Introduction:
The aim of the study was to assess the changing incidence of Lyme borreliosis (LB) in a children’s group in Wielkopolska, and the influences of gender and age as well as erythema migrans (EM) occurrence on the development of various forms of LB in children.

Material and methods:
Retrospective analysis covered the medical records of 206 children diagnosed with LB, hospitalised in the Department of Infectious Diseases and Child Neurology in Poznań and consulted at its Clinic of Infectious Diseases from 1 January 2012 to 30 October 2021. For an epidemiological analysis, the study population was limited to patients from Wielkopolska. A total of 196 qualified subjects were divided into 2 time periods, the first covering the years 2012–2016, in which LB was confirmed in 52 children, and the second covering 2017–2021, in which the disease was diagnosed in 144 children. The relationship between the course of LB and the gender and age of the patients was analysed in both groups. Statistical analysis of the data was performed, and the results were compared with published data.

Results:
The epidemiological analysis showed a more than a twofold increase in the number of LB cases in the analysed time periods, mainly diagnosed as EM. The high incidence of LB neurological complications in children, including those with incorrectly diagnosed EM, remains constant. There was no relationship between the clinical forms of the disease and the child’s sex, but an increase in the number of EM diagnoses in younger children was confirmed.

Conclusions:
The study confirmed the increase in the number of LB diagnoses, analogous to the entire population of the region. The significant increase in the number of early stages of the disease and the frequent occurrence of neurological complications in children with undiagnosed and untreated EM indicate the need for ongoing education in the diagnosis of LB.