Journal Article

Molecular characterization of oriental eyeworm (Thelazia callipaeda) detected from raccoon (Procyon lotor) and Japanese raccoon dog (Nyctereutes viverrinus) in Kanto region, Japan

Shyun Chou, Takuya Kato, Toshihiro Tokiwa, Fumiaki Yamasaki, Shin-ichi Hayama, Miyu Imoto, Kandai Doi

2023

Overview

Background 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. Methods 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. Results 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. Conclusions 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. Graphical Abstract

• Publisher: Springer Science and Business Media LLC,BioMed Central,Springer Nature B.V,BMC
• Subject: Animals / Biomedical and Life Sciences / Biomedicine / Carcasses / Carnivores / Cytochrome / Cytochrome-c oxidase / Cytochromes / Dogs / Domestic animals / Entomology / Eye / eyes / Females / Gene sequencing / genes / Genetic analysis / Haplotypes / human population / Human populations / Infections / Infectious and parasitic diseases / Infectious Diseases / inflammation / Invasive species / Japan / Japan - epidemiology / Males / Mitochondria / mixed infection / Nyctereutes / Nyctereutes procyonoides / Oriential eyeworm / oxidoreductases / Parasites / Parasitology / Procyon lotor / Procyonidae / Raccoon / Raccoon dog / Raccoon Dogs / Raccoon Dogs - parasitology / Raccoons / Raccoons - parasitology / RC109-216 / species / Spirurida Infections / Spirurida Infections - epidemiology / Spirurida Infections - veterinary / Thelazia callipaeda / Thelazioidea / Thelazioidea - genetics / Tropical Medicine / Veterinary Medicine/Veterinary Science / Virology / Worms