''Elaeophora elaphi'' is a

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

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

microfilaria ::''Microfilaria may also refer to an informal "collective group" genus name, proposed by Cobbold in 1882. While a convenient category for newly discovered microfilariae which can not be assigned to a known species because the adults are unknown, ...

e (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.

Discovery and nomenclature

''Elaeophora elaphi'' was first described in 1986, from specimens found in the

hepatic The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

blood vessels of

Red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...

(''Cervus elaphus'') from "Sierra Morena", Córdoba, Spain. The "note added in proof" in that study mentions that similar worms were also found in

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...

. Both male and female adults, as well as microcercariae dissected from the uterus of females were described.

Hosts and geographic distribution

So far, ''E. elaphi'' has only been described from Spain, in

(''Cervus elaphus'') and a

(''Ovis aries'').

Description and life cycle

The life cycle of ''E. elaphi'' has not been studied in detail. However, the seasonal cycle of adult ''E. elaphi'' abundance in its host ''Cervus elaphus'' is similar to the seasonal abundance cycle of ''

Elaeophora schneideri ''Elaeophora schneideri'' (arterial worm; carotid 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 trans ...

''.

Clinical significance

Adult ''E. elaphi'' have been found attached to the inner walls of the hepatic (

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

) arteries and veins. Their presence affects the blood vessels in several ways, including inflammation of veins ( phlebitis), blood clots (

thrombosis Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thro ...

), and thickening of

artery An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...

walls. They also appear to induce a local humoral immune response in the host, including production of lymphoid tissue and

granuloma A granuloma is an aggregation of macrophages that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such substances include infectious ...

tous lesions. These lesions are sometimes found in the absence of the parasites, or in the presence of dead, calcified ''E. elaphi''. Reported rates of infestation vary from 6 to 41% of sampled deer. The number of ''E. elaphi'' found per infested deer (intensity of infestation) ranges from 1 to 21, with averages of 8.5 and 9 in the two studies. Even though the deer in the study had the lesions mentioned above, none of them displayed any overt clinical symptoms. A red deer (''Cervus elaphus'') transported from Germany to Spain was not so fortunate. Six months after transport, it was found staggering and feverish; and it died the next day.Höfle, J., J. Vicente, D. Nagora, A. Hurtado, A. Peña, J. de la Fuente, and C. Gortazas (2004) "The risks of translocating wildlife: Pathogenic infection with ''Theileria'' sp. and ''Elaeophora elaphi'' in an imported red deer." ''Veterinary Pathology'' 126(3-4):387-395. Necropsy revealed 100 ''E. elaphi'' in its hepatic (liver) blood vessels - a much higher infestation intensity than was found in local deer - in addition to ''

Theileria ''Theileria'' is a genus of parasites that belongs to the phylum Apicomplexa, and is closely related to ''Plasmodium''. Two ''Theileria'' species, ''T. annulata'' and ''T. parva'', are important cattle parasites. ''T. annulata'' causes tropical ...

'' infection. Because ''E. elaphi'' has never been found in Germany, the authors suggest that this deer may not have developed a sufficient immune background to deal with ''E. elaphi'' infestation once it was relocated to the ''E. elaphi''-

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

area of Spain.

References

{{Taxonbar, from=Q5353123 Spirurida Parasitic nematodes of mammals Cervus Veterinary helminthology Nematodes described in 1986