Molecular detection and genetic diversity of Rickettsia spp. in pet dogs and their infesting ticks in Harbin, northeastern China

Background Pet dogs are important companion animals that share the environment within households, and play an important role in local community life. In addition, pet dogs also are reservoirs of zoonotic agents, including Rickettsia spp., thus increasing the risk of rickettsial infections in humans. It's meaningful to investigate the epidemiology of rickettsial agents in pet dogs, and make contribute to the surveillance of rickettsioses in human in China. Results In this study, a total of 496 pet dogs' blood samples and 343 ticks infested in pet dogs were collected, and the presence and prevalence of Rickettsia were determined by amplifying the partial gltA and 17-kDa genes, with an overall positive rate of 8.1 % in blood samples and 14.0 % in tick samples. In addition, the rrs, gltA, groEL, and ompA genes of rickettsial were also recovered to determine the species of Rickettsia detected furtherly. Sequencing blast and phylogenetic analyses revealed the presence of three human pathogenic Rickettsia species (Rickettsia raoultii, Candidatus Rickettsia tarasevichiae and Rickettsia felis) in samples associated with pet dogs. Moreover, all the sequences of Rickettsia that we obtained presented close relationship with others available in GenBank, and Rickettsia raoultii was the most predominant Rickettsia species infected in pet dogs' blood samples or in tick samples. Conclusions This study provides the molecular epidemiology data about the Rickettsia spp. infection associated with pet dogs in urban areas of Harbin city. Three rickettisae species pathogenic to humans were identified from pet dogs' blood and the infested ticks in urban areas of Harbin city. Considering the intimate relationship between human and pets, these results indicate the potential transmission risk of human rickettisal infections from pet dogs through ectoparasites, and also highlighting that more attention should be paid to rickettsial infection in pet dogs and the infested ticks from the "One health" perspective.