Slovakia reports highest occurrence of alimentary tick-borne encephalitis in Europe: Analysis of tick-borne encephalitis outbreaks in Slovakia during 2007-2016

Background: Slovakia is well-known for tick-borne encephalitis alimentary (TBE) outbreaks in Europe for a long time. Since the first known and largest TBE alimentary outbreak in 1951 (at territory of Slovakia) until today, none of the European countries report a comparable number of TBE alimentary outbreaks with probable and laboratory confirmed food transmission factor as Slovakia. Methods: We analyzed TBE outbreak confirmed cases reported in Slovakia from web-based Epidemiological Information System (EPIS) during the period 2007-2016. Results: During years 2007-2016 we recorded 26 TBE alimentary outbreaks. In most outbreaks (22 out of 26) the probable transmission factor of TBE virus was identified within epidemiological context. In 4 outbreaks the transmission factor was laboratory confirmed. The most common probable and confirmed transmission factor of alimentary TBE outbreaks was milk and milk products of goat origin. Conclusion: There should be more effort of laboratory clarification of TBE transmission factor in Slovakia. It is important to be aware of the issue of Slovakia from the point of tourism and prevention, but also due to potential risks of consumption of raw milk and its products that became popular in recent years not only in Slovakia.