title: Tick-borne bacterial pathogens in southwestern Finland.
abstract: BACKGROUND
  Ixodes ricinus and Ixodes persulcatus are the main vectors of Lyme borreliosis spirochetes and several other zoonotic bacteria in northern Europe and Russia. However, few studies screening bacterial pathogens in Finnish ticks have been conducted. Therefore, reports on the occurrence and prevalence of several bacterial pathogens detected from ticks elsewhere in Europe and Russia are altogether missing from Finland. The main aim of the current study was to produce novel data on the occurrence and prevalence of several tick-borne bacterial pathogens in ticks collected from southwestern Finland.
  
  
  METHODS
  Ticks were collected in 2013-2014 by blanket dragging from 25 localities around southwestern Finland, and additionally from a dog in Lempäälä. Collected ticks were molecularly identified and screened for Borrelia burgdorferi s.l., Borrelia miyamotoi, Rickettsia, Bartonella and Candidatus Neoehrlichia mikurensis using quantitative PCR. Furthermore, detected Rickettsia spp. were sequenced using conventional PCR to determine species.
  
  
  RESULTS
  A total of 3169 ticks in 1174 DNA samples were screened for the listed pathogens. The most common bacteria detected was B. burgdorferi (s.l.) (18.5 % nymphal and 23.5 % adult ticks), followed by Rickettsia spp. (1.1 %; 5.1 %) and B. miyamotoi (0.51 %; 1.02 %). B. miyamotoi and Rickettsia spp. were also detected in larval samples (minimum infection rates 0.31 % and 0.21 %, respectively). Detected Rickettsia spp. were identified by sequencing as R. helvetica and R. monacensis. All screened samples were negative for Bartonella spp. and Ca. N. mikurensis.
  
  
  CONCLUSIONS
  In the current study we report for the first time the presence of Rickettsia in Finnish ticks. Furthermore, Rickettsia spp. and B. miyamotoi were found from larval tick samples, emphasizing the importance they may have as vectors of these pathogens. Comparisons of tick density estimates and B. burgdorferi (s.l.) prevalence made between the current study and a previous study conducted in 2000 in ten out of the 25 study localities suggest that an increase in tick abundance and B. burgdorferi (s.l.) prevalence has occurred in at least some of the study localities.
authors.affiliation: Department of Biology, University of Turku, FI-20014, Turku, Finland.|Archipelago Research Institute, University of Turku, FI-20014, Turku, Finland.
authors.forename: Jani J
authors.initials: JJ
authors.lastname: Sormunen
authors.affiliation: Zoological Museum, Department of Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Ritva
authors.initials: R
authors.lastname: Penttinen
authors.affiliation: Department of Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Tero
authors.initials: T
authors.lastname: Klemola
authors.affiliation: Archipelago Research Institute, University of Turku, FI-20014, Turku, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Hänninen
authors.affiliation: Archipelago Research Institute, University of Turku, FI-20014, Turku, Finland.
authors.forename: Ilppo
authors.initials: I
authors.lastname: Vuorinen
authors.affiliation: Department of Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Laaksonen
authors.affiliation: Zoological Museum, Department of Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Ilari E
authors.initials: IE
authors.lastname: Sääksjärvi
authors.affiliation: Department of Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Kai
authors.initials: K
authors.lastname: Ruohomäki
authors.affiliation: Department of Biology, University of Turku, FI-20014, Turku, Finland. eero.z.vesterinen@helsinki.fi.|Department of Agricultural Sciences, University of Helsinki, FI-00014, Helsinki, Finland. eero.z.vesterinen@helsinki.fi.
authors.forename: Eero J
authors.identifier: http://orcid.org/0000-0003-3665-5802
authors.initials: EJ
authors.lastname: Vesterinen
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D005387:Finland; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013987:Ticks / Q000382:microbiology*
keywords: Bartonella; Borrelia burgdorferi; Borrelia miyamotoi; Candidatus Neoehrlichia mikurensis; Finland; Ixodes persulcatus; Ixodes ricinus; Rickettsia; Tick-borne diseases