Background
Tick-borne encephalitis (TBE) case numbers and incidence rates fluctuate annually. Over the past 15 years, Europe has experienced an overall increase in TBE cases.
This overview provides an early retrospective assessment of the TBE burden in 2024, preceding the official data releases expected from national authorities in late winter or spring 2025. To achieve this, preliminary case numbers reported up to autumn (primarily November/December) were gathered from European countries with significant TBE burdens and well-established surveillance systems.
Country Overview
Scandinavia and Baltic countries
- Finland: Until December 9, a total of 197 TBE cases have been reported. Thus, 2024 will be a year with the highest number of cases ever reported in Finland.
- Norway: The number of cases has increased this year compared to 2022 (90 cases) and 2023 (113) cases, and there were two fatal cases.
- Estonia: As of September, 116 TBE cases had been reported, which is within the range of the number of cases reported during the last five years.
- Latvia: Until November 19, 160 TBE cases have been reported. This is significant less than reported for the last five years (200-260 cases).
- Lithuania: A total of 752 TBE cases have been reported until the end of September. This is the highest number in more than 20 years, and by the end of this year, the number may increase to an even higher top.
Central Europe / (Sub)Alpine Region
- Slovakia: Until November 8, 153 TBE cases have been notified. This number is in the range of 100 to 200 cases per year which have been yearly reported since 2010.
- Czech Republic: Until the end of November, 634 TBE cases have been reported. This number is in the range of the last five years.
- Austria: As of November 22, a total of 148 cases have been reported. This number lies in the range of TBE cases notified during the last five years (100-200) and may be classified as medium-high. It should be noted that the rate of vaccinated individuals is much higher in Austria compared to other countries, and thus, the incidence rate in non-vaccinated people is high in Austria.
- Germany: Until the end of November, 658 cases have been reported, the second highest number ever reported after the year 2020, when 717 cases occurred. Notably is the strong increase in the number of cases in the Federal State of Saxony.
- Switzerland: Until the end of October, a total of 400 cases have been reported, the second highest number after the year 2020, when 454 cases occurred.
- Italy: Until the end of November, 48 autochthonous TBE cases have been reported in Italy of which nearly all were seen in northeastern Italy indicating the continuation of a high burden of TBE disease in this region.
- Slovenia: Until December 9, 79 cases have been reported. This is in the range of notifications during the last 10 years (from 62 to 187 cases), but lower compared to the period from 2000 to 2013 (163 to 372 cases).
Discussion
Preliminary TBE case numbers from 12 European countries at the end of the 2024 TBE season suggest a high disease burden across endemic regions. Late notifications may further elevate case numbers in certain countries, potentially leading to new peaks.
These findings emphasize the critical importance of sustained surveillance and the implementation of preventive measures for populations at risk. Comparative analyses with previous years, such as those presented in Figure 1a (Chapter 12, TBE Book), will offer further insights.
Remark
The data presented here are preliminary, may contain inaccuracies, and should be interpreted with caution.
Acknowledgements
Special thanks to the following colleagues for their collaboration and for sharing national data:
Åshild Kristine Andreassen, Anu Jääskeläinen, Jana Kerlik, Kuulo Kutsar, Auksė Mickienė, Petr Pazdiora, Karin Stiasny, Valentina Tagliapietra, Dace Zavadska, Kyra Denise Zens.
Author: Dr. Michael Bröker
Compiled: November/December 2024