Nienaltowski et al.
Occurrence of meningitis in patients of the Department of Infectious Diseases and Neuroinfections at the Medical University of Białystok, 2022-2024. Przegl Epidemiol. Published online August 14, 2026. doi:10.32394/pe/230919
According to surveillance data from the European Centre for Disease Prevention and Control (ECDC), tick-borne encephalitis (TBE) remains an important public health concern in Poland, with marked regional variation in reported incidence and a particularly high burden in the north-eastern part of the country. An overall increase in reported TBE cases has been observed over the past decade (see The TBE Book, Chapter 13).
A retrospective study was conducted at the Medical University of Bialystok in north-eastern Poland (Podlaskie Voivodeship) to characterize the etiology of meningitis among patients hospitalized at the Department of Infectious Diseases and Neuroinfections between 2022 and 2024.
A total of 357 patients were hospitalized with meningitis during the study period, of whom 59.66% were men and 40.34% were women. The mean age was 46.7 years. The majority of patients were from urban areas (59.10%), while 40.90% were from rural areas.
Viral etiology predominated in the study population, whereas bacterial and unspecified etiologies were considerably less frequent. TBE virus (TBEV) was the most frequently identified viral etiological agent, accounting for 197 cases, or 55.2% of all meningitis cases included in the study. The annual number of TBE cases increased from 49 in 2022 to 72 in 2023 and 76 in 2024. Other identified viral etiologies were uncommon, comprising three cases of herpes simplex virus infection and one case of varicella-zoster virus infection. A total of 47 cases (13.2%) were attributed to bacterial etiology.
The relatively low proportion of bacterial meningitis may partly reflect the impact of established vaccination programs against major vaccine-preventable bacterial causes of meningitis, although this retrospective study was not designed to establish such a causal relationship. In this cohort of hospitalized patients in north-eastern Poland, TBEV was the predominant identified viral cause of meningitis, and the number of TBE cases increased over the three-year study period. These findings underscore the continuing burden of TBE in Podlaskie Voivodeship and support strengthened prevention efforts, including increased awareness and uptake of TBE vaccination among populations at risk.