Molecular prevalence and ecoregion distribution of select tick-borne pathogens in Texas dogs

Tick-borne diseases (TBD), caused by borrelial, rickettsial and babesial pathogens, are common across the United States and can cause severe clinical disease in susceptible hosts, such as domestic dogs. However, there are limited TBD molecular epidemiological reports for dogs in Texas, and none for the non-Lyme borrelial pathogen responsible for causing tick-borne relapsing fever (TBRF). Therefore, data to support the prevalence of TBRF in the canine population is inadequate. This study aimed to characterize the molecular prevalence of 11 causative agents responsible for three TBD groups within domestic dogs with an emphasis on pathogen distribution within Texas ecoregions. A total representative number of 1,171 whole-blood samples were collected opportunistically from two Texas veterinary diagnostic laboratories. A layerplex real-time PCR assay was utilized to screen the dog samples for all 11 pathogens simultaneously. The overall molecular infection prevalence of disease was 0.68% borrelial, 1.8% rickettsial and 0.43% babesial pathogens, for a TBD total of 2.73% across Texas. Higher molecular prevalence was observed when analysed by ecoregion distinction, including 5.78% rickettsial infections by Ehrlichia canis and Anaplasma platys in the Rolling Plains ecoregion, and an average of 1.1% Borrelia turicatae and 1.0% Babesia gibsoni across detected ecoregions. To our knowledge, our findings indicate the first molecular detection of A. platys in Texas, and the first report of coinfections with E. canis and A. platys in dogs of Texas. The zoonotic concerns associated with TBDs, in conjunction with dogs' implication as an effective sentinel for human disease, highlight the importance of characterizing and monitoring regions associated with active infections in dogs. Surveillance data obtained from this study may aid public health agencies in updating maps depicting high-risk areas of disease and developing preventative measures for the affected areas.