@article{oai:ir.kagoshima-u.ac.jp:00010804,
 author = {日高, 富男 and 矢野原, 良民 and 柴田, 俊幸},
 journal = {鹿児島大学水産学部紀要=Memoirs of Faculty of Fisheries Kagoshima University},
 month = {2016-10-31},
 note = {The authors isolated the causative bacteria of head ulcer disease in cultured eels (Anguilla japonica). And then the isolates were examined their characteristics and were identified as
three bacterial species. We also estimated the pathogenicity of the causative bacteria to eels
and the seasonal distribution of them in water of a eel culture pond. The obtained results were as follows.
1) The three species of causative bacteria were isolated from ulcer in eels at three eel
culture farms respectively. They were Aeromonas hydrophila, from fresh-water ponds in Sendai and Miyakoshima farms, Vibrio sp., from brackish-water ponds in Miyakoshima farm,
and Edwardsilla tarda, from fresh-water ponds in Hiyoshi farm.
2) The pathogenicity of the causative bacteria, A.hydrophila and E.tarda, against eels
were tested by means of intramuscular injection. About 10^<7> cells of each bacterium per 100
g of eel body weight was the adequate dose for inoculation. Under this condition, more than 80% of the tested eels ulcerated and died in four days after the inoculation of A.hydrophila. In case of E.tarda, 80% of the tested eels ulcerated and 70% of them died in six days after
the inoculation. The pathogenicity of E.tarda was slightly weak than A.hydrophila.
3) Field surveys of the abundance of A.hydrophila and E.tarda in water of a eel culture
pond were made nine times in Hiyoshi farm. There were 3-30×10^<5> cells of total bacteria, 1-10×10^<4> cells of A.hydrophila, and 1-4×10^<3> cells of E.tarda in one ml of the water. The
seasonal fluctuation of the bacterial cell counts was not observed, because the water
temperature was controled at 22°-26°C. When some eels with head ulcer disease by E.tarda
were found in the pond, the E.tarda cell counts in the water were fourfold higher than at
other times.
4) All of the causative bacteria are facultative pathogens. It seems that they infect through some damages at head skin tissue of eels., 近年,養殖ウナギの頭部に潰瘍を生じる疾病が発生している。本報ではその原因菌を分離し,細菌学的性状を究明し菌種を同定した。次いでそれら菌種のウナギに対する病原性や養鰻池水中における分布をも検討した。それらの結果から,次のような知見を得た。1. 川内市の養鰻場と宮古島の淡水池で発生したウナギ頭部潰瘍症の患部から分離された原因菌はAeromonas hydrophila subsp. hydrophilaと同定された。また宮古島の汽水池でのそれはVibrio sp.,日吉町の養鰻池でのそれは,Edwardsiella tardaであった。このように原因菌は養鰻場によって異なったが,同じ養鰻場では2年間に行った数回の調査では,同一原因菌が検出された。2. 原因菌の病原性は,接種(皮下注射)菌量10^<7> cells/100gウナギ体重で,A.hydrophilaでは接種4日後に試験魚の80%が典型的な潰瘍を生じ,発症魚の全てが死に致る程度であった。他方,E.tardaでは接種6日後に80%が発症し重症のもの70%が死に致る程度で,E.tardaの発症性はA.hydrophilaのそれよりやや弱かった。3. 日吉町の淡水養鰻池水中にあって,全生菌数3~30×10^<5>/mlに対し,A.hydrophila生菌数は1~10×10^<4>/ml,E.tarda生菌数は1~4×10^<3>/ml程度が常時存在していた。そして,その池でE.tardaによる潰瘍症が発生した頃には,全生菌数は増加し,A.hydrophilaは減少し,原因菌であるE.tardaはふつう時の4倍に増加し,池水中の細菌相に量的変化が現れた。4. ウナギ頭部潰瘍症の発症要因は,投餌の際エサカゴの不備などによって被ったウナギ頭部の損傷,あるいはストレスを負ったウナギの咬み合いによって受けた頭部の傷などを感染門戸として,原因菌が感染し,ストレスの負荷などによって抵抗力が低下していたことなどと相俊って発病に至ったと考えられる。},
 pages = {147--165},
 title = {養殖ウナギの頭部潰瘍症の原因菌について},
 volume = {32},
 year = {}
}