Pathology of Ulcerous Disease in Cultivated Snakehead, Channa argus

양식 가물치 궤양병의 병리 연구

Haemorrhagic ulcer in cultured snakehead(Chann0 argus) is widespread in Korea during the summer season. Round haemorrhagic ulcers as the main symptom of this epizootic disease can be found on the skin of the head. body, as well as fins of this fish. This study was conducted to investigate the pathology of this disease. First. Aeromonas veronii. the dominant species. was isolated from diseased snakeheads. Then this bacterium was injected into healthy snakeheads hypodermically. Such injection was found to induce haemorrhagic ulcers very similar to those observed in naturally infected fish. One or two days afier the injection, a red spot developed around the injection site. and grew bigger to from a red area. This enlarged area then developed into haemorrhagic ulcer, accompanied by substantial skin loss. Within five days. muscle necrosis proceeded to the extent that a perforation was made between the injection site and the opposite side. The fifty per cent lethal dosage was found to be $1\times10^{5}$CFU/0.25 ml by intraperitoneal injection. The results of this experiment lead us to conclude that Arromonas veronii is a major bacterium which causes haemorragic ulcer in cultured snakcheads.

본 연구는 한국산 양식 가물치에 큰 피해를 주는 출혈성 궤양증의 원인과 병리를 연구할 목적으로 수행되었다. 가물치의 출혈성 궤양증은 그 원인이 세균성이었고 궤양 및 장기로부터 분리된 Aeromonas veronii 가 주원인균이었다. A veronii 를 건강한 가물치의 피하에 인공 접종한 결과 양식 가물치에서 관찰된 병증과 유사한 궤양을 유발시켰다. 초기 증세는 주사부위를 중심으로 피부에 붉은 반점이 나타났고, 점차 확대되면서 피부가 탈락되고 출혈이 수반되었다. 곧이여 근육괴사가 진행되어 조사된 반대쪽에 구멍이 뚫렸다. $10^{5}$/CFU/0.25 ml 의 세균은 복강주사시 72시간이내에 시험개체의 50%가 치사되었다. 본 균은 cephalothin, chlorampenicol, gentamicin, tetracyline 등의 항생제에 감수성을 나타내었다.