Metagonimoides

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Metagonimoides
Scientific classification
Kingdom:
Animalia
Phylum:
Platyhelminthes
Class:
Trematoda
Order:
Plagiorchiida
Family:
Heterophyidae
Genus:
Metagonimoides
Species:
M. oregonensis
Binomial name
Metagonimoides oregonensis
Price, 1931

Metagonimoides oregonensis is a trematode, or fluke worm, in the family Heterophyidae. This North American parasite is found primarily in the intestines of raccoons ( Procyon lotor ), American minks (Neovision vision), frogs in the genus Rana , and freshwater snails in the genus Goniobasis . [1] [2] It was first described in 1931 by E. W. Price. The parasite has a large distribution, from Oregon to North Carolina. [3] Adult flukes vary in host range and morphology dependent on the geographical location. This results in different life cycles, as well as intermediate hosts, across the United States. On the west coast, the intermediate host is freshwater snails (Goniobasis), while on the east coast the intermediate host is salamanders ( Desmognathus ). The parasites on the west coast are generally much larger than on the east coast. For example, the pharynx as well as the body of the parasite are distinctly larger in Oregon than in North Carolina. [3] The reverse pattern is observed on the east coast for uterine eggs, which are larger on the west coast. In snails, there is also a higher rate of infection in female snails than in males. [4] Research on the life history traits of the parasites have been performed with hamsters and frogs as model species.

Contents

Life cycle

In order to understand the life cycle, biologists have used hamsters as model species. Hamsters are infected with adult parasites that are able to lay eggs inside their intestines. [5] While hamsters are not an ideal host, the parasite still infects them and deposits brown eggs in the intestines. For the studies, the eggs are taken out of the hamster's intestines and put into an incubator to resemble the intestines of the hamster giving the parasites an ideal environment to grow. It only takes 23 days of incubation for the egg to hatch into a moving, ciliated miracidium. Miracidium is the stage in which the larvae are free swimming and are able to move to its first intermediate host. [6] After continual incubation of around 4 months there was no physiological change in the miracidium, which means Metagonimoides oregonensis can start infecting its first intermediate host in less than a month. This was followed by an experiment that was testing if warm water and different solutions would create the miracidium. Testing this might answer if and when the miracidium would form and be able to infect in different geological locations. All of the trials failed leaving biologist unable to give direct answers. [5]

Biologists began looking at the different life cycle stages involved in Metagonimoides oregonensis in the wild compared to the parasite in captivity. For this experiment snails were used as the intermediate host. Rediae are larvae which are produced within the sporocyst of trematodes that creates more rediae or can become cercariae. [7] Cercariae are larval trematode worms that form from rediae. [8] When the snail was infected in the wild there was no sign of immature rediae. This means there was no reproduction of the parasite. When looking at the snail in captivity though, there were signs of the immature rediae. [5] Since the snails in captivity were not being exposed to the parasite there was no reinfection occurring. In conclusion this experiment shows that rediae reproduced when they were not being continually exposed. When they were being continually exposed though, rediae were not being produced.

Primary host

In the western United States the primary host are mainly raccoons ( Procyon lotor ) with the possibility of minks ( Neovison vison ) as well. Adult Metagonimoides oregonensis are found in the intestines of these mammals. Through the parasite's eggs in the primary host's fecal matter transmission to another host is made easy. Prosobranch snails which are found in rivers and streams are then infected with miracidia from the fecal matter from the primary hosts. It is unknown if a prosobranch snail needs to ingest the miracidia to become infected, or if the miracidia are free-swimming. This is how our first intermediate host becomes infected. [2]

First intermediate host

As previously stated there are different adult morphologies of the parasite depending on the part of the United States they are in. [5] This applies to the first intermediate host as well. Considering in different parts of the country there are different species, the parasites naturally have to adapt to different hosts in order to survive. In the west it has been found that the first intermediate host are freshwater snails Juga oxytrema or Juga goniobasis . [9] While in the eastern part of the United States another species of fresh water snails ( Pleurocera goniobasis ) has been found to be the first intermediate host for Metagonimoides oregonensis. [2] Furthermore, studies have shown that the parasite can display life cycle variations also on a smaller scale, as for instance seen in different parts of Oregon. [9]

Second intermediate host

Looking at Metagonimoides oregonensis in Oregon, freshwater snails Juga silicula are its first intermediate host. There are a couple different situations that can arise concerning the life cycle. [10] It is possible that the metacercariae will immediately form within the snail it has already infected, or Metagonimoides oregonensis can produce free-swimming cercariae that will soon become metacercariae if it infects the Rana genus of frogs. [10] Studies have shown that it is possible for the cercariae to infect multiple different frogs, including red-legged frogs ( Rana aurora ), bullfrogs ( Lithobates catesbeianus , formerly Rana catesbeiana), and leopard frogs ( Lithobates pipiens , formerly Rana pipiens). In another case where Juga nigrina , another species of freshwater snail, is the first intermediate host the metacercariae can not become free-swimming and therefore do not gain a second intermediate host. [10]

In the eastern part of the United States it is believed that metacercariae does not form in the first intermediate host, but rather free swimming cercariae are formed from the rediae and immediately infect the larva of stream salamanders. One of the most common secondary intermediate hosts is the black-bellied salamander ( Desmognathus quadramaculatus ). [2] These salamanders are found mainly in streams and small rivers, and rarely seen out of the water, which could explain why they are such a popular host for the free swimming cercariae. They are only located in a couple states on the eastern side of the country, so this could also explain why this pattern is not seen on the western side. [11]

Related Research Articles

<span class="mw-page-title-main">Trematoda</span> Class of parasitic flatworms

Trematoda is a class of flatworms known as flukes or trematodes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host, where the flukes sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five traditional vertebrate classes: mammals, birds, amphibians, reptiles, and fish.

<i>Clonorchis sinensis</i> Species of fluke

Clonorchis sinensis, the Chinese liver fluke, is a liver fluke belonging to the class Trematoda, phylum Platyhelminthes. It infects fish-eating mammals, including humans. In humans, it infects the common bile duct and gall bladder, feeding on bile. It was discovered by British physician James McConnell at the Medical College Hospital in Calcutta (Kolkata) in 1874. The first description was given by Thomas Spencer Cobbold, who named it Distoma sinense. The fluke passes its lifecycle in three different hosts, namely freshwater snail as first intermediate hosts, freshwater fish as second intermediate host, and mammals as definitive hosts.

<i>Fasciola</i> Genus of flukes

Fasciola, commonly known as the liver fluke, is a genus of parasitic trematodes. There are two species within the genus Fasciola: Fasciolahepatica and Fasciolagigantica, as well as hybrids between the two species. Both species infect the liver tissue of a wide variety of mammals, including humans, in a condition known as fascioliasis. F. hepatica measures up to 30 mm by 15 mm, while F. gigantica measures up to 75 mm by 15 mm.

<span class="mw-page-title-main">Trematode life cycle stages</span>

Trematodes are parasitic flatworms of the class Trematoda, specifically parasitic flukes with two suckers: one ventral and the other oral. Trematodes are covered by a tegument, that protects the organism from the environment by providing secretory and absorptive functions.

Ribeiroia is a genus of trematode parasites that sequentially infect freshwater snails in the family Planorbidae as first intermediate hosts, fish and larval amphibians as second intermediate hosts, and birds and mammals as definitive hosts. In North America, infection by Ribeiroia has been linked to amphibians with limb malformations. The connection between parasitic infection and limb malformations has generated questions about (a) whether parasite-induced malformations in amphibians are increasing, and (b) the consequences of such abnormalities for amphibian population conservation.

<i>Echinostoma</i> Genus of flukes

Echinostoma is a genus of trematodes (flukes), which can infect both humans and other animals. These intestinal flukes have a three-host life cycle with snails or other aquatic organisms as intermediate hosts, and a variety of animals, including humans, as their definitive hosts.

<span class="mw-page-title-main">Paragonimiasis</span> Medical condition

Paragonimiasis is a food-borne parasitic disease caused by several species of lung flukes belonging to genus Paragonimus. Infection is acquired by eating crustaceans such as crabs and crayfishes which host the infective forms called metacercariae, or by eating raw or undercooked meat of mammals harboring the metacercariae from crustaceans.

Ribeiroia ondatrae, or the frog-mutating flatworm is a parasite in the genus Ribeiroia which is believed to be responsible for many of the recent increases in amphibian limb malformations, particularly missing, malformed, and additional hind legs.

<i>Fasciolopsis</i> Genus of flukes

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<i>Nanophyetus</i> Genus of flukes

Nanophyetus salmincola is a food-borne intestinal trematode parasite prevalent on the Pacific Northwest coast. The species may be the most common trematode endemic to the United States.

Halipegus eccentricus is a monoecious, digenea parasitic trematode commonly found in true frogs in North America. It was first described in 1939.

<i>Echinostoma revolutum</i> Species of fluke

Echinostoma revolutum is a trematode parasites, of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.

Echinostoma hortense is an intestinal fluke of the class Trematoda, which has been found to infect humans in East Asian countries such as Korea, China, and Japan. This parasite resides in the intestines of birds, rats and other mammals such as humans. While human infections are very rare in other regions of the world, East Asian countries have reported human infections up to about 24% of the population in some endemic sub-regions. E. hortense infections are zoonotic infections, which occurs from eating raw or undercooked freshwater fish. The primary disease associated with an E. hortense infection is called echinostomiasis, which is a general name given to diseases caused by Trematodes of the genus Echinostoma.

<i>Telogaster</i> Genus of flukes

Telogaster opisthorchis is an endoparasite in the class Trematoda within the phylum Platyhelminthes. This fluke is known for causing tumor like malformations in fishes by attaching onto its spinal region in the metacercariae form. Malformations cause fish to become more susceptible to fish eating predators allowing T. opisthorchis to continue with its lifecycle.

<i>Clinostomum marginatum</i> Species of fluke

Clinostomum marginatum is a species of parasitic fluke. It is commonly called the "yellow grub". It is found in many freshwater fish in North America, and no fish so far is immune to this parasite. It is also found in frogs. Clinostomum marginatum can also be found in the mouth of aquatic birds such as herons and egrets. They are commonly present in the esophagus of fish-eating birds and reptiles. Eggs of these trematodes are shed in the feces of aquatic birds and released into water. Aquatic birds become hosts of this parasite by ingesting infected freshwater fish. The metacercariae are found right beneath the skin or in the muscles of host fish.

Megalodiscus temperatus is a Digenean in the phylum Platyhelminthes. This parasite belongs to the Cladorchiidae family and is a common parasite located in the urinary bladder and rectum of frogs. The primary host is frogs and the intermediate hosts of Megalodiscus temeperatus are freshwater snails in the genus Helisoma.

<i>Philophthalmus gralli</i> Species of fluke

Philophthalmus gralli, commonly known as the Oriental avian eye fluke, parasitises the conjunctival sac of the eyes of many species of birds, including birds of the orders Galliformes and Anseriformes. In Brazil this parasite was reported in native Anseriformes species. It was first discovered by Mathis and Leger in 1910 in domestic chickens from Hanoi, Vietnam. Birds are definitive hosts and freshwater snail species are intermediate hosts. Human cases of philophthalmosis are rare, but have been previously reported in Europe, Asia, and America.

Coitocaecum parvum is a digeneic trematode or flatworm (Platyhelminthes) that is parasitic to the intestine of the common bully or upland bully. The common and upland bully are freshwater fish of New Zealand that C. parvum uses as its definitive host. C. parvum is a hermaphroditic freshwater trematode that can omit its definitive host and produce eggs by selfing or progenesis inside its amphipod second intermediate host

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References

  1. ↑ Price, Emmet W. (1931). "Metagonimoides oregonensis, a New Trematode from a Raccoon". Journal of the Washington Academy of Sciences. 21: 405–407.
  2. 1 2 3 4 Belden, Lisa K.; Peterman, William E.; Smith, Stephen A.; Brooks, Lauren R.; Benfield, E. F. (2012). "Metagonimoides oregonensis (Heterophyidae: Digenea) infection in pleurocerid snails and Desmognathus quadramaculatus salamander larvae in Southern Appalachian streams". Journal of Parasitology. 98 (4): 760–767. doi:10.1645/ge-2986.1. hdl: 10919/49057 . PMID   22394058. S2CID   1000470.
  3. 1 2 Lang, BZ; Dronen Jr., NO; Rachford, FW; Gleason, LN (1974). "Metagonimoides oregonensis Price, 1931 (Trematoda: Heterophyidae) from California, Washington, Oregon, and Michigan and its development in hamsters". Journal of Northwest Science. 48 (2): 125–131.
  4. ↑ Lang, Bruce Z.; Gleason, L. N.; Rachford, Fred W. (1970). "Effects of Metagonimoides oregonensis Price, 1931 (Trematoda: Heterophyidae) and Mosesia chordeilesia McMullen, 1936 (Trematoda: Lecithodendriidae) on Goniobasis proxima (Say) (Gastropoda: Pleuroceridae) in North Carolina". Journal of Parasitology. 56 (5): 836–838. doi:10.2307/3277734. JSTOR   3277734.
  5. 1 2 3 4 Burns, W. M.; Pratt, Ivan (1953). "The Life Cycle of Metagonimoides oregonensis Price (Trematoda: Heterophyidae)". Journal of Parasitology. 39 (1): 60–69. doi:10.2307/3274061. JSTOR   3274061. PMID   13035585.
  6. ↑ "Miracidium". Merriam-Webster Dictionary. Merriam-Webster.
  7. ↑ "Redia". Merriam-Webster.
  8. ↑ "Cercaria". Merriam-Webster.
  9. 1 2 Meade & Pratt 1966.
  10. 1 2 3 Lang Ford, Bennie R., Bruce Zelner; Gleason, Narry Neil; Ford, Bennie R. (1968). "Morphological differences between population samples of Metagonimoides oregonensis Price 1931 (trematoda, Heterophyidae) from Oregon and North Carolina". Journal of the Elisha Mitchell Scientific Society. 84 (2).
  11. ↑ "Checklist of Amphibian Species and Identification Guide." NPWRC :: Checklist of Amphibian Species and Identification Guide". Northern Prairie Wildlife Research Center. Archived from the original on 2009-05-13.

Sources

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