. 2020 Jul 29;13(1):384.

doi: 10.1186/s13071-020-04259-z.

Questing abundance of adult taiga ticks Ixodes persulcatus and their Borrelia prevalence at the north-western part of their distribution


Background: Because ixodid ticks are vectors of zoonotic pathogens, including Borrelia, information of their abundance, seasonal variation in questing behaviour and pathogen prevalence is important for human health. As ticks are invading new areas northwards, information from these new areas are needed. Taiga tick (Ixodes persulcatus) populations have been recently found at Bothnian Bay, Finland. We assessed seasonal variation in questing abundance of ticks and their pathogen prevalence in coastal deciduous forests near the city of Oulu (latitudes 64-65°) in 2019.

Methods: We sampled ticks from May until September by cloth dragging 100 meters once a month at eight study sites. We calculated a density index (individuals/100 m2) to assess seasonal variation. Samples were screened for Borrelia burgdorferi (sensu lato) (including B. afzelii, B. garinii, B. burgdorferi (sensu stricto) and B. valaisana), Borrelia miyamotoi, Anaplasma phagocytophilum, Rickettsia spp., Neoehrlichia mikurensis, Francisella tularensis and Bartonella spp., Babesia spp. and for the tick-borne encephalitis virus.

Results: All except one nymph were identified as I. persulcatus. The number of questing adults showed a strong peak in May (median: 6.5 adults/100 m2), which is among the highest values reported in northern Europe, and potentially indicates a large population size. After May, the number of questing adults declined steadily with few adults still sampled in August. Nymphs were present from May until September.

  • We found a striking prevalence of Borrelia spp. in adults (62%) and nymphs (40%)
  • B. garinii (51%) and B. afzelii (63%) being the most common species
  • 26% of infected adults were coinfected with at least two Borrelia genospecies, mainly B. garinii and B. afzelii, which are associated with different host species

Conclusions: The coastal forest environments at Bothnian Bay seem to provide favourable environments for I. persulcatus and the spread of Borrelia. High tick abundance, a low diversity of the host community and similar host use among larvae and nymphs likely explain the high Borrelia prevalence and coinfection rate. Research on the infestation of the hosts that quantifies the temporal dynamics of immature life stages would reveal important aspects of pathogen circulation in these tick populations.



Yes, humans are hosts for Taiga ticks.

There is a misnomer in this article:  “As ticks are invading new areas northwards....”  This false narrative tries to make tick movement and disease proliferation a climate issue, when it’s not.

This makes it sound as if ticks are ONLY invading new areas to the North.  They are also invading new areas in the South (and everywhere else for that matter) and all of this despite the weather.  

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