[Primary progressive forms of tick-borne encephalitis].

The report contains data concerning examinations of 14 patients with a progressive development of tick-borne encephalitis In all the observed cases an acute period in the development of the disease was not diagnosed. The examined contingent constituted 18% of the number of established chronic forms of tick-borne encephalitis. The states were mostly latent forms of infections which were much more frequent than clinically forms of tick-borne encephalitis.