Exposure of Domestic Cats to Three Zoonotic Bartonella Species in the United States

Viability and Desiccation Resistance of Bartonella henselae in Biological and Non-Biological Fluids: Evidence for Pathogen Environmental Stability

Pathogen environmental stability is an often-neglected research priority for pathogens that are known to be vector-transmitted. Bartonella henselae, the etiologic agent of Cat Scratch Disease, has become a "pathogen of interest" in several serious human illnesses, which include neoplastic, cardiovascular, neurocognitive, and rheumatologic conditions. Survival in the flea gut and feces as well as the association with a biofilm in culture-negative endocarditis provides insight into this organism's ability to adjust to environmental extremes. The detection of B. henselae DNA in blood and tissues from marine mammals also raises questions about environmental stability and modes of pathogen transmission. We investigated the ability of B. henselae to survive in fluid matrices chosen to mimic potential environmental sources of infective materials. Feline whole blood, serum and urine, bovine milk, and physiologic saline inoculated with a laboratory strain of B. henselae San Antonio 2 were subsequently evaluated by culture and qPCR at specified time intervals. Bacterial viability was also assessed following desiccation and reconstitution of each inoculated fluid matrix. Bartonella henselae SA2 was cultured from feline urine up to 24 h after inoculation, and from blood, serum, cow's milk, and physiologic saline for up to 7 days after inoculation. Of potential medical importance, bacteria were cultured following air-desiccation of all fluid inoculates. The viability and stability of Bartonella within biological and non-biological fluids in the environment may represent a previously unrecognized source of infection for animals and human beings.

Risk Factors for Bartonella Seroreactivity Among Veterinary Workers in the Pacific Northwest

Background: Exposure to zoonotic diseases is a significant occupational risk in veterinary medicine. In this study, we characterized personal protective equipment use, injury frequency, and Bartonella seroreactivity in Washington State veterinary workers. Methods: Using a risk matrix developed to reflect occupational risk factors for exposure to Bartonella and multiple logistic regression, we explored determinants of risk for Bartonella seroreactivity. Results: Depending on the titer cutoff used, Bartonella seroreactivity was between 24.0% and 55.2%. No significant predictors of seroreactivity were found, although the relationship between high-risk status and increased seroreactivity for some Bartonella species approached significance. Serology for other zoonotic and vector borne pathogens did not identify consistent cross reactivity with Bartonella antibodies. Conclusion: The predictive power of the model was likely limited by the small sample size and high level of exposure to risk factors for most participants. Given the high proportion of veterinarians seroreactive to one or more of the three Bartonella spp. known to infect dogs and cats in the United States, as well as seroreactivity to other zoonoses, and the unclear relationship between occupational risk factors, seroreactivity, and disease expression, more research is needed in this area.

Comparison of Biological Activities of BafA Family Autotransporters within Bartonella Species Derived from Cats and Rodents

Bartonella species are hemotropic, facultative intracellular bacteria, some of which cause zoonoses, that are widely disseminated among many mammals, including humans. During infection in humans, vascular endothelial cells play a crucial role as a replicative niche for Bartonella, and some are capable of promoting vascular proliferation. Along with well-studied pathogenic factors such as a trimeric autotransporter adhesin BadA or VirB/D4 type IV secretion system, bacteria-secreted protein BafA is also involved in Bartonella-induced vasoproliferation. Genes encoding BafA orthologs have been found in the genomes of most Bartonella species, but their functionality remains unclear. In this study, we focused on three cat-derived zoonotic species (B. henselae, B. koehlerae, and B. clarridgeiae) and two rodent-derived species (B. grahamii and B. doshiae) and compared the activity of BafA derived from each species. Recombinant BafA proteins of B. henselae, B. koehlerae, B. clarridgeiae, and B. grahamii, species that also cause human disease, induced cell proliferation and tube formation in cultured endothelial cells, while BafA derived from B. doshiae, a species that is rarely found in humans, showed neither activity. Additionally, treatment of cells with these BafA proteins increased phosphorylation of both vascular endothelial growth factor receptor 2 and extracellular signal-regulated kinase 1/2, with the exception of B. doshiae BafA. Differential bafA mRNA expression and BafA secretion among the species likely contributed to the differences in the cell proliferation phenotype of the bacteria-infected cells. These findings suggest that the biological activity of BafA may be involved in the infectivity or pathogenicity of Bartonella species in humans.

Prevalence of selected pathogens in ectoparasites from free-roaming domestic cats in the southern Great Plains of the United States

Rickettsia sp. and Bartonella sp. were detected in ectoparasites of free-roaming domestic cats (Felis catus) from a trap-neuter-release program in central Oklahoma during January and February 2020. We used polymerase chain reaction and sequencing to identify fleas containing DNA of five different pathogens: Rickettsia felis (84%), 'Candidatus R. andeanae' (8%), Bartonella henselae (32%), Bartonella clarridgeiae (36%), and Bartonella sp. (8%). Co-infections with R. felis with three Bartonella species were identified. One tick was positive for R. felis, one flea was positive for 'Candidatus R. andeanae' and one ear mite was positive for a Bartonella species. These results highlight the need for more focus on free-roaming domestic cats and their ectoparasites in the Great Plains region.

Detection of antibodies against three zoonotic Bartonella spp. and cross-reactivity among species and Coxiella burnetii in dogs and cats from Central Thailand

Dogs and cats are important reservoir hosts of bacterial zoonotic pathogens, especially the Proteobacteria, Bartonella spp., and Coxiella burnetii. Bartonella spp. and C. burnetii are Gram-negative intracellular bacteria causing cat-scratch disease and query fever, respectively. Despite these two pathogens being dangerous, studies of their seroprevalence and cross-reactivity are limited in Thailand. The objectives of this study were to detect the seroprevalence of three zoonotic species of Bartonella and to evaluate cross-reactivity among Bartonella spp. and with C. burnetii. In total, 570 dog and cat serum samples were detected for antibodies against Bartonella spp. and C. burnetii using an indirect immunofluorescence antibody (IFA) test. At titer ≥ 1:64, tested serum that had a fluorescent intensity score ≥ 2 was interpreted as positive. Additionally, possible factors related to the seroprevalence were analyzed consisting of sex, breed, age, residing area, and ectoparasite control. Overall, the seroprevalence levels of Bartonella spp. and C. burnetii were 13.16% and 1.23%, respectively. All antigens of Bartonella were reacted to sera (1.23-7.72%), furthermore, both phases of C. burnetii were revealed in sera (0.35-1.05%). Interestingly, there was a poor agreement of cross-reactivity among Bartonella spp. at 5.56-8.70%, while cross-reactivity between Bartonella spp. and C. burnetii also showed poor agreement (2.80%). It is suggested that dogs and cats are important reservoirs of Bartonella spp., even in animals with ectoparasite control. The Bartonella seroprevalence was high in pure-breed animals with ectoparasite control, reflecting that Bartonella spp. infections can occur in owned, well-cared-for, and asymptomatic dogs and cats.