Echinostoma revolutum

Echinostoma revolutum
Two specimens of Echinostoma revolutum, from:[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Platyhelminthes
Class:	Trematoda
Order:	Plagiorchiida
Family:	Echinostomatidae
Genus:	Echinostoma
Species:	E. revolutum
Binomial name
Echinostoma revolutum (Fröhlich, 1802) Looss, 1899
Synonyms[2]
E. armatum Barker & Irvine, 1915 E. audyi Lie & Umathevy, 1965 E. columbae Zunker, 1925 E. dilatatum (Miram, 1940) Cobbold, 1860 E. echinocephalum (Rudolphi, 1819) Cobbold, 1860 E. erraticum Lutz, 1924 E. ivaniosi Mahandas, 1973 E. limicoli Johnson, 1920 E. mendax Dietz, 1909 E. microrchis Lutz, 1924 E. neglectum Lutz, 1924 E. nephrocystis Lutz, 1924 E. oxycephalum (Rudolphi, 1819) Railliet, 1896 E. revolutum tenuicollis Bashikirova, 1941 E. revolutum var. japonicum Kurisu, 1932 E. stromi Bashikirova, 1946 E. sudanense Odhner, 1910

Echinostoma revolutum is a trematode parasites, of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.^[1]

Morphology

The worms are leaflike, elongated, and an average of 8.8 mm long (8.0–9.5 mm) and 1.7 mm wide (1.2–2.1 mm). When first passed in the feces, they were pinkish red and coiled in a "c" or "e" shape. The eggs in uteri were an average of 105 μm long (97–117 μm) and 63 μm wide (61–65 μm).^[1]

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  a-e)Echinostoma revolutum
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  Cercariae of Echinostoma revolutum from snails

Life cycle

Infection of Echinostoma revolutum usually results from ingestion of raw snails or frogs that serve as an intermediate host. This parasite is predominantly found throughout North America. Two asexual generations occur in a snail or mollusc.^[3] The first snail host is penetrated by a miracidium, producing a sporocyst. Many sporocysts are produced and mother rediae emerge. Mother rediae asexually reproduce daughter rediae, which also multiply. Each rediae then develop into a cercariae, which penetrates a second host. The second host could be another snail or a tadpole, in which development into metacercaria occurs. Cercariae typically find a snail host through chemotaxis. The cercariae are attracted to the slime of the snail, which contains small peptides. The first larval stage is the miracidium, and are found to be attracted to macrocmolecular glycoconjugates associated with a possible snail host. Environmental stimuli such as light and gravity can also be used to assist in searching for a host.

Distribution

Echinostoma revolutum is the most widely distributed species of the known 20 Echinostomatidae species; it is found in Asia, Oceania, Europe, and the Americas.^[8] In Asian countries the disease is endemic to humans. Outbreaks have been reported in North America after travellers returned from Kenya and Tanzania.^[9]

In humans

In Pursat Province, Cambodia, children eating undercooked snails or clams were identified as a possible source of infection in humans.^[1]

References

Further reading

Kelly, Cynthia (2009). "Echinostoma revolutum". Archived from the original on 13 August 2007. Retrieved 2017-02-17.