Elaeophora elaphi
Encyclopedia
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 microfilaria
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.
blood vessels of Red deer
(Cervus elaphus) from "Sierra Morena", Córdoba, Spain. The "note added in proof" in that study mentions that similar worms were also found in sheep. Both male and female adults, as well as microcercariae dissected from the uterus of females were described.
(Cervus elaphus) and a sheep (Ovis aries).
.
) arteries and veins. Their presence affects the blood vessels in several ways, including inflammation of veins (phlebitis
), blood clots (thrombosis
), and thickening of artery
walls. They also appear to induce a local humoral immune
response in the host, including production of lymphoid tissue
and granulomatous
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. 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
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 area of Spain.
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
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
The microfilaria is a stage in the life cycle of certain parasitic nematodes in the family Onchocercidae. In these species, the adults live in the circulatory system of vertebrates while the early larval stages develop in blood-feeding arthropod vectors...
e (in utero
In utero
In utero is a Latin term literally meaning "in the womb". In biology, the phrase describes the state of an embryo or fetus. In legal contexts, the phrase is used to refer to unborn children. Under common law, unborn children are still considered to exist for property transfer purposes.-See also:*...
) 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 hepaticLiver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
blood vessels of Red deer
Red Deer
The red deer is one of the largest deer species. Depending on taxonomy, the red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being...
(Cervus elaphus) from "Sierra Morena", Córdoba, Spain. The "note added in proof" in that study mentions that similar worms were also found in sheep. 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 Red deerRed Deer
The red deer is one of the largest deer species. Depending on taxonomy, the red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being...
(Cervus elaphus) and a sheep (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 schneideriElaeophora schneideri
Elaeophora schneideri 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...
.
Clinical significance
Adult E. elaphi have been found attached to the inner walls of the hepatic (liverLiver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
) arteries and veins. Their presence affects the blood vessels in several ways, including inflammation of veins (phlebitis
Phlebitis
Phlebitis is an inflammation of a vein, usually in the legs.When phlebitis is associated with the formation of blood clots , usually in the deep veins of the legs, the condition is called thrombophlebitis...
), blood clots (thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
), and thickening of artery
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
walls. They also appear to induce a local humoral immune
Humoral immunity
The Humoral Immune Response is the aspect of immunity that is mediated by secreted antibodies produced in the cells of the B lymphocyte lineage . B Cells transform into plasma cells which secrete antibodies...
response in the host, including production of lymphoid tissue
Lymph node
A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...
and granulomatous
Granuloma
Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
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. Necropsy
Autopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...
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
Theileria is a genus of parasitic protozoan 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 theileriosis and T. parva causes East Coast fever. Theileria are...
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 area of Spain.