Department of Environmental Science, School of Life and Environmental Science, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan.
Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato, Hakodate, Hokkaido, Japan.
Parasitol Int. 2021 Aug;83:102327. doi: 10.1016/j.parint.2021.102327. Epub 2021 Mar 9.
The genus Anisakis is a well-known group of nematodes that parasitize cetaceans as the final host and cause mucosal damage to their stomach. However, little has been done to precisely identify the nematodes recovered from the final hosts, especially in the Western Pacific, because of taxonomic confusion about the discrimination of sibling species and the difficulties of obtaining specimens from cetaceans. We describe the results of genetic identification and histopathological observations of specimens recovered from an ulcerated lesion and stomach contents in the forestomach of a female harbor porpoise accidentally caught by a set net fishery in Usujiri, southern Hokkaido, Japan. All the specimens arbitrarily collected from the lesion and stomach contents were identified as Anisakis simplex sensu stricto according to their ITS rDNA sequences. The size of the ulcer was approximately 6.3 mm in diameter and it was infected with 119 individual nematodes, mostly consisting of L3 and L4 stage larvae (95.0%). Histological sections were characterized by a locally extensive ulcer with the parasites penetrating into the muscularis externa that caused a thickening of the surrounding mucosa.
棘头虫属是一类广为人知的线虫，它们以鲸目动物为终末宿主寄生，并导致其胃黏膜受损。然而，由于对同属种的鉴别存在分类学上的混淆，以及从鲸目动物获取标本的困难，人们对从终末宿主回收的线虫进行准确鉴定的研究很少，特别是在西太平洋地区。本研究描述了在日本北海道南部臼杵市的定置网渔业中意外捕获的一只雌性港湾鼠海豚的溃疡病变和前胃胃内容物中回收的标本的遗传鉴定和组织病理学观察结果。根据 ITS rDNA 序列，任意从病变和胃内容物中采集的所有标本均被鉴定为单纯异形棘头虫。溃疡的直径约为 6.3 毫米，感染了 119 条线虫，主要由 L3 和 L4 期幼虫（95.0%）组成。组织学切片的特征是局部广泛的溃疡，寄生虫穿透外肌层，导致周围黏膜增厚。
