The Tissue Distribution of Atypical Aeromonas salmonicida in Artificially Infected Japanese Eels, Anguilla japonica

人為感染させたニホンウナギにおける非定型Aeromonas salmonicidaの消長

Nakai Toshihiro

Miyakawa Munenori

Muroga Kiyokuni

Kamito Kumiko

魚病研究

The multiplication and distribution of an atypical Aeromonas salmonicida strain, which was isolated as a causative agent of "head ulcer disease" of cultured eels, in artificially infected Japanese eels (Anguilla japonica) were studied by bacteriological culture technique. When the eels were injected intramuscularly with a lethal dose of the atypical A. salmonicida strain at 20°C, the pathogen was recovered at high concentrations (10^7-10^9 CFU/g) from the muscle of the injected site throughout the course of infection. But in the spleen and kidney very small numbers of the pathogen were detected even at the moribund stage, and the blood and brain were almost aseptic. A similar result was obtained in the eels which were artificially injured on the skin and infected with the pathogen. These data indicate that the disease does not attain to distinct septicemic condition but the local proliferation of the pathogen will be the death of the host fish, and this pathological feature is in a striking contrast to other bacterial infections of eels. It was also found that the bacterial growth was significantly inhibited both in vitro and in vivo at 30°C, which uggests that temperature manipulation of pond water will be an effective measure to control the disease.

ウナギ病魚(頭部潰瘍病)由来の非定型A.salmonicida株をニホンウナギに接種し, 各組織における生菌数の消長を培養法により調べた。その結果, 接種した筋肉組織では1時間後から死亡直前まで10 7-9CFU/gの菌数が検出されたが, 脾臓および腎臓では10 2-5CFU/gと低く, 血液および脳からは殆ど検出されなかった。また, 魚の皮膚に切り傷をつけて感染を図った場合にも同様の結果が得られ, 本病はウナギの他の細菌感染症とは異なり終始局所感染の形をとることが明らかになった。

Zoology [ 480 ]

eng

日本魚病学会

Copyright (c) 1989 The Japanese Society of Fish Pathology

[ISSN] 0388-788X

[ISSN] 1881-7335

[NCID] AN00063165