The present study aimed to detect and characterize Borrelia spp. in ticks attached to dogs in Korea. Overall, 562 ticks (276 pools) attached to dogs were collected and tested for Borrelia infection by PCR targeting the 5S-23S rRNA intergenic spacer region (rrf-rrl). One tick larva (pool level, 0.4%; individual level, 0.2%) was confirmed by sequencing Borrelia garinii, a zoonotic pathogen. For molecular characterization, the outer surface protein A (ospA) and flagellin genes were analyzed. Phylogenetic ospA analysis distinguished B. garinii from B. bavariensis, which has been recently identified as a novel Borrelia species. On the other hand, phylogenetic analysis showed that single gene analysis involving rrf-rrl or flagellin was not sufficient to differentiate B. garinii from B. bavariensis. In addition, the B. garinii-infected tick was identified as Ixodes nipponensis by sequencing according to mitochondrial 16S rRNA and the second transcribed spacer region. To our knowledge, this is the first study to report the molecular detection of B. garinii in I. nipponensis parasitizing a dog in Korea. Continuous monitoring of tick-borne pathogens in ticks attached to animals is required to avoid disease distribution and possible transmission to humans.
Keywords: Borrelia garinii; Ixodes nipponensis; Lyme borreliosis; differential diagnosis; dog; tick-borne pathogen.