Lyme Borreliosis Incidence Across Europe, 2015-2023: A Surveillance-Based Review and Analysis.

Background: Lyme borreliosis (LB) is the most common tick-borne disease in Europe. Incidence is increasing partly due to climate change and changing human behaviors. This review compiled updated national European LB surveillance data to assess recent incidence trends from 2015 to 2023. Methods: Publicly available LB surveillance data sources were identified for 29 European countries. Cases were collected from reports and dashboards. Estimates of population-based incidence were calculated. Countries were categorized based on their case classification criteria and geographic region. Subnational regions were classified as high-incidence areas if they reported ≥10 cases per 100,000 population per year (PPY) over a three-year period. The percentage of people residing in these high-incidence regions was calculated. Results: An average of 132,000 LB cases were reported to surveillance systems annually. Countries that included both erythema migrans and laboratory-confirmed LB cases in their reporting had the highest incidence rates-particularly Estonia, Finland, and Slovenia, exceeding 100 cases per 100,000 PPY. Overall, variation of incidence at the subnational level was observed, showing incidence at the national level can mask subnational differences in rates. Temporary decreases in incidence were observed during 2019-2021, but incidence increased from 2021 to 2023. A minimum of 223 million people, equating to 30% of the entire European population and 51% of those living in a European country with available subnational data, live in an area with high LB incidence. Conclusion: High LB incidence across Europe was observed from 2015 to 2023, particularly in parts of Northern, Eastern, and Western Europe. For nearly 70% of countries with recently published LB surveillance, incidence increased an average of 36% in the last two years of reporting. These findings emphasize the need for continued monitoring of LB across Europe and new public health prevention tools, such as enhanced tick prevention campaigns, improved education among health care providers, and effective vaccines.