Molecular Identification of Borrelia spp. from Ticks in Pastures Nearby Livestock Farms in Korea

Ticks are vectors that spread pathogenic bacteria, viruses, and protozoa. As the number of ticks increases due to climate change, the importance of the study of tick-borne pathogens has also increased. This study was conducted to investigate the distribution of the major tick species causing Lyme borreliosis and regional differences in the prevalence of Borrelia spp. by tick species. Borrelia infection was confirmed not only in Ixodes ticks, which are the major vectors of Borrelia spp., but also in Haemaphysalis and Amblyomma ticks. PCR targeting the 5S-23S rRNA intergenic spacer region (rrf-rrl) was performed to confirm Borrelia positivity. A total of 6102 ticks (736 pools) were tested, and the proportion was Haemaphysalis longicornis nymphs and adults at 69.2%, Haemaphysalis flava nymphs and adults at 13.9%, Haemaphysalis spp. larva at 14.3%, Ixodes nipponensis at 0.8%, and Amblyomma testudinarium at 1.9%. Ixodes nipponensis showed the highest minimum infection rate (MIR: 34.00; 17 pools/50 ticks) for Borrelia spp., followed by A. testudinarium (MIR: 0.88), and H. longicornis (MIR: 0.05). In particular, to our knowledge Borrelia infection was first confirmed in A. testudinarium in Korea. As a result of phylogenetic analysis, all sequences were grouped with Borreliaafzelii isolates and showed a close relationship with high identity. Considering that B. afzelii causes infectious zoonotic diseases, continuous monitoring and attention are needed, although it has a low prevalence in this study.