Occurrence of the Myxosporean Emaciation Disease Caused by Enteromyxum leei in Cultured Japanese Flounder Paralichthys olivaceus
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Abstract:
The myxosporean emaciation disease has been recently found in Japanese flounder Paralichthys olivaceus cultured in land-based tanks in Miyazaki Prefecture, Japan. Affected fish showed external signs of distended abdomen, rectal prolapse, sunken eyes and a typical bony ridge on the skull. Parasitological and histopathological examinations revealed that the developmental stages of Enteromyxum Ieei parasitized the intestinal epithelium of diseased fish. No other enteric myxozoans were observed in the affected fish. A molecular analysis of SSU rDNA confirmed that the causative myxozoan was identified as E. leei. Experimental transmission of E. leei was achieved to naive Japanese flounder and tiger puffer Takifugu rubripes by feeding with gut tissues taken from infected Japanese flounder. The present study indicates that the myxosporean emaciation disease of Japanese flounder is caused by E. leei.Keywords:
Emaciation
Paralichthys
Myxozoa
Takifugu rubripes
Myxosporea
Olive flounder
Takifugu rubripes
Myxozoa
Emaciation
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The myxosporean emaciation disease has been recently found in Japanese flounder Paralichthys olivaceus cultured in land-based tanks in Miyazaki Prefecture, Japan. Affected fish showed external signs of distended abdomen, rectal prolapse, sunken eyes and a typical bony ridge on the skull. Parasitological and histopathological examinations revealed that the developmental stages of Enteromyxum Ieei parasitized the intestinal epithelium of diseased fish. No other enteric myxozoans were observed in the affected fish. A molecular analysis of SSU rDNA confirmed that the causative myxozoan was identified as E. leei. Experimental transmission of E. leei was achieved to naive Japanese flounder and tiger puffer Takifugu rubripes by feeding with gut tissues taken from infected Japanese flounder. The present study indicates that the myxosporean emaciation disease of Japanese flounder is caused by E. leei.
Emaciation
Paralichthys
Myxozoa
Takifugu rubripes
Myxosporea
Olive flounder
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Myxosporean emaciation disease of cultured red sea bream Pagrus major and spotted knifejaw Oplegnathus punctatus has recently occurred in Japan. Morphological features and molecular analysis of SSU rDNA indicated that myxozoans from the intestine of affected fishes were identified as Enteromyxum leei, one of the causative organisms of the emaciation disease of tiger puffer Takifugu rubripes. A one-year periodic examination of E. leei infection in cultured red sea bream revealed that cumulative mortalities reached about 10% during the first summer, but surviving fish were not infected in the following year. Experimental transmission of E. leei from infected tiger puffer to naive red sea bream was achieved by both cohabitation with infected fish and exposure to effluent from a tank containing infected fish. This study suggests that fish-to-fish transmission occurs among different fish species in culture fields.
Takifugu rubripes
Pagrus major
Emaciation
Myxozoa
Sparidae
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In the present study, we isolated three populations of Myxobolus ampullicapsulatus from the gills of crucian carp, Carassius auratus auratus, two from Yongchuan, Chongqing area and one from Poyang Lake, Jiangxi area, China, sequenced their complete small subunit ribosome RNA gene, analyzed their genetic distance and gene similarity, and explored their relationship based on Bayesian inference and maximum likelihood analyses of their small subunit ribosomal DNA. The results combined with their morphological characteristics suggest that M. ampullicapsulatus infecting the gills and pharynx of allogynogenetic gibel carp, Carassius auratus gibelio, should be Myxobolus honghuensis. This study highlights the importance of DNA sequence comparisons for distinguishing Myxobolus species and indicates that the intra-species identification for the two Myxobolus species mentioned in the present research should be less than ten variation sites. In morphology, M. honghuensis Liu et al. (2012) parasitic on the gills of C. auratus auratus (goldfish) was collected from Chongqing area, and its mature spore was 16.5-19.5 × 8.5-10.0 μm in size, polar capsule was 7.0-10.0 × 2.5-4.0 μm in size, and polar filament had 9-10 coils. M. honghuensis Liu et al. (2012) isolated from the pharynx of C. auratus gibelio was sampled in Hubei area, and its mature spore was 15.1-19.5 × 9.0-11.3 μm in size, polar capsule was 7.9-8.1 × 3.0-4.5 μm in size, and polar filament had 7-8 coils.
Myxosporea
Myxozoa
Myxobolus
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The examination of gills from 240 fish from Paraná river, Brazil, showed the presence of small cysts in five fish species. Observation of the cysts showed they are plasmodia of Henneguya spp. (Myxozoa, Myxosporea, Myxobolidae). The morphometric and morphologic characteristics of the parasites are described.
Myxosporea
Myxozoa
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Experimental transmission of Myxidium fugu and Myxidium sp. TP (formerly described as Myxidium sp. in tiger puffer Takifugu rubripes) among tiger puffer was successful by the following 3 methods; 1) feeding infected gut tissue, 2) cohabitation with infected fish, 3) exposure to effluent from a tank containing infected fish. Regardless of the transmission methods, prevalences of infection in the intestine with M. fugu reached 100%. However, those with Myxidium sp. TP, which is suspected of an etiological agent of the emaciation disease, varied among experiments conducted in different months, suggesting that development of Myxidium sp. TP was strongly influenced by the ambient temperature. It was evident that trophozoites of Myxidium sp. TP excreted from the infected fish were transmittable directly to other fish. Mortalities and morbidities in fish experimentally infected with Myxidium sp. TP seemed to be associated with the parasite's development which might be promoted by higher temperature. The present study suggests that fish-to-fish transmission of Myxidium spp. occurs in sea cages, inducing a rapid spread of the emaciation disease among farmed tiger puffer.
Myxozoa
Emaciation
Takifugu rubripes
Myxosporea
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Myxosporea
Myxozoa
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Myxosporea
Myxozoa
West bengal
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Enteromyxum leei has been reported to cause emaciation disease in various fish species. To determine the effect of parasite intensity on cultured olive flounder Paralichthys olivaceus, we investigated the relationship between the relative condition factor (rCF = CF/standard CF × 100) and parasite load with quantitative polymerase chain reaction (qPCR) and the challenge test. A total of 57 cultured olive flounders were obtained from 11 fish farms and divided into five groups based on their rCF. We investigated the parasite intensity in the posterior intestine of the fish. The parasite load was closely matched to severe loss of body weight. In addition, olive flounders were inoculated either orally or anally with intestinal scrapings of infected fish or phosphate-buffered saline. The fish were reared at natural water temperature and transferred to different tanks, and the water temperature was adjusted to 20°C after 6 weeks of inoculation. When the water temperature was increased to 20°C, the rCF decreased in the experimentally infected group. The results demonstrated that qPCR can be utilized to determine the relative abundance of E. leei in olive flounders and water temperature is an important factor to track the progress of the emaciation disease.
Paralichthys
Olive flounder
Myxozoa
Myxosporea
Emaciation
Parasite load
Trichodina
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