Molecular detection and phylogenetic analysis of Bartonella in small rodents from southwestern Shanxi, China

Background Bartonella species are emerging zoonotic pathogens that cause human bartonellosis. The rodents are the main hosts of Bartonella , and Bartonella distribution varied in different rodents and regions. This study was conducted to investigate the prevalence and genetic diversity of Bartonella infection in rodents from Yuncheng City, southwestern Shanxi Province of China. Methods Small rodents were captured using the night-trapping method. Liver, spleen, and kidney tissues were collected for Bartonella detection by real-time PCR targeting the small stable RNA A ( ssrA ) gene. Phylogenetic analysis and genetic diversity of Bartonella were performed based on the citrate synthase ( gltA ) gene sequencing. Results A total of 106 rodents were captured, including Apodemus agrarius (59), Eothenomys inez (21), Niviventer confucianus (12), Apodemus draco (8), Cricetulus longicaudatus (3), Tscherskia triton (2), and Mus musculus (1), of which 49 were positive for Bartonella . The overall positivity rate was 46.23% (95% CI: 36.58%​-55.87%). A significant overall difference in Bartonella DNA positivity was observed among tissue types ( P = 0.03), although pairwise differences were not significant after Bonferroni correction. No significant differences were observed according to sex, habitat (forest vs. farmland), or sampling site ( P > 0.05). A total of seven Bartonella taxa were detected from 41 sequences, including B. grahamii (17), B. fuyuanensis (5), B. queenslandensis (4), B. taylorii (4), B. phoceensis (3), Candidatus B. rudakovii (5), and one unclassified Bartonella lineage (3). Some Bartonella taxa showed host-associated distribution patterns, and B. grahamii was the predominant taxon and was grouped into four clusters. Among the 17 B . grahamii sequences, seven haplotypes were identified. A. agrarius had the largest number of haplotypes (H = 4) and showed substantial haplotype diversity (Hd = 0.745 ± 0.098). Conclusions A high prevalence and substantial genetic diversity of Bartonella were found in small rodents from southwestern Shanxi Province. These findings indicate that small rodents may serve as important reservoirs of diverse Bartonella taxa in this area and highlight the importance of continued surveillance of rodent-associated Bartonella .