Meningitis and encephalitis in Poland in 2021

Area of Science:

• Epidemiology
• Infectious Diseases
• Public Health Surveillance

Background:

• Meningitis and/or encephalitis are monitored in Poland via routine epidemiological surveillance.
• Key etiological agents include Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, and tick-borne encephalitis virus.
• Immunoprophylaxis through vaccinations is a strategy to prevent these neuroinfections.

Purpose of the Study:

• To evaluate the 2021 epidemiological incidence of meningoencephalitis and encephalitis in Poland.
• To analyze the influence of the COVID-19 pandemic on neuroinfection rates.

Main Methods:

• Analysis of data from Voivodeship Sanitary and Epidemiological Stations.
• Utilized published bulletins: "Infectious diseases and poisonings in Poland in 2021" and "Protective vaccination in Poland in 2021".
• Incorporated individual epidemiological interviews from the EpiBase system.

Main Results:

• A total of 973 meningitis and/or encephalitis cases were registered in 2021, a 16.1% increase from 2020 but a 57% decrease from 2019.
• Bacterial infections, including neuroborreliosis, rose by 38.3%. Notable changes were observed in Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae incidence.
• Viral infections constituted 47% of cases, showing a slight 2% decrease. Tick-borne encephalitis cases increased by 32.9% compared to 2020.

Conclusions:

• 2021 indicated an upward trend in bacterial meningitis/encephalitis and a slight decrease in viral cases compared to 2020.
• Overall case numbers in 2021 remained below pre-pandemic (2019) levels.
• COVID-19 containment measures likely reduced the transmission of various airborne and droplet-borne pathogens, including those causing meningitis/encephalitis.