Fish Pathology
Online ISSN : 1881-7335
Print ISSN : 0388-788X
Volume 49 , Issue 1
Showing 1-5 articles out of 5 articles from the selected issue
Research Articles
  • Azumi Yamashita, Akihiko Takechi, Shusaku Takagi, Ayano Sato
    2014 Volume 49 Issue 1 Pages 1-6
    Published: 2014
    Released: March 25, 2014
    Therapeutic effect of fosfomycin (FOM) was studied in red sea bream experimentally and naturally infected with Edwardsiella tarda. Minimum inhibitory concentration of FOM against 67 strains of E. tarda isolated from red sea bream cultured in Ehime Prefecture ranged from 1 to 4 μg/mL, and no strains resistant to FOM were observed. In experimental infections, the mortality decreased with the increase in FOM dosage, and a remarkable therapeutic effect of FOM was demonstrated by oral administration at a dose of 40-80 mg/kg body weight/day for 6 days. In field trials, FOM was administered to high and low mortality cases of red sea bream naturally infected with E. tarda orally for consecutive 6 days at a dosage of 40 mg/kg/day. Cumulative mortalities of the FOM-medicated groups were significantly lower than those of the non-medicated groups in both cases. In medicated groups, the administration of FOM was more efficient in the lower mortality case. These results indicate that FOM administration is effective against edwardsiellosis in red sea bream and the treatment in early stages of infection is important to obtain a favorable outcome.
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  • Shinpei Wada, Osamu Kurata, Hitoshi Hatakeyama, Azumi Yamashita, Shusa ...
    2014 Volume 49 Issue 1 Pages 7-15
    Published: 2014
    Released: March 25, 2014
    In 2008, several episodes of mortality were recorded in cultured populations of juvenile greater amberjack reared in the southwest region of Japan. Diseased fish had asymmetrical abdominal distention and pale gills. The head kidney, trunk kidney, and spleen of every fish that was examined was enlarged and discolored. The results of all microbiological and molecular biological assays of tissues taken from diseased fish were negative for major known pathogens. Histopathologically, the disease was characterized by proliferative interstitial nephritis and proliferative splenitis associated with minute, round structures within the cytoplasm of proliferating mono-nucleated cells. Transmission trial using the enlarged trunk kidney from a naturally infected fish successfully reproduced the disease. The results indicate that this disease is caused by an infectious microorganism, and the most likely etiological agent is the minute, round structures which are probably a hitherto unknown eukaryotic microorganism.
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  • Nuria Castro, Sabela Balboa, Soledad Núñez, Alicia E. To ...
    2014 Volume 49 Issue 1 Pages 16-22
    Published: 2014
    Released: March 25, 2014
    Tenacibaculum soleae is a recently described pathogen that has been reported as the causative agent of considerable losses in sole cultures in Spain. This report documents the first case of T. soleae as an etiological agent of tenacibaculosis in farmed sea bass Dicentrarchus labrax. Its identification was performed employing phenotypical, serological and molecular methods. Although the sea bass isolates were homogeneous from a biochemical, chemotaxonomic and molecular point of view, they belonged to a serological group different from the type strain CECT7292, which can be of great importance in the development of future vaccines and other methods of disease prevention in sea bass industry. Virulence assays with a representative isolate confirmed the pathogenic potential for sea bass. The disease was experimentally reproduced by prolonged bath, while no mortalities could be recorded by intraperitoneal injection. The results presented here show that T. soleae must be taken into account as an important pathogen in the marine aquaculture industry.
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