Abstract

Simple SummaryLyme borreliosis is caused by a spirochete from the Borrelia burgdorferi sensu lato group. Borrelia afzelii and B. garinii are known to be pathogenic to humans. The main vector for Lyme borreliosis is the Ixodes tick. In this study, Borrelia infection was confirmed in Ixodes, Haemaphysalis, and Amblyomma ticks. To our knowledge Borrelia infection was first confirmed in Amblyomma testudinarium in Korea. Based on phylogenetic analysis, all sequences were aligned with B. afzelii isolates and showed a close relationship with high identity. Considering that B. afzelii causes infectious zoonotic diseases, continuous monitoring and attention are still required (although a low prevalence was recorded in this study).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 Borrelia afzelii 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.

Highlights

  • Ticks are ectoparasites that feed on humans as well as wild and domestic animals

  • The main vectors of Lyme borreliosis are the ticks of the genus Ixodes and the main species in Asia are Ixodes persulcatus and I. nipponensis [7,8]

  • After B. burgdorferi s. l. was first identified in Korea in 1993, a human Lyme borreliosis case occurred during the same year

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Summary

Introduction

Ticks are ectoparasites that feed on humans as well as wild and domestic animals. Ticks are a vector for spreading viruses and protozoa, as well as bacteria, e.g., Borrelia, Coxiella, or Rickettsiales [1,2]. In Korea, B. afzelii and B. garinii were first identified in Ixodes ticks and wild rodents. B. bavariensis, B. tanukii, B. turdi, B. valaisiana, and B. yangtzensis were identified in ticks and wild animals [7], whereas B. afzelii and B. garinii were detected in domestic and wild animals [4,7,13]. In a study examining the national prevalence of Borrelia in ticks of wild rodents in Korea, regional features of Borrelia spp. were observed; B. afzelii was found in all regions except Jeju Island, and some species were found only in the southern regions (Borrelia valaisiana, B. yangtzensis, and B. tanukii). B. burgdorferi sensu stricto, known to cause Lyme borreliosis in northern America, has been identified for the first time in Korea [10]. This study aimed to identify regional differences of ticks in the distribution and prevalence of Borrelia spp. based on tick species near a farm environment and to identify Borrelia infections in Ixodes ticks, which are the major vectors of Borrelia spp., and in Haemaphysalis and Amblyomma ticks

Tick Collection and Species Identification
Findings
Molecular and Phylogenetic Analyses
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