Lyme disease in Poland in 2022.

Introduction: In Poland, Lyme disease has been subject to mandatory reporting and registration since 1996, and following EU law, cases of neuroborreliosis have been reported to the European Centre for Disease Prevention and Control (ECDC) since 2019. Lyme disease is transmitted by ticks of the Ixodes genus, and humans become infected through the bite of an infected tick. Due to the varied symptoms, diagnosis can be difficult and usually involves two-stage serological diagnostics. The aim of the study was to assess the epidemiological situation of Lyme disease in Poland in 2022 compared to the situation in previous years.

Material and methods: The epidemiological situation of Lyme disease in Poland was assessed on the basis of the data sent to NIPH NIH - NRI by voivodeship sanitary-epidemiological stations and published in the bulletin "Infectious diseases and poisoning in Poland in 2022".

Results: In 2022, 17 369 cases of Lyme disease were registered, including 776 hospitalizations. This was a significant increase in cases by 38.96% and hospitalizations by 88.81% compared to the previous year. The seasonality that characterizes Lyme disease was noticeable in individual quarters, i.e. an increase in the number of cases from 1 151 in Q1 to 7 267 in Q3 and a decrease in Q4 to 5 708. At the voivodeship level, the highest incidence was recorded in the Podlaskie (81.2 per 100 000), Małopolskie (79.8 per 100 000) and Lubelskie (76.8 per 100 000) voivodeships.

Conclusions: The epidemiological situation of Lyme disease is gradually returning to the state before the COVID-19 pandemic. The percentage of hospitalized cases increased slightly (from 3.3% in 2021 to 4.5% in 2022), which, combined with the increase in the number of cases, meant an increase in the number of hospitalizations due to Lyme disease by almost 89%. The highest incidence was consistently observed in the eastern part of Poland (Podlaskie, Warmińsko-mazurskie, Lubelskie voivodeships).