Page 329 - TBE_Book_V2_2019

Chapter 12b

TBE in Latvia

Dace Zavadska and Zane Odzelevica

History and Current Situation

Aggregated data on TBE cases in Latvia are All three main TBEV subtypes are carried by
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available from 1955, but serological testing ticks in area of Latvia - the European, Siberian
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for TBE began in the 1970’s. Since TBE and Far-Eastern subtype. 4,5,6 Epidemiological
became notifiable in Latvia, epidemiological investigations suggests, that in Latvia, ticks
changes of disease incidence have been carry a higher TBEV load than in other at-risk
outstanding. Between 1990–2000 Latvia had countries, and up to 20-40% of ticks are
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the highest rates of TBE incidence in the infected in highly endemic areas. Latvia also
world, ranging from 8 to 53 cases per 100,000 has one the highest reported rates of TBEV
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population. Although, incidence has de- transmission via unpasteurized dairy products,
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creased significantly in past 10 years - annual mainly goat’s milk, which accounts for 0.5-
incidence of TBE has decreased two times - 3.5% of total cases (2011-2018).
from 14.58/100.000 in 2010 to 7.86/100.000
in 2018, nevertheless, Latvia still ranks The largest recent study in Latvia describes
between European countries with the highest that main characteristics of affected TBE
annual TBE incidence. Distribution of TBE population recently are in age group “18-59
cases in Latvia varies between different years”, mostly males, representing TBE risk
regions and indicates areas with different population due to active lifestyle, increased
levels of endemicity. For example, the highest outdoor activities, travelling, that can increase
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incidence usually is registered in regions near the risk of tick-human contact.
the northwest coast.
In children (0-17 years) in Latvia TBE is less
The Centre for Disease Prevention and common reported than in adults - only 5.6% of
Control (CDPC) of Latvia is the institution that all cases. The most common clinical manifesta-
provides TBE surveillance in Latvia. Based on tion of TBE was meningitis, with highest
national legislation, there is countrywide number of cases in age group”18-59 years”.
mandatory case-based passive reporting, For children, meningitis was also most
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guided by the European Centre for Disease frequent cause of hospitalization. Comparing
Prevention and Control (ECDC) case definition to other age groups, more severe TBE clinical
for TBE. In Latvia it was officially adapted in forms (meningoencephalitis, etc.) was report-
2012. Adoption of standardized European case ed among age group ‘’60+ years’’.
definition for TBE in Latvia has allowed to
Vaccination remains the most effective
ensure more correct TBE epidemiological data 10,11,12
protective measure against TBE. In
and impact of vaccination.
Latvia, there is only a partial National
The main vector of the TBE virus in Latvia are Immunization Program, which provides
ticks of family Ixodidae, mainly Ixodes ricinus vaccine free of charge for children living in
and Ixodes persulcatus (eastern part of highly endemic areas since 2006 and orphans /
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country). children without parental care in the whole
country since 2010.

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