RESEARCH PAPER
Systematic comparative analysis of Lyme disease emergence trajectories in Canada and Nordic countries
1
Department of (Clinical) Epidemiology and Global Health, Utrecht University, Utrecht, the Netherlands
Submission date: 2026-02-20
Final revision date: 2026-03-21
Acceptance date: 2026-03-30
Online publication date: 2026-06-08
Corresponding author
Gurkeerat Gill
Department of (Clinical) Epidemiology and Global Health, Utrecht University, Utrecht, the Netherlands
Department of (Clinical) Epidemiology and Global Health, Utrecht University, Utrecht, the Netherlands
KEYWORDS
TOPICS
ABSTRACT
Background:
Lyme disease (LD) is the most prevalent vector-borne infection in the Northern Hemisphere. Canada and the Nordic countries occupy analogous positions at the northern frontier of tick range expansion, yet no study has systematically compared their emergence trajectories. These regions present a natural experiment: identical climatic forcing operates upon fundamentally different vector-pathogen-host systems and surveillance architectures.
Material and methods:
Data were drawn from companion analyses: a 16-year Canadian national surveillance time series and a 7-year Nordic multi-country analysis. Comparative metrics included compound annual growth rates (CAGR), normalized growth indices, COVID-19 impact comparisons, and ecological-surveillance framework mapping.
Results:
Both regions demonstrate unambiguous upward trajectories consistent with climate-driven expansion. Canada’s CAGR (27.1%) exceeded Norway’s (6.8%) and Denmark’s (19.1%). During 2018-2024, Canadian cases increased 252% versus 48.2% (Norway) and 184.8% (Denmark). Critical divergences include pathogen complexity, co-circulating tick-borne encephalitis (TBE) in the Nordic countries, different surveillance architectures, and emergence phases.
Conclusions:
Convergent emergence across ecologically distinct systems confirms climate warming as the overarching driver, while divergent ecologies and surveillance systems produce fundamentally different disease profiles, underscoring the need for internationally harmonized surveillance standards.
Lyme disease (LD) is the most prevalent vector-borne infection in the Northern Hemisphere. Canada and the Nordic countries occupy analogous positions at the northern frontier of tick range expansion, yet no study has systematically compared their emergence trajectories. These regions present a natural experiment: identical climatic forcing operates upon fundamentally different vector-pathogen-host systems and surveillance architectures.
Material and methods:
Data were drawn from companion analyses: a 16-year Canadian national surveillance time series and a 7-year Nordic multi-country analysis. Comparative metrics included compound annual growth rates (CAGR), normalized growth indices, COVID-19 impact comparisons, and ecological-surveillance framework mapping.
Results:
Both regions demonstrate unambiguous upward trajectories consistent with climate-driven expansion. Canada’s CAGR (27.1%) exceeded Norway’s (6.8%) and Denmark’s (19.1%). During 2018-2024, Canadian cases increased 252% versus 48.2% (Norway) and 184.8% (Denmark). Critical divergences include pathogen complexity, co-circulating tick-borne encephalitis (TBE) in the Nordic countries, different surveillance architectures, and emergence phases.
Conclusions:
Convergent emergence across ecologically distinct systems confirms climate warming as the overarching driver, while divergent ecologies and surveillance systems produce fundamentally different disease profiles, underscoring the need for internationally harmonized surveillance standards.
REFERENCES (52)
1.
Mead P. Epidemiology of Lyme disease. Infect Dis Clin North Am. 2022; 36(3): 495-521. https://doi.org/10.1016/j.idc.....
2.
Kugeler KJ, Schwartz AM, Delorey MJ, Mead PS, Hinckley AF. Estimating the frequency of Lyme disease diagnoses, United States, 2010-2018. Emerg Infect Dis. 2021; 27(2): 616-619. https://doi.org/10.3201/eid270....
3.
Angulo FJ, Colby E, Lebech AM, Lindgren P-E, Moniuszko-Malinowska A, Strle F, et al. Incidence of symptomatic Lyme borreliosis in nine European countries. Int J Infect Dis. 2024; 149: 107242. https://doi.org/10.1016/j.ijid....
4.
Burn L, Phuong Tran TM, Pilz A, Vyse A, Fletcher MA, Angulo FJ, et al. Incidence of Lyme borreliosis in Europe from national surveillance systems (2005-2020). Vector Borne Zoonotic Dis. 2023; 23(4): 156-171. https://10.1089/vbz.2022.0071.
5.
Steere AC, Strle F, Wormser GP, Hu LT, Branda JA, Hovius JW, et al. Lyme borreliosis. Nat Rev Dis Primers. 2016; 2: 16090. https://doi.org/10.1038/nrdp.2....
6.
Rizzoli A, Hauffe HC, Carpi G, Vourc’h GI, Neteler M, Rosà R. Lyme borreliosis in Europe. Euro Surveill. 2011; 16(27): 19906. https://doi.org/10.2807/ese.16....
7.
Nagarajan A, Skufca J, Vyse A, Pilz A, Begier E, Riera-Montes M, et al. The landscape of Lyme borreliosis surveillance in Europe. Vector Borne Zoonotic Dis. 2023; 23(4): 142-155. https://doi.org/10.1089/vbz.20....
8.
Voyiatzaki C, Papailia SI, Venetikou MS, Pouris J, Tsoumani ME, Papageorgiou EG, et al. Climate changes exacerbate the spread of Ixodes ricinus and the occurrence of Lyme borreliosis and tick-borne encephalitis in Europe. How climate models are used as a risk assessment approach for tick-borne diseases. Int J Environ Res Public Health. 2022; 19(11): 6516. https://doi.org/10.3390/ijerph....
9.
Gilbert L. The impacts of climate change on ticks and tick-borne disease risk. Annu Rev Entomol. 2021; 66: 373-388. https://doi.org/10.1146/annure....
10.
Jore S, Vanwambeke SO, Viljugrein H, Isaksen K, Kristoffersen AB, Woldehiwet Z, et al. Climate and environmental change drives Ixodes ricinus geographical expansion at the northern range margin. Parasit Vectors. 2014; 7: 11. https://doi.org/10.1186/1756-3....
11.
Clow KM, Leighton PA, Ogden NH, Lindsay LR, Michel P, Pearl DL, et al. Northward range expansion of Ixodes scapularis evident over a short timescale in Ontario, Canada. PLoS One. 2017; 12(12): e0189393. https://doi.org/10.1371/journa....
12.
Gasmi S, Koffi JK, Nelder MP, Russell C, Graham-Derham S, Lachance L, et al. Surveillance for Lyme disease in Canada, 2009-2019. Can Commun Dis Rep. 2022; 48(5): 219-227. https://doi.org/10.14745/ccdr.....
13.
Public Health Agency of Canada. Annual report: Lyme disease and other tick-borne diseases surveillance in Canada [Internet]. Ottawa: Public Health Agency of Canada; 2025 [access 2025 May 1]. Available from: https://health-infobase.canada....
14.
Lindgren E, Tälleklint L, Polfeldt T. Impact of climatic change on the northern latitude limit and population density of the disease-transmitting European tick Ixodes ricinus. Environ Health Perspect. 2000; 108(2): 119-123. https://doi.org/10.1289/ehp.00....
15.
Da Re D, Gilson GF, Dalaiden Q, Goosse H, Bødker R, Jung Kjær L, et al. Northward expansion of the thermal limit for the tick Ixodes ricinus over the past 40 years. Parasit Vectors. 2025; 18: 449. https://doi.org/10.1186/s13071....
16.
Bennet L, Halling A, Berglund J. Increased incidence of Lyme borreliosis in southern Sweden following mild winters and during warm, humid summers. Eur J Clin Microbiol Infect Dis. 2006; 25: 426-432. https://doi.org/10.1007/s10096....
17.
Ogden NH, Lindsay LR, Morshed M, Sockett PN, Artsob H. The emergence of Lyme disease in Canada. CMAJ. 2009; 180(12): 1221-1224. https://doi.org/10.1503/cmaj.0....
18.
Bouchard C, Leonard E, Koffi JK, Pelcat Y, Peregrine A, Chilton N, et al. The increasing risk of Lyme disease in Canada. Can Vet J. 2015; 56(7): 693-699.
19.
Diuk-Wasser MA, VanAcker MC, Fernandez MP. Impact of land use changes and habitat fragmentation on the eco-epidemiology of tick-borne diseases. J Med Entomol. 2021; 58(4): 1546-1564. https://doi.org/10.1093/jme/tj....
20.
Stanek G, Wormser GP, Gray J, Strle F. Lyme borreliosis. Lancet. 2012; 379(9814): 461-473. https://doi.org/10.1016/S0140-....
21.
Lindquist L, Vapalahti O. Tick-borne encephalitis. Lancet. 2008; 371(9627): 1861-1871. https://doi.org/10.1016/S0140-....
22.
Süss J. Tick-borne encephalitis 2010: epidemiology, risk areas, and virus strains in Europe and Asia – an overview. Ticks Tick Borne Dis. 2011; 2(1): 2-15. https://doi.org/10.1016/j.ttbd....
23.
Marques AR, Strle F, Wormser GP. Comparison of Lyme disease in the United States and Europe. Emerg Infect Dis. 2021; 27(8): 2017-2024. https://doi.org/10.3201/eid270....
24.
Baker RE, Mahmud AS, Miller IF, Rajeev M, Rasambainarivo F, Rice BL, et al. Infectious disease in an era of global change. Nat Rev Microbiol. 2022; 20(4): 193-205. https://doi.org/10.1038/s41579....
25.
Medlock JM, Hansford KM, Bormane A, Derdakova M, Estrada-Peña A, George J-C, et al. Driving forces for changes in geographical distribution of Ixodes ricinus ticks in Europe. Parasit Vectors. 2013; 6: 1. https://doi.org/10.1186/1756-3....
26.
Public Health Agency of Canada. Lyme disease: monitoring [Internet]. Ottawa: Public Health Agency of Canada; 2025 [access 2025 May 1]. Available from: https://www.canada.ca/en/publi....
27.
Gasmi S, Ogden NH, Lindsay LR, Burns S, Fleming S, Badcock J, et al. Surveillance for Lyme disease in Canada: 2009-2015. Can Commun Dis Rep. 2017; 43(10): 194-199. https://doi.org/10.14745/ccdr.....
28.
Ogden NH, Dumas A, Gachon P, Rafferty E. Estimating the incidence and economic cost of Lyme disease cases in Canada in the 21st century with projected climate change. Environ Health Perspect. 2024; 132(2): 27005. https://doi.org/10.1289/ehp137....
29.
Dahl V, Wisell KT, Giske CG, Tegnell A, Wallensten A. Lyme neuroborreliosis epidemiology in Sweden 2010 to 2014: clinical microbiology laboratories are a better data source than the hospital discharge diagnosis register. Euro Surveill. 2019; 24(20): 1800453. https://doi.org/10.2807/1560-7....
30.
Tetens MM, Haahr R, Dessau RB, Krogfelt KA, Bodilsen J, Andersen NS, et al. Changes in Lyme neuroborreliosis incidence in Denmark, 1996 to 2015. Ticks Tick Borne Dis. 2020; 11(6): 101549. https://doi.org/10.1016/j.ttbd....
31.
Nygard K, Brantsaeter AB, Mehl R. Disseminated and chronic Lyme borreliosis in Norway, 1995-2004. Euro Surveill. 2005; 10(10): 235-238. https://doi.org/10.2807/esm.10....
32.
Blanchard L, Jones-Diette J, Lorenc T, Sutcliffe K, Sowden A, Thomas J. Comparison of national surveillance systems for Lyme disease in humans in Europe and North America: a policy review. BMC Public Health. 2022; 22: 1307. https://doi.org/10.1186/s12889....
33.
Westcott JR, Bowden JJ, Savage J, Doody KM. Rapid northward expansion of the blacklegged tick, Ixodes scapularis, in response to climate change. Glob Chang Biol. 2025; 31(11): e70591. https://doi.org/10.1111/gcb.70....
34.
Leighton PA, Koffi JK, Pelcat Y, Lindsay LR, Ogden NH. Predicting the speed of tick invasion: an empirical model of range expansion for Ixodes scapularis in Canada. J Appl Ecol. 2012; 49(2): 457-464. https://doi.org/10.1111/j.1365....
35.
Davidson A, Angulo FJ, Davis J, Halsby K, Brestrich G, Moïsi JC, et al. Comparison of the number of Lyme neuroborreliosis cases in European Centre for Disease Prevention and Control (ECDC) data and national public surveillance reports, 2018-2023. Ticks Tick Borne Dis. 2025; 16(6): 102542. https://doi.org/10.1016/j.ttbd....
36.
European Centre for Disease Prevention and Control. Surveillance atlas of infectious diseases [Internet]. Stockholm: ECDC; 2025 [access 2025 Feb]. Available from: https://atlas.ecdc.europa.eu/p....
37.
McCormick DW, Kugeler KJ, Marx GE, Jayanthi P, Dietz S, Mead P, et al. Effects of COVID-19 pandemic on reported Lyme disease, United States, 2020. Emerg Infect Dis. 2021; 27(10): 2715-2717. https://doi.org/10.3201/eid271....
38.
Sun YQ, Zhu XY, Fan TC, Ma T, Ge HH, Shi RF, et al. Projecting Lyme disease risk in the United States: a machine learning approach integrating environmental, socioeconomic and vector factors. One Health. 2025; 21: 101111. https://doi.org/10.1016/j.oneh....
39.
Jore S, Viljugrein H, Hjertqvist M, Dub T, Mäkelä H. Outdoor recreation, tick borne encephalitis incidence and seasonality in Finland, Norway and Sweden during the COVID-19 pandemic (2020/2021). Infect Ecol Epidemiol. 2023; 13(1): 2281055. https://doi.org/10.1080/200086....
40.
Skarpaas T, Golovljova I, Vene S, Ljøstad U, Sjursen H, Plyusnin A, et al. Tickborne encephalitis virus, Norway and Denmark. Emerg Infect Dis. 2006; 12(7): 1136-1138. https://doi.org/10.3201/eid120....
41.
Jaenson TGT, Jaenson DGE, Eisen L, Petersson E, Lindgren E. Changes in the geographical distribution and abundance of the tick Ixodes ricinus during the past 30 years in Sweden. Parasit Vectors. 2012; 5: 8. https://doi.org/10.1186/1756-3....
42.
Palmborg A, Angulo FJ, Zhang P, Pilz A, Stark J, Moïsi JC, et al. Tick-borne encephalitis vaccine uptake, effectiveness, and impact in Sweden from 2018 to 2022. Sci Rep. 2025; 15: 2927. https://doi.org/10.1038/s41598....
43.
Askling HH, Zavadska D. Tick-borne encephalitis (TBE) vaccine in the National Immunisation Programme – for whom, when and where?. Acta Paediatr. Forthcoming 2025. https://doi.org/10.1111/apa.70....
44.
Beauté J, Spiteri G, Warns-Petit E, Zeller H. Tick-borne encephalitis in Europe, 2012 to 2016. Euro Surveill. 2018; 23(45): 1800201. https://doi.org/10.2807/1560-7....
45.
Ostfeld RS, Keesing F. Biodiversity series: the function of biodiversity in the ecology of vector-borne zoonotic diseases. Can J Zool. 2000; 78(12): 2061-2078. https://doi.org/10.1139/z00-17....
46.
Hofmeester TR, Coipan EC, van Wieren SE, Prins HHT, Takken W, Sprong H. Few vertebrate species dominate the Borrelia burgdorferi s.l. life cycle. Environ Res Lett. 2016; 11(4): 043001. https://doi.org/10.1088/1748-9....
47.
Crandall KE, Millien V, Kerr JT. High-resolution environmental and host-related factors impacting questing Ixodes scapularis at their northern range edge. Ecol Evol. 2024; 14(2): e10855. https://doi.org/10.1002/ece3.1....
48.
Ogden NH, Bouchard C, Badcock J, Drebot MA, Elias SP, Hatchette TF, et al. What is the real number of Lyme disease cases in Canada?. BMC Public Health. 2019; 19: 849. https://doi.org/10.1186/s12889....
49.
Jung Kjær L, Bødker R, Król N, Skarphédinsson S, Jensen PM. Potential for integrated monitoring of tick-borne diseases: indices of tick activity, citizen science, and tick-borne Lyme neuroborreliosis in Denmark from 2017 to 2024. Ticks Tick Borne Dis. 2026; 17(1): 102602. https://doi.org/10.1016/j.ttbd....
50.
European Commission. Commission Implementing Decision (EU) 2018/945 of 22 June 2018 on the communicable diseases and related special health issues to be covered by epidemiological surveillance. Off J Eur Union. 2018; L 170: 1-74.
51.
Yang H, Gould CA, Jones R, St. Juliana A, Sarofim M, Rissing M, et al. By-degree health and economic impacts of Lyme disease, eastern and midwestern United States. Ecohealth. 2024; 21: 56-70. https://doi.org/10.1007/s10393....
52.
Lantos PM, Rumbaugh J, Bockenstedt LK, Falck-Ytter YT, Aguero-Rosenfeld ME, Auwaerter PG, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis, and Treatment of Lyme Disease. Arthritis Care Res. 2021; 73(1): 1-9. https://doi.org/10.1002/acr.24....
Share
RELATED ARTICLE
| eISSN: | 2354-0265 |
| ISSN: | 2353-6942 |
We process personal data collected when visiting the website. The function of obtaining information about users and their behavior is carried out by voluntarily entered information in forms and saving cookies in end devices. Data, including cookies, are used to provide services, improve the user experience and to analyze the traffic in accordance with the Privacy policy. Data are also collected and processed by Google Analytics tool (more).
You can change cookies settings in your browser. Restricted use of cookies in the browser configuration may affect some functionalities of the website.
You can change cookies settings in your browser. Restricted use of cookies in the browser configuration may affect some functionalities of the website.
