such as sheep, elk, moose, and goats, infection with E. schneideri leads to elaeophorosis. Symptoms of elaeophorosis include necrosis of the muzzle, ears, and optic nerves; lack of coordination (ataxia); facial or lower limb dermatitis; horn deformities; blindness; and death.