Meningitis and encephalitis in Poland in 2020

Meningitis and/or encephalitis are one of the main infectious diseases of the nervous system. These diseases are most commonly caused by bacterial and viral etiological factors. In this publication, meningitis and/or encephalitis caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and those with a viral origin - in Poland, most often caused by tick-borne encephalitis virus - are presented in detail. In addition to epidemiological surveillance, immunoprophylaxis in the form of mandatory and recommended vaccinations is used in Poland to prevent these infections.

The aim of this study was to to assess the epidemiological situation of meningitis and encephalitis in Poland, in 2020.

To analyse the epidemiological situation of neuroinfections in Poland were used data sent to NIPH NIH - NRI by Voivodeship Sanitary and Epidemiological Stations and published in the annual bulletins: "Infectious diseases and poisonings in Poland in 2020" and "Protective vaccination in Poland in 2020" and individual epidemiological interviews registered in the EpiBaza system.

In 2020, a total of 831 cases of meningitis and/or encephalitis were registered in Poland. This is a decrease in incidence of up to 62.9% compared to 2019. For infections of bacterial etiology, including cases of neuroborreliosis (incidence of 2.40 per 100,000), the number of cases decreased by 60.4% (from 931 to 369). In the viral infection group, there was a 64.9% decrease (from 1,318 to 462 cases). Of all registered cases, 56% were infections with a viral etiology. Compared to 2019, the number of cases with an S. pneumoniae etiology decreased by 61.3% and for N. meningitidis by 41.1%. It is interesting to note that, in the case of H. influenzae, we can speak of a 20% increase in cases compared to the previous year. In addition, we can see a decrease in the incidence of tick-borne encephalitis - from 265 in 2019 to 158 in 2020 (a decrease of 40.4%).

Overall, a downward trend in incidence was shown for both bacterial and viral meningitis and/or encephalitis. The SARS-CoV-2 pandemic and the introduction of restrictions on personto-person contact and various forms of activity, resulting in a reduction in pathogen transmission, were key to the significant reduction in the number of meningitis and/or encephalitis cases in 2020, but a reduction in the availability of medical facilities or the completeness of case reports due to the burden of anti-epidemic measures on the Sanitary Inspectorate cannot be excluded either. Only in the case of cases caused by H. influenzae was a slight increase observed compared to the previous year (12 versus 10 cases). Meningoencephalitis and/or encephalitis, due to its wide etiological range, poses a major challenge to the health care system, particularly in terms of correct clinical diagnosis.