Risk factors for Lyme disease among residents of rural, suburban, and urban areas in the United States: A Case-Control Study.

lyme disease (LD) is the most common vector-borne disease in the United States, with 476,000 cases estimated each year. It is unclear how LD risk factors vary by residential setting. We conducted a case-control study on LD risk by rural, urban, and suburban residential settings. Individuals from 15 high-incidence states and the District of Columbia in the Optum Research Database were identified as cases (LD medical claim) or controls (no LD medical claim, matched by county of residence and census block group population density). Participants were surveyed about LD history, outdoor activities, and residential characteristics. The final analytic dataset had 750 LD cases and 965 controls. Residence in a rural setting had increased LD risk (OR 1.41, 95% CI 1.16, 1.72). In multivariable analyses, activities associated with LD were hiking/walking/running or having an occupation in forests, wooded areas, or areas of tall grass (all respondents), and spending time in a yard (rural and urban residents only). Public health interventions can help prevent LD in high-incidence jurisdictions by reinforcing the nearuniversal LD risk for rural residents, and highlighting activities that lead to increased LD risk for those in areas with less ubiquitous tick exposure like in urban and suburban settings.

Validation of Claims-Based Algorithm for Lyme Disease, Massachusetts, USA.

Compared with notifiable disease surveillance, claims-based algorithms estimate higher Lyme disease incidence, but their accuracy is unknown. We applied a previously developed Lyme disease algorithm (diagnosis code plus antimicrobial drug prescription dispensing within 30 days) to an administrative claims database in Massachusetts, USA, to identify a Lyme disease cohort during July 2000-June 2019. Clinicians reviewed and adjudicated medical charts from a cohort subset by using national surveillance case definitions. We calculated positive predictive values (PPVs). We identified 12,229 Lyme disease episodes in the claims database and reviewed and adjudicated 128 medical charts. The algorithm's PPV for confirmed, probable, or suspected cases was 93.8% (95% CI 88.1%-97.3%); the PPV was 66.4% (95% CI 57.5%-74.5%) for confirmed and probable cases only. In a high incidence setting, a claims-based algorithm identified cases with a high PPV, suggesting it can be used to assess Lyme disease burden and supplement traditional surveillance data.

Systematic Review and Meta-analysis of Lyme Disease Data and Seropositivity for Borrelia burgdorferi, China, 2005‒2020.

Since its initial identification in 1986, Lyme disease has been clinically diagnosed in 29 provinces in China; however, national incidence data are lacking. To summarize Lyme disease seropositivity data among persons across China, we conducted a systematic literature review of Chinese- and English-language journal articles published during 2005‒2020. According to 72 estimates that measured IgG by using a diagnostic enzyme-linked assay (EIA) alone, the seropositivity point prevalence with a fixed-effects model was 9.1%. A more conservative 2-tier testing approach of EIA plus a confirmatory Western immunoblot (16 estimates) yielded seropositivity 1.8%. Seropositivity by EIA for high-risk exposure populations was 10.0% and for low-risk exposure populations was 4.5%; seropositivity was highest in the northeastern and western provinces. Our analysis confirms Lyme disease prevalence, measured by seropositivity, in many Chinese provinces and populations at risk. This information can be used to focus prevention measures in provinces where seropositivity is high.

Suitability of databases in the Asia-Pacific for collaborative monitoring of vaccine safety.

INTRODUCTION: Information regarding availability of electronic healthcare databases in the Asia-Pacific region is critical for planning vaccine safety assessments particularly, as COVID-19 vaccines are introduced. This study aimed to identify data sources in the region, potentially suitable for vaccine safety surveillance. This manuscript is endorsed by the International Society for Pharmacoepidemiology (ISPE). METHODS: Nineteen countries targeted for database reporting were identified using published country lists and review articles. Surveillance capacity was assessed using two surveys: a 9-item introductory survey and a 51-item full survey. Survey questions related to database characteristics, covariate and health outcome variables, vaccine exposure characteristics, access and governance, and dataset linkage capability. Other questions collated research/regulatory applications of the data and local publications detailing database use for research. RESULTS: Eleven databases containing vaccine-specific information were identified across 8 countries. Databases were largely national in coverage (8/11, 73%), encompassed all ages (9/11, 82%) with population size from 1.4 to 52 million persons. Vaccine exposure information varied particularly for standardized vaccine codes (5/11, 46%), brand (7/11, 64%) and manufacturer (5/11, 46%). Outcome data were integrated with vaccine data in 6 (55%) databases and available via linkage in 5 (46%) databases. Data approval processes varied, impacting on timeliness of data access. CONCLUSIONS: Variation in vaccine data availability, complexities in data access including, governance and data release approval procedures, together with requirement for data linkage for outcome information, all contribute to the challenges in building a distributed network for vaccine safety assessment in the Asia-Pacific and globally. Common data models (CDMs) may help expedite vaccine safety research across the region.

Impact of variable look-back periods on the incidence rates of chronic diseases using real world data.

PURPOSE: Estimating disease incidence based on secondary data requires a look-back period to exclude patients with pre-existing disease from the incidence risk set. However, the optimal length of the look-back period and its impact on incidence rates are often unknown. We studied the impact of the length of the look-back period on incidence rates of 24 different chronic diseases. METHODS: Everyone residing in Sweden between January 1, 2005 and December 31, 2013 were identified from national registries and followed up to 2 years (through December 31, 2015). Outcome events were identified from inpatient and outpatient hospital contacts and incidence rates were calculated per 100 000 person-years. The length of the look-back period was varied with 6-month increments, starting at 6 months. The maximum look-back period of 9 years was used as reference period. RESULTS: There were 7 943 807 individuals with a look-back period of at least 9 years (mean age 46.5 years) and a mean follow-up time of 1.97 years. Incidence rates were higher across all diseases when restricting the look-back to 1 year compared to 9 years, with a magnitude of overestimation of the incidence rates between 13% (temporal arteritis) and 174% (type 1 diabetes). However, for most diseases the effect of extending the look-back period beyond 3-5 years appeared comparably small. CONCLUSIONS: This study illustrates how short look-back periods cause overestimation of the incidence rates of chronic diseases, suggesting that sensitivity analyses with respect to look-back period are considered, particularly using data sources with limited information on past medical history.

Teaching on the Continuum: Epidemiology Education From High School Through Graduate School.

Epidemiology education is increasingly recognized as a core science necessary for career preparation throughout the health sector, and graduate epidemiology instruction is continually being reevaluated to ensure students receive appropriate training. Recent work has also focused on the potential for epidemiology to be formally incorporated as a stand-alone discipline in undergraduate education and even integrated into wide-scale high-school science learning. As epidemiology educators, however, we face a tremendous challenge in that we should appreciate differences in students' instructional needs and goals (e.g., concepts and skills) at each educational level. In this article we propose an epidemiology learning continuum for students from high school through graduate school. We call for a student-centered instructional approach to best hone learners' grasp of concepts and skills. Furthermore, we propose scaffolded learning to help epidemiology students to develop more advanced insights and abilities as they progress in the field. This approach will not only best serve the discipline but also is well-aligned with the Association of Schools and Programs of Public Health's "Framing the Future" initiative for public health education for the 21st century.

Validation studies of claims data in the Asia-Pacific region: A comprehensive review.

PURPOSE: To describe published validation studies of administrative health care claims data in the Asia-Pacific region. METHODS: A comprehensive literature search was conducted in PubMed for English language articles published through 31-Oct-2017 in humans from 10 Asian-Pacific countries or regions (Japan, Australia, New Zealand, China, Hong Kong, India, Singapore, South Korea, Taiwan, and Thailand) that validated claims-based diagnoses with a gold standard data source. Search terms included the: validation, validity, accuracy, sensitivity, agreement, specificity, positive predictive value, kappa, kappa coefficient, and Cohen's kappa. RESULTS: Forty-three studies across six countries were identified: Australia (21); Japan (6); South Korea (6); Taiwan (7); Singapore (2); and New Zealand (1). Gold standard diagnoses were obtained from: medical records (18); registry data (11); self-reported questionnaires (5); and other data sources (9). Validity measures used included sensitivity, specificity, positive and negative predictive values (12); sensitivity, specificity, and positive predictive value (4); sensitivity and specificity (4); sensitivity and positive predictive value (4); and combinations of other measures (19). Validated outcomes included medical conditions (28); disease-specific comorbidities (8); death, smoking, and other (ie, injury, hospital outcome measures) (5); medication/transfusion (2). Approximately 72% of the studies were published within the last 5 years. CONCLUSIONS: Validation studies of claims data published in the English language in the Asia-Pacific region are very limited. Given the increased reliance on administrative health care databases for pharmacoepidemiology and the need for ensuring the credibility of results from such data, additional support for the conduct of validation research of claims data in the Asia-Pacific region is needed.

Teaching Epidemiology at the Undergraduate Level: Considerations and Approaches.

The rapid growth in undergraduate public health education has offered training in epidemiology to an increasing number of undergraduate students. Epidemiology courses introduce undergraduate students to a population health perspective and provide opportunities for these students to build essential skills and competencies such as ethical reasoning, teamwork, comprehension of scientific methods, critical thinking, quantitative and information literacy, ability to analyze public health information, and effective writing and oral communication. Taking a varied approach and incorporating active learning and assessment strategies can help engage students in the material, improve comprehension of key concepts, and further develop key competencies. In this commentary, we present examples of how epidemiology may be taught in the undergraduate setting. Evaluation of these approaches and others would be a valuable next step.

Relationship between Recreational Resources in the School Neighborhood and Changes in Fitness in New York City Public School Students.

Physical fitness in children has many beneficial effects, including the maintenance of a healthy weight. The built environment may influence youths' physical fitness by encouraging physical activity. This paper assessed whether higher density of parks, playgrounds, and sports facilities around a school is related to improvements in fitness in middle school boys and girls. Fitness scores and other student covariates collected as part of NYC FITNESSGRAM between the 2006-2007 and 2010-2011 school years were linked with school neighborhood data on characteristics of the built environment for NYC public school students in grades 6-8. Data were analyzed in 2015. Medium, but not high, density of recreational resources in the area surrounding a school was associated with greater annual improvements in fitness for both boys and girls. This association appeared to be driven mainly by the presence of parks. Findings for sports facilities and playgrounds were inconsistent. Overall, few associations were observed between recreational resources near a school and changes in student fitness. Future studies of school influences on student fitness should consider the influence of school resources and the home neighborhood.

The impact of neighborhood park access and quality on body mass index among adults in New York City.

OBJECTIVE: To evaluate the association between adult individuals' body mass index (BMI) and characteristics of parks (size and cleanliness) in an urban environment taking into account the physical and social environments of the neighborhood. METHODS: Cross-sectional, hierarchical linear models were used to determine whether park effects were associated with BMI using self-reported height and weight data obtained from the Community Health Survey in New York City (2002-2006). RESULTS: Both the proportion of the residential zip code that was large park space and the proportion that was small park space had significant inverse associations with BMI after controlling for individual socio-demographic and zip code built environment characteristics (-0.20 BMI units across the inter-quartile range (IQR) for large parks, 95% CI -0.32, -0.08; -0.21 BMI units across the IQR for small parks, 95% CI -0.31, -0.10, respectively). Poorer scores on the park cleanliness index were associated with higher BMI, 0.18 BMI units across the IQR of the park cleanliness index (95% CI 0.05, 0.30). CONCLUSIONS: This study demonstrated that proportion of neighborhoods that was large or small park space and park cleanliness were associated with lower BMI among NYC adults after adjusting for other neighborhood features such as homicides and walkability, characteristics that could influence park usage.

Racial and ethnic disparities in Lyme disease in the United States.

INTRODUCTION: Lyme disease (LD), caused by the spirochete Borrelia burgdorferi, is the most common vector-borne disease in the United States. Although most surveillance-reported cases are in people who are White, data suggest worse outcomes among people from racial and ethnic minority groups. METHODS: We conducted a systematic literature review to describe racial disparities in LD. We described the epidemiology of LD by race and ethnicity, including clinical presentation at diagnosis, and summarised the literature on knowledge, attitudes and practices related to LD and ticks by race and ethnicity. RESULTS: Overall, the incidence and prevalence of LD were 1.2-3.5 times higher in White persons than in persons who identified as Asian or Pacific Islander and 4.5-6.3 times higher in White persons than in persons who identified as Black. Across multiple studies, people from racial and ethnic minority groups were more likely than White people to have disseminated manifestations of LD, including neurological manifestations and arthritis, and less likely to have erythema migrans. People from racial and ethnic minority groups were also more likely to report disease onset in the fall and less likely to report disease onset in the summer. Possible reasons for these disparities include lack of recognition of the disease in people with darker skin tones, lack of knowledge of disease risk for some groups and differences in exposure risk. CONCLUSIONS: Taken together, these results reinforce that all people residing in high-incidence areas are at risk of LD, regardless of race or ethnicity. Future prevention measures should be broadly targeted to reach all at-risk populations.

Excess Healthcare Costs and Resource Utilisation of Lyme Borreliosis in Germany: A Propensity Score-Matched Cohort Study.

AIM: Lyme borreliosis (LB) is the most common tick-borne disease in Germany; however, data on the economic burden of LB are limited. In this study, we aim to report healthcare costs, healthcare resource utilisation (HCRU) and diagnostic consumption associated with LB by clinical manifestation. METHOD: Using specific case definitions, patients with localised disease (erythema migrans [EM]) or disseminated disease (Lyme arthritis [LA], Lyme neuroborreliosis [LNB] and other rarer manifestations [OTH]) were identified from a claims database in 2016 and followed up for 3 years (2016-2019). After propensity score matching, excess costs and HCRU were calculated as the differences between each LB cohort and the matched control cohort. RESULTS: On a per-patient basis, the excess all-cause healthcare cost was €130 for EM during Quarter 1 of Year 1, and €1539 for LA, €3248 for LNB and €4137 for OTH during Year 1. Only for OTH, additional €1860 was observed in Year 2. No increase in costs was observed in Year 3. When extrapolated to all German patients with statutory health insurance, LB was associated with €64.5 million in excess costs. Although disseminated manifestations only accounted for 7.8% of all LB cases, they were responsible for 66% of overall costs. In addition, LB patients consumed healthcare resources of 1.4 million excess outpatient visits, 13,000 excess hospitalisations, 96,000 ELISAs and 65,000 Western blots. CONCLUSION: This study shows the substantial economic burden of LB to the German healthcare system.

Using the Health Belief Model to understand intention to vaccinate for Lyme disease in the United States.

AIMS: A growing number of Lyme disease (LD) cases in the U.S. are reported in states neighbouring those with high-incidence (>10 cases per 100,000 population) rates. Considering the evolving epidemiology, high-incidence counties in many of these "neighbouring states," and the forthcoming vaccines, understanding the drivers of vaccination intention is critical, particularly how drivers of intention in neighbouring states vary relative to regions currently classified as high incidence. This study uses the Health Belief Model (HBM) to determine the key drivers associated with vaccine intention for U.S. adults and caregivers of children residing in neighbouring states. METHODS AND RESULTS: Using an established panel with quotas for age, sex, race/ethnicity and urbanity, we surveyed 887 adults and 822 caregivers of children residing in U.S. neighbouring states. Survey items included measures of intention and HBM constructs, all of which were assessed using 5-point Likert scales. We subsequently used structural equation modelling to understand the influence of the HBM constructs on LD vaccine intention. Estimates from structural equation modelling show that the HBM constructs explain much of the variation in intention to vaccinate against LD. Intentions to vaccinate for both adults and caregivers are positively influenced by cues to action, perceived susceptibility of LD, and perceived benefits to vaccination. Both are also negatively influenced by perceived barriers to vaccination. The caregiver's intention to vaccinate is also positively influenced by the perceived severity of LD. CONCLUSION: The intention to vaccinate for respondents residing in LD neighbouring states is strongly influenced by recommendations from healthcare providers or the Centers for Disease Control and Prevention (CDC). As incidence rises in neighbouring states and the need to prevent disease becomes more overt, public health officials should strongly recognize the influence of healthcare providers and CDC recommendations on intention to vaccinate against LD.

Publicly available surveillance data on tick-borne encephalitis in Europe, 2023.

The European Centre for Disease Prevention and Control (ECDC) defines a case of tick-borne encephalitis (TBE) as an infection by the TBE virus (TBEV) with clinical manifestations of central nervous system inflammation (e.g., meningitis, encephalitis). To better understand the TBE surveillance landscape, online searches were conducted to determine if cases of TBE, TBEV infection, acute meningitis or encephalitis, or viral meningitis or encephalitis were subject to statutory reporting in European countries in 2023. In countries with statutory reporting, notification responsibility and available information on surveillance-reported cases were determined. The number of TBE cases reported to ECDC were compared with the number of cases recorded in national surveillance reports. Of 44 countries of the Europe Region of the United Nations, 37 (84 %) mandated statutory reporting of cases of TBE, TBEV infection, or acute/viral meningitis/encephalitis. Twenty-six (87 %) of 30 countries with identified surveillance reports recorded TBE cases in 2020-2023. Of these countries, 17 (65 %) required TBE reporting by clinicians and laboratories, 5 (19 %) by clinicians only, and 4 (15 %) by laboratories only. Twenty-four countries reported on TBE cases to ECDC in 2020; however, surveillance for TBE in Europe is heterogeneous. Standardization of TBE surveillance would enhance the understanding of TBE disease burden in Europe.

Intention to vaccinate for Lyme disease using the Health Belief Model.

AIMS: Lyme disease (LD) cases in the United States are estimated to be approaching 500,000 annually. Protective measures, such as repellent use and wearing protective clothing are recommended by public health officials. However, no protective measure has been proven to be consistently effective, partly because they require consistent and persistent behaviour change. While safe and effective vaccines are in development, it is unclear what factors influence the intention to vaccinate against LD. This study uses the Health Belief Model (HBM) framework to determine key drivers associated with vaccine intention. The HBM is widely applied in public health research and uses the following constructs: perceived susceptibility and severity of disease, perceived benefits and barriers to disease prevention, and cues to action for disease prevention to predict health behaviours. To date, the HBM framework has not been applied to vaccination intention for LD. METHODS AND RESULTS: Data were collected from 874 adults and 834 caregivers of children residing in US states endemic to LD. Sampling adults and caregivers allows us to explore how the intention to vaccinate differs among those at-risk. Estimates from structural equation modelling (SEM) show that the HBM constructs explain much of the variation in intention to vaccinate against LD. Both adult and caregiver intentions to vaccinate are positively influenced by cues to action, perceived susceptibility of LD, and perceived benefits to vaccination. However, there is variation in the influence of constructs across the samples. Caregiver's intention to vaccinate is positively influenced by the perceived severity of LD and negatively influenced by safety concerns about the vaccine, whereas adult intention is negatively influenced by perceived barriers to vaccination. CONCLUSION: A strong relationship of cues to action on vaccine intention in samples of adults and caregivers suggests the importance of a recommendation from a healthcare provider or the Centers for Disease Control and Prevention (CDC).

Evolution of Lyme Borreliosis Epidemiology in Primary Care and Hospital Settings in France During the COVID-19 Pandemic.

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.

Estimated incidence of symptomatic Lyme borreliosis cases in five southern coastal counties in Norway, 2022.

Lyme borreliosis (LB), the most common tick-borne disease in Europe, is endemic to southern coastal Norway. LB commonly presents as erythema migrans, which can disseminate, resulting in more severe disease such as Lyme neuroborreliosis or arthritis. In Norway, public health LB surveillance is conducted via mandatory reporting of laboratory-confirmed disseminated cases. From 2012 to 2022, Norway's surveillance-reported incidence of laboratory-confirmed disseminated LB increased by 78%. Although surveillance provides estimates of the incidence of disseminated LB, this study sought to estimate the incidence of symptomatic LB to better understand Norway's LB disease burden. Two studies were identified that, when combined, estimated an LB seroprevalence of 6.8% in the general adult population in southern Norway. Utilizing data from these seroprevalence studies, public health surveillance, and results from literature searches indicating that 37% of seroconverted LB cases are symptomatic and that the duration of LB antibody detection ranges from 10 to 20 years, we estimated that there were 315-630 symptomatic LB cases per 100,000 adult population in five southern coastal counties in Norway in 2022 and 24-48 cases of symptomatic LB for every public health surveillance-reported LB case in adults in these five counties in Norway.

Incidence of Lyme Borreliosis in Germany: A retrospective observational healthcare claims study.

Lyme borreliosis (LB) is the most common tick-borne disease in Germany. Although the incidence of LB in Germany has been assessed in several studies, those studies either used data from statutory surveillance, which frequently underreport cases, or data from health claims databases, which may overestimate cases due to non-specific LB case definitions. Here, using a more specific case definition, we describe the incidence of medically-attended LB by disease manifestation, age group, and federal state for the period 2015-2019. Both inpatient and outpatient cases were analyzed from a claims database. To be eligible for inclusion, patients were required to have an LB specific ICD-10 GM diagnosis code plus an antibiotic prescription, and for disseminated manifestations, a laboratory test order additionally. LB cases were classified as erythema migrans (EM), or disseminated disease including Lyme arthritis (LA), Lyme neuroborreliosis (LNB), and all other disease manifestations (OTH). Between 2015 and 2019, the incidence of medically-attended LB cases ranged from 195.7/100,000 population per year (95% confidence interval [CI], 191.0 - 200.5) to 254.5/100,000 population per year (95% CI, 249.0 - 260.0) per year. The majority of cases (92.2%) were EM, while 2.8% presented as LA, 3.8% as LNB, and 1.2% as OTH. For both EM and disseminated disease, the incidence peaked in children aged 5-9 years and in older adults. By federal state, the incidence of medically-attended EM ranged from 74.4/100,000 population per year (95% CI, 71.9 - 77.0) per year in Hamburg, to 394.1/100,000 population per year (95% CI, 370.7 - 417.6) per year in Saxony, whereas for medically-attended disseminated disease, the highest incidence was in Thuringia, Saxony, and Bavaria (range: 22.0 [95% CI, 19.9 - 24.0] to 35.7 [95% CI, 34.7 - 36.7] per 100,000 population per year). This study comprehensively estimated the incidence of all manifestations of medically-attended LB and showed a high incidence of LB throughout Germany. Results from the study support performing epidemiological studies in all federal states to measure the burden of LB and to invest in public health interventions for prevention.

Borrelia burgdorferi sensu lato prevalence in Ixodes scapularis from Canada: A thirty-year summary and meta-analysis (1990-2020).

Borrelia burgdorferi sensu lato (Bb) are a complex of bacteria genospecies that can cause Lyme disease (LD) in humans after the bite of an infected Ixodes spp. vector tick. In Canada, incidence of LD is increasing in part due to the rapid geographic expansion of Ixodes scapularis across the southcentral and eastern provinces. To better understand temporal and spatial (provincial) prevalence of Bb infection of I. scapularis and how tick surveillance is utilized in Canada to assess LD risk, a literature review was conducted. Tick surveillance studies published between January 1975 to November 2023, that measured the prevalence of Bb in I. scapularis via "passive surveillance" from the public citizenry or "active surveillance" by drag or flag sampling of host-seeking ticks in Canada were included for review. Meta-analyses were conducted via random effects modeling. Forty-seven articles, yielding 26 passive and 28 active surveillance studies, met inclusion criteria. Mean durations of collection for I. scapularis were 2.1 years in active surveillance studies (1999-2020) and 5.5 years by passive surveillance studies (1990-2020). Collectively, data were extracted on 99,528 I. scapularis nymphs and adults collected between 1990-2020 across nine provinces, including Newfoundland & Labrador (33 ticks) and Alberta (208 ticks). More studies were conducted in Ontario (36) than any other province. Across nine provinces, the prevalence of Bb infection in I. scapularis collected by passive surveillance was 14.6% with the highest prevalence in Nova Scotia at 20.5% (minimum studies >1). Among host-seeking I. scapularis collected via active surveillance, Bb infection prevalence was 10.5% in nymphs, 31.9% in adults, and 23.8% across both life stages. Host-seeking I. scapularis nymphs and adults from Ontario had the highest Bb prevalence at 13.6% and 34.8%, respectively. Between 2007-2019, Bb infection prevalence in host-seeking I. scapularis was positively associated over time (p<0.001) which is concurrent with a ∼25-fold increase in the number of annually reported LD cases in Canada over the same period. The prevalence of Bb-infection in I. scapularis has rapidly increased over three decades as reported by tick surveillance studies in Canada which coincides with increasing human incidence for LD. The wide-ranging distribution and variable prevalence of Bb-infected I. scapularis ticks across provinces demonstrates the growing need for long-term standardized tick surveillance to monitor the changing trends in I. scapularis populations and best define LD risk areas in Canada.

Incidence of symptomatic Borrelia burgdorferi sensu lato infection in Romania, 2018-2023.

BACKGROUND: Lyme borreliosis (LB), caused by Borrelia burgdorferi sensu lato (Bbsl), is the most common tick-borne disease in Europe. Although public health surveillance for LB has been conducted in Romania since 2007, the extent of under-detection of Bbsl infections by LB surveillance has not been estimated. We therefore estimated the under-detection of symptomatic Bbsl infections by LB surveillance to better understand the LB burden in Romania. METHODS: The number of incident symptomatic Bbsl infections were estimated from a seroprevalence study conducted in six counties (population 2.3 M) and estimates of the symptomatic proportion and duration of persistence of anti-Bbsl immunoglobulin G (IgG) antibodies. The number of incident symptomatic Bbsl infections were compared with the number of surveillance-reported LB cases to derive an under-detection multiplier, and then the under-detection multiplier was applied to LB surveillance data to estimate the incidence of symptomatic Bbsl infection from 2018 to 2023. RESULTS: We estimate that there were 1968 individuals with incident symptomatic Bbsl infection in the six counties where the seroprevalence study was conducted in 2020, compared with the 187 surveillance-reported LB cases, resulting in an under-detection multiplier of 10.5 (i.e., for every surveillance-reported LB case, there were 10.5 symptomatic incident Bbsl infections). The incidence of symptomatic Bbsl infection in the six counties was 86.9/100,000 population in 2023, similar to the incidence in 2018-2020 (86.0) and higher than in 2021-2022 (40.3). CONCLUSIONS: There is a higher incidence of symptomatic Bbsl infection than is reported through public health surveillance for LB in Romania. Additional efforts are needed to strengthen disease prevention and address the important public health problem of LB.