Thelazia callipaeda (Spirurida, Thelaziidae) in wild animals: report of new host species and ecological implications

Thelazia callipaeda infects the eyes of carnivores and humans in Far Eastern Asiatic and European countries. Studies have demonstrated the occurrence of T. callipaeda in foxes from areas where canine thelaziosis is endemic. However, there is little information on the role of wild carnivores as hosts of this nematode. From May 2003 to May 2009, a total of 130 carcasses of red foxes (Vulpes vulpes; n=75), wolves (Canis lupus; n=2), beech martens (Martes foina; n=22), brown hares (Lepus europaeus; n=13), Eurasian badgers (Meles meles; n=10), and wild cats (Felis silvestris; n=8) were examined in an area of southern Italy where canine thelaziosis is highly prevalent. At necropsy, animals were examined and nematodes were collected from the conjunctival sacs of both eyes. All nematodes were morphologically identified and at least five specimens from each of the five host species were molecularly processed by PCR amplification and sequencing of a partial mitochondrial cytochrome c oxidase subunit 1 gene (cox1). Five out of the six wild animal species examined were found to be infected with eyeworms. The overall infection rate, excluding the Eurasian badgers that were all negative, was 39.1%. All the 189 adult nematodes collected (intensity of infection=4+/-2.2) were morphologically identified as T. callipaeda. The molecular analysis confirmed that the only haplotype of T. callipaeda circulating in Europe (i.e., haplotype 1) is present in that area. The competence of red foxes, wolves, beech martens, brown hares, and wild cats as definitive hosts for T. callipaeda is discussed in relationship to their ecology and their likely exposure to the vector Phortica variegata in the study area. The role the wild fauna plays in maintaining and spreading eyeworm infection in humans and domestic animals is also discussed.