Bucephalus polymorphus

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Bucephalus polymorphus
Bucephalus EncBrit1911.png
Cercaria larva of B. polymorphus from Encyclopædia Britannica, Eleventh Edition
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Platyhelminthes
Order: Plagiorchiida
Family: Bucephalidae
Genus: Bucephalus
Species:
B. polymorphus
Binomial name
Bucephalus polymorphus
Baer, 1827

Bucephalus polymorphus is a type of flatworm. This species is within the Bucephalidae family of Digenea, which in turn is a subclass of Trematodes within the phylum Platyhelminthes (i.e. flatworm). It is characterized by having a mouth near the middle of its body, along with a sac-like gut. The mouth opening is located in the centre of the ventral surface. This is a specific body type of cecaria known as a gastrostome.

Contents

The adults occur in the gut of marine and fresh-water fish. The metacercariae encyst in smaller fish, sometimes in the nervous system. These parasitic flatworms are dorso-ventrally flattened animals [1] characterized by a bilaterally symmetrical body enclosed within a syncytial tegument. They have a distal, anucleate later (distal cytoplasm). The distal cytoplasm contains vesicular inclusions that are Golgi derived. [2] The adults of these acoelomate worms are common in the digestive tract, but are also found in other organs of vertebrates. The adult parasite attaches via a characteristic anterior adhesive organ with tentacles. This organ is recognized as a holdfast, which helps Bucephalus to stay attached to the host's organs. [3] Bucephalus are native to North American fresh waters that parasitize freshwater bivalves. [4]

Taxonomy

Bucephalid cercaria larva from Ernst Haeckel's Kunstformen der Natur (1904). Haeckel Platodes Bucephalus.png
Bucephalid cercaria larva from Ernst Haeckel's Kunstformen der Natur (1904).

The genus Bucephalus was based on this species, which was the earliest known, initially described by Baer (1827) from its cercaria. Von Siebold (1848) believed that the adult bucephalid he named Gasterostomum fimbriatum represented an adult form of the same bucephalid, but this identity has never been proven. [5]

Life cycle

Dignetic flatworm species require more than one host to complete a full life cycle. Bucephalus polymorphus requires three hosts. Dreissena polymorpha, a small freshwater mussel, is the first intermediate host parasitized by the hatching miracidium. Within the visceral mass of Dreissena, the miracidium transforms into a mother (primary) sporocyst. Asexual reproduction produces many daughter (secondary) sporocysts which are called cecariacysts, that eventually release cercariae. Unlike most digenetic trematodes, Bucephalus Polymorphus lacks a redial stage and thus emerges as a cecaria directly from the sporocyst stage. Rapid proliferation of sporocysts results in a knotted white mass of tubules, which is found primarily in the gonads of the mussel. Released from the infected mussels, cercariae attach to fish (second intermediate host), encyst, and transforms into metacercariae. The third (definitive) hosts are predatory fish that consume the infected foraging fish. [6] It has been shown experimentally that cercarial emergence exhibits a circadian rhythm of shedding with a peak in the dark period of a light:dark 12:12 h photoperiod. [7] Bucephaluslifecycle.jpg

Influence on Host

Bucephalus polymorphus is a parasite residing exclusively in host connective tissues. The gonads of its first intermediate host, Dreissena, is the primary target of infection and sporocyst proliferation. As infection intensifies, the sporocyst develops branches through connective tissue passages, emerges from the gonads, and can spread into other body regions. Such secondary sites of infection have been previously reported to occur in the digestive glands, the gills, the bundles of adductor muscle, and the mantle epithelium lining the interior of the shells. [4] [8] [9] The study found that the digestive glands of infected bivalves appeared to be relatively normal when compared to full bodied, uninfected specimens. Within the sporocyst, the cercariae existed within a wide range of developmental stages, indicating that its development is asynchronous. It was also observed that heavy infection of the parasite led to host castration, which left the entire gonadal space often occupied by the sporocysts. By limiting the infection almost exclusively to the gonads, the parasites have developed an interesting strategy to only use the reproductive energy of their hosts, thereby minimizing the risk of host mortality. Extending the life of a bucephalus infected host is important because this allows the parasite to proliferate continuously from year to year, since infected gonads produce cercariae instead of gametes. [10] The location of the sporocyst (primarily in gonads), its overall shape, irregular branches, and the morphology of its cercariae with a bifurcated tail, distinguish B. polymorphus from other trematode parasites of zebra mussels in histological sections.

Prevalence

Infection of B. polymorphus is geographically widely distributed. However, prevalence of infection in zebra mussel population is not common. [11] A study by Lajtner et al., which surveyed the zebra mussel population in the Drava River in Croatia, found a prevalence of 21.3%. In the most extensive study conducted to date, a prevalence of 73% was recorded in zebra mussel in South-Eastern France. [12] Low rates of prevalence were also recorded: 1% (Kuperman et al. 1994), [13] 1-4% (Baturo 1977), [9] 2-5% (Smirnova and Ibrasheva 1967), [14] 9% (Malloy et al. 1996), [4] and 13-28% (de Kinkelin et al. 1968). [8] Therefore, the prevalence of Bucephalus polymorphus can vary widely depending on the ecosystem.

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Trematode life cycle stages

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.

Swimmers itch Medical condition

Swimmer's itch, cercarial dermatitis or schistosome dermatitis is a short-term allergic immune reaction occurring in the skin of humans that have been infected by water-borne schistosomes, a type of flatworms. It is common in freshwater, brackish and marine habitats worldwide. Incidence may be on the rise, although this may also be attributed to better monitoring. Nevertheless, the condition has been regarded as an emerging infectious disease.

<i>Echinostoma</i> Genus of flukes

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<i>Leucochloridium paradoxum</i> Parasitic flatworm

Leucochloridium paradoxum, the green-banded broodsac, is a parasitic flatworm. Its intermediate hosts are land snails, usually of the genus Succinea. The pulsating, green broodsacs fill the eye stalks of the snail, thereby attracting predation by birds, the primary host. These broodsacs visually imitate caterpillars, a prey of birds. The adult parasite lives in the bird's cloaca, releasing its eggs into the faeces.

<i>Leucochloridium variae</i> Species of fluke

Leucochloridium variae, the brown-banded broodsac, is a species of trematode whose life cycle involves the alternate parasitic invasion of certain species of snail and bird. While there is no external evidence of the worm's existence within the bird host, the invasion of the snail host involves the grotesque swelling of one or both of the snail's eye stalks. This invasion does not cause the snail's death.

<i>Nanophyetus</i> Genus of flukes

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


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<i>Heterophyes heterophyes</i> Species of fluke

Heterophyes heterophyes was discovered by Theodor Maximaillian Bilharz in 1851. This parasite was found during an autopsy of an Egyptian mummy. H. heterophyes is found in the Middle East, West Europe and Africa. They use different species to complete their complex lifestyle. Humans and other mammals are the definitive host, first intermediate host are snails, and second intermediate are fish. Mammals that come in contact with the parasite are dogs, humans, and cats. Snails that are affected by this parasite are the Cerithideopsilla conica. Fish that come in contact with this parasite are Mugil cephalus, Tilapia milotica, Aphanius fasciatus, and Acanthgobius sp. Humans and mammals will come in contact with this parasite by the consumption of contaminated or raw fish. This parasite is one of the smallest endoparasite to infect humans. It can cause intestinal infection called heterophyiasis.

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>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.

<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.

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<i>Bucephalus</i> (trematode) Genus of flukes

Bucephalus is the genus name for many trematode flatworms that are parasites of molluscs and fish. Like other Bucephalidae, they are found in fish both as adults and as metacercariae. In marine and freshwater teleosts, they live as parasites inside the digestive tract, especially the intestine.

<i>Alaria</i> (trematode) Genus of flukes

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<i>Metagonimus yokogawai</i> Species of fluke

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Heterobilharzia is a genus of trematodes in the family Schistosomatidae. The species Heterobilharzia Americana is a parasite of the Southeastern United States and typically found in raccoons. Species of this genus are responsible for Schistosoma in canines. Cercariae found in freshwater may also cause Swimmer's itch in humans.

References

  1. ↑ "Platyhelminthes -- Encylopedic Reference of Parasitology". Archived from the original on 2009-03-12. Retrieved 2009-05-08.
  2. ↑ G. Schmidt and L. Roberts: Foundations of Parasitology (Seventh Ed.) McGraw-Hill. New York, NY, 2005.
  3. ↑ Yamaguti, S.: Synopsis of digenetic trematodes of vertebrates Keigaku Publishing Company. Tokyo, 1971.
  4. 1 2 3 Malloy et al.: "Survey of the Parasites of Zebra Mussels (Bivalvia: Dreissenidae) in Northwestern Russia, with Comments on Records of Parasitism in Europe and North America." J. Helminthol. Soc. Wash. 63(2), 1996, pp. 251-256
  5. ↑ Gibson, David Ian (2002). Keys to the Trematoda. CABI. pp. 74–75. ISBN   0-85199-547-0.
  6. ↑ Malloy et al.: “Natural Enemies of Zebra Mussels: Predators, Parasites, and Ecological Competitors”. Dreissena: Zebra Mussel Information Clearinghouse. 7(6), Winter-Spring 1997.
  7. ↑ Smyth, J. D.; Wakelin, Derek (1994-11-24). Introduction to Animal Parasitology. ISBN   9780521428118.
  8. 1 2 de Kinkelin et al.: "Etude epizootiologique de la bucephalose larvaire a Bucephalus polymorphus (Baer 1827) dans le peuplement piscicole du bassin de la Seine." Recherches Veterinaires, 1, 77-98, 1968
  9. 1 2 Baturo B.: "Bucephalus polymorphus Baer, 1827 and Rhipidocotyle illense (Ziegler, 1883)(Trematoda, Bucephalidae): morphology and biology of developmental stages." Acta Parasitologica Polonica, 24, 203-220, 1977.
  10. ↑ Taskinen et al.: "Studies on bucephalid digeneans parasitising molluscs and fishes in Finland. I. Ecological data and experimental studies." Systematic Parasitology, 19:81-94, 1991.
  11. ↑ Lajtner et al.: "The effects of the trematode Bucephalus polymorphus on the reproductive cycle of the zebra mussel Dreissena polymorpha in the Drana River." Acta Parasitologica, 53(1), 85-92, 2008.
  12. ↑ Wallet M., Lambert A. "Enquete sur la repartition et l'evolution du parasitisme a Bucephalus polymorphus Baer, 1827 chez le mollusque Dreissena polymorpha dans le sud-est de la France." Bulletin Francais de la Peche et de la Pisciculture, 300, 19-24, 1986.
  13. ↑ Kuperman et al. "Parasites of Dreissena polymorpha (Pallas) molluscs of the Volga basin." Parazitologiya, 28, 396-402, 1994.
  14. ↑ Smirnova and Ibrasheva: "Larval trematodes from freshwater molluscs in the western Kazakhstan." Trudy Instituta Zoologii Akademii Nauk Kazakhskoy SSR, 27, 53-87, 1967.
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