Wild cats may be carrying bacteria linked not only to domestic cats, but also to the rodents and fleas they hunt. That changes how scientists think about disease moving through Brazil’s wildlife. Bartonella are bacteria that live inside animal cells and can infect several kinds of mammals.

They usually stay with particular host species and can remain in those animals for a long time without obvious illness. In people, accidental infections can cause several illnesses, most commonly cat-scratch disease, with less frequent problems including serious blood-vessel and heart infections.

Brazil has a rich variety of wild cats, with eight of its eleven recognized wild-felid species found in Rio Grande do Sul. Yet few studies have explored the molecular diversity of Bartonella in these hosts, leaving a gap in understanding how the bacteria circulate in Brazilian wildlife.

So the study looked for Bartonella in wild cats from several regions of Brazil, aiming to improve understanding of circulation and possible risks to people. This map places the wild-cat sampling across Brazil, from several distant states rather than one local area.

That broad geographic spread matters because any detected infection can be compared across very different parts of the country. The testing found Bartonella in wild-felid blood, spleen, and liver samples. The positive samples came from several wild-cat species, showing that the bacteria were not limited to one kind of animal.

The amount of bacterial genetic material could be estimated in most of the positive samples. The genetic sequences from one wild cat matched a Bartonella sequence previously found in domestic cats, placing it near cat-associated bacteria.

But a sequence from another wild cat grouped with Bartonella sequences previously found in wild rodents and the fleas associated with them. The study reports molecular evidence of Bartonella circulating in free-living wild felids from municipalities in Bahia, Minas Gerais, and Rio Grande do Sul.

Reports of these bacteria in wild felids remain scarce, especially in South America. The detected occurrence might be an underestimate, because earlier work found that combining several laboratory approaches can improve detection of Bartonella in biological samples.

The researchers say future studies should use additional detection methods and examine the complete genetic material of isolated bacteria to clarify their diversity in these mammals. Wild felids may carry Bartonella associated with cats, but they may also act as accidental hosts for Bartonella associated with wild small mammals, possibly after eating infected prey.

Wild felids may therefore carry Bartonella associated with cats as well as Bartonella associated with wild small mammals, perhaps after predation. The study found Bartonella in free-living wild felids, with genetic evidence pointing to both cat-associated bacteria and bacteria linked to wild rodents and fleas.

Wildlife health and possible human exposure are connected through the food web.