Molecular Detection and Phylogenetic Characterization of Bartonella bovis in Dairy Cattle From Central Thailand

Bartonella bovis is an emerging ruminant pathogen with zoonotic potential. Although various Bartonella species have been detected in animals in Thailand, none have been reported in dairy cattle. We investigated the occurrence and genetic characteristics of Bartonella spp. in dairy cattle from central Thailand and examined associations with farm management practices. Blood samples were collected from 522 cattle on 43 farms in four provinces and examined for Bartonella DNA by PCR targeting the gltA, rpoB, and ribC genes. Sequencing, phylogenetic analyses, and nucleotide sequence type (ntST) network analyses were also performed. Risk factors were assessed using Fisher's exact test and multivariable logistic regression. Bartonella DNA was detected in 4.21% of samples, with all positives identified as B. bovis. Univariable analysis showed significantly higher prevalence in small/medium-scale farms and separate feeding systems. However, in the multivariable model, farm size showed a strong trend toward association with B. bovis detection, although the association did not reach statistical significance. The dominant gltA sequence type (ntST04) was detected across all farm sizes and feeding practices, whereas a peripheral variant (ntST02) differed by nine nucleotide substitutions from a ked-associated Bartonella sequence (GenBank ID: OQ716819). Both rpoB and ribC networks revealed seven distinct groups that were closely related to the B. bovis reference sequences, with nucleotide identities of 99.42%-100% and 99.41%-100%, respectively. This study provides new molecular evidence of B. bovis circulation in the Thai dairy cattle population, highlighting the need for improved surveillance and biosecurity, particularly in small-scale operations, to mitigate potential zoonotic risks within a One Health framework.