Meningitis and encephalitis in Poland in 2022.

Introduction: Monitoring of meningitis and/or encephalitis regardless of etiology is part of routine epidemiological surveillance in Poland. In this study, we discuss in detail meningitis and/or encephalitis in 2022 caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, and tick-borne encephalitis virus.
Objective: The aim of this study was an epidemiological assessment of the occurrence of meningoencephalitis and encephalitis in Poland in 2022, taking into account the analysis of the impact of the COVID-19 pandemic.
Material and Methods: To analyze the epidemiological situation of neuroinfections in Poland, we used data sent to NIPH NIH-NRI by the Sanitary and Epidemiological Stations and published in the annual bulletins: "Infectious Diseases and Poisons in Poland in 2022" and "Vaccinations in Poland in 2022" as well as individual epidemiological interviews registered in the EpiBase system.
Results: In 2022, a total of 1747 cases of meningitis and/or encephalitis were registered in Poland. This was a 79.4% increase in the number of cases compared to 2021, when 974 cases were recorded. For infections of bacterial etiology, including cases of neuroborreliosis, the number of cases increased by 62.3% . The incidence of meningitis and/or encephalitis of N. meningitidis etiology meningitidis increased by 30.8%, with etiology of H. influenzae compared to 2021 increased by 300%, and for S. pneumoniae by 71.9%. Infections of viral etiology accounted for 52% of all registered cases. There was an increase in their number by 99.1% compared to 2021. Among viral infections, tick-borne encephalitis was the most numerous group, with 466 cases compared to 210 in 2021.
Summary and Conclusions: The year 2022 showed an overall upward trend in the number of registered cases of bacterial and viral meningitis and/or encephalitis compared to 2021. Still, the observed number of cases of meningitis and/or encephalitis of both bacterial and viral origin remains below the levels observed in the period before the COVID-19 pandemic.