Bartonella species are the etiological agents of a number of human conditions including: cat scratch disease, encephalitis, endocarditis, myocarditis, and trench fever. While the degree of pathogenicity of many Bartonella species is poorly understood, an increasing number of species are being identified as real or potential human pathogens. Many of these pathogens are known to infect both primary and incidental hosts with long periods of asymptomatic latency. Additionally, several Bartonella species are known to be transmissible to humans through the bite of arthropod vectors including: fleas, lice, and ticks. The potential of rodents as reservoirs has been suggested but not thoroughly studied. This study sought to identify the presence and prevalence of Bartonella spp. among prairie dependent rodent species in northern Illinois. Rodents were live trapped during the summers of 2015-2017. Upon capture animals were identified to species and given a unique PIT tag number. Any observed ticks were removed from the animals and a tissue sample was collected. DNA was extracted from tissues and screened for Bartonella spp. via PCR of 16S-23S intergenic spacer region using Bartonella specific primers.
Results/Conclusions
A total of 614 unique individuals were trapped over the three year period. These represent four rodent species: Ictidomys tridecemlineatus, Microtus pennsylvanicus, Peromyscus maniculatus, and Zapus hudsonius. At a community level, 28.5% of individuals captured were identified to harbor Bartonella DNA. Species specific infection rates range from 22% in Zapus to 39% in Ictidomys. Infection rates showed little interannual variation except in Ictidomys which experienced a 6% increase in infection rate from 2015-2016. Presence of coinfection with Borrelia burgdorferi was also assessed. While approximately 10% of individuals were coinfected with both bacteria, the incidence was not significantly greater than expected using a Chi-square Goodness of Fit (p=0.565). These data suggest that several prairie dependent rodent species may represent reservoirs of pathogenic Bartonella species. Additional monitoring, and assessment of tick specimens are needed to verify these results and identify a route of transmission.