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Rickettsial infection in dog-associated ticks in three rural communities of Yucatan, Mexico was investigated using qPCR and nested PCR assays. A total of 319 dogs were studied and ticks samples were collected. A total of 170 dogs were infested with ticks (frequency of 53.4%). Overall, 1,380 ticks representing seven species were collected: Amblyomma mixtum, A. ovale, A. parvum, A. cf. oblongoguttatum, Ixodes affinis, Rhipicephalus microplus, and R. sanguineus sensu lato. The most abundant species was R. sanguineus s.l. with a mean intensity of 7.4 ticks/host. Dogs in the communities of Chan San Antonio and Yaxcheku were 2.84 and 2.41 times more likely to be infected with R. sanguineus compared with Sucopo (p < 0.05). Adult pools of A. mixtum, A. parvum, I. affinis, R. microplus, and A. c.f. oblongoguttatum were negative to E. chaffeensis, E. ewingii, A. phagocytophilum, and R. rickettsii. However, pools of R. sanguineus s.l. adults and A. ovale adults, as well as nymphs of Amblyomma spp. were positive to E. canis. Sequencing analysis of the nested PCR products amplifying the 16S rRNA gene fragment of E. canis confirmed the results and revealed 100% identity with sequences of E. canis. This is the first report worldwide of E. canis infection in A. ovale by PCR. This finding does not necessarily indicate that A. ovale is a competent vector of E. canis because pathogen transmission of this specific tick to a naïve dog remains to be documented. This study documented that different tick species parasitize dogs in Yucatan, Mexico, where R. sanguineus s.l., A. ovale, and nymphs of Amblyomma spp. were shown to be infected with E. canis. These findings highlight the need for control strategies against tick infestations in dogs to prevent the risk of tick-borne disease transmission among companion animal and probably human populations.

No abstract

Summary 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.