Miracidium are are positively phototactic. Cercariae are negatively phototactic (Kanev, 1994).
Perception Channels: visual ; chemical
The world-wide population size of this species is unknown. It has not been considered for conservation status by any agency.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Adult E. revolutum use avian species, primarily waterfowl as their definitive hosts. Adults are hermaphrodites and live four to eight weeks, occupying the digestive tract of infected birds (Sorensen and Minchella, 1998). Adults begin to produce and release many self-fertilized eggs ten days after infecting the definitive host (Kanev, 1994).
Eggs: The eggs hatch in fresh water in nine to twelve days. Exposure to light stimulates hatching. Eggs hatch into miracidia (Kanev, 1994).
Miracidium: The swimming larval stage can survive six to eight hours before it finds a primary intermediate host, which must be a snail in the family Lymnaeidae (Kanev, 1994). Once a miracidium successfully infects the ovotestis/digestive gland area of the host, it asexually produces three distinct asexual stages, a mother sporocyst and two subsequent redial stages over the course of a month (Sorensen and Minchella, 1998). The final redial produces infective free living cercaria for 25 to 28 days (Kanev, 1994). The cercaria exits the primary intermediate host and infects a secondary intermediate host.
Cercariae: The initialy free-living form infects an aquatic secondary intermediate host within three to six hours. This host can be various pulmonate and prosobranch snails, freshwater mussels (Unionidae), frogs, and freshwater turtles (Testundines) (Kanev, 1994). In the host, cercaria asexually produce metacercariae (Sorensen and Minchella, 1998).
Metacercariae: This stage becomes infective within one to two days (Kanev, 1994). It remains in this stage until the secondary intermediate host has been eaten by the definitive vertebrate host, usually a bird. Once ingested, metacercariae develop into hermaphroditic adults (Sorensen and Minchella, 1998).
Development - Life Cycle: metamorphosis ; diapause
Worms in the genus Echinostoma have been known to infect humans who have eaten raw snails or other molluscs.
Negative Impacts: injures humans (causes disease in humans )
In Indonesia, Suhardono et al. (2006) have shown that E. revolutum will act competitively to infect Lymnaea rubiginosa. L. rubiginosa is more commonly infected by Fasciola gigantica. L. rubiginosa infected with F. gigantica causes fasciolosis in cattle stocks feeding on harvested rice crop infested with the snails. E. revolutum will compete with F. gigantica, and when successful, prevents F. gigantica from infecting L. rubiginosa (a necessary stage in its life cycle). Inhibition of F. gigantica prevents further life stages and consequently prevents parasitic infection of cattle. E. revolutum will occupy the intermediate host (L. rubiginosa) but will not infect the cattle feeding on the rice crop.
Infection of Lymnaea elodes by E. revolutum significantly affects growth, fecundity, and survival rates (Sorensen and Minchella, 1998). Snail mortality between zero and four weeks post infection can be attributed to an increase in energetic demands and starvation, while snails four to seven weeks post infection die from tissue degredation (Sorensen and Minchella, 1998).
At five weeks post infection E. revolutum pathology involves destruction of the digestive gland and ovotestis (Sorensen and Minchella, 1998). This type of parasitic castration along with reduced nutrients results in a reduction in snail egg production. It is proposed by Sousa (1983) that gigantism will occur in trematode infected mollusc species because excess host energy reserves are made available via parasitic castration.
Brown et al. (1988) and Sorensen and Minchella (1998) both demonstrate a correlation between increased snail size and trematode infection. E. revolutum infection tends to cause gigantism in lymnaea species. In 1975, Baudoin presented hypotheses to explain the correlation between host size and prevalence of infection. These hypotheses included three basic mechanisms including increased host growth rates, host mortality rates, and host size-specific preferences of parasites. It is proposed that a combination of multiple hypotheses will result in gigantism of the host (Sorensen and Minchella, 1998).
Species Used as Host:
Sporocysts lack ambulatory musculature and absorb primary intermediate host nutrients via their tegument. Rediae have a muscular pharynx and primitive gut. Rediae actively consume and digest primary intermediate host tissues while moving throughout the infected host (Sorensen and Minchella, 1998).
Echinostoma revolutum can be found in the snail Lymnaea elodes in North America (Serensen et al., 1997) and in other lymnaeid species across Eurasia. It has been reported from Germany, Austria, Poland, Bulgaria, England, Russia, Malaysia, Thailand, India, and Vietnam (Kanev, 1994).
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native )
Eggs of Echinostoma revolutum are found in fresh water habitats (Kanev, 1994) where waterfowl occur. The subsequent life stages are all found in intermediate or definitive hosts, all of which are found in the same still or slow-moving freshwater habitats. As a miracidium, E. revolutum can be found in the ovotestis or digestive gland of the intermediate host (Kanev, 1994). Studies have shown that Lymnaea stagnalis is a widespread spread and common intermediate host for E. revolutum (Kanev, 1994).
Habitat Regions: temperate ; tropical ; freshwater
Aquatic Biomes: lakes and ponds; temporary pools
Wetlands: marsh ; swamp
E. revolutum is the nominal member of the 37-collar-spined E. revolutum group (Kanev, 1994; Kanev et al., 1995). The group consists of the closely related species: E. revolutum (Froelich, 1802), E. echinatum (Zeder, 1803), E. trivolvis (Cort, 1914), E. jurini (Skvortzov, 1924), E. caproni (Richard, 1964), and E. paraensei (Lie and Basch, 1967). All miracidia in this group have eighteen epidermal plates, showing a common pattern of 6:6:4:2 (anterior to posterior), six body papillae, two eyespots, and two excretory pores (Dimitrov et al., 1999).
At time of initial infection, metacercariae average 240 micrometers long and 0.02 square mm in body area. By day 14 post infection, worms reach an average of 3.5 mm in length and 2.0 square mm in body area (Humphries et al., 1997).
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
We have no information on particular predators of this species. It is likely that the host-seeking stages (miracidia, cercariae) are consumed by predators that eat zooplankton. This species depends on predation of its intermediate host to enter its definitive avian hosts.
Adult Echinostoma revolutum are hermaphrodites, and produce both self-fertilized and cross-fertilized eggs once in the definitive host. We have no information on mating behavior or mating systems in this species.
This species reproduces asexually at two stages in its life cycle. Sporocysts and rediae, both produce large numbers of offspring asexually, resulting in hundreds or thousands of cercarie generated from a single parent miracidium infecting a snail. Adults worms are hermaphroditic and self- and cross-fertilize.
'Echinostome Echinostoma parasitism peaks in the late summer and wanes throughout the winter (Sorensen and Minchella, 1998).
The trematode, E. revolutum, has a complex three-host life cycle. Adult E. revolutum use avian species, primarily waterfowl as the definitive host (Sorensen and Minchella, 1998). Adults are hermaphrodites and live four to eight weeks. Adults begin to produce and release many self fertilized eggs ten days after infecting the definitive host (Kanev, 1994). Adults after 14 days contain at least 50 eggs (Humphries et at., 1997). Eggs are passed by feces of the definitive host (Sorensen and Minchella, 1998).
Breeding interval: Echinostome parasitism peaks in the late summer and wanes throughout the winter
Range gestation period: 9 to 12 days.
Average gestation period: 10-12 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; simultaneous hermaphrodite; sexual ; asexual ; fertilization (Internal ); oviparous
There is no parental investment beyond the limited provisioning of eggs.
Parental Investment: no parental involvement; pre-fertilization (Provisioning)
Echinostoma revolutum is a trematode parasites, of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.[1]
Echinostoma revolutum is the most widely distributed species of the known 20 Echinostomatidae species; it is found in Asia, Oceania, Europe, and the Americas.[3] In Asian countries the disease is endemic to humans. Outbreaks have been reported in North America after travellers returned from Kenya and Tanzania.[4]
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]
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.[5] 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.
Intermediate hosts of Echinostoma revolutum include:
In Pursat Province, Cambodia, children eating undercooked snails or clams were identified as a possible source of infection in humans.[1]
The first reported human infection was in Taiwan in 1929.[1] The prevalence of Echinostoma revolutum trematodes in Taiwan during 1929–1979 varied from 0.11% to 0.65%.[1] Small Echinostoma revolutum–endemic foci or a few cases of human infection were discovered in the People's Republic of China, Indonesia, and Thailand until 1994.[1] However, no information is available about human Echinostoma revolutum infection after 1994, even in areas where the parasite was previously endemic.[1] In 2007 prevalence of E. revolutum adults in school children in Pursat Province, Cambodia ranged from 7.5% to 22.4%.[1]
Authors reported echinostomiasis as an endemic trematode infection among schoolchildren in Pursat.[1]
Signs of infection in humans due to this type of fluke can result to weakness and emaciation. In cases where infection is heavy, hemorrhagic enteritis can occur.
Echinostoma revolutum could be detected through observing feces containing eggs under a microscope.
Albendazole and praziquantel[1] are typically prescribed to rid the parasite from the body.
Echinostoma revolutum is a trematode parasites, of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.
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