EU/EEA countries with mandatory TBE reporting: Austria, the Czech Republic, Estonia, Finland, Germany, Greece, Hungary, Latvia, Lithuania, Norway, Poland, the Slovak  Republic, Slovenia, and Sweden. Sources:  Personal communication Dr Oliver Donoso Mantke, Robert Koch Institute, Germany, 8 June 2010 Suss J. Tick-borne encephalitis in Europe and beyond – the epidemiological situation as of 2007. Euro Surveill. 26 Jun 2008 ;13(26).

There are indications that TBE is increasing in Europe, and that the geographical areas where ticks are infected are growing. However, it is not clear whether the increase in the number of reported cases in some European countries during the last two decades truly reflects more infections or results from the fact that the public as well as health professionals have become more aware of the disease, or a combination of the two. Some researchers believe that climate change may have resulted in an expansion of the tick habitat in Europe and consequently in the geographical distribution of TBE-infected ticks.However, although there are reports in support of this theory of ticks being found at higher altitudes and latitudes, it is unlikely that climate change alone could explain the increase in TBE cases. A review published in the journal Eurosurveillance estimated the mean number of TBE cases in Europe to be 2805 per year during the 18-year period leading up to 2007.  

Given that it is common for TBE patients to suffer from long-term neurological disabilities, and that up to 1.4% will die from the infection, it can be concluded that TBE contributes considerably to the burden of infectious disease in Europe.

TBE is currently not in the group of communicable diseases under active surveillance in the European Union, and TBE cases in EU Member States are not actively reported to the European Centre for Disease Prevention and Control (ECDC). It is mandatory to report TBE cases in thirteen EU countries (Austria, the Czech Republic, Estonia, Finland, Germany, Greece, Hungary, Latvia, Lithuania, Poland, the Slovak Republic, Slovenia, and Sweden) and Norway.

The lack of a common TBE case definition and diagnostic criteria for Europe, incomplete mandatory reporting, and the fact that most TBE infections are mild or subclinical, makes monitoring of trends and geographical distribution a challenge. Risk assessment is often based on the number of reported cases by geographical area, and immunisation uptake will impact on disease numbers. This is illustrated by Austria where high vaccination coverage (88%) has resulted in a 90% decline in the number of cases over the last two decades. However, since vaccination does not reduce the proportion of ticks infected with the TBE virus, the risk for an unvaccinated person to contract TBE in Austria today is likely to be similar to what it was 20 years ago.

ECDC will review the TBE situation in Europe, in the near future, with the aim of characterising the different reporting systems, assessing the epidemiological situation and identifying key risk areas and risk groups for TBE. Learning more about the risk of TBE is important for providing information and advice to health professionals and the general public on vaccination and other preventive measures.

More information on this research:
Call for tender on epidemiologic situation analysis of Tick Borne Encephalitis and Rickettsiosis in the European Union
Call for tender on epidemiologic situation analysis of Lyme borreliosis in the European Union

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