engleski

EFFICACY OF TRIMETOSUL 48% SUSPENSION AGAINST EIMERIA DICENTRARCHI INFECTION IN EUROPEAN SEA BASS: A PRELIMINARY STUDY

Information on the control of coccidial infections in fish is scare in the literature. The purpose of this study was to assess efficacy of Trimetosul 48% suspension for the treatment of Eimeria dicentrarchi infection in cultured European sea bass. Furthermore, the study presents the actual site of infection of this coccidian species. A case of vibriosis (caused by Listonella anguillarum was observed in a cage among juvenile European sea bass (Dicentrarchus labrax L.). Fish (average body weight 49 g) were treated with Trimetosul 48% suspension (VETERINA d.o.o.) administered orally at a daily dose of 9.84 mg of trimethoprim and 49.2 mg of sulfadiazine per kg of body weight for a period of 9 days. To prepare the medicated feed, the suspension was diluted in water and sprayed onto commercial pellets. Prior to and after treatment, a total of 60 fish were examined for coccidial infection. The infection was evaluated in fresh preparations of mucus and mucosal scrapings and in histological sections. For purpose of histological examination, the digestive tract was divided into stomach, pyloric caeca, anterior and posterior intestine. Small samples of each were fixed in a 10% buffered formaldehyde solution. The fixed material was embedded in paraffin and serially sectioned at 5 μm. Sections were stained with haematoxylin and eosin, toluidine blue and periodic acid-Schiff reaction. Several sections were also stained with alcian blue at pH 2.5. Prior to treatment, 19 of 30 fish (63.3%) were found to be infected with E. dicentrarchi. Oocysts were in a sporulated stage in both mucus and mucosal scrapings. Unsporulated and semisporulated oocysts were also observed within the same material, although only occasionally. Histological examination revealed that the infection was restricted to the pyloric caeca, anterior and posterior part of the intestine. However, the infection was more intense in the anterior intestine. Following treatment, no E. dicentrarchi infection was observed. The results of this preliminary study suggest that Trimetosul 48% suspension could be affective in the treatment of E. dicentrarchi infection in European sea bass.

Eimeria dicentrarchi; Trimetosul; European sea bass

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