Efficacy and toxicity of orally administered anticoccidial drugs for innovative treatments of Polysporoplasma sparis (Sitja-Bobadilla and Alvarez-Pellitero 1985) infection in Sparus aurata L.

The purpose of this study was to test experimentally different drugs and therapeutic schemes in order to find a efficient commercial treatment for fish infected with myxosporeans. Two series of land‐based experiments and one experimental cage trial were performed for this purpose. In the first land‐based experiment, 10 and 30 g Sparus aurata naturally infected in the kidneys with Polysporoplasma sparis were used. Initially, six different doses of Fumagillin, two doses of Toltrazuril, and one dose of Amprolium, ESB₃ and Salinomycin were tested. In the second land‐based experiment, 25 and 50 g fish infected with the same parasite were treated with Origanum essential oils, Toltrazuril with propylene glycol, Amprolium, and a combination of Salinomycin 12% + Amprolium (SA). In the field trials, 15 and 155 g S. aurata infected with the same parasite were treated with SA, Origanum essential oils and Fumagillin. In all trials the drugs were incorporated in food and administered according to the selected schemes, while their efficacy was evaluated in terms of mortality (acceptable level <2%), pathology and prevalence rate of P. sparis. According to our results the SA combination proved to be the most effective treatment against P. sparis infection in S. aurata: (i) the therapeutic scheme and commercial product used was not toxic and (ii) a significant reduction in percentage of prevalence was observed.