FIG. 3. Number of serologically confirmed TBE cases in Stockholm County (source: Swedish Institute for Infectious Disease Control) during the study period 1960-1995 (lower half of columns), compared with the rest of the country (upper half of columns). All hospitalized cases of encephalitis in Stockholm County have been tested for TBE virus since the late 1950s, so the increase in number of cases during the study period is a real increase.