Molecular Detection and Isolation of <i>Bartonella</i> Species in Bats and Their Ectoparasites Along the China–Myanmar Border

<i>Bartonella</i> are parasitic pathogens that infect many mammals, including humans, and cause significant diseases. This study investigates the presence, genetic diversity, and tissue tropism of <i>Bartonella</i> in bats and their ectoparasites along the China-Myanmar border. Bats and ectoparasites were collected from Yingjiang, Ruili, and Gengma Counties. Nested PCR (nPCR) and quantitative real-time PCR (qPCR) were used to detect and quantify <i>Bartonella</i> in bat tissues. <i>Bartonella</i> was isolated using brain-heart infusion broth and tryptone soy agar medium containing 5% sheep blood (TSA containing 5% sheep blood), and DNA sequences were analyzed with Clustal W and MEGA X. In total, 601 bats from 11 species (four families and seven genera) and 32 ectoparasites (two orders, three families, and four genera) were collected. The qPCR results revealed <i>Bartonella</i> detection rates of 22.96% (138/601) in bats and 62.50% (5/8) in ectoparasites. Using nPCR to detect the <i>Bartonella gltA</i> and <i>rpoB</i> genes in bats, ectoparasites, and strains isolated from bat blood samples, yielding 58 and 10 strains, respectively. When comparing bats, ectoparasites, and isolated strains to other <i>Bartonella</i> in GenBank, the <i>gltA</i> gene was 74.21%-100.00% at the nucleotide level of similarity and 75.70%-100.00% at the amino acid level. In comparison, the <i>rpoB</i> gene was 79.58%-100.00% at the nucleotide level of similarity and 89.71%-100.00% at the amino acid level. By phylogenetic analysis except for <i>Bartonella</i> sp. and uncultured <i>Bartonella</i> sp., we found a clade that was less than 96.0% at the nucleotide level of similarity in the <i>gltA</i> gene and less than 95.4% at the nucleotide level of similarity in the <i>rpoB</i> gene. Based on the threshold values for the delineation of new species of <i>Bartonella</i>, we believe that a new species of <i>Bartonella</i> prevalent in bats was discovered in this study, which we named "<i>Candidatus Bartonella dianxisis</i>". Otherwise, the average copy number of <i>Bartonella</i> in bat tissues (blood, spleen, heart, brain, kidney, lung, liver, and rectum) ranged from 1.15 × 10⁴ to 6.87 × 10⁴ copies/μL, with the highest levels observed in blood and spleen. Our findings highlight the genetic diversity of <i>Bartonella</i> in bats and ectoparasites along the China-Myanmar border and underscore potential public health risks associated with these pathogens.