Bristles and small spines probably act as tactile receptors, and these animals also may have reduced chemoreceptors.
Perception Channels: tactile ; chemical
US Federal List: no special status
CITES: no special status
These organisms may require up to four hosts to complete one cycle. Adult flukes, residing in the intestines of the definitive canid hosts, pass unembryonated eggs through the feces of the host. After two weeks, these eggs hatch in water, releasing the miracidium. The miracidia locate species of planorbid snails as the next host and once inside, develop into a sporocyst. After nearly a year of maturation, daughter sporocysts release cercariae, which exit the snail and swim to the water surface. The cercariae then locate a tadpole, inside of which they develop into the mesocercaria stage. The mesocercariae may then be ingested by the definitive host, but more frequently pass on to a water snake, where they develop into diplostomula. The definitive host then ingests the water snake, and the diplostomula migrate to the small intestine. Here, they mature into adult flukes, thus completing the reproductive cycle.
Mature worms of this species are typically highly pathogenic and often cause severe enteritis, killing the definitive host. The worm does not frequently infect humans, due to infrequent contact with tadpoles or water snakes that carry the infective mesocercariae. However, human infection has been demonstrated in a few cases, likely to be caused by ingestion of inadequately cooked frog legs.
Negative Impacts: injures humans (causes disease in humans ); causes or carries domestic animal disease
Alaria americana adults are found in the small intestine of its final definitive host, usually carnivorous mammals, specifically species of the family Canidae. In their developing stages, they may be found in several intermediate hosts including planorbid snails, tadpoles, and water snakes.
Ecosystem Impact: parasite
Species Used as Host:
Adult Alaria americana are endoparasitic and are located in the small intestine of carnivorous mammals, specifically species of the family Canidae. In their developing stages, they may be found in several intermediate hosts including planorbid snails, tadpoles, and water snakes. Adult flukes lack a mouth for feeding as well as a digestive system. In order to receive nutrients, the ventral sucker is used for digestion and absorption of mucus and tissue from the wall of the host intestine.
Animal Foods: blood; body fluids
Primary Diet: carnivore (Eats body fluids)
Alaria americana are most frequently found in temperate regions, predominantly in northern North America.
Biogeographic Regions: nearctic (Native )
The habitat of this organism is extremely diverse, as it occupies four different hosts throughout its lifetime. The species thrives in areas close to water, which is needed for several developmental stages to occur. Adult flukes may occupy a range of definitive hosts including wolves, coyotes, foxes, cattle, lynx, bobcats, martens, and skunks.
Habitat Regions: temperate ; tropical ; terrestrial ; freshwater
Terrestrial Biomes: forest ; rainforest ; mountains
Aquatic Biomes: lakes and ponds; rivers and streams; temporary pools
Wetlands: marsh ; swamp
Other Habitat Features: urban ; suburban ; agricultural
The adult Alaria americana ranges from 2.5-4.0 mm in length. It is dorso-ventrally flattened with a long forebody containing a pair of anterior flaps ventrally. This species is monoecious, with male and female reproductive organs found within each individual consisting of an ovary and a single testis. Adult flukes have oral and ventral suckers to aid in absorption and digestion of nutrients, which eventually leave the body through a single posterior pore. The genital pore is located posteriorly on the mid-hind body. This species is additionally characterized by the presence of pointed processes flanking the oral sucker as well as a pharynx and bifurcate intestine. Also found within Alaria americana are the vitelline glands which function in yolk production.
Range length: 2.5 to 4.0 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
This species is monoecious, with male and female reproductive organs found within each individual consisting of an ovary and a single testis. Adult Alaria americana reproduce in the intestines of the definitive canid hosts, then pass unembryonated eggs through the feces.
Key Reproductive Features: simultaneous hermaphrodite; sexual ; fertilization (Internal ); oviparous
There is no parental investment beyond release of the eggs.
Parental Investment: no parental involvement; pre-fertilization (Provisioning)
Alaria americana is a species of trematode in the family Diplostomidae. All Diplostomidae species infect carnivorous mammals by living in their small intestines as mature worms. A. americana is most frequently found in temperate regions, predominantly in northern North America. Its habit is extremely diverse, as the species occupies four different hosts throughout its lifetime. It thrives in areas close to water as water is needed for several developmental stages to occur. It has been isolated to a wide range of North American mammals as definitive hosts, including cattle, lynx, martens, skunks, bobcats, foxes, coyotes, and wolves.[2]
A. americana is very small, a fluke no bigger than 6mm in length and 2mm in width. The anterior portion is flat; the posterior half has a cylindrical shape. It has two small suckers about 100 um wide to aid in absorption and digestion of nutrients. As is common with other flukes, there are no external signs of segmentation. The mouth ends in the pharynx that allows for sucking. The digestive tract is blind, meaning it has no rectum, and is not linear, as in most animals, but branched, ending in several blind ducts.[2]
The species is monoecious, meaning the individual has both male and female reproductive organs, consisting of a single ovary and testes. It reproduces in the definitive host and then passes unembryonated eggs in the feces. It is oviparous - a key reproductive feature: the female releases the eggs and the development of offspring occurs outside the mother's body. There is no parental investment from the trematode beyond the release of its eggs.[2]
Habitats include tropical as well as temperate regions, in both terrestrial and freshwater locations. Terrestrial biomes include forests, rainforests, and mountains. Aquatic biomes include lakes, ponds, rivers, streams and temporary pools. Wetlands include marshes and swamps. Other habitat features include urban areas, suburbs and agricultural areas.
Alaria americana is a three-host trematode that lives as adults in the intestine of the dog as typical definitive host.[1] Eggs are passed in feces and hatch in water, releasing miracidia which penetrate the helisomid freshwater snails (first intermediate host) and develop through the sporocyst stage into cercariae.[1] Cercariae released from snails actively penetrate the second intermediate host (tadpoles) becoming infective mesocercariae in about two weeks.[1] In the tadpole or in the frogs (following the metamorphosis), mesocercariae accumulate and may be ingested by a number of paratenic hosts (e.g. other frogs, snakes) or directly by the definitive host.[1]
A. americana is not infectious to humans through normal routes (skin contact, or ingestion of feces of, for instance, infected household pets). Cases of human intraocular infection with mesocercariae of this and other Alaria species have been recorded in patients who had ingested undercooked contaminated frog legs.[1] Both patients presented with pigmentary tracks in the retina, areas of active or healed retinitis and signs of diffuse unilateral subacute neuroretinitis.[1] There has been a report of a fatal infection with Alaria americana in a hiker.[3]
It is not common for A. americana to infect common household animals, but infection of dogs or cats can occur and may go unnoticed since it is harmless and asymptomatic to these animals. It can be acquired by drinking contaminated water infested with eggs that have released miracidia larvae, which are highly motile.
This article incorporates CC-BY-2.0 text from the reference[1]
Alaria americana is a species of trematode in the family Diplostomidae. All Diplostomidae species infect carnivorous mammals by living in their small intestines as mature worms. A. americana is most frequently found in temperate regions, predominantly in northern North America. Its habit is extremely diverse, as the species occupies four different hosts throughout its lifetime. It thrives in areas close to water as water is needed for several developmental stages to occur. It has been isolated to a wide range of North American mammals as definitive hosts, including cattle, lynx, martens, skunks, bobcats, foxes, coyotes, and wolves.
