Could climate trends disrupt the contact rates between Ixodes ricinus (Acari, Ixodidae) and the reservoirs of Borrelia burgdorferi s.l.?

PLoS One. 2020 May 29;15(5):e0233771. doi: 10.1371/journal.pone.0233771. eCollection 2020.

Abstract

This study addresses the modifications that future climate conditions could impose on the transmission cycles of Borrelia burgdorferi s.l. by the tick Ixodes ricinus in Europe. Tracking the distribution of foci of a zoonotic agent transmitted by vectors as climate change shapes its spatial niche is necessary to issue self-protection measures for the human population. We modeled the current distribution of the tick and its predicted contact rates with 18 species of vertebrates known to act as reservoirs of the pathogen. We approached an innovative way for estimating the possibility of permanent foci of Borrelia afzelii or Borrelia garinii tracking separately the expected spatial overlap among ticks and reservoirs for these pathogens in Europe. Environmental traits were obtained from MODIS satellite images for the years 2002-2017 (baseline) and projected on scenarios for the years 2030 and 2050. The ratio between MODIS baseline/current interpolated climatologies (WorldClim), and the ratio between MODIS-projected year 2050 with five climate change scenarios for that year (WorldClim) revealed no significant differences, meaning that projections from MODIS are reliable. Models predict that contact rates between the tick and reservoirs of either B. garinii or B. afzelii are spatially different because those have different habitats overlap. This is expected to promote different distribution patterns because of the different responses of both groups of reservoirs to environmental variables. Models for 2030 predict an increase in latitude, mainly in the circulation of B. garinii, with large areas of expected permanent contact between vector and reservoirs in Nordic countries and central Europe. However, climate projections for the year 2050 predict an unexpected scenario of contact disruption. Though large areas in Europe would be suitable for circulation of the pathogens, the predicted lack of niche overlap among ticks and reservoirs could promote a decrease in permanent foci. This development represents a proof-of-concept for the power of jointly modeling both the vector and reservoirs in a common framework. A deeper understanding of the unanticipated result regarding the year 2050 is needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachnid Vectors / microbiology
  • Arachnid Vectors / physiology
  • Borrelia burgdorferi Group / physiology*
  • Climate Change*
  • Ecosystem
  • Europe
  • Humans
  • Ixodes* / microbiology
  • Ixodes* / physiology
  • Lyme Disease* / epidemiology
  • Lyme Disease* / microbiology
  • Models, Spatial Interaction

Associated data

  • Dryad/10.5061/dryad.2h3f2

Grants and funding

Parts of this study were funded by the European Union under the FP7 program, and the COST Action TD1202. Parts of this study were funded by the Research Program of the Regional Government of Aragón (Spain), funding strategic research groups, under the contract 218376. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.