Tick-borne encephalitis in Poland in years 1993-2008-epidemiology and clinical presentation. A retrospective study of 687 patients

Background and purpose: Tick-borne encephalitis (TBE) is an emerging disease in Europe as in Poland, especially in north-eastern part of the country. The aim of the study was to characterize the epidemiology and clinical features of TBE in this region. Methods: Clinical and epidemiological data of 687 patients hospitalized between 1993 and 2008 at the Department of Infectious Diseases and Neuroinfections with the diagnosis of TBE were analysed. Results: In the case of 59 patients (9.5%), the disease was job related (forestry workers, farmers). In the examined group, TBE presented with meningitis in 282 cases (41%), with meningoencephalitis in 353 cases (51.3%) and with meningoencephalomyelitis in 52 cases (7.6%). The most common neurological abnormalities were ataxia in 88 cases (14.17%) and pareses in 53 cases (8.53%). Four patients (0.6%) died, 144 patients (23.2%) were discharged with neurological sequelae of TBE. Two hundred and seventy-two patients (43.8%) required further psychiatric treatment. At least 38 patients (6.1%) developed long-term sequelae and required further hospitalizations. Dexamethasone in the dosage of 6-32 mg was administered in 407 patients for 1-64 days. Conclusions: The diagnosis of TBE sometimes is difficult as the disease symptoms may be non-characteristic. Therefore, a detailed anamnesis is very important in the process of TBE diagnosis and may alone justify lumbar puncture conduction. Despite usually mild course of the disease, patients may develop neurological and psychiatrical sequelae.