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Background: Lyme borreliosis (LB) remains a public health concern in France despite improved patient management and medical care. Stay-at-home restrictions during the COVID-19 pandemic, which affected participation in outdoor recreational activities and disrupted access to health care services, may have impacted the risk of developing LB. Methods: We analyzed data from two general practitioner networks in France (Sentinel Network and an electronic medical records database [EMR]) and the national hospital discharge database to describe LB epidemiology in 2020-2021 and compare it to previous years. Google Trends' search volume was used to evaluate the association between the population's interest in LB and the evolving epidemiology. Results: Annual LB incidence rates in primary care decreased from 104 cases/100,000 population in 2018 to 71/100,000 in 2021 and from 82/100,000 to 60/100,000 according to Sentinel Network and EMR, respectively. Google Trends' search volume for "Lyme" followed a similar trend, one year earlier. Annual hospitalizations were stable from 2012-2019 (1.6/100,000 on average) and declined to 1.3/100,000 in 2020 and 1.1/100,000 in 2021. This decline was observed primarily in adults ( e.g., 3.4/100,000 in 2017-2019 to 1.8/100,000 in 2020-2021 for 70-79 years of age). Changes in regional incidence rates in primary care from 2017-2019 to 2020-2021 ranged from -75% to 208%. Hospitalizations decreased in all regions except in Bretagne. Conclusions: The estimated LB incidence decreased in 2020 and 2021 compared with previous years but this change may not be related to COVID-19. The incidence decrease observed in primary care could result from reduced population interest in LB, leading to lower care-seeking behavior. The decrease in LB hospitalizations may be explained by changes in clinical practice. Surveillance systems are critical to understand the evolution of LB epidemiology. However, external factors impacting incidence estimates should be considered.

Introduction: Lyme borreliosis (LB) is a growing public health concern requiring accurate and comprehensive epidemiological knowledge to inform health care interventions. This study compared the epidemiology of LB in primary care and hospital settings, using for the first time in France three sources of data, and highlighted specific populations at higher risk of developing LB. Methods: This study analyzed data from general practitioner networks ( i.e ., Sentinel network, Electronic Medical Records [EMR]) and the national hospital discharge database to describe the LB epidemiology from 2010 to 2019. Results: The average annual incidence rates of LB in primary care increased from 42.3 cases/100,000 population in 2010-2012 to 83.0/100,000 in 2017-2019 for the Sentinel Network and 42.7/100,000 to 74.6/100,000 for the EMR, following a marked rise in 2016. The annual hospitalization rate remained stable from 2012 to 2019 fluctuating between 1.6 and 1.8 hospitalizations/100,000. Women were more likely to present with LB in primary care setting compared with men (male-to-female incidence rate ratio [IRR] = 0.92), whereas men were predominant among hospitalizations (IRR = 1.4), with the largest discordance among adolescents aged 10-14 years (IRR = 1.8) and adults aged 80 years and older (IRR = 2.5). In 2017-2019, the average annual incidence rate peaked among persons aged 60-69 years in primary care (>125/100,000) and aged 70-79 years among hospitalized patients (3.4/100,000). A second peak occurred in children aged 0-4 or 5-9 years depending on sources. Incidence rates in Limousin and the north-eastern regions were the highest for both primary care and hospital settings. Conclusions: Analyses showed disparities in the evolution of incidence, sex-specific incidence rates, and predominant age groups between primary care and hospital settings that merit further exploration.

Background: There is a need for updated incidence rates (IRs) of Lyme borreliosis (LB) in Europe, including the Netherlands. We estimated LB IRs stratified by geographic area, year, age, sex, immunocompromised status, and socioeconomic status (SES). Methods: All subjects registered in the PHARMO General Practitioner (GP) Database without prior diagnosis of LB or disseminated LB and having ≥1 year of continuous database enrolment were included. IRs and corresponding confidence intervals (CIs) of GP-recorded LB, erythema migrans (EM), and disseminated LB were estimated during the period 2015‒2019. Results: We identified 14,794 events (suspected, probable, or confirmed) with a diagnostic code for LB that included 8219 with a recorded clinical manifestation: 7985 (97%) with EM and 234 (3%) with disseminated LB. National annual LB IRs were relatively consistent, ranging from 111 (95% CI 106‒115) in 2019 to 131 (95% CI 126‒136) in 2018 per 100,000 person-years. Incidence of LB showed a bimodal age distribution, with peak IRs observed among subjects aged 5‒14 and 60‒69 years in men and women. Higher LB incidence was found in subjects who were residents of the provinces of Drenthe and Overijssel, immunocompromised, or of lower SES. Similar patterns were observed for EM and disseminated LB. Conclusions: Our findings confirm that LB incidence remains substantial throughout the Netherlands with no indication of decline in the past 5 years. Foci in two provinces and among vulnerable populations suggest potential initial target groups for preventive strategies such as vaccination.

Background: Lyme borreliosis (LB) is the most common tick-borne disease in Europe, but the burden of disease is incompletely described. Methods: We conducted a systematic review across PubMed, EMBASE, and CABI Direct (Global Health) databases, from January 1, 2005, to November 20, 2020, of epidemiological studies reporting incidence of LB in Europe (PROSPERO, CRD42021236906). Results: The systematic review yielded 61 unique articles describing LB incidence (national or subnational) in 25 European countries. Substantial heterogeneity in study designs, populations sampled, and case definitions restricted data comparability. The European Union Concerted Action on Lyme Borreliosis (EUCALB)-published standardized LB case definitions were used by only 13 (21%) of the 61 articles. There were 33 studies that provided national-level LB incidence estimates for 20 countries. Subnational LB incidence was available from an additional four countries (Italy, Lithuania, Norway, and Spain). The highest LB incidences (>100 cases per 100,000 population per year [PPY]) were reported in Belgium, Finland, the Netherlands, and Switzerland. Incidences were 20-40/100,000 PPY in the Czech Republic, Germany, Poland, and Scotland and <20/100,000 PPY in Belarus, Croatia, Denmark, France, Ireland, Portugal, Russia, Slovakia, Sweden, and the United Kingdom (England, Northern Ireland, and Wales); markedly higher incidences were observed at the subnational level (up to 464/100,000 PPY in specific local areas). Conclusions: Although countries in Northern (Finland) and Western (Belgium, the Netherlands, and Switzerland) Europe reported the highest LB incidences, high incidences also were reported in some Eastern European countries. There was substantial subnational variation in incidence, including high incidences in some areas of countries with low overall incidence. This review, complemented by the incidence surveillance article, provides a comprehensive view into LB disease burden across Europe that may guide future preventive and therapeutic strategies-including new strategies on the horizon.

Background: In Poland, Lyme borreliosis (LB) has been subject to mandatory public health surveillance since 1996 and, in accordance with EU regulations, Lyme neuroborreliosis has been reported to the European Centre for Disease Prevention and Control since 2019. In this study, the incidence, temporal trends, and geographic distribution of LB and its manifestations in Poland are described for the period 2015-2019. Methods: This retrospective incidence study of LB and its manifestations in Poland was based on data sent to the National Institute of Public Health-National Institute of Hygiene-National Research Institute (NIPH-NIH-NRI) by district sanitary epidemiological stations using the electronic Epidemiological Records Registration System and data from the National Database on Hospitalization. Incidence rates were calculated using population data from the Central Statistical Office. Results: During 2015-2019, Poland reported 94,715 cases of LB with an overall average incidence of 49.3 cases per 100,000 population. Cases increased from 2015 (11,945) to 2016 (20,857) and then remained stable through 2019. Hospitalization due to LB also rose during these years. LB was more common among women (55.7%). Erythema migrans and Lyme arthritis were the most common manifestations of LB. The highest incidence rates occurred among >50-year-olds, with a peak in 65-69-year-olds. The highest number of cases was recorded in the third and fourth quarters of the year (July-December). Incidence rates in the eastern and northeastern regions of the country were higher than the national average. Conclusions: LB is endemic in all regions of Poland, and many regions reported high incidence rates. Large variations in spatially granular incidence rates highlight the need for targeted prevention strategies.

Purpose: Lyme borreliosis (LB) is the most prevalent tick-borne disease in Europe and the incidence of LB is increasing owing to an expansion in tick habitats. However, LB surveillance is quite heterogeneous across the continent, and for those countries with publicly available data, it is difficult to understand the differences in incidence between countries. The objective of our study was to summarize the publicly available data from surveillance for LB in the form of surveillance reports and/or dashboards and to compare the information available for various countries. Methods: We identified publicly available LB data (online dashboards and surveillance reports) in the European Union, European Economic Area, the United Kingdom, Russia, and Switzerland. Results: Of the 36 countries studied, 28 had LB surveillance in place; 23 had surveillance reports, and 10 had dashboards. The dashboards, in general, had more granular data compared with the surveillance reports, but the reports covered longer time periods. LB annual cases, incidence, age, and sex-stratified LB data; manifestations; and regional data were available for most of the countries. LB case definitions varied significantly among the countries. Conclusion: The study highlights large differences in LB surveillance systems, including representativeness, case definitions, type of data available that might inhibit comparison of data between countries and accurate determination of burden of disease, and risk groups within countries. Standardization of case definitions across countries would be a useful first step enabling comparisons between countries and contribute to recognizing the true burden of LB in Europe.

Background: Lyme borreliosis (LB) is a tick-borne zoonotic disease endemic in many European countries, including Finland. We describe the incidence, time trends, and geographical distribution of LB in Finland for the period 2015-2020. The data generated can help inform public health policy, including prevention strategies. Methods: We retrieved online-available LB cases and incidence from two Finnish national databases. Microbiologically confirmed LB cases were identified from the National Infectious Disease Register and clinically diagnosed LB cases from the National Register of Primary Health Care Visits (Avohilmo), with the total LB cases equal to the sum from these two sources. Results: A total of 33,185 LB cases were reported for the 2015-2020 period, of which 12,590 (38%) were microbiologically confirmed and 20,595 (62%) were clinically diagnosed. The average annual national incidences for total, microbiologically confirmed, and clinically diagnosed LB were, respectively, 99.6, 38.1, and 61.4 per 100,000 population. The total LB incidence was highest in the south to southwestern coastal areas by the Baltic Sea and in eastern areas, with average annual incidences of 109.0 to 207.3/100,000. The Åland Islands were a hyperendemic region with an average annual incidence of 2473.9/100,000. The highest incidence was among persons aged >60 years, peaking at age 70-74 years. Most cases were reported between May and October, with a peak in July and August. Conclusions: The incidence of LB varied substantially by hospital district, and many regions reached incidences comparable with other high incidence countries, suggesting preventive measures such as vaccines may be an efficient use of resources.

Background: Lyme borreliosis (LB), a tick bite-transmitted infection caused by Borrelia burgdorferi sensu lato ( Bbsl ) complex spirochetes, is the most common tickborne disease in Europe. Studies in European countries have reported LB seroprevalence (prevalence of antibodies to Bbsl infection) and diagnostic strategies used for testing. We conducted a systematic literature review to summarize contemporary LB seroprevalence in Europe. Methods: PubMed, Embase, and CABI Direct (Global Health) databases were searched from 2005 to 2020 to identify studies reporting LB seroprevalence in European countries. Reported single-tier and two-tier test results were summarized; algorithms (standard or modified) were used to interpret final test results from studies that used two-tier testing. Results: The search yielded 61 articles from 22 European countries. Studies used a range of diagnostic testing methods and strategies (48% single-tier, 46% standard two-tier, and 6% modified two-tier). In 39 population-based studies, of which 14 were nationally representative, seroprevalence estimates ranged from 2.7% (Norway) to 20% (Finland). There was substantial heterogeneity among studies in terms of design, cohort types, periods sampled, sample sizes, and diagnostics, which limited cross-study comparisons. Nevertheless, among studies that reported seroprevalence in persons with greater exposure to ticks, LB seroprevalence was higher among these groups than in the general population (40.6% vs. 3.9%). Furthermore, among studies that used two-tier testing, general population LB seroprevalence was higher in Western Europe (13.6%) and Eastern Europe (11.1%) than in Northern Europe (4.2%) and Southern Europe (3.9%). Conclusion: Despite variations in LB seroprevalence between and within European subregions and countries, high seroprevalence was observed in certain geographic regions and particular risk groups, suggesting significant disease burden and supporting the need for improved, targeted public health interventions such as vaccination. Harmonized approaches to serologic testing and more nationally representative seroprevalence studies are needed to better understand the prevalence of Bbsl infection in Europe.

Background: Lyme borreliosis (LB) is the most common tick-borne disease in Europe. To inform European intervention strategies, including vaccines under development, we conducted a systematic review for LB incidence. Methods: We searched publicly available surveillance data reporting LB incidence in Europe from 2005 to 2020. Population-based incidence was calculated as the number of reported LB cases per 100,000 population per year (PPY), and high LB risk areas (incidence >10/100,00 PPY for 3 consecutive years) were estimated. Results: Estimates of LB incidence were available for 25 countries. There was marked heterogeneity in surveillance systems (passive vs. mandatory and sentinel sites vs. national), case definitions (clinical, laboratory, or both), and testing methods, limiting comparison across countries. Twenty-one countries (84%) had passive surveillance; four (Belgium, France, Germany, and Switzerland) used sentinel surveillance systems. Only four countries (Bulgaria, France, Poland, and Romania) used standardized case definitions recommended by European public health institutions. Among all surveillance systems and considering any case definition for the most recently available years, national LB incidences were highest in Estonia, Lithuania, Slovenia, and Switzerland (>100 cases/100,000 PPY), followed by France and Poland (40-80/100,000 PPY), and Finland and Latvia (20-40/100,000 PPY). Incidences were lowest in Belgium, Bulgaria, Croatia, England, Hungary, Ireland, Norway, Portugal, Romania, Russia, Scotland, and Serbia (<20/100,000 PPY). At the subnational level, highest LB incidences (>100/100,000 PPY) were observed in areas of Belgium, Czech Republic, France, Germany, and Poland. Overall, on average 128,888 cases are reported annually. An estimated 202/844 million (24%) persons in Europe reside in areas of high LB incidence and 202/469 million (43.2%) persons reside in areas of high LB incidence among countries with surveillance data. Conclusion: Our review showed substantial variability in reported LB incidence across and within European countries, with highest incidences reported from the Eastern, Northern (Baltic states and Nordic countries), and Western Europe surveillance systems. Standardization of surveillance systems, including wider implementation of common case definitions, is urgently needed to interpret the range of differences in LB incidence observed across European countries.

Background: Public surveillance of Lyme borreliosis (LB) occurs in 9 out of 16 federal states of Germany and remains a critical facet of disease epidemiology and trends. We describe the incidence, time trends, seasonality, and geographic distribution of LB in Germany using publicly reported surveillance data. Methods: We obtained LB cases and incidence (2016-2020) from the online platform SurvStat@RKI 2.0, maintained by the Robert Koch Institute (RKI). Data included clinically diagnosed and laboratory-confirmed LB reported by nine out of 16 federal states of Germany where LB notification is mandatory. Results: During 2016-2020, the nine federal states reported 63,940 LB cases, of which 60,570 (94.7%) were clinically diagnosed, and 3370 (5.3%) also had laboratory confirmation, with an average of 12,789 cases annually. Incidence rates were mostly stable over time. The average annual LB incidence was 37.2/100,000 person-years and varied by spatial level, ranging from 22.9 to 64.6/100,000 person-years among nine states; from 16.8 to 85.6/100,000 person-years among 19 regions; and from 2.9 to 172.8/100,000 person-years among 158 counties. Incidence was lowest among persons 20-24 years old (16.1/100,000 person-years) and highest among those 65-69 years old (60.9/100,000 person-years). Most cases were reported between June and September, with a peak in July of every year. Conclusion: The risk of LB varied substantially at the smallest geographic unit and by age group. Our results underscore the importance of presenting LB data at the most spatially granular unit and by age to allow implementation of efficient preventive interventions and reduction strategies.