High Diversity of Sarcocystis Species Identified in Intestines of Red Foxes (Vulpes vulpes) from Lithuania.

Sarcocystis spp. are apicomplexan parasites with an obligatory two-host prey-predator life cycle. While the intermediate hosts (IHs) of many species are well known, the definitive hosts (DH) of numerous Sarcocystis spp., especially those involving wildlife predators, remain poorly understood. In the current study, Sarcocystis species richness was investigated in the intestines of 69 red foxes (Vulpes vulpes) from Lithuania. Intestinal samples were examined by light microscopy and nested PCR targeting the cytochrome c oxidase I gene (cox1) sequence of species associated with ungulate IH and the internal transcribed spacer I (ITS1) region of species using birds as IH, followed by Sanger sequencing and phylogenetic analyses. Red foxes harboured a broad spectrum of Sarcocystis species, with those utilising ungulate IHs being considerably more common than species associated with birds. Seven species, Sarcocystis alces, Sarcocystis bertrami, Sarcocystis capreolicanis, Sarcocystis hjorti, Sarcocystis iberica, Sarcocystis linearis, and Sarcocystis morae, were identified in red foxes for the first time. Nine previously reported species, Sarcocystis albifronsi, Sarcocystis arieticanis, Sarcocystis capracanis, Sarcocystis cruzi, Sarcocystis gracilis, Sarcocystis miescheriana, Sarcocystis pilosa, Sarcocystis rileyi, and Sarcocystis tenella, were also detected. In addition, two potentially novel Sarcocystis taxa were identified and warrant further investigation. These findings highlight the role of red foxes as an important DH and provide a valuable framework for comparative studies of Sarcocystis distribution in predatory mammals.