Genetic diversity of Bartonella spp. in rodents and fleas from Poland

Bartonella spp. are parasites of mammalian erythrocytes and endothelial cells, and are transmitted by blood-feeding arthropod ectoparasites, including fleas. This study aimed to: (i) identify the main flea species responsible for Bartonella transmission and the specific Bartonella species they carry, (ii) evaluate how host-related factors influence the prevalence of Bartonella, (iii) examine the genetic diversity of Bartonella from different flea species and mammalian hosts, including rodents and European moles, and (iv) determine the haplotypes of Bartonella derived from rodents. Blood samples were collected from seven rodent species and two European moles in Poland (n = 994), and fleas were collected from rodents (n = 833). Bartonella spp. were identified and genotyped through rpoB and gltA genes. Phylogenetic analysis revealed two dominant Bartonella spp. in rodents and fleas: B. grahamii and B. taylorii. Moreover, 17 haplotypes of B. taylorii and 9 of B. grahamii were identified. The sequences of Bartonella sp. from T. europaea clustered in a unique separate group, possibly indicating a novel species. The study confirmed fleas as vectors of Bartonella transmission in rodents and highlighted the significant genetic diversity of Bartonella spp. in both fleas and rodents.