''Alaria'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of flatworms, or

trematodes Trematoda is a class of flatworms known as trematodes, and commonly as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is a moll ...

, in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Diplostomidae Diplostomidae is a family of trematodes in the order Diplostomida Diplostomida is an order of trematodes in the subclass Digenea. It is synonymous with Strigeatida Poche, 1926. Families Order Diplostomida *Suborder Diplostomata **Superfamily ...

. ''Alaria'' is a genus of small parasitic worm about 2–6 mm long and approximately 2 mm wide. It is usually found in the small intestine of dogs, cats, or wild carnivores. It is most commonly found in Europe, Asia, and the Americas. The body consists of two shaped parts: the anterior, which is flat, and the posterior, which is conical to cylindrical. Species of ''Alaria'' have two suckers, the oral and the ventral. They have only one opening, the mouth. They are

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

Life cycle

Species of ''Alaria'' have complex indirect life cycles. There are two intermediate hosts involved, but there can also be paretic hosts, such as snakes, mice, birds, and humans. The eggs, which are oval, operculated, and light brown, are released from adult ''Alaria'' and excreted from the final host's faeces and hatched into

miracidium The miracidium is the second stage in the life cycle of trematodes. When trematode eggs are laid and come into contact with fresh water, they hatch and release miracidium. In this phase, miracidia are ciliated and free-swimming. This stage is comp ...

that infect the snail host, in which the eggs then give rise to the asexual stage known as sporocysts. The sporocysts then produce cercariae. The

cercariae A cercaria (plural cercariae) is a larval form of the trematode class of parasites. It develops within the germinal cells of the sporocyst or redia. A cercaria has a tapering head with large penetration glands. It may or may not have a long swim ...

then leave the snail and infect the tadpole via penetration where a non-reproductive form is developed, which is known as mesocercariae. It usually takes about two weeks to develop. The mesocercariae transfer to their tissues and remain at this life-cycle stage. Finally, the parasite reaches its final host once ingested, usually a

canid Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

. Other hosts include cats, foxes, and minks. It has been reported that in the United States, raccoons were also found to act as an intermediate host.

Infection and pathogenesis

After the immature ''Alaria'' parasite is ingested it makes its way to the lungs and further develops into adults in the small intestine. Usually, they are not associated with intestinal illness. If the infection levels are high, then it may cause pulmonary damage along with haemorrhage which can lead to clinical disease. Paratenic hosts also become infected when eating the contaminated intermediate host, either tadpoles or frogs. The mesocercariae remain in organs such as the muscles, connective tissue or lungs, and eyes. They are mostly harmless in dogs as well as the paratenic hosts. However, prevalence of ''Alaria'' in dogs in the United States and foxes in Germany are up to 30%. Unfortunately for humans, it can be quite harmful and even cause death. Humans can be infected by ingesting ''Alaria'' larvae, which can be from eating undercooked frog legs or contaminated boar or pig meat.

Diagnosis and treatment

Infections of ''Alaria'' can be diagnosed through faecal examination or thoracic radiographs of dogs and cats. There are no forms of diagnosis in humans. This infection can be treated with

praziquantel Praziquantel, sold under the brandname Biltricide among others, is a medication used to treat a number of types of parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is used to treat schist ...

. It's been noted that another possible treatment is with

fenbendazole Fenbendazole is a broad-spectrum benzimidazole anthelmintic used against gastrointestinal parasites including: roundworms, hookworms, whipworms, the tapeworm genus '' Taenia'' (but not effective against '' Dipylidium caninum'', a common dog ...

Control and prevention

''Alaria'' infections can be prevented by keeping canines from scavenging or eating infected prey. Preventing predation when feasible. In humans, you can prevent this by not eating undercooked meat of infected hosts.

Cases of infection

There have been cases reported of fatal disease with systematic infection with ''Alaria'' larvae ingestion of undercooked frog legs and waterfowl. One of the first cases reported was a single worm in the eye of a woman from Ontario, Canada. It is believed that she contracted the parasite from rubbing her eyes while preparing frogs legs.

References

* http://dailyparasite.blogspot.com * http://www.merckvetmanual.com/mvm/digestive_system/gastrointestinal_parasites_of_small_animals/flukes_in_small_animals.html * http://parasitipedia.net/index.php?option=com_content&view=article&id=2570&Itemid=2852 * https://web.archive.org/web/20170117003406/https://www.capcvet.org/capc-recommendations/trematodes/ * * * http://www.aavp.org/wiki/trematodes-2/trematodes-small-intestine/diplostomatidae/alaria-marcianae/ * http://www.vetbook.org/wiki/dog/index.php?title=Alaria_spp * http://r1.ufrrj.br/adivaldofonseca/wp-content/uploads/2014/06/Carter-G-R-2001-Internal-parasitic-Diseases-of-dogs-and-cats.pdf {{Taxonbar, from=Q5022943 Digenea genera Diplostomida