In endemic areas of Austria and Southern Germany, TBE prevalence has been found to be 4–8%. Only in the most severely affected areas in the east and southeast of Austria figures of up to 14% may be reached. Prevalence is extremely high in some areas of the former USSR and former Czechoslovakia.
A much higher percentage of TBE positive individuals has been observed among risk groups such as:
• Individuals working in agriculture and forestry
• Hikers, ramblers, people engaged in outdoor sports
• Collectors of mushrooms and berries.
During the past two decades, however, the number of infections has substantially declined, particularly among individuals engaged in agriculture and forestry who have participated in the vaccination programs.
At present, mainly people who come to TBE endemic areas in pursuit of their recreational activities develop the disease. Recent increases of TBE cases in Central Europe and the Baltic states may have arisen largely from changes in human behavior that have brought more people into contact with infected ticks. On account of environmental concerns, the rigorous treatment of TBE natural focus territory in Russia was discontinued in the 1980s. That may partly explain the increase of the tick population and rate of infective ticks in this region.
Infection with TBE virus may happen at home, when infected ticks are inadvertently carried in with bunches of wild flowers, Christmas trees, clothes, or by dogs. Moreover, TBE virus infections are more and more frequently reported to have occurred in the patients’ own gardens, even in urban areas.