Elaeophora schneideri

Elaeophora schneideri
Scientific classification
Kingdom:	Animalia
Phylum:	Nematoda
Class:	Secernentea
Order:	Spirurida
Family:	Onchocercidae
Genus:	Elaeophora
Species:	E. schneideri
Binomial name
Elaeophora schneideri Wehr & Dikmans, 1935

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.

Symptoms of elaeophorosis were first observed in 1933, in sheep (New Mexico) and mule deer (Utah) infested by an unknown nematode worm. Specimens were first described as Macdonaldius sp. in 1934, and later revised to Elaeophora schneideri Wehr and Dikmans, 1935. A more complete description of adults from elk, sheep and deer was published in 1968.

The female adults are 60–120 mm long and 56-89 µm wide, while males are 55–85 mm long and 40-68 µm wide. The microfilariae are 239-279 µm long and 11-15 µm wide.

The normal definitive hosts for E. schneideri are the Mule deer and Black-tailed deer. It has also been found in several other wild mammalian hosts: White tailed deer, elk, moose, Bighorn sheep, Barbary sheep, Domestic sheep. Infestation was also found in sika deer on Texas ranches. Infestations of cattle, horses or humans have not been reported. The vectors of E. schneideri are blood-feeding Horse-flies of the family Tabanidae, genera Hybomitra, Tabanus, or Silvius.

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