Molecular Survey and Genetic Characteristics of Vector-Borne Pathogens in Domestic Dogs from Four Regions of China

SIMPLE SUMMARY: Canine vector-borne diseases (CVBDs) can affect the health of domestic and wild animals, and their prevalence is increasing worldwide. As potential reservoirs of zoonotic pathogens, dogs might transfer these pathogens to humans. There is limited knowledge about the vector-borne pathogens circulating in dogs in China. To investigate the current epidemiological status and genetic characteristics of Ehrlichia spp., Hepatozoon spp., and Mycoplasma spp., blood samples were collected from healthy pet dogs in four regions of China. There was no evidence of Ehrlichia spp. or Mycoplasma spp., and only Hepatozoon canis was detected in these dogs. High haplotype diversity and the occurrence of genetic variation were observed among these H. canis isolates. These results will be useful for developing effective control approaches against CVBDs in companion animals. ABSTRACT: Canine vector-borne diseases are widely distributed around the world. They are transmitted by arthropods, and many seriously threaten the health of animals and humans. In China, our knowledge of Ehrlichia, Hepatozoon, and Mycoplasma species circulating in dogs is still poorly understood. Therefore, the aim of this study was to understand the prevalence and genetic characteristics of canine Ehrlichia spp., Hepatozoon spp., and Mycoplasma spp. in Chongqing (southwest), Fujian (southeast), Shandong (southeast), and Hubei (central) Provinces of China. Blood samples from healthy pet dogs were processed to detect Ehrlichia, Hepatozoon, and Mycoplasma DNA with PCR. Haplotype and phylogenetic analyses were performed on 18S rRNA sequences. Among 306 dogs, no Ehrlichia spp. or Mycoplasma spp. were detected, whereas one Hepatozoon sp. was detected in 10 (3.27%) of the animals. Only Hepatozoon canis was identified and was endemic to Chongqing (2.46%) and Hubei (8.77%). A haplotype analysis identified eight haplotypes among the H. canis isolates. A phylogenetic analysis showed that the H. canis isolates in this study clustered into four clades, together with isolates from different countries and hosts, forming a large group that was clearly separate from other Hepatozoon species. These findings provided new information on the epidemiological characteristics of canine vector-borne diseases in China and will be helpful in the development of efficient measures to safeguard the health and well-being of companion animals and their owners.