水族館のアザラシに発生したイヌジステンパー様疾患 Occurrence of a canine distemper-like disease in aquarium seals.

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Abstract

1987年の秋から1988年の夏にかけて, 北欧海域並びにバイカル湖に生息するアザラシにイヌジステンパー様の急性疾患による大量死が発生した. これら発生の最中, バイカル湖で捕獲され日本の水族館に導入されたアザラシと同室に飼育されていた他のアザラシに類似疾患が発生した. 罹患した6頭のうち4頭のアザラシは, 食欲不振, 呼吸困難, チックなどの臨床症状を示して死亡した. これらのアザラシにはII型肺胞上皮細胞の増殖と合胞性巨細胞形成をともなった, 急性間質性肺炎が特徴的に認められた. 好酸性核内並びに細胞質封入体がII型肺胞上皮細胞と気管支粘膜, 胆管, 膵臓の導管及び腎孟粘膜の各上皮細胞, リンパ節の細網細胞などに検出され, それらは電子顕微鏡的に morbilliviruses感染細胞に出現するものと同様な構造を持っていた. 回復したアザラシにはイヌジステンパーウイルスに対する中和抗体が存在した. 本発生例は我が国のアザラシにおける morbillivirus感染症の最初の報告である.

Outbreaks of a canine distemper-like acute disease brought high mortalities to seal populations in north-west Europe and Lake Baikal from late 1987 to 1988. During these outbreaks three seals which were introduced from Lake Baikal to an aquarium in Japan developed a distemper-like disease and other seals raised in the same room were similarly affected. Clinical signs of dead seals were anorexia, diphasic fever, dyspnea, and neuromuscular tics. Characteristic microscopic lesions of acute interstitial pneumonia seen in the lung were accompanied with hyperplasia and syncytial giant cell formation of type II pneumocytes. Eosinophilic intranuclear and cytoplasmic inclusion bodies were present in bronchial epithelial cells, type II pneumocytes, epithelial cells of bile ducts and interlobular ducts of pancreas, transitional epithelium of renal pelvis, and reticular cells of lymph nodes. Ultrastructure of inclusion bodies was similar to that seen in cells infected with morbilliviruses. Serum samples from recovered seals had virus-neutralization antibodies against canine distemper virus. The present cases were the first report of morbillivirus infection of aquarium seals in Japan.

Journal

  • The Japanese Journal of Veterinary Science

    The Japanese Journal of Veterinary Science 52(3), 469-477, 1990

    JAPANESE SOCIETY OF VETERINARY SCIENCE

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