Work

First report of canine thelaziosis caused by Thelazia callipaeda in Bhutan

Year: 2026

Type: article

Abstract: ABSTRACT Thelazia callipaeda is a vector-borne zoonotic nematode causing ocular infection in animals and humans, with an expanding geographical range across Asia, Europe, and North America. Although the parasite is endemic in neighbouring countries China and India, no cases of canine thelaziosis have previously been reported in Bhutan. Here we describe the first case of canine ocular thelaziosis, in a 7-year-old mixed-breed dog from Punakha District presenting with bilateral lacrimation and epiphora, conjunctival hyperemia, and blepharospasm. Thirty-two whitish, thread-like nematodes were recovered from the conjunctival sacs of both eyes and identified morphologically as T. callipaeda based on cuticular striae, buccal capsule morphology, and characteristic male and female reproductive structures. Molecular confirmation was achieved by sequencing a fragment of the mitochondrial cytochrome c oxidase subunit 1 ( cox 1) gene, which showed 99.6% identity to an isolate of T. callipaeda from India. Phylogenetic analysis placed the Bhutan isolate within the Asian clade, clustering most closely with the Indian isolate. This report describes the diagnosis and successful management of the first confirmed case of canine ocular thelaziosis in Bhutan, underscoring the need for veterinary and public health surveillance of thelaziosis in this region.

Source: Current Research in Parasitology and Vector-Borne Diseases

DOI: 10.1016/j.crpvbd.2026.100450

Authors: Rinchen Tshering, Karma Wangchuk, Domenico Otranto

Institutions: Chulalongkorn University, City University of Hong Kong, University of Bari Aldo Moro

Language: English

Topic: Parasitic Diseases Research and Treatment

Subfield: Infectious Diseases

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,350