Thelazia callipaeda, an Endemic Parasite of Red Foxes (Vulpes vulpes) in Western Romania

Abstract Thelazia callipaeda (Spirurida, Thelaziidae) is a vector-borne zoonotic nematode parasite of the conjunctival sac of a large spectrum of hosts, currently having an expanding distribution range throughout Europe. In Romania, the parasite has a relatively large distribution range and host spectrum. However, the presence of T. callipaeda in red foxes (Vulpes vulpes) has not yet been confirmed. The aim of the present study was to assess the prevalence and geographical distribution of T. callipaeda in red foxes from Romania. A total of 514 animals originating from 10 counties of western Romania were evaluated for the presence of T. callipaeda. Overall, 151 red foxes (29.38%) were positive. No significant differences were noticed between sex and age groups of positive foxes. In total, 3,350 adult nematodes were recovered. The intensity of infection had a mean value of 23.2, while the sex ratio was 2.2:1 in favor of females. In 91 foxes, both eyes were affected, while 60 harbored unilateral infection. Sequence analysis of the cox 1 gene of one nematode from each positive fox (n=151) revealed the exclusive presence of haplotype h1. We report a relatively high prevalence and distribution range of T. callipaeda infection in red foxes in Romania, highlighting their potential role as a wildlife reservoir.