Prevalence and Molecular Characterization of Bartonella spp. in Ectoparasites of Cats and Dogs in Northwestern Italy.

Bartonella spp. is a Gram-negative bacterium transmitted by arthropod vectors, implicated in a range of zoonotic infections affecting both humans and animals. Among zoonotic species, B. henselae is primarily associated with domestic cats and B. vinsonii with dogs. In Italy, Bartonella infections have been reported in both southern and northern regions. This study investigates the presence of Bartonella spp. in fleas and ticks collected from companion animals in Piedmont region, northwestern Italy. A total of 176 flea and 85 tick specimens were obtained from 92 animals (dogs and cats) between May 2018 and February 2020. Arthropods were morphologically identified using identification keys, and screened for Bartonella DNA by PCR targeting the 16s rRNA gene. Positive samples were further analyzed by amplifying the rpoB gene. Selected 16s-positive and all rpoB-positive samples were sequenced and subjected to phylogenetic analysis. Fleas were mostly identified as Ctenocephalides felis, recovered from 44 cats and 12 dogs; a single C. canis specimen was found in one cat. Ticks were Ixodes ricinus (from 14 cats and 10 dogs), Rhipicephalus sanguineus s.l. (3 cats, 7 dogs), and Dermacentor marginatus (one dog). Bartonella prevalence was 38.4%, with 34.2% positivity in fleas and 45.6% in ticks. All sequences corresponded to B. henselae. These findings confirm the active circulation of B. henselae in ectoparasites of pets and raise questions about the potential role of ticks in its transmission.