Epidemiological description of a new viral disease afflicting cultured Cyprinus carpio in Israel

Since spring 1998, a new disease causing high mortality has afflicted cultured ornamental and common carps (Cyprinus carpio) in Israel. The clinical signs of the disease are fatigue, gasping movements in shallow water, gill necrosis, sunken eyes, pale patches on the skin and increased mucus secretion. The disease was experimentally transmitted to koi and common carp of various ages by injection with affected tissue filtrates, cohabitation trials and exposure to the isolated viral agent. Immersion of healthy fish in tanks containing 2.7 × 10⁴ plaque forming units (PFU) per l or intraperitoneal injection (0.2 ml) of a viral inoculum of 1000 PFU/ml were sufficient to induce the terminal disease in over 80% of the fish. Here we report that the disease is restricted to C. carpio, that young fish of 2.5 g and 6 g are more sensitive to the virus than adults (230 g) and that the virus remains active in the water for at least four hours.