ABSTRACT. In intensive fish rearing system, fish are kept in high densities and their chance to be exposed to micro organisms that can cause infection, such as bacteria, parasites or viruses, is very high. Under these circumstances, the problem of infectious diseases is becoming very important and has significant results. Bacterial and viral diseases of the cultured fish species have led to high mortalities and have decreased the income of the fish farming industries. There are many examples in the Mediterranean Sea, in the production of sea bream (Spams aurata), sea bass (Dicentrarchus labrax) and many other cultured fish species. In the last years, this production has been followed by important outbreaks of known diseases and also by the appearance and identification of new ones. Until recently, for the control of the bacterial and parasite diseases, only antibiotics and chemical products were used that often demonstrated side effects, like residues in the fish muscle, development of resistance to the antibiotics and environmental pollution. Moreover, for the viral diseases, for which there is no treatment, the onset of the disease usually demands the destruction of the infected population. All the above, showed that there was a need to find methods to prevent the infection of the fish populations and this led to the development of vaccines. At the beginning, vaccines were produced only for the most common diseases and were easy to prepare bacterial vaccines, for example for vibriosis, furunculosis and red mouth disease (ERM). Nowadays, the production of new and more effective vaccines has began, even for diseases that are caused by viruses, like the subunit vaccines, the live recombinant and the genetic vaccines.Keywords: vaccines, Mediterranean, aquaculture ΠΕΡΙΛΗΨΗ. Στις υδατοκαλλιέργειες, σύμφωνα με το εντατικό σύστημα εκτροφής, τα ψάρια εκτρέφονται σε υψηλές ιχθυο-πυκνότητες και η πιθανότητα έκθεσης τους σε μικροοργανισμούς, που προκαλούν νοσήματα, όπως βακτήρια, παράσιτα ή ιοί, κατά τη διάρκεια του παραγωγικού κύκλου, είναι πολύ υψηλή. Βακτηριδιακά και ιογενή νοσήματα των εκτρεφόμενων ψαριών έ χουν προκαλέσει υψηλές θνησιμότητες και έχουν μειώσει τα οικονομικά έσοδα της βιομηχανίας των ιχθυοκαλλιεργειών. Τα πα ραδείγματα είναι πολλά. Στη Μεσόγειο, τα τελευταία χρόνια, η παραγωγή της τσιπούρας (Sparus aurata), του λαυρακιού (Dicentrarchus labrax), καθώς και διαφόρων άλλων, νέων, εκτρεφόμενων ειδών, έχει συνοδευτεί από σοβαρές εξάρσεις γνω στών νοσημάτων, καθώς και από την εμφάνιση και αναγνώριση νέων. Μέχρι πρόσφατα, για τον έλεγχο των βακτηριδιακών και παρασιτικών νοσημάτων χρησιμοποιούνταν αποκλειστικά μόνο αντιβιοτικά και χημικά προϊόντα, τα οποία όμως συχνά εμφα νίζουν ανεπιθύμητες παρενέργειες, όπως κατάλοιπα στη σάρκα των ψαριών, ανθεκτικότητα αντοχής των βακτηριδίων και μό λυνση του υδάτινου περιβάλλοντος. Επιπρόσθετα, για ιογενεις ασθένειες, για τις οποίες δεν υπάρχει θεραπεία, η εμφάνιση της ασθένειας στις εγκαταστάσεις των μονάδων συνήθως απαιτεί την καταστροφή του προσβεβλημένου πληθυσμού. Όλα ...
Enteromyxum leei, Ceratomyxa spp., Polysporoplasma spans are myxosporea usually found in cultured Mediterranean marine fish. The present study refers to the evaluation of the seasonality and prevalence caused by myxosporea infections in cultured sharpsnout seabream (Puntazzo puntazzo C.) and gilthead seabream {Spams aurata L.). The main target organ of all infected fish was the intestine and some-times the gallbladder and the kidney were also target organs. The highest prevalence was observed during summer in cultured sharpsnout seabream. P. sparis has been observed in gilthhead seabream, which proved to be the main host of this parasite, but it was also observed in cultured sharpsnout seabream. The main target organ in all infected fish was the kidney. The highest prevalence was observed during summer in cultured gilthead seabream. Mature spores of Ceratomyxa diplodae were observed in sharpsnout seabream. The main target organ of the parasite in cultured fish was the gallbladder. The morphology and size observations of myxosporeans mentioned above were also studied. Freezing in -20 °C (for 1 and 6 months) and the effect of Giemsa staining in myxosporean mature spore's size were evaluated. According to the results, 6 months freezing and Giemsa staining reduced significantly the size of mature spores. Finally, the protocol for Giemsa staining for the three different myxosporea species, usually found in cultured mediterranean marine fish, was standardized. Fresh smears were stained by Giemsa, according to protocol used for fresh smears. For E. leei the best results were obtained after immersing the smears in the stain for 20 min, for C diplodae after immersing the smears in the stain for 30 min and for P. sparis after immersing the smears in the stain for 24 min.
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