국내기사
국내 담수 자연산 어류와 양식 무지개송어에서의 세균성신장병(BKD) 모니터링 = Monitoring of bacterial kidney disease (BKD) in wild freshwater fish and farmed rainbow trout in Korea
Bacterial kidney disease (BKD) is a major chronic infectious disease in salmonid fish, yet its preva- lence in natural river systems and aquaculture environments in Korea remains largely unknown. In this study, a total of 846 wild fish collected from four major river systems (575 non-salmonid fish from 26 species and 271 chum salmon) and 243 farmed rainbow trout from eight aquaculture facilities were examined to determine the presence of Renibacterium salmoninarum. Clinical examination, bacte- rial culture on KDM-2 medium, and nested PCR targeting the msa gene were conducted. Most wild fish showed no BKD-specific clinical signs, and R. salmoninarum was not isolated from any sample. However, the msa gene was detected in five asymptomatic chum salmon collected from the Namdae- cheon River, indicating the presence of low-level BKD infection in natural waters. In contrast, no clinical signs, bacterial isolates, or PCR-positive results were observed in farmed rainbow trout. This study provides the first molecular evidence confirming the presence of BKD in Korean natural river systems and suggests that returning chum salmon may act as a reservoir with potential for pathogen maintenance and transmission. Although the current aquaculture environment appears stable, con- tinuous molecular surveillance, assessment of pathogen movement between natural waters and aqua- culture facilities, and intensified monitoring during low-temperature seasons are required to prevent potential BKD outbreaks.