Wild felids are not just possible carriers of the Bartonella associated with domestic cats. In Brazil, their sequences also clustered with Bartonella linked to wild rodents and fleas. Bartonella comprises fastidious, facultative intracellular, Gram-negative alpha-proteobacteria that parasitize erythrocytes and endothelial cells of several mammalian species.

These bacteria usually exhibit high host specificity and often establish long-lasting asymptomatic bacteremia in their natural mammalian reservoirs. Despite Brazil's ecological diversity and rich wild feline fauna, few studies have explored the molecular diversity of Bartonella species in these hosts.

The study aimed to molecularly detect and characterize Bartonella species in blood, liver, and spleen samples from wild felids across Brazil's North, Northeast, Central-West, Southeast, and South regions. Between 2017 and 2026, 211 blood, 77 spleen, and three liver samples were collected from wild felids across nine Brazilian states.

The sampling covered the North, Northeast, Central-West, Southeast, and South regions of the country. Samples positive in quantitative real-time PCR were subjected to PCR assays targeting eight molecular markers selected from previously published protocols for molecular characterization and phylogenetic analysis of Bartonella species.

The markers included gltA, ftsZ, groEL, nuoG, pap31, rpoB, ribC, and the sixteen to twenty-three S ribosomal RNA intergenic spacer region. Quantitative real-time PCR assays based on the nuoG gene detected Bartonella positivity in 3.09 percent of wild-felid blood, spleen, and liver samples, or nine of 291 samples.

Positive samples came from Leopardus pardalis, Leopardus geoffroyi, Panthera onca, Herpailurus yagouaroundi, and Leopardus wiedii. The number of copies of a Bartonella nuoG gene fragment could be estimated for seven of the nine positive samples. The BLASTn analysis found that the gltA sequence from Leopardus wiedii had one hundred percent identity with a Bartonella henselae sequence previously detected in Felis catus from China.

The gltA sequence from Leopardus geoffroyi had ninety-eight point fifteen percent identity with a Bartonella species sequence previously detected in Hylaeamys perenensis from Peru. In the maximum likelihood analysis, the Leopardus geoffroyi Bartonella species sequence was positioned in the same sub-clade as sequences previously detected in wild rodents and their associated ectoparasites from Brazil.

In the middle and lower portions of the tree, the two red-highlighted tips fall into separate clusters: the Leopardus geoffroyi sequence branches among rodent-associated Bartonella, while the Leopardus wiedii sequence is embedded beside Bartonella henselae sequences from wild and domestic felids.

The neighboring branch-support values are generally high, including several nodes labeled ninety-nine or one hundred. In the ftsZ row, the Identity column reports two database matches for the same sequence: one at ninety-nine point eighty-two percent and another at ninety-six point eighty-four percent.

The table also shows that both reference records come from Brazil, while their listed hosts are a wild rodent and Thrichomys fosteri, respectively. The Leopardus wiedii gltA sequence was positioned in the same sub-clade as Bartonella species sequences previously detected in domestic cats and their associated fleas from Chile, and in a Puma concolor from the United States.

That sub-clade was positioned in the same clade as Bartonella henselae. Because pre-enrichment liquid culture and isolation in blood or chocolate agar combined with quantitative real-time PCR can enhance Bartonella detection, the molecular occurrence reported here might be underestimated.

Digital PCR, combinations of PCR and serological assays, and microscopic examination may also contribute to improving Bartonella detection in biological samples. Future studies performing isolation and whole genome sequencing of Bartonella isolates associated with Neotropical wild felids are needed to clarify Bartonella diversity in these mammals.

Besides harboring Bartonella species associated with cats, wild felids may also act as accidental hosts for Bartonella species associated with wild small mammals, possibly as a consequence of predation. The study detected Bartonella DNA in nine of 291 wild-felid samples, with different sequences linking some felids to cats and others to wild rodents and fleas.

That pattern supports a broader ecological role for wild felids.