. 2024 Nov 22;17(1):481.

doi: 10.1186/s13071-024-06518-9.

Spatial and temporal distribution of Ixodes scapularis and tick-borne pathogens across the northeastern United States

Lucas E Price¹, Jonathan M Winter², Jamie L Cantoni^#³, Duncan W Cozens^#³, Megan A Linske^#³, Scott C Williams^#⁴, Griffin M Dill^#⁵, Allison M Gardner^#⁶, Susan P Elias^#⁷, Thomas F Rounsville Jr⁵, Robert P Smith Jr⁷, Michael W Palace^#⁸, Christina Herrick^#⁸, Melissa A Prusinski^#⁹, Patti Casey^#¹⁰, Eliza M Doncaster^#¹⁰, Joseph D T Savage^{2

11}, Dorothy I Wallace¹², Xun Shi²

Affiliations

¹ Department of Geography, Dartmouth College, 6017 Fairchild, Hanover, NH, 03755, USA. Lucas.E.Price@Dartmouth.edu.
² Department of Geography, Dartmouth College, 6017 Fairchild, Hanover, NH, 03755, USA.
³ Department of Entomology, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
⁴ Department of Environmental Science and Forestry, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
⁵ Diagnostic and Research Laboratory, University of Maine Cooperative Extension, 17 Godfrey Drive, Orono, ME, 04473, USA.
⁶ School of Biology and Ecology, University of Maine, 5722 Deering Hall, Orono, ME, 04469, USA.
⁷ Vector-borne Disease Laboratory, MaineHealth Institute for Research, 81 Research Drive, Scarborough, ME, 04074, USA.
⁸ Institute for the Study of Earth, Oceans and Space, Department of Earth Sciences, University of New Hampshire, Morse Hall, Durham, NH, 03824, USA.
⁹ Vector Ecology Laboratory, Bureau of Communicable Disease Control, New York State Department of Health, Biggs Laboratory C-456-C-470A, Wadsworth Center, Empire State Plaza, Albany, NY, 12237, USA.
¹⁰ Environmental Surveillance Program, Vermont Agency of Agriculture Food & Markets, 116 State Street, Montpelier, VT, 05620, USA.
¹¹ Graduate Program in Ecology, Evolution, Environment, and Society, Dartmouth College, Hanover, NH, 03755, USA.
¹² Department of Mathematics, Dartmouth College, 6188 Kemeny Hall, Hanover, NH, 03755, USA.

^# Contributed equally.

PMID: 39574137
PMCID: PMC11583392
DOI: 10.1186/s13071-024-06518-9

Spatial and temporal distribution of Ixodes scapularis and tick-borne pathogens across the northeastern United States

Lucas E Price et al. Parasit Vectors. 2024.

. 2024 Nov 22;17(1):481.

doi: 10.1186/s13071-024-06518-9.

Authors

Affiliations

¹ Department of Geography, Dartmouth College, 6017 Fairchild, Hanover, NH, 03755, USA. Lucas.E.Price@Dartmouth.edu.
² Department of Geography, Dartmouth College, 6017 Fairchild, Hanover, NH, 03755, USA.
³ Department of Entomology, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
⁴ Department of Environmental Science and Forestry, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
⁵ Diagnostic and Research Laboratory, University of Maine Cooperative Extension, 17 Godfrey Drive, Orono, ME, 04473, USA.
⁶ School of Biology and Ecology, University of Maine, 5722 Deering Hall, Orono, ME, 04469, USA.
⁷ Vector-borne Disease Laboratory, MaineHealth Institute for Research, 81 Research Drive, Scarborough, ME, 04074, USA.
⁸ Institute for the Study of Earth, Oceans and Space, Department of Earth Sciences, University of New Hampshire, Morse Hall, Durham, NH, 03824, USA.
⁹ Vector Ecology Laboratory, Bureau of Communicable Disease Control, New York State Department of Health, Biggs Laboratory C-456-C-470A, Wadsworth Center, Empire State Plaza, Albany, NY, 12237, USA.
¹⁰ Environmental Surveillance Program, Vermont Agency of Agriculture Food & Markets, 116 State Street, Montpelier, VT, 05620, USA.
¹¹ Graduate Program in Ecology, Evolution, Environment, and Society, Dartmouth College, Hanover, NH, 03755, USA.
¹² Department of Mathematics, Dartmouth College, 6188 Kemeny Hall, Hanover, NH, 03755, USA.

^# Contributed equally.

PMID: 39574137
PMCID: PMC11583392
DOI: 10.1186/s13071-024-06518-9

Erratum in

Correction: Spatial and temporal distribution of Ixodes scapularis and tick-borne pathogens across the northeastern United States.
Price LE, Winter JM, Cantoni JL, Cozens DW, Linske MA, Williams SC, Dill GM, Gardner AM, Elias SP, Rounsville TF Jr, Smith RP Jr, Palace MW, Herrick C, Prusinski MA, Casey P, Doncaster EM, Savage JDT, Wallace DI, Shi X. Price LE, et al. Parasit Vectors. 2025 Feb 21;18(1):65. doi: 10.1186/s13071-024-06625-7. Parasit Vectors. 2025. PMID: 39984988 Free PMC article. No abstract available.

Abstract

Background: The incidence of tick-borne diseases is increasing across the USA, with cases concentrated in the northeastern and midwestern regions of the country. Ixodes scapularis is one of the most important tick-borne disease vectors and has spread throughout the northeastern USA over the past four decades, with established populations in all states of the region.

Methods: To better understand the rapid expansion of I. scapularis and the pathogens they transmit, we aggregated and analyzed I. scapularis abundance and pathogen prevalence data from across the northeastern USA, including the states of Connecticut, Maine, New Hampshire, New York and Vermont, from 1989 to 2021. Maine was the only state to collect data during the entire time period, with the other states collecting data during a subset of this time period starting in 2008 or later. We harmonized I. scapularis abundance by county and tick season, where the nymph season is defined as May to September and the adult season is October to December, and calculated I. scapularis pathogen infection prevalence as the percentage of ticks that tested positive for Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi, and Borrelia miyamotoi. We then explored temporal trends in I. scapularis abundance and pathogen prevalence data using linear models.

Results: The resulting dataset is one of the most spatially and temporally comprehensive records of tick abundance and pathogen prevalence in the USA. Using linear models, we found small or insignificant changes in the abundance of nymphs and adults over time; however, A. phagocytophilum, B. microti and B. burgdorferi prevalence in both nymphs and adults has increased over time. For the period 2017-2021, the statewide average prevalence of B. burgdorferi ranged from 19% to 25% in I. scapularis nymphs and from to 49% to 54% in I. scapularis adults. The statewide average prevalence of all other pathogens in I. scapularis for 2017-2021, including A. phagocytophilum (4-6% for nymphs, 4-9% for adults), B. microti (4-8% for nymphs, 2-13% for adults) and B. miyamotoi (1-2% for nymphs, 1-2% for adults), was considerably less.

Conclusions: Our efforts revealed the complications of creating a comprehensive dataset of tick abundance and pathogen prevalence across time and space due to variations in tick collection and pathogen testing methods. Although tick abundance has not changed along the more southern latitudes in our study over this time period, and only gradually changed in the more northern latitudes of our study, human risk for exposure to tick-borne pathogens has increased due to increased pathogen prevalence in I. scapularis. This dataset can be used in future studies of I. scapularis and pathogen prevalence across the northeastern USA and to evaluate models of I. scapularis ecology and population dynamics.

Keywords: Borrelia burgdorferi; Ixodes scapularis; Northeastern United States; Pathogen prevalence.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Figures

**Fig. 1**
Study area and time period for *Ixodes scapularis* sampling in the northeastern USA by county. Top-left panel shows the first year of sampling for nymphal *I. scapularis*, top-right panel shows the first year of sampling for adult *I. scapularis*, bottom-left panel shows the total number of years sampled for nymphal *I. scapularis* and bottom right panel shows the total number of years sampled for adult *I. scapularis*. Counties without color fill (light gray) were those for which we had no sampling data

**Fig. 2**
Abundance of nymphal *Ixodes scapularis* per hectare over time in the northeastern USA on a logistic scale, with each point representing a county’s abundance within a season. The nymphal season was from May to September, with the abundance calculated as the total number of nymphs collected divided by the total area sampled during the season within a county

**Fig. 3**
Average abundance of nymphal *Ixodes scapularis* per hectare in the northeastern USA. The nymphal season was from May to September, with the abundance calculated as the total number of nymphs collected divided by the total area sampled during a single season within a county. An average was taken of all abundance estimates for each county, and these are shown using a logistic scale, with dark-gray shading denoting counties that were sampled, but no nymphs found. Counties without color fill (light gray) were those for which we had no sampling data

**Fig. 4**
Abundance of adult *Ixodes scapularis* per hectare over time in the northeastern USA on a logistic scale, with each point representing a county’s abundance within a season. The adult season was from October to December, with the abundance calculated as the total number of adults collected divided by the total area sampled during the season within a county

**Fig. 5**
Average abundance of adult *Ixodes scapularis* per hectare in the northeastern USA. The adult season was from October to December, with the abundance calculated as the total number of adults collected divided by the total area sampled during a single season within a county. An average was taken of all abundance estimates for each county, and these are shown using a logistic scale, with dark-gray shading denoting counties that were sampled, but no adults found. Counties without color fill (light gray) were those for which we had no sampling data

**Fig. 6**
Percent pathogen prevalence of nymphal *Ixodes scapularis* in the northeastern USA, with each point representing a county’s pathogen prevalence. Pathogen prevalence was calculated as the total number of nymphs testing positive for a pathogen divided by the total number of nymphs tested for that pathogen. Top-left panel shows the prevalence of *Borrelia burgdorferi*, top-right panel shows the prevalence of *Anaplasma phagocytophilum*, bottom-left panel shows the prevalence of *Babesia microti* and bottom-right panel shows the prevalence of *Borrelia miyamotoi*

**Fig. 7**
Average pathogen prevalence of nymphal *Ixodes scapularis* in the northeastern USA. Pathogen prevalence was calculated as the total number of nymphs testing positive for a pathogen divided by the total number of nymphs tested for that pathogen within a county. An average was taken of all pathogen prevalence estimates for each county, with the dark-gray shading denoting counties that were sampled for ticks, but no pathogen prevalence data were available. Counties without color fill (light gray) were those for which we had no sampling data. Top-left panel shows the prevalence of *Borrelia burgdorferi*, top-right panel shows the prevalence of *Anaplasma phagocytophilum*, bottom-left panel shows the prevalence of *Babesia microti* and bottom-right panel shows the prevalence of *Borrelia miyamotoi*

**Fig. 8**
Percent pathogen prevalence of adult *Ixodes scapularis* in the northeastern USA, with each point representing a county’s pathogen prevalence. Pathogen prevalence was calculated as the total number of adults testing positive for a pathogen divided by the total number of adults tested for that pathogen. Top-left panel shows the prevalence of *Borrelia burgdorferi*, top-right panel shows the prevalence of *Anaplasma phagocytophilum*, bottom-left panel shows the prevalence of *Babesia microti* and bottom-right panel shows the prevalence of *Borrelia miyamotoi*

**Fig. 9**
Average pathogen prevalence of adult *Ixodes scapularis* in the northeastern USA. Pathogen prevalence was calculated as the total number of nymphs testing positive for a pathogen divided by the total number of adults tested for that pathogen within a county. An average was taken of all pathogen prevalence estimates for each county, with the dark-gray shading denoting counties that were sampled for ticks, but no pathogen prevalence data were available. Counties without color fill (light gray) were those for which we had no sampling data. Top-left panel shows the prevalence of *Borrelia burgdorferi*, top-right panel shows the prevalence of *Anaplasma phagocytophilum*, bottom-left panel shows the prevalence of *Babesia microti* and bottom-right panel shows the prevalence of *Borrelia miyamotoi*

See this image and copyright information in PMC

References

1. Rosenberg R. Vital signs: trends in reported vectorborne disease cases—United States and territories, 2004–2016. MMWR Morb Mortal Wkly Rep. 2018;67(17):496–501. 10.15585/mmwr.mm6717e1. - DOI - PMC - PubMed
1. U.S. CDC (Centers for Disease Control and Prevention). Tickborne disease surveillance data summary. 2022. https://www.cdc.gov/ticks/data-summary/index.html. Accessed 25 June 2023.
1. 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;27:616–9. - DOI - PMC - PubMed
1. Dennis DT, Nekomoto TS, Victor JC, Paul WS, Piesman J. Forum: reported distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the United States. J Med Entomol. 1998;35:629–38. - DOI - PubMed
1. Eisen RJ, Eisen L, Beard CB. County-scale distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the continental United States. J Med Entomol. 2016;53:349–86. - DOI - PMC - PubMed

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Spatial and temporal distribution of Ixodes scapularis and tick-borne pathogens across the northeastern United States

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Spatial and temporal distribution of Ixodes scapularis and tick-borne pathogens across the northeastern United States

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