Page 240 - TBE_Book_V2_2019

Chapter 12b

TBE in Austria

Karin Stiasny, Heidemarie Holzmann and Franz-Xaver Heinz

History and Current Situation

Since 1972, the documentation of human in the population 41 to 80 years of age (Figure
cases of tick-borne encephalitis (TBE) in 2). In addition to virus transmission by tick
Austria has been performed by the Center for bites, alimentary infections through the
Virology, Medical University of Vienna, which consumption of infected goat cheese have
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acts as the National Reference Laboratory for been documented. TBE viruses isolated in
TBE and other flavivirus infections. Only Austria from ticks and humans were shown
hospitalized patients with a recent tick-borne through molecular analyses to be members of
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encephalitis virus (TBEV) infection confirmed the European subtype of TBEV (TBEV-Eu) [ ,
by laboratory diagnosis are counted as cases. and Dobler personal communication].
Confirmation is usually based on immuno-
globulin (Ig) serology (namely enzyme-linked Mapping of the most likely sites of human
immunosorbent assay [ELISA] for IgM and infection has been performed by the National
IgG). However, this confirmation may be Reference Laboratory since 1972 through the
supplemented by virus neutralization and use of questionnaires sent to TBE patients
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polymerase chain reaction (PCR) analyses if with confirmed laboratory diagnosis. These
needed. data are shown in Figure 3. Although many of
the most affected regions remained constant
In 2012, TBE became a notifiable disease in throughout the observation period, new
Austria as in other countries of the European endemic zones – especially in previously
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Union. The annual incidence rates of TBE in unaffected alpine regions in western Austria –
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Austria have declined substantially since the were established. The first TBE case in the
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1980s. This decline was associated with an Federal State of Tyrol was documented in
increasing rate of vaccination and was not 1984 and in Vorarlberg in 2000, in the
observed in some neighboring countries, for subsequent years certain valleys in both states
example Czech Republic and Slovenia, where became sites of infection for a substantial
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vaccination coverage is much lower than in number of human TBE cases.
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Austria.
However, the causes for establishment of new
Incidences of TBE in the unvaccinated and endemic regions in Austria are unknown. In
vaccinated population in Austria from 2010 to parallel, the incidences in the northeastern
2018 are shown in Figure 1. Strong annual part of the country (comprising regions with
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fluctuations are a characteristic feature of the relatively low altitudes) declined, suggesting a
epidemiology of TBE in Austria, indicating a change to less favorable conditions for virus
complex interplay of factors that control viral circulation in this area. In the traditional core
transmission dynamics in natural hosts and TBE zones of Austria, no evidence has been
human risk exposure. The age distribution of seen for a shift of infection sites to higher
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TBE incidences in Austria is strongly shifted altitudes.
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towards older people and reveals now a peak
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