The Emergence and Dynamics of Tick-Borne Encephalitis Virus in a New Endemic Region in Southern Germany

Tick-borne encephalitis (TBE) is the most important viral tick-borne infection in Europe and Asia. It is emerging in new areas. The mechanisms of emergence are fairly unknown or speculative. In the Ravensburg district in southern Germany, TBE emerged, mainly over the last five years. Here, we analyzed the underlying epidemiology in humans. The resulting identified natural foci of the causal TBE virus (TBEV) were genetically characterized. We sampled 13 potential infection sites at these foci and detected TBEV in ticks (Ixodes ricinus) at eight sites. Phylogenetic analysis spurred the introduction of at least four distinct TBEV lineages of the European subtype into the Ravensburg district over the last few years. In two instances, a continuous spread of these virus strains over up to 10 km was observed.

Automated summary

Tick-borne encephalitis (TBE) is an important viral tick-borne infection in Europe and Asia. The emergence of TBE in new areas, such as the Ravensburg district in southern Germany, has been analyzed to identify the natural foci of the causative TBE virus (TBEV). Through genetic characterization and phylogenetic analysis, several distinct TBEV lineages were identified, suggesting the continuous spread of these virus strains over a certain distance.