ERYTHRODERMATITIS A NEW AND INCREASINGLY PREVALENT DISEASE IN ISRAEL
and S. Maurice2
Central Fish Health Laboratory, 19150 Nir David, Israel
Institute of Biochemistry, Food Science and Nutrition, Faculty of Agriculture,
Food and Environmental Quality Sciences, The Hebrew University of Jerusalem,
P.O.Box 12, 76100 Rechovot, Israel
common carp (Dor 70 x Yugoslavian) is intensively cultured in out-door
earthen ponds thoughout the central and northern regions of Israel. Carp
erythrodermatitis, a disease that has plagued European carp for several decades,
was not observed in Israeli carp prior to 1997.
Subsequent to the initial observation at the Central Fish Health Laboratory (CFHL) in Nir David, the incident of reported cases has consistently increased, with and increase of 96% from 1997 to 1998 and an additional 28% by summer 1999. An analysis of the temporal appearance of disease symptoms demonstrated a relatively broad temperature range of 11-230C with a mean of 16.7±2.60C. Disease symptoms were first observed in association with a decrease in ambient temperature during the fall and persisted during the colder winter days. Once water temperature exceeded 230C, ulcers rapidly healed and new cases were not observed. Clinical signs consist of deep ulcers accompanied by peripheral necrosis which is present in the epidermis and extends into the underlying musculature, hemorrhagic inflammation at the base of the finnage, and in extreme cases, slight to extreme exophthalmia. The symptoms are limited to external involvement only, and no pathologic signs are apparent on gross examination of the internal organs. A comparative chemical analysis of serum from ulcerated and apparently healthy fish was performed and the findings were similar to those previously by recorded data. Achromogenic atypical Aeromonas salmonicida was consistently isolated on trypticase soy agar containing 0.01% Coomassie Brilliant Blue-R-250 from samples taken from the periphery of small ulcers. Identification of the bacterial isolates was performed by PCR for the presence of the virulent A-protein gene, SDS-PAGE of total bacterial proteins, biochemical enzymatic activity and DNA typing. These isolates were compared with cultures acquired from Japanese Koi carp (Cyprinus carpio) and goldfish (Carassius auratus) that are co-cultured with the common carp. It was determined that a single atypical strain is the causative agent of carp erythrodermatitis in Israeli carp and Koi while a different strain is responsible for goldfish ulcer disease.
Note: 23C = 73.4F
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