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Chapter 12a: Epidemiology by country – overview

potential risk of exposure, depending on their bases available, it is fair to conclude that the
activity and mobility. true TBEV disease burden is significantly
3,8
underestimated.
Recommendations in other countries, if they
exist at all, are linked to certain conditions, In this article we adhere to the ECDC definition
e.g. predefined risk areas, age, or possible of TBE (Table 1), requiring 1) clinically
occupational exposure (Figure 1 and Table 2). apparent disease of the central nervous
system plus 2) at the same time, a valid
Overall, TBE surveillance in Europe is more microbiological documentation of current
sporadic than systematic. In the end, the real infection in the patient with TBEV. In
burden of disease from TBE remains unknown accordance with the above criteria, the
and the identification of TBEV endemic areas reported numbers of TBE cases by country and
is far from being complete. With only by year are summarized in Table 3.
inconsistent and incomplete scientific data-

Table 1: TBE case definition by the ECDC4 ‘NA’= Not applicable
TICK-BORNE ENCEPHALITIS
1. Clinical Criteria
Any person with symptoms of inflammation of the CNS
(e.g. meningitis, meningoencephalitis, encephalomyelitis, encephaloradiculitis)
2. Laboratory Criteria
*
Laboratory criteria for case confirmation:
At least one of the following five:
- TBE specific IgM AND IgG antibodies in blood
- TBE specific IgM antibodies in CSF
- Sero-conversion or four-fold increase of TBE-specific antibodies in paired serum samples
- Detection of TBE viral nucleic acid in a clinical specimen,
- Isolation of TBE virus from clinical specimen
Laboratory criteria for a probable case:
- Detection of TBE-specific IgM-antibodies in a unique serum sample
3. Epidemiological Criteria
Exposure to a common source (unpasteurized daily products)
Case Classification
A. Possible case NA
B. Probable case
Any person meeting the clinical criteria and the laboratory criteria for a probable case
OR
Any person meeting the clinical criteria and with an epidemiological link
C. Confirmed case
Any person meeting the clinical and laboratory criteria for case confirmation

*Serological results should be interpreted according to the vaccination status and previous exposure to other
flaviviral infections. Confirmed cases in such situations should be validated by serum neutralization assay or
other equivalent assays.

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