Abstract
In Korea, mass mortalities occurred among cultured common carp Cyprinus carpio in 1998. Moribund fish showed clinical signs like those of koi herpesvirus (KHV) disease. In this study, we applied in situ hybridization (ISH) method to detect KHV DNA in paraffin-embedded tissue specimens that had been prepared from the moribund carp of nine fish farms at four different regions in 1998. ISH-positive cells were found in various tissues including kidney, spleen, heart, liver, gills and intestine from eight fish farms. Our results suggest that the mass mortality of carp in 1998 was associated with KHV infection and thus KHV was introduced into fish culture farms in South Korea in 1998 or earlier.
