Canine onchocercosis in Greece: report of further 20 cases and molecular characterization of the parasite and its Wolbachia endosymbiont

Abstract

Recently, sporadic cases of subconjunctival Onchocerca infection have been reported in dogs in Greece and Hungary. Herein we report further cases from Greece and the results of the molecular analysis of Onchocerca sp. removed from Greek dogs and its Wolbachia endosymbionts. Twenty dogs of various breeds, 1–11 years of age with subconjunctival onchocercosis (4 cases each in right or left eye, 12 cases in both eyes) were presented having similar manifestations. Periorbital swelling, exophthalmos, lacrimation, discharge, photophobia, conjunctival congestion, corneal edema, protrusion of the nictitating membrane, and subconjunctival granuloma or cyst formation were the most important clinical signs. After surgical excision of the periocular masses containing the worms, all animals recovered fully from onchocercosis. Based on the similarities of the clinical picture of the Greek and Hungarian cases, the similar morphology of the Greek and Hungarian isolates, and the identical sequences of the cytochrome oxidase gene of the filarial parasites and that of the 16S ribosomal RNA gene from their Wolbachia endosymbionts, the Onchocerca sp. isolated from dogs in Greece and Hungary appears to belong to the same species.