福島県内で感染したと推定される東洋眼虫症の1例

A case of human ocular thelaziasis in Fukushima Prefecture

要約　目的：福島県内で感染したと推定される東洋眼虫症の1例を経験し，光学顕微鏡による形態観察および遺伝子解析を行い同定したので報告する。

症例：福島県北部在住の52歳，男性が左眼異物感を主訴に受診した。哺乳類のペット飼育はなく，過去1年間に県外への移動はなかった。

所見：左眼結膜囊内に白色線状の虫体を1隻認め摘出した。光学顕微鏡による形態観察を行い，東洋眼虫の雌成虫と同定した。また虫体のミトコンドリアDNAのCOX1遺伝子を解析した結果，既報の熊本県と大分県の症例，および関東地方の犬や野生肉食獣から検出されたハプロタイプ10と一致した。

結論：福島県で初となる東洋眼虫症の1例を経験した。東洋眼虫症の分布は東北地方へ拡大傾向にあり，今後症例の続発が予想される。

Abstract　Purpose：To report a case of human ocular thelaziasis in Fukushima Prefecture, Japan, which was identified by morphological observation and genetic analysis.

Case：A 52-year-old man living in the northern part of Fukushima Prefecture presented with a chief complaint of foreign body sensation in his left eye. He had no pet mammals and had not traveled outside the prefecture in the past year.

Findings：One white linear worm was found on the conjunctiva of the left eye and was removed. Morphological observation using an optical microscope identified it as an adult female worm of the species Thelazia callipaeda. Analysis of the COX1 gene in the mitochondrial DNA was consistent with haplotype 10, which was previously detected in two humans in Kumamoto and Oita Prefectures as well as dogs and wild carnivores in Kanto Region.

Conclusion：We have reported the first case of human ocular thelaziasis in Fukushima Prefecture. The distribution of ocular thelaziasis is expanding into the Tohoku region and a succession of cases is predicted to occur in the future.