Clinical peculiarities and blood levels of several cytokines were studied in 199 children, aged from 1 to 15 years, in the acute period of different tick-borne infections. The mixed infection manifested itself by the more severe progression of general clinical presentations compared to monoinfections. Etiologically unspecific changes of blood concentrations of cytokines in the acute period of the
disease were found. These data were associated with different clinical forms of tick-borne infections. The decrease in the interferon gamma production was associated with the most severe
disease progression with focal nervous system disorders. The use of cycloferon as immune modulator in the complex therapy led to the increase in the interferon gamma level and the decrease of general clinical manifestations during tick-borne encephalitis and mixed infection.