Epidemiological study of relapsing fever borreliae detected in Haemaphysalis ticks and wild animals in the western part of Japan

PLoS One. 2017 Mar 31;12(3):e0174727. doi: 10.1371/journal.pone.0174727. eCollection 2017.

Abstract

The genus Borrelia comprises arthropod-borne bacteria, which are infectious agents in vertebrates. They are mainly transmitted by ixodid or argasid ticks. In Hokkaido, Japan, Borrelia spp. were found in deer and Haemaphysalis ticks between 2011 and 2013; however, the study was limited to a particular area. Therefore, in the present study, we conducted large-scale surveillance of ticks and wild animals in the western part of the main island of Japan. We collected 6,407 host-seeking ticks from two regions and 1,598 larvae obtained from 32 engorged female ticks and examined them to elucidate transovarial transmission. In addition, we examined whole blood samples from 190 wild boars and 276 sika deer, as well as sera from 120 wild raccoons. We detected Borrelia spp. in Haemaphysalis flava, Haemaphysalis megaspinosa, Haemaphysalis kitaokai, Haemaphysalis longicornis, and Haemaphysalis formosensis. In addition, we isolated a strain from H. megaspinosa using Barbour-Stoenner-Kelly medium. The minimum infection rate of ticks was less than 5%. Transovarial transmission was observed in H. kitaokai. Phylogenetic analysis of the isolated strain and DNA fragments amplified from ticks identified at least four bacterial genotypes, which corresponded to the tick species detected. Bacteria were detected in 8.4%, 15%, and 0.8% of wild boars, sika deer, and raccoons, respectively. In this study, we found seasonal differences in the prevalence of bacterial genotypes in sika deer during the winter and summer. The tick activity season corresponds to the season with a high prevalence of animals. The present study suggests that a particular bacterial genotype detected in this study are defined by a particular tick species in which they are present.

MeSH terms

  • Animals
  • Animals, Wild / microbiology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Borrelia / pathogenicity*
  • Genotype
  • Japan
  • Multilocus Sequence Typing
  • Phosphoric Diester Hydrolases / genetics
  • Phylogeny
  • Polymerase Chain Reaction
  • RNA, Ribosomal, 16S / genetics
  • Raccoons
  • Real-Time Polymerase Chain Reaction
  • Relapsing Fever / epidemiology*
  • Relapsing Fever / microbiology
  • Relapsing Fever / parasitology
  • Relapsing Fever / transmission
  • Ticks / microbiology*
  • Ticks / pathogenicity

Substances

  • Bacterial Proteins
  • RNA, Ribosomal, 16S
  • Phosphoric Diester Hydrolases
  • glpQ protein, Bacteria

Grants and funding

This work was supported in part by the Research Program on Emerging and Re-emerging Infectious Diseases from Japan Agency for Medical Research and Development, AMED (http://www.amed.go.jp/en/), and Program to Disseminate Tenure Tracking System, MEXT, Japan (http://www.jst.go.jp/tenure/index.html) and JSPS KAKENHI (https://www.jsps.go.jp/english/index.html), Grant Number 15H05262. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.