Molecular and Phylogenetic Characterization of Ehrlichia canis in Cats from the Western Aegean Coastal Region of Türkiye

This study presents the first molecular and phylogenetic evidence of Ehrlichia canis infection in cats from the coastal Western Aegean region of Türkiye, with a particular focus on associated risk factors. A total of 203 cats were examined using both microscopic and PCR-based methods, with infection prevalences of 3.44% and 13.30%, respectively. Phylogenetic analysis of the 16S rRNA gene revealed a high degree of genetic similarity (99.1-100%) between feline-derived isolates and previously published E. canis sequences, including those from dogs in Türkiye, suggesting that a common strain is circulating between host species. No phylogeographic structuring was observed among isolates from different provinces. A statistically significant association was found between E. canis infection and outdoor cats, co-infections with other pathogens, and lack of regular antiparasitic treatment, while no significant association was observed with sex or age. Despite increasing global reports, feline ehrlichiosis remains underdocumented in Türkiye. This study contributes novel data to the limited national literature and highlights the importance of including cats in surveillance programs for tick-borne diseases in endemic regions, as well as the potential role of cats in the natural transmission cycle of E. canis.