Bestehorn et al.
Phylogenetics of tick-borne encephalitis virus in endemic foci in the upper Rhine region in France and Germany.
PLoS ONE 13 (10):20204790. https://doi.org/10.1371/journal.pone.0204790

The Upper Rhine valley (adjoining The Netherlands) is the most western region where the TBE virus has been reported. Between 2016 and 2018, the authors have collected more than 4000 ticks at twelve sampling sites in the Upper Rhine region – in France (Alsace) and in Germany (Ortenaukreis, Federal State of Baden-Wuerttemberg, adjacent to Alsace). The authors could identify three new TBE foci (Schiltach and Aubachstrasse in Germany and Foret de la Robertsau in France), and they compared envelope gene sequences with 16 selected regional, national and international TBE virus strains including the reference strain Neudoerfl. Strains isolated at Aubachstrasse in 2016 and 2017 were clustering with strains from eastern Bavaria and Austria, while a strain isolated in 2018 showed a different sequence and was clustering with a strain from Schiltach and an historical strain isolated in Alsace in 1971. A strain isolated from Foret de la Robertsau showed a relationship to eastern Bavarian and Czech strains. In the upper Rhine region, there are at least three different TBE virus strains circulating and in Alsace, there are at least two independent TBE virus strains. Three newly described TBE virus strains collected in this region in 2016 and 2017 have a close phylogenetic relationship to strains from eastern Europe while a strain collected in 2018 (strain Aubachstrasse) was closely related to the strain Schiltach. The close genetic relationship of the newly identified strains on both sides of the Rhine river with strains from eastern Europe may be explained by long-distance import of ticks by migrating birds from eastern to western European areas.

TBE Book