Król N, et al.
Identification of New Microfoci and Genetic Characterization of Tick-Borne Encephalitis Virus Isolates from Eastern Germany and Western Poland.
Viruses. 2024;16(4):637. doi:10.3390/v16040637

The TBE virus circulates within small areas, often not larger than a soccer field or even smaller (microfoci). Therefore, collecting ticks from the ground (by flagging or dragging) in a region without further indication where to collect ticks and to analyze them for the presence of TBE virus is cumbersome, and there is a very low chance of finding ticks that have been infected by the virus, especially in regions that have reported only a few sporadic TBE virus infections. As a means of increasing the probability of success, a German/Polish team has collected ticks in areas where patients had been bitten by ticks in the past.

This approach resulted in a total of 19 potential TBE microfoci being selected for further study from the northeastern German states (Brandenburg, Mecklenburg-West Pomerania, Saxony) and Western Poland (voivodeships Lower Silesia, Lubush).

Between spring 2021 and summer 2022, 8,400 ticks were collected at the selected sites using a flagging method. Among the six so far unknown TBE sites, five are in Germany and one is in Poland. In addition to Ixodes ricinus, TBE virus has also been detected in Dermacentor reticulatus. A phylogenetic analysis based on the glycoprotein E gene revealed that the new isolates had the closest genetic relationship to other strains from Germany.

Based on these results, it appears that the patient-derived approach is effective in the search for new TBE microfoci. Detection of previously unknown TBE microfoci highlights the risk of acquiring a TBE virus infection even in areas that are officially non-endemic.

TBE Book