TBE foci in Switzerland

Area of Science:

• Epidemiology
• Infectious Diseases
• Public Health

Background:

• Tick-borne encephalitis (TBE) is a significant public health concern in Switzerland, with mandatory reporting of cases to national and cantonal health authorities.
• TBE is endemic in northern Switzerland and Liechtenstein, with reported annual cases ranging from 60 to 120, often resulting in neurological manifestations.

Purpose of the Study:

• To provide an updated overview of the TBE situation in Switzerland, with a specific focus on the canton of Thurgau.
• To identify and analyze the emergence and geographical distribution of TBE virus foci in Switzerland over the past two decades.

Main Methods:

• Collection and analysis of epidemiological data from diagnostic laboratories, official reports, and published studies.
• Utilizing historical data, patient follow-up questionnaires, and modern tools like GPS for microfoci determination.
• Review of data from studies conducted in Switzerland and Liechtenstein, including recent publications and historical records.

Main Results:

• A notable increase in reported TBE cases in Switzerland over the last 10 years, rising from 30-70 to 60-120 cases annually.
• The cantons of Thurgau, Aargau, and St. Gallen in northeastern Switzerland have shown a significant emergence of TBE.
• Canton Thurgau has become the most affected region, with new TBE foci identified east of previously known areas, and TBE virus microfoci are increasingly recognized across eastern Switzerland.

Conclusions:

• Despite vaccination, the incidence of TBE in Switzerland has risen, with canton Thurgau emerging as a primary risk area.
• New TBE virus foci continue to emerge, particularly in eastern Switzerland, indicating an evolving epidemiological landscape.
• Current data suggest no TBE foci in western or southern Switzerland, but ongoing surveillance is crucial for emerging threats.