Tick-borne encephalitis after active immunization

A large part of Slovenia is endemic for tick-borne encephalitis (TBE). The incidence of the disease is relatively high, and the proportion of population vaccinated against TBE is low. At our institution, patients with aseptic meningitis or meningoencephalitis are routinely tested for the infection with TBE virus. Out of 1036 patients > 15 years, diagnosed with TBE at our department in the period from January 2000 to December 2006, 7 (0.7%) had received at least 2 doses of vaccine against TBE prior to the onset of their illness. Three out of these 7 patients had received complete basic vaccination (I of them also a booster dose). These 3 patients were analyzed thoroughly for the present report. All 3 were females, aged 51, 51, and 55 years, respectively. Time interval between the last dose of TBE vaccine and the onset of their illness was 11, 21; and 38 months. All 3 patients reported tick bite and had febrile illness associated with lymphocytic pleocytosis. The diagnosis of TBE was established by the demonstration of serum IgM and IgG antibodies against TBE virus (in 2 patients the production of IgM antibodies was rather delayed) and by high intrathecal TBE virus IgG antibody synthesis. The clinical course of acute illness was relatively mild (in 2 patients who presented with clinical signs and symptoms of meningitis) to moderately severe (in I patient with signs and symptoms of meningoencephalitis). The outcome was favorable: all patients survived, no paresis developed. (C) 2008 Elsevier GmbH. All rights reserved.