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

<i>Bartonella</i> 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, <i>B. henselae</i> is primarily associated with domestic cats and <i>B. vinsonii</i> with dogs. In Italy, <i>Bartonella</i> infections have been reported in both southern and northern regions. This study investigates the presence of <i>Bartonella</i> 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 <i>Bartonella</i> DNA by PCR targeting the <i>16s</i> rRNA gene. Positive samples were further analyzed by amplifying the <i>rpoB</i> gene. Selected <i>16s</i>-positive and all <i>rpoB</i>-positive samples were sequenced and subjected to phylogenetic analysis. Fleas were mostly identified as <i>Ctenocephalides felis</i>, recovered from 44 cats and 12 dogs; a single <i>C. canis</i> specimen was found in one cat. Ticks were <i>Ixodes ricinus</i> (from 14 cats and 10 dogs), <i>Rhipicephalus sanguineus</i> s.l. (3 cats, 7 dogs), and <i>Dermacentor marginatus</i> (one dog). <i>Bartonella</i> prevalence was 38.4%, with 34.2% positivity in fleas and 45.6% in ticks. All sequences corresponded to <i>B. henselae</i>. These findings confirm the active circulation of <i>B. henselae</i> in ectoparasites of pets and raise questions about the potential role of ticks in its transmission.