A brief history of the discovery of tick-borne encephalitis virus in the late 1930s (based on reminiscences of members of the expeditions, their colleagues, and relatives).

Tick-borne encephalitis virus is the etiological agent of a severe human disease transmitted by hard ticks. It occurs in large parts of eastern, central, and western Asia and in Europe with thousands of human cases each year. Here, the discovery of the virus by Soviet scientists in the late 1930s in the Far East is described. The pioneering work involved with this discovery, which resulted in great scientific and epidemiological achievement, was undertaken under the most difficult conditions, and some of the scientists and their technical assistants paid for it with their health and even their lives. This paper briefly outlines the steps on the way that elucidated the basic etiology and eco-epidemiology of the disease, and does not omit that, as one result of the expeditions and the political situation in the former Soviet Union at that time, some scientists were sent to prison.