Chapter 12a: Epidemiology by country – an overview

Abstract

• TBE is a flavivirus infection of the central nervous system (CNS), transmitted by ticks and in some rare instances by ingestion of unpasteurized milk. • TBE is diagnosed in the forested belts of Northern Eurasia ranging from eastern France and Norway down to northern Italy through central and Eastern Europe, Russia, Kazakhstan, and China to the northern Japanese island of Hokkaido. • About 10,000 cases of TBE are reported annually. • The European Centers for Disease Control (E-CDC) have put TBE on their list of notifiable diseases; their case definition requires clinical symptoms of CNS infection plus microbiolog-ical confirmation of the infection, usually by detection of specific immunoglobulins, IgG and IgM. • Despite this, surveillance of the TBEV in both ticks and humans is incomplete. Reported incidences do not reflect actual risk since this fluctuates annually as a result of changes in exposure, vaccine uptake, intensity of case finding and reporting, and climate, just to men-tion the most relevant factors. • For largely unknown reasons (including human behavior, improved diagnostics, or climate change) TBEV appears to be spreading north, east, and even south to areas that were pre-viously believed to be free of the virus. • The country reports in Chapter 12b provide a current and official ‘state-of-the-art’ survey on TBE, with available information about the virus, vectors, modes of transmission, case reporting, vaccine and prevention efforts, burden of disease over time, age and gender distribution of cases, virus isolation data, and risk area distribution. • Chapter 12c provides a risk map for TBEV based on documented TBE cases, TBEV infection, as well as on the detection of TBEV in nature. This map does not reflect the incidence of the disease or the prevalence of the virus in a given area. As the intensity and complete-ness of epidemiological surveillance varies between different countries, the map presented here may not be entirely complete, and very likely TBEV infections and thus TBE may occur in additional (‘new’) areas.