Emerging Risk of Flea-Borne Bartonella in Tropical Cities: Evidence from Stray Cats in the Klang Valley, Malaysia

Urban stray cats are often associated with ectoparasites and zoonotic pathogens due to their unsanitary living conditions and lack of veterinary care. Fleas, especially <i>Ctenocephalides</i> spp., are competent vectors of <i>Bartonella</i> spp., a genus of emerging bacterial pathogens with both public health and veterinary relevance. This study investigated the presence of <i>Bartonella</i> DNA in ectoparasitic fleas infesting stray cats in various urban habitats within the Klang Valley, Malaysia. A total of 204 fleas were collected from 89 stray cats. Fleas were identified morphologically using established taxonomic keys under a light microscope and further validated through PCR amplification of the mitochondrial cytochrome <i>c</i> oxidase subunit I (<i>cox1</i>) gene. Detection of <i>Bartonella</i> spp. was conducted by targeting the citrate synthase (<i>gltA</i>) gene. All fleas were confirmed as <i>Ctenocephalides felis</i>, with an infestation prevalence of 39.33% among the cats sampled. Of 118 <i>C. felis</i> specimens tested, 86.44% were positive for <i>Bartonella</i> DNA, one of the highest worldwide and significantly surpassing previous Malaysian reports. Sequencing of 12 positive samples showed identities with <i>B. claridgeiae</i> (58.3%), <i>B. henselae</i> (25.0%), an uncultured <i>Bartonella</i> species (8.3%) and a <i>Bartonella</i> isolate from a dog in Chile (8.3%). These results highlight the significant presence of <i>Bartonella</i>, causative agent of cat-scratch disease in stray cats, emphasizing their potential role as urban reservoirs and vectors. The findings underscore the need for ectoparasite surveillance and zoonotic pathogen control as integral components of stray animal management in Malaysia's urban settings.