Fascioloides magna, also known as Large American liver fluke or Giant liver fluke, is a parasitic flatworm in the class Trematoda, Phylum Platyhelminthes, which grows to a maximum length of 100 millimeters, and is thick and oval in shape. It is distinguished from other members of the genus Fasciola by the lack of an anterior projecting cone. It occurs in domestic and wild ruminants, elk and deer being the normal hosts. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Myxozoa (slime animals) Superphylum Deuterostomia (blastopore becomes anus) Chordata (vertebrates, etc. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... Subclasses Aspidogastrea Digenea The Trematoda is a class within the phylum Platyhelminthes, which contains two groups of parasitic worms. ... Orders within the Digenea Strigeidida Azygiida Echinostomida Plagiorchiida Opisthorchiida The digenea (Gr. ... In biology, binomial nomenclature is the formal method of naming species. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... Subclasses Aspidogastrea Digenea The Trematoda is a class within the phylum Platyhelminthes, which contains two groups of parasitic worms. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... Liver flukes are a polyphyletic group of a trematodes (a kind of flatworm). ... Families Antilocapridae Bovidae Cervidae Giraffidae Moschidae Tragulidae A ruminant is any hooved animal that digests its food in two steps, first by eating the raw material and regurgitating a semi-digested form known as cud, then eating the cud, a process called ruminating. ... Elk may refer to two distinct species of large deer: In Europe it refers to Alces alces, which is called a Moose in North America In North America it refers to Cervus elaphus, which is called a Red Deer in Europe. ... Subfamilies Capreolinae Cervinae Hydropotinae Muntiacinae A deer is a ruminant mammal belonging to the family Cervidae. ...

History and Epizootiology

Fascioloides magna was once limited to North America, but a translocation of wapiti to Italy in the 19th century led to establishing the parasite in Europe. The North American elk (or European red deer, or wapiti, Cervus elaphus) is the natural reservoir for F. magna, although white tailed deer (Odoicoleus virginianus), mule deer (O. hemionus) and possibly caribou (Rangifer tarandus) can be competent hosts. In Europe, the host is likely the red deer. The geographic distribution of the parasite depends on several factors, including the presence of an intermediate host, since they have indirect life cycles. Since the intermediate host is a snail (usually in the genus Lymnae), F. magna only occurs where the snail can exist (usually low, moist soils) or survive (irrigated pastures). Elk may refer to two distinct species of large deer: In Europe it refers to Alces alces, which is called a Moose in North America In North America it refers to Cervus elaphus, which is called a Red Deer in Europe. ... Binomial name Cervus elaphus Linnaeus,, 1758 Subspecies Numerous - see text. ... This article is about red deer. ... Binomial name Odocoileus virginianus Zimmermann, 1780 The White-tailed deer (Odocoileus virginianus), also known as the Virginia deer, is a medium-sized deer found throughout most of the continental United States, southern Canada, Mexico, Central America and northern portions of South America as far south as Peru. ... Binomial name Rangifer tarandus The reindeer, known as caribou in North America, is an Arctic-dwelling deer (Rangifer tarandus). ...

Life cycle

F. magna has an indirect life cycle. The natural host (elk) sheds parasite eggs in the feces. These eggs hatch into a miracidium, which in turn enters the foot of a Lymnae spp. snail. Cercaria hatch from the snail, and encyst into metacercariae that attach to vegetation where they are ingested by the herbivorous animal. The parasite migrates from the intestinal tract to the liver, where (in the natural host) it encysts in a fibrous capsule that communicates with the bile duct. Eggs are released through the bile duct and into the intestinal tract where the cycle can begin once again. In the natural host, pathogenicity is low, and limited primarily to the fluke's local damage to the animal's liver. The liver may be distorted and pitted with fibrous scars, but animals rarely die. The adult flukes live in the liver and can measure 5 cm in length. Pathogenicity is the ability of an organism to cause disease in another organism. ... The liver is the largest internal organ of the human body. ...

In sheep and goats, which are aberrant hosts, the parasite does not encyst. A few wandering parasites can cause death due to extensive fluke migration through the liver parenchyma and abdominal cavity. In cattle and bison, the parasite never completes the cycle because they get encapsulated in a heavy fibrous capsule. In animals The parenchyma are the functional parts of an organ in the body (i. ...

In these animals, the parasite never encapsulates and instead continues to migrate through the cattle, F. magna cause severe tissue reaction, resulting in thick-walled encapsulations that do not communicate with bile ducts. In sheep, encapsulations do not develop, and the parasites migrate in the liver and other organs, causing tremendous damage. Histologically, infected livers of cattle, sheep, and deer show black, tortuous tracts formed by migrations of young flukes.

Diagnosis and treatment

While the eggs of F. magna resemble those of F. hepatica, this similarity is of limited use; eggs usually are not passed in cattle and sheep. Recovery of the parasites at necropsy, as well as proper identification of F. hepatica or F. gigantica is necessary for definite diagnosis. When domestic ruminants and deer share the same grazing areas, the presence of disease due to F. magna should be kept in mind. Mixed infections with F. hepatica occur in cattle. Binomial name Fasciola hepatica The Fasciola hepatica, commonly known as the liver fluke, is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects the hepatic bile ducts of sheep and cattle, sometimes also humans, causing fascioliasis also known as fasciolosis. ...

Oxyclozanide has been reported to be effective against F. magna in white-tailed deer, and rafoxanide has been used successfully against natural infections in cattle. Albendazole (7.5 mg/kg), clorsulon (15 mg/kg), and closantel (15 mg/kg) have shown efficacy against this fluke in sheep. Currently no products are approved for use against this fluke in the USA. Deer are required for completion of the life cycle; if they can be excluded from the areas grazed by cattle and sheep, then infection can be controlled. Control of the intermediate host (lymnaeid snails) may be possible once it has been identified in a region and the nature of its habitat examined. Albendazole marketed as Albenza or Zentel, is indicated for the treatment of a variety of work infestations. ... The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. ...

See also

• Fascioliasis

Fascioliasis is caused by the trematodes Fasciola hepatica (the sheep liver fluke) and Fasciola gigantica, parasites of herbivores that can infect humans accidentally. ...

External link

• Viral, parasitic and prion diseases of farmed deer and bison (PDF format)