Laboratory of Wildlife Medicine, Nippon Veterinary and Life Science University, Kyonancho, Musashino, Tokyo, Japan.
Forestry and Forest Products Research Institute, Matsunosato, Tsukuba, Ibaraki, Japan.
Parasit Vectors. 2023 Mar 30;16(1):116. doi: 10.1186/s13071-023-05736-x.
The oriental eyeworm Thelazia callipaeda (Spirurida: Thelaziidae) is an emerging parasitic ocular nematode of carnivores and humans. In domestic animals and humans, the infection causes varying degrees of inflammation and lacrimation, and wild carnivores represent an important reservoir. In this study we examined the infection status and molecular characterization of T. callipaeda in two urban carnivores, raccoons Procyon lotor and wild Japanese raccoon dogs Nyctereutes viverrinus, in the Kanto region of Japan.
From January 2020 to December 2021, 193 carcasses including 178 raccoons and 15 raccoon dogs were examined for the presence of worms in the eye. The worms from infected animals (one worm per host) were morphologically identified as T. callipaeda. Worms (1-5 worms per host) were subjected to genetic analysis using mitochondrial cytochrome c oxidase subunit I gene sequences.
The prevalence of T. callipaeda in raccoons and Japanese raccoon dogs was 20.2% (36/178) and 13.3% (2/15), respectively. The cox1 sequences from 56 worms from 38 animals revealed three haplotypes (h9, h10, and h12). Analysis of multiple worms for five raccoons showed co-infection of two different haplotypes (h9 and h10) in a single host. Comparing our data with published sequences, three sequences obtained from raccoons and raccoon dogs shared the same haplotypes as those reported in humans, dogs, and cats in Japan.
Our findings show a high prevalence of T. callipaeda in raccoons, suggesting that this invasive carnivore species serves as an important natural reservoir of T. callipaeda in the Kanto region of Japan, an area with the highest human population of the country.
东方眼虫 Thelazia callipaeda（旋尾目：Thelaziidae）是一种新兴的寄生性食肉动物和人类眼部线虫。在家畜和人类中，感染会引起不同程度的炎症和流泪，而野生动物则是重要的储存宿主。在这项研究中，我们检查了日本关东地区两种城市食肉动物——浣熊和野生日本小灵猫中的东方眼虫 T. callipaeda 的感染状况和分子特征。
从 2020 年 1 月至 2021 年 12 月，检查了 193 具尸体，包括 178 只浣熊和 15 只日本小灵猫，以确定眼部是否存在蠕虫。从受感染动物（每只动物 1 只蠕虫）中分离出的蠕虫在形态上被鉴定为 T. callipaeda。从每只宿主（1-5 只蠕虫）中提取的蠕虫，采用线粒体细胞色素 c 氧化酶亚单位 I 基因序列进行遗传分析。
浣熊和日本小灵猫感染 T. callipaeda 的患病率分别为 20.2%（36/178）和 13.3%（2/15）。从 38 只动物的 56 只蠕虫的 cox1 序列中发现了 3 种单倍型（h9、h10 和 h12）。对 5 只浣熊的多只蠕虫进行分析表明，同一宿主同时感染了两种不同的单倍型（h9 和 h10）。将我们的数据与已发表的序列进行比较，从浣熊和日本小灵猫中获得的 3 个序列与日本报告的人类、狗和猫中的相同单倍型相同。
我们的研究结果表明，浣熊中 T. callipaeda 的感染率很高，这表明这种入侵的食肉动物物种在日本关东地区是 T. callipaeda 的一个重要自然储存宿主，该地区是日本人口最密集的地区。
