First observations of carp erythrodermatitis caused by atypical Aeromonas salmonicida in Israeli bred Cyprinus carpio

The majority of Israeli fish farms that breed goldfish of the species Carassius auratus have dealt with goldfish ulcer disease since early 1980. During the spring of 1997 the first case of carp erythrodermatitis was observed within the Israeli leather common carp population, Cyprinus carpio (line Dor 70 x Yugoslavia). The disease spread quickly throughout the central and northern regions of the country, with the number of affected farms reaching 37 by summer 1999. Coomassie-positive, slow-growing bacteria were cultured from the wounds of affected fish. The isolates were compared with a strain of atypical Aeromonas salmonicida cultured from Israeli goldfish. This was accomplished by phenotypic and biochemical criteria as well as PCR and SDS-PAGE. Most of the isolates demonstrated an outer membrane protein profile seen in the atypical strain as well as a major 50 kDa outer membrane protein comparable to virulent A-protein of A. salmonicida. The 1400 bp vap gene was also cloned by PCR. Blood serum chemistry demonstrated an acute disease status.