|Keywords: Mediterranean, Mariculture, Myxosporea, Enteromyxum leei
EPIZOOTIOLOGY OF Enteromyxum leei (MYXOZOA: MYXOSPOREA)
IN MEDITERRANEAN MARICULTURE SYSTEMS
A. Diamant(1)*,O. Palenzuela(2), P. Alvarez-Pellitero(2), F. Athanassopoulou(3), E. Golomazou(3) , G. Albiñana(4), F. Padrós(4), S. Crespo(4), A. Lipshitz(1), C. Ghittino(5),
F. Agnetti(5), A. Marques(6) A. Le Breton(7), J.F. Raymond(8)
(1) Israel Oceanographic and Limnological Research, National Center for Mariculture, P.O. Box 1212, Eilat 88112, Israel
(2) CSIC - Instituto de Acuicultura Torre de la Sal, Ribera de Cabanes, 12595 Castellón, Spain
(3) Laboratory of Ichthyology & Fish Pathology, Faculty of Veterinary Medicine, University of Thessaly, 221 Trikalon str., Karditsa 43100, Greece
(4) Universitat Autònoma de Barcelona, Facultat de Veterinària, 08193 Cerdanyola del Vallés, Spain
(5) Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, 06126 Perugia, Italy
(6) Ecolag UMRCNRS 5119, Université de Montpellier II, F34095 Montpellier 5, France
(7) Fish Health Consultant, F31330 Grenade sur Garonne, France.
(8) SAVU CNPMEM, F34430 Saint Jean de Védas, France.
An epizootiological survey of Enteromyxum leei was carried out on maricultured gilthead sea bream Sparus aurata and Diplodus puntazzo in 12 farms from 5 countries in the Atlantic [(Canary Islands (Spain) and English Channel (France)], western Mediterranean (Spain, France and Italy), eastern Mediterranean (Greece and Israel) and northern Red Sea (Israel). Infections were determined by use of a highly specific PCR assay. A total of 1875 fish were sampled. Nine of the farms had significant E. leei infections, with an overall mean prevalence of 20% in S. aurata. Significantly higher prevalence levels of enteromyxosis were observed in land-based pond systems vs. sea cage farms. Factors that enhance enteromyxosis in the ponds appeared to be year-round elevated water temperatures (>20ºC), poor water exchange and/or re-intake of contaminated effluent water. A prolonged culture period necessary for production of large fish (>400g) was an additional aggravating factor. Prevalence at some pond farms (e.g. in France) reached 90% in 500g fish and 100% in 700g fish towards the end of the production cycle. In S. aurata cultured in sea cage farms, infected stocks normally displayed moderate levels of enteromyxosis, but high prevalences (reaching 60% in the Red Sea) occurred in some samples. D. puntazzo juvenile stocks in sea cages in Greece displayed a very high prevalence (80%), associated with mortalities. However, survivors of such outbreaks appeared to recover fully, testing PCR-negative upon marketing and ostensibly free of infection. The implementation of sanitary management practices at infected cage farms for appreciably reducing the risk of horizontal transmission of enteromyxosis is discussed.