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Schoville SD, Burke RL, Dong DY, Ginsberg HS, Maestas L, Paskewitz SM, Tsao JI. Genome resequencing reveals population divergence and local adaptation of blacklegged ticks in the United States. Mol Ecol 2024; 33:e17460. [PMID: 38963031 DOI: 10.1111/mec.17460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 03/12/2024] [Accepted: 04/15/2024] [Indexed: 07/05/2024]
Abstract
Tick vectors and tick-borne disease are increasingly impacting human populations globally. An important challenge is to understand tick movement patterns, as this information can be used to improve management and predictive modelling of tick population dynamics. Evolutionary analysis of genetic divergence, gene flow and local adaptation provides insight on movement patterns at large spatiotemporal scales. We develop low coverage, whole genome resequencing data for 92 blacklegged ticks, Ixodes scapularis, representing range-wide variation across the United States. Through analysis of population genomic data, we find that tick populations are structured geographically, with gradual isolation by distance separating three population clusters in the northern United States, southeastern United States and a unique cluster represented by a sample from Tennessee. Populations in the northern United States underwent population contractions during the last glacial period and diverged from southern populations at least 50 thousand years ago. Genome scans of selection provide strong evidence of local adaptation at genes responding to host defences, blood-feeding and environmental variation. In addition, we explore the potential of low coverage genome sequencing of whole-tick samples for documenting the diversity of microbial pathogens and recover important tick-borne pathogens such as Borrelia burgdorferi. The combination of isolation by distance and local adaptation in blacklegged ticks demonstrates that gene flow, including recent expansion, is limited to geographical scales of a few hundred kilometres.
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Affiliation(s)
- Sean D Schoville
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Russell L Burke
- Department of Biology, Hofstra University, Hempstead, New York, USA
| | - Dahn-Young Dong
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Howard S Ginsberg
- United States Geological Survey, Eastern Ecological Science Center, Woodward Hall - PSE, Field Station at the University of Rhode Island, Kingston, Rhode Island, USA
| | - Lauren Maestas
- Cattle Fever Tick Research Laboratory, USDA, Agricultural Research Service, Edinburg, Texas, USA
| | - Susan M Paskewitz
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jean I Tsao
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, USA
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, Michigan, USA
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Pelletier J, Bouchard C, Aenishaenslin C, Beaudry F, Ogden NH, Leighton PA, Rocheleau JP. Pharmacological studies and pharmacokinetic modelling to support the development of interventions targeting ecological reservoirs of Lyme disease. Sci Rep 2024; 14:13537. [PMID: 38866918 PMCID: PMC11169648 DOI: 10.1038/s41598-024-63799-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 06/03/2024] [Indexed: 06/14/2024] Open
Abstract
The development of interventions targeting reservoirs of Borrelia burgdorferi sensu stricto with acaricide to reduce the density of infected ticks faces numerous challenges imposed by ecological and operational limits. In this study, the pharmacokinetics, efficacy and toxicology of fluralaner were investigated in Mus musculus and Peromyscus leucopus mice, the main reservoir of B. burgdorferi in North America. Fluralaner showed rapid distribution and elimination, leading to fast plasma concentration (Cp) depletion in the first hours after administration followed by a slow elimination rate for several weeks, resulting in a long terminal half-life. Efficacy fell below 100% while Cp (± standard deviation) decreased from 196 ± 54 to 119 ± 62 ng/mL. These experimental results were then used in simulations of fluralaner treatment for a duration equivalent to the active period of Ixodes scapularis larvae and nymphs. Simulations showed that doses as low as 10 mg/kg have the potential to protect P. leucopus against infestation for a full I. scapularis active season if administered at least once every 7 days. This study shows that investigating the pharmacology of candidate acaricides in combination with pharmacokinetic simulations can provide important information to support the development of effective interventions targeting ecological reservoirs of Lyme disease. It therefore represents a critical step that may help surpass limits inherent to the development of these interventions.
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Affiliation(s)
- Jérôme Pelletier
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.
- Centre de recherche en santé publique de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada.
| | - Catherine Bouchard
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - Cécile Aenishaenslin
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - Francis Beaudry
- Département de biomédecine vétérinaire, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche sur le cerveau et l'apprentissage (CIRCA), Université de Montréal, Montréal, Québec, Canada
| | - Nicholas H Ogden
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - Patrick A Leighton
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - Jean-Philippe Rocheleau
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Département de santé animale, CÉGEP de Saint-Hyacinthe, Saint-Hyacinthe, Québec, Canada
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Lantos PM, Janko M, Nigrovic LE, Ruffin F, Kobayashi T, Higgins Y, Auwaerter PG. Mapping the distribution of Lyme disease at a mid-Atlantic site in the United States using electronic health data. PLoS One 2024; 19:e0301530. [PMID: 38820472 PMCID: PMC11142662 DOI: 10.1371/journal.pone.0301530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 03/18/2024] [Indexed: 06/02/2024] Open
Abstract
Lyme disease is a spatially heterogeneous tick-borne infection, with approximately 85% of US cases concentrated in the mid-Atlantic and northeastern states. Surveillance for Lyme disease and its causative agent, including public health case reporting and entomologic surveillance, is necessary to understand its endemic range, but currently used case detection methods have limitations. To evaluate an alternative approach to Lyme disease surveillance, we have performed a geospatial analysis of Lyme disease cases from the Johns Hopkins Health System in Maryland. We used two sources of cases: a) individuals with both a positive test for Lyme disease and a contemporaneous diagnostic code consistent with a Lyme disease-related syndrome; and b) individuals referred for a Lyme disease evaluation who were adjudicated to have Lyme disease. Controls were individuals from the referral cohort judged not to have Lyme disease. Residential address data were available for all cases and controls. We used a hierarchical Bayesian model with a smoothing function for a coordinate location to evaluate the probability of Lyme disease within 100 km of Johns Hopkins Hospital. We found that the probability of Lyme disease was greatest in the north and west of Baltimore, and the local probability that a subject would have Lyme disease varied by as much as 30-fold. Adjustment for demographic and ecological variables partially attenuated the spatial gradient. Our study supports the suitability of electronic medical record data for the retrospective surveillance of Lyme disease.
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Affiliation(s)
- Paul M. Lantos
- Duke University School of Medicine, Durham, NC, United States of America
- Duke Global Health Institute, Durham, NC, United States of America
| | - Mark Janko
- Duke Global Health Institute, Durham, NC, United States of America
| | - Lise E. Nigrovic
- Boston Children’s Hospital, Boston, MA, United States of America
| | - Felicia Ruffin
- Duke University School of Medicine, Durham, NC, United States of America
| | - Takaaki Kobayashi
- University of Iowa Hospital and Clinics, Iowa City, IA, United States of America
| | - Yvonne Higgins
- Sherrilyn and Ken Fisher Center for Environmental Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Paul G. Auwaerter
- Sherrilyn and Ken Fisher Center for Environmental Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
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Case BKM, Dye-Braumuller KC, Evans C, Li H, Rustin L, Nolan MS. Adapting vector surveillance using Bayesian experimental design: An application to an ongoing tick monitoring program in the southeastern United States. Ticks Tick Borne Dis 2024; 15:102329. [PMID: 38484538 PMCID: PMC10993663 DOI: 10.1016/j.ttbdis.2024.102329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 03/24/2024]
Abstract
Maps of the distribution of medically-important ticks throughout the US remain lacking in spatial and temporal resolution in many areas, leading to holes in our understanding of where and when people are at risk of tick encounters, an important baseline for informing public health response. In this work, we demonstrate the use of Bayesian Experimental Design (BED) in planning spatiotemporal surveillance of disease vectors. We frame survey planning as an optimization problem with the objective of identifying a calendar of sampling locations that maximizes the expected information regarding some goal. Here we consider the goals of understanding associations between environmental factors and tick presence and minimizing uncertainty in high risk areas. We illustrate our proposed BED workflow using an ongoing tick surveillance study in South Carolina parks. Following a model comparison study based on two years of initial data, several techniques for finding optimal surveys were compared to random sampling. Two optimization algorithms found surveys better than all replications of random sampling, while a space-filling heuristic performed favorably as well. Further, optimal surveys of just 20 visits were more effective than repeating the schedule of 111 visits used in 2021. We conclude that BED shows promise as a flexible and rigorous means of survey design for vector control, and could help alleviate pressure on local agencies by limiting the resources necessary for accurate information on arthropod distributions. We have made the code for our BED workflow publicly available on Zenodo to help promote the application of these methods to future surveillance efforts.
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Affiliation(s)
- B K M Case
- Department of Epidemiology and Biostatistics, University of Georgia, Athens, GA, USA; Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - Kyndall C Dye-Braumuller
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - Chris Evans
- South Carolina Department of Health and Environmental Control, Columbia, SC, USA
| | - Huixuan Li
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - Lauren Rustin
- South Carolina Department of Health and Environmental Control, Columbia, SC, USA
| | - Melissa S Nolan
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA; South Carolina Department of Health and Environmental Control, Columbia, SC, USA.
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Foster E, Holcomb KM, Eisen RJ. Density of host-seeking Ixodes scapularis nymphs by region, state, and county in the contiguous United States generated through national tick surveillance. Ticks Tick Borne Dis 2024; 15:102316. [PMID: 38325243 DOI: 10.1016/j.ttbdis.2024.102316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/09/2024]
Abstract
The majority of vector-borne disease cases reported annually in the United States are caused by pathogens spread by the blacklegged tick, Ixodes scapularis. The number and geographic distribution of cases have increased as the geographic range and abundance of the tick have expanded in recent decades. A large proportion of Lyme disease and other I. scapularis-borne diseases are associated with nymphal tick bites; likelihood of such bites generally increases with increasing nymphal densities. National tick surveillance was initiated in 2018 to track changes in the distribution and abundance of medically important ticks at the county spatial scale throughout the United States. Tick surveillance records, including historical data collected prior to the initiation of the national program, are collated in the ArboNET Tick Module database. Through exploration of ArboNET Tick Module data, we found that efforts to quantify the density of host-seeking I. scapularis nymphs (DON) were unevenly distributed among geographic regions with the greatest proportion of counties sampled in the Northeast and Upper Midwest. Submissions covering tick collections from 2004 through 2022 revealed extensive variation in DON estimates at collection site, county, state, and regional spatial scales. Throughout the entire study period, county DON estimates ranged from 0.0 to 488.5 nymphs/1,000 m2 . Although substantial variation was recorded within regions, DON estimates were greatest in the Northeast, Upper Midwest, and northern states within the Southeast regions (Virginia and North Carolina); densities were intermediate in the Ohio Valley and very low in the South and Northern Rockies and Plains regions. The proportion of counties classified as moderate or high DON was lower in the Northeast, Ohio Valley, and Southeast regions during the 2004 through 2017 time period (prior to initiation of the national tick surveillance program) compared to 2018 through 2022; DON estimates remained similarly low between these time periods in the South and the Northern Rockies and Plains regions. Despite the limitations described herein, the ArboNET Tick Module provides useful data for tracking changes in acarological risk across multiple geographic scales and long periods of time.
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Affiliation(s)
- Erik Foster
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, Fort Collins 80521, CO, USA.
| | - Karen M Holcomb
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, Fort Collins 80521, CO, USA
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, Fort Collins 80521, CO, USA
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6
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Ostfeld RS, Adish S, Mowry S, Bremer W, Duerr S, Evans AS, Fischhoff IR, Keating F, Pendleton J, Pfister A, Teator M, Keesing F. Effects of residential acaricide treatments on patterns of pathogen coinfection in blacklegged ticks. Parasitology 2024:1-7. [PMID: 38494476 DOI: 10.1017/s0031182024000349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Medically important ixodid ticks often carry multiple pathogens, with individual ticks frequently coinfected and capable of transmitting multiple infections to hosts, including humans. Acquisition of multiple zoonotic pathogens by immature blacklegged ticks (Ixodes scapularis) is facilitated when they feed on small mammals, which are the most competent reservoir hosts for Anaplasma phagocytophilum (which causes anaplasmosis in humans), Babesia microti (babesiosis) and Borrelia burgdorferi (Lyme disease). Here, we used data from a large-scale, long-term experiment to ask whether patterns of single and multiple infections in questing nymphal I. scapularis ticks from residential neighbourhoods differed from those predicted by independent assortment of pathogens, and whether patterns of coinfection were affected by residential application of commercial acaricidal products. Quantitative polymerase chain reaction was used for pathogen detection in multiplex reactions. In control neighbourhoods and those treated with a fungus-based biopesticide deployed against host-seeking ticks (Met52), ticks having only single infections of either B. microti or B. burgdorferi were significantly less common than expected, whereas coinfections with these 2 pathogens were significantly more common. However, use of tick control system bait boxes, which kill ticks attempting to feed on small mammals, eliminated the bias towards coinfection. Although aimed at reducing the abundance of host-seeking ticks, control methods directed at ticks attached to small mammals may influence human exposure to coinfected ticks and the probability of exposure to multiple tick-borne infections.
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Affiliation(s)
| | - Sahar Adish
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
| | - Stacy Mowry
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
| | - William Bremer
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
| | - Shannon Duerr
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
| | - Andrew S Evans
- Department of Behavioral and Community Health, Dutchess County, NY 12601, USA
| | | | - Fiona Keating
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
| | | | - Ashley Pfister
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
| | - Marissa Teator
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
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Bellman S, Fausett E, Aeschleman L, Long A, Roeske I, Pilchik J, Piantadosi A, Vazquez-Prokopec G. Mapping the distribution of Amblyomma americanum in Georgia, USA. Parasit Vectors 2024; 17:62. [PMID: 38342907 PMCID: PMC10860309 DOI: 10.1186/s13071-024-06142-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/17/2024] [Indexed: 02/13/2024] Open
Abstract
BACKGROUND Amblyomma americanum, the lone star tick, is an aggressive questing species that harbors several pathogens dangerous to humans in the United States. The Southeast in particular has large numbers of this tick due to the combined suitable climate and habitats throughout the region. No studies have estimated the underlying distribution of the lone star tick across the state of Georgia, a state where it is the dominant species encountered. METHODS Ticks were collected by flagging 198 transects of 750 m2 at 43 state parks and wildlife management areas across the state from March to July of 2022. A suite of climate, landscape, and wildlife variables were assembled, and a logistic regression model was used to assess the association between these environmental factors and the presence of lone star ticks and to predict the distribution of these ticks across the state. RESULTS A total of 59/198 (30%) transects sampled contained adult or nymph A. americanum, with the majority of transects containing these ticks (54/59, 91.5%) in forested habitats. The presence of A. americanum was associated with elevation, normalized difference vegetation index (NDVI) on January 1, isothermality, temperature seasonality, and precipitation in the wettest quarter. Vast regions of central, eastern, and southern coastal Georgia (57% of the state) were categorized as suitable habitat for the lone star tick. CONCLUSIONS This study describes the distribution of the lone star tick across the state of Georgia at a finer scale than the current county-level information available. It identifies specific variables associated with tick presence and provides a map that can be used to target areas for tick prevention messaging and awareness.
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Affiliation(s)
- Stephanie Bellman
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Ellie Fausett
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Leah Aeschleman
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Audrey Long
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Isabella Roeske
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Josie Pilchik
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Anne Piantadosi
- Department of Pathology and Laboratory Medicine, School of Medicine, Emory University, Atlanta, GA, USA
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Guillot C, Aenishaenslin C, Acheson ES, Koffi J, Bouchard C, Leighton PA. Spatial multi-criteria decision analysis for the selection of sentinel regions in tick-borne disease surveillance. BMC Public Health 2024; 24:294. [PMID: 38267914 PMCID: PMC10809750 DOI: 10.1186/s12889-024-17684-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 01/05/2024] [Indexed: 01/26/2024] Open
Abstract
BACKGROUND The implementation of cost-effective surveillance systems is essential for tracking the emerging risk of tick-borne diseases. In Canada, where Lyme disease is a growing public health concern, a national sentinel surveillance network was designed to follow the epidemiological portrait of this tick-borne disease across the country. The surveillance network consists of sentinel regions, with active drag sampling carried out annually in all regions to assess the density of Ixodes spp. ticks and prevalence of various tick-borne pathogens in the tick population. The aim of the present study was to prioritize sentinel regions by integrating different spatial criteria relevant to the surveillance goals. METHODS We used spatially-explicit multi-criteria decision analyses (MCDA) to map priority areas for surveillance across Canada, and to evaluate different scenarios using sensitivity analyses. Results were shared with stakeholders to support their decision making for the selection of priority areas to survey during active surveillance activities. RESULTS Weights attributed to criteria by decision-makers were overall consistent. Sensitivity analyses showed that the population criterion had the most impact on rankings. Thirty-seven sentinel regions were identified across Canada using this systematic and transparent approach. CONCLUSION This novel application of spatial MCDA to surveillance network design favors inclusivity of nationwide partners. We propose that such an approach can support the standardized planning of spatial design of sentinel surveillance not only for vector-borne disease BDs, but more broadly for infectious disease surveillance where spatial design is an important component.
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Affiliation(s)
- C Guillot
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Montreal, Quebec, Canada.
- Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada.
- Centre de recherche en santé publique (CRESP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, University of Montreal, Montreal, Quebec, Canada.
| | - C Aenishaenslin
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Montreal, Quebec, Canada
- Centre de recherche en santé publique (CRESP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, University of Montreal, Montreal, Quebec, Canada
| | - E S Acheson
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Montreal, Quebec, Canada
- Public Health Risk Sciences Divisions, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - J Koffi
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Montreal, Quebec, Canada
- Policy Integration and Zoonoses Division, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - C Bouchard
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Montreal, Quebec, Canada
- Public Health Risk Sciences Divisions, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - P A Leighton
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Montreal, Quebec, Canada
- Centre de recherche en santé publique (CRESP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, University of Montreal, Montreal, Quebec, Canada
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9
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Bowser N, Bouchard C, Sautié Castellanos M, Baron G, Carabin H, Chuard P, Leighton P, Milord F, Richard L, Savage J, Tardy O, Aenishaenslin C. Self-reported tick exposure as an indicator of Lyme disease risk in an endemic region of Quebec, Canada. Ticks Tick Borne Dis 2024; 15:102271. [PMID: 37866213 DOI: 10.1016/j.ttbdis.2023.102271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/13/2023] [Accepted: 10/07/2023] [Indexed: 10/24/2023]
Abstract
BACKGROUND Lyme disease (LD) and other tick-borne diseases are emerging across Canada. Spatial and temporal LD risk is typically estimated using acarological surveillance and reported human cases, the former not considering human behavior leading to tick exposure and the latter occurring after infection. OBJECTIVES The primary objective was to explore, at the census subdivision level (CSD), the associations of self-reported tick exposure, alternative risk indicators (predicted tick density, eTick submissions, public health risk level), and ecological variables (Ixodes scapularis habitat suitability index and cumulative degree days > 0 °C) with incidence proportion of LD. A secondary objective was to explore which of these predictor variables were associated with self-reported tick exposure at the CSD level. METHODS Self-reported tick exposure was measured in a cross-sectional populational health survey conducted in 2018, among 10,790 respondents living in 116 CSDs of the Estrie region, Quebec, Canada. The number of reported LD cases per CSD in 2018 was obtained from the public health department. Generalized linear mixed-effets models accounting for spatial autocorrelation were built to fulfill the objectives. RESULTS Self-reported tick exposure ranged from 0.0 % to 61.5 % (median 8.9 %) and reported LD incidence rates ranged from 0 to 324 cases per 100,000 person-years, per CSD. A positive association was found between self-reported tick exposure and LD incidence proportion (ß = 0.08, CI = 0.04,0.11, p < 0.0001). The best-fit model included public health risk level (AIC: 144.2), followed by predicted tick density, ecological variables, self-reported tick exposure and eTick submissions (AIC: 158.4, 158.4, 160.4 and 170.1 respectively). Predicted tick density was the only significant predictor of self-reported tick exposure (ß = 0.83, CI = 0.16,1.50, p = 0.02). DISCUSSION This proof-of-concept study explores self-reported tick exposure as a potential indicator of LD risk using populational survey data. This approach may offer a low-cost and simple tool for evaluating LD risk and deserves further evaluation.
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Affiliation(s)
- Natasha Bowser
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de Recherche en Santé Publique (CReSP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada; Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Canada.
| | - Catherine Bouchard
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada; Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Canada
| | | | - Geneviève Baron
- Direction de la Santé Publique, CIUSSS de l'Estrie-CHUS, Québec, Canada; Département Des Sciences de la Santé Communautaire, Faculté de Médecine et Des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Canada
| | - Hélène Carabin
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de Recherche en Santé Publique (CReSP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada; Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Canada; Département de Médecine Sociale et Préventive, École de santé publique de l'Université de Montréal, Canada
| | - Pierre Chuard
- Department of Geography, Planning and Environment, Concordia University, Montreal, Canada
| | - Patrick Leighton
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de Recherche en Santé Publique (CReSP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada; Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Canada
| | - François Milord
- Département Des Sciences de la Santé Communautaire, Faculté de Médecine et Des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Canada; Institut national de santé publique du Québec, Québec, Canada
| | - Lucie Richard
- Centre de Recherche en Santé Publique (CReSP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada; Faculté des Sciences Infirmières, Université de Montréal, Canada
| | - Jade Savage
- Department of Biology and Biochemistry, Bishop's University, Canada
| | - Olivia Tardy
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - Cécile Aenishaenslin
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de Recherche en Santé Publique (CReSP) de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada; Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Canada
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10
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Keesing F, Tilley E, Mowry S, Adish S, Bremer W, Duerr S, Evans AS, Fischhoff IR, Keating F, Pendleton J, Pfister A, Teator M, Ostfeld RS. Spatial variation in risk for tick-borne diseases in residential areas of Dutchess County, New York. PLoS One 2023; 18:e0293820. [PMID: 37943804 PMCID: PMC10635528 DOI: 10.1371/journal.pone.0293820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/19/2023] [Indexed: 11/12/2023] Open
Abstract
Although human exposure to the ticks that transmit Lyme-disease bacteria is widely considered to occur around people's homes, most studies of variation in tick abundance and infection are undertaken outside residential areas. Consequently, the patterns of variation in risk of human exposure to tick-borne infections in these human-dominated landscapes are poorly understood. Here, we report the results of four years of sampling for tick abundance, tick infection, tick encounters, and tick-borne disease reports on residential properties nested within six neighborhoods in Dutchess County, New York, USA, an area of high incidence for Lyme and other tick-borne diseases. All properties were within neighborhoods that had been randomly assigned as placebo controls in The Tick Project; hence, none were treated to reduce tick abundance during the period of investigation, providing a unique dataset of natural variation within and between neighborhoods. We estimated the abundance of host-seeking blacklegged ticks (Ixodes scapularis) in three types of habitats on residential properties-forests, lawns, and gardens. In forest and lawn habitats, some neighborhoods had consistently higher tick abundance. Properties within neighborhoods also varied consistently between years, suggesting hot spots and cold spots occurring at a small (~ 1-hectare) spatial scale. Across neighborhoods, the abundance of nymphal ticks was explained by neither the amount of forest in that neighborhood, nor by the degree of forest fragmentation. The proportion of ticks infected with three common tick-borne pathogens did not differ significantly between neighborhoods. We observed no effect of tick abundance on human encounters with ticks, nor on either human or pet cases of tick-borne diseases. However, the number of encounters between ticks and outdoor pets in a neighborhood was negatively correlated with the abundance of questing ticks in that neighborhood. Our results reinforce the need to understand how human behavior and neglected ecological factors affect variation in human encounters with ticks and cases of tick-borne disease in residential settings.
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Affiliation(s)
| | - Emma Tilley
- Bard College, Annandale, NY, United States of America
| | - Stacy Mowry
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Sahar Adish
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - William Bremer
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Shannon Duerr
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Andrew S. Evans
- Department of Behavioral and Community Health, Dutchess County, NY, United States of America
| | - Ilya R. Fischhoff
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Fiona Keating
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Jennifer Pendleton
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Ashley Pfister
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Marissa Teator
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
| | - Richard S. Ostfeld
- Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America
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11
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Fellin E, Varin M, Millien V. Risky business: human-related data is lacking from Lyme disease risk models. Front Public Health 2023; 11:1113024. [PMID: 38026346 PMCID: PMC10662633 DOI: 10.3389/fpubh.2023.1113024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 10/09/2023] [Indexed: 12/01/2023] Open
Abstract
Used as a communicative tool for risk management, risk maps provide a service to the public, conveying information that can raise risk awareness and encourage mitigation. Several studies have utilized risk maps to determine risks associated with the distribution of Borrelia burgdorferi, the causal agent of Lyme disease in North America and Europe, as this zoonotic disease can lead to severe symptoms. This literature review focused on the use of risk maps to model distributions of B. burgdorferi and its vector, the blacklegged tick (Ixodes scapularis), in North America to compare variables used to predict these spatial models. Data were compiled from the existing literature to determine which ecological, environmental, and anthropic (i.e., human focused) variables past research has considered influential to the risk level for Lyme disease. The frequency of these variables was examined and analyzed via a non-metric multidimensional scaling analysis to compare different map elements that may categorize the risk models performed. Environmental variables were found to be the most frequently used in risk spatial models, particularly temperature. It was found that there was a significantly dissimilar distribution of variables used within map elements across studies: Map Type, Map Distributions, and Map Scale. Within these map elements, few anthropic variables were considered, particularly in studies that modeled future risk, despite the objective of these models directly or indirectly focusing on public health intervention. Without including human-related factors considering these variables within risk map models, it is difficult to determine how reliable these risk maps truly are. Future researchers may be persuaded to improve disease risk models by taking this into consideration.
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Affiliation(s)
- Erica Fellin
- Department of Biology, McGill University, Montréal, QC, Canada
- Redpath Museum, McGill University, Montréal, QC, Canada
| | - Mathieu Varin
- Centre d'Enseignement et de Recherche en Foresterie (CERFO), Québec City, QC, Canada
| | - Virginie Millien
- Department of Biology, McGill University, Montréal, QC, Canada
- Redpath Museum, McGill University, Montréal, QC, Canada
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12
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Holcomb KM, Khalil N, Cozens DW, Cantoni JL, Brackney DE, Linske MA, Williams SC, Molaei G, Eisen RJ. Comparison of acarological risk metrics derived from active and passive surveillance and their concordance with tick-borne disease incidence. Ticks Tick Borne Dis 2023; 14:102243. [PMID: 37611506 PMCID: PMC10885130 DOI: 10.1016/j.ttbdis.2023.102243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/19/2023] [Accepted: 08/15/2023] [Indexed: 08/25/2023]
Abstract
Tick-borne diseases continue to threaten human health across the United States. Both active and passive tick surveillance can complement human case surveillance, providing spatio-temporal information on when and where humans are at risk for encounters with ticks and tick-borne pathogens. However, little work has been done to assess the concordance of the acarological risk metrics from each surveillance method. We used data on Ixodes scapularis and its associated human pathogens from Connecticut (2019-2021) collected through active collections (drag sampling) or passive submissions from the public to compare county estimates of tick and pathogen presence, infection prevalence, and tick abundance by life stage. Between the surveillance strategies, we found complete agreement in estimates of tick and pathogen presence, high concordance in infection prevalence estimates for Anaplasma phagocytophilum, Borrelia burgdorferi sensu stricto, and Babesia microti, but no consistent relationships between actively and passively derived estimates of tick abundance or abundance of infected ticks by life stage. We also compared nymphal metrics (i.e., pathogen prevalence in nymphs, nymphal abundance, and abundance of infected nymphs) with reported incidence of Lyme disease, anaplasmosis, and babesiosis, but did not find any consistent relationships with any of these metrics. The small spatial and temporal scale for which we had consistently collected active and passive data limited our ability to find significant relationships. Findings are likely to differ if examined across a broader spatial or temporal coverage with greater variation in acarological and epidemiological outcomes. Our results indicate similar outcomes between some actively and passively derived tick surveillance metrics (tick and pathogen presence, pathogen prevalence), but comparisons were variable for abundance estimates.
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Affiliation(s)
- Karen M Holcomb
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States.
| | - Noelle Khalil
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Duncan W Cozens
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Jamie L Cantoni
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Doug E Brackney
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Megan A Linske
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Scott C Williams
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Goudarz Molaei
- Center for Vector Biology and Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, CT, United States; Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States
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13
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Foster E, Maes SA, Holcomb KM, Eisen RJ. Prevalence of five human pathogens in host-seeking Ixodes scapularis and Ixodes pacificus by region, state, and county in the contiguous United States generated through national tick surveillance. Ticks Tick Borne Dis 2023; 14:102250. [PMID: 37703795 PMCID: PMC10629455 DOI: 10.1016/j.ttbdis.2023.102250] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/28/2023] [Accepted: 08/30/2023] [Indexed: 09/15/2023]
Abstract
The majority of vector-borne disease cases reported in the United States (U.S.) are caused by pathogens spread by the blacklegged tick, Ixodes scapularis. In recent decades, the geographic ranges of the tick and its associated human pathogens have expanded, putting an increasing number of communities at risk for tick-borne infections. In 2018, the U.S. Centers for Disease Control and Prevention (CDC) initiated a national tick surveillance program to monitor changes in the distribution and abundance of ticks and the presence and prevalence of human pathogens in them. We assessed the geographical representativeness of prevalence data submitted to CDC as part of the national tick surveillance effort. We describe county, state, and regional variation in the prevalence of five human pathogens (Borrelia burgdorferi sensu stricto (s.s.), Borrelia mayonii, Borrelia miyamotoi, Anaplasma phagocytophilum, and Babesia microti) in host-seeking I. scapularis and I. pacificus nymphs and adults. Although I. scapularis and I. pacificus are widely distributed in the eastern and western U.S., respectively, pathogen prevalence was estimated predominantly in ticks collected in the Northeast, Ohio Valley, and Upper Midwest regions, where human Lyme disease cases are most commonly reported. Within these regions, we found that state and regional estimates of pathogen prevalence generally reached predictable and stable levels, but variation in prevalence estimates at the sub-state level was considerable. Borrelia burgdorferi s.s. was the most prevalent and widespread pathogen detected. Borrelia miyamotoi and A. phagocytophilum shared a similarly broad geographic range, but were consistently detected at much lower prevalence compared with B. burgdorferi s.s. Babesia microti was detected at similar prevalence to A. phagocytophilum, where both pathogens co-occurred, but was reported over a much more limited geographic range compared with A. phagocytophilum or B. burgdorferi s.s. Borrelia mayonii was identified at very low prevalence with a focal distribution within the Upper Midwest. National assessments of risk for tick-borne diseases need to be improved through collection and testing of ticks in currently under-represented regions, including the West, South, Southeast, and eastern Plains states.
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Affiliation(s)
- Erik Foster
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA.
| | - Sarah A Maes
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
| | - Karen M Holcomb
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
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14
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Maxwell SP, Brooks C, Kim D, McNeely CL, Cho S, Thomas KC. Improving Surveillance of Human Tick-Borne Disease Risks: Spatial Analysis Using Multimodal Databases. JMIR Public Health Surveill 2023; 9:e43790. [PMID: 37610812 PMCID: PMC10483298 DOI: 10.2196/43790] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 04/24/2023] [Accepted: 06/27/2023] [Indexed: 08/24/2023] Open
Abstract
BACKGROUND The extent of tick-borne disease (TBD) risk in the United States is generally unknown. Active surveillance using entomological measures, such as presence and density of infected nymphal Ixodes scapularis ticks, have served as indicators for assessing human risk, but results have been inconsistent and passive surveillance via public health systems suggests TBDs are underreported. OBJECTIVE Research using various data sources and collection methods (eg, Google Trends, apps, and tick bite encounters [TBEs] reports) has shown promise for assessing human TBD risk. In that vein, and engaging a One Health perspective, this study used multimodal databases, geographically overlaying patient survey data on TBEs and concomitant reports of TBDs with data drawn from other sources, such as canine serological reports, to glean insights and to determine and assess the use of various indicators as proxies for human TBD risk. METHODS This study used a mixed methods research strategy, relying on triangulation techniques and drawing on multiple data sources to provide insights into various aspects of human disease risk from TBEs and TBDs in the United States. A web-based survey was conducted over a 15-month period beginning in December 2020 to collect data on TBEs. To maximize the value of the covariate data, related analyses included TBE reports that occurred in the United States between January 1, 2000, and March 31, 2021. TBEs among patients diagnosed with Lyme disease were analyzed at the county level and compared to I scapularis and I pacificus tick presence, human cases identified by the Centers for Disease Control and Prevention (CDC), and canine serological data. Spatial analyses employed multilayer thematic mapping and other techniques. RESULTS After cleaning, survey results showed a total of 249 (75.7%) TBEs spread across 148 respondents (61.9% of all respondents, 81.7% of TBE-positive respondents); 144 (4.7%) counties in 30 states (60%) remained eligible for analysis, with an average of 1.68 (SD 1.00) and median of 1 (IQR 1) TBEs per respondent. Analysis revealed significant spatial matching at the county level among patient survey reports of TBEs and disease risk indicators from the CDC and other official sources. Thematic mapping results included one-for-one county-level matching of reported TBEs with at least 1 designated source of human disease risk (ie, positive canine serological tests, CDC-reported Lyme disease, or known tick presence). CONCLUSIONS Use of triangulation methods to integrate patient data on TBE recall with established canine serological reports, tick presence, and official human TBD information offers more granular, county-level information regarding TBD risk to inform clinicians and public health officials. Such data may supplement public health sources to offer improved surveillance and provide bases for developing robust proxies for TBD risk among humans.
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Affiliation(s)
- Sarah P Maxwell
- School of Economic, Political and Policy Sciences, University of Texas at Dallas, Richardson, TX, United States
| | - Chris Brooks
- Laboratory for Human Neurobiology, Boston University School of Medicine, Boston, MA, United States
| | - Dohyeong Kim
- School of Economic, Political and Policy Sciences, University of Texas at Dallas, Richardson, TX, United States
| | - Connie L McNeely
- Schar School of Policy and Government, George Mason University, Fairfax, VA, United States
| | - Seonga Cho
- Department of Geography, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Kevin C Thomas
- Laboratory for Human Neurobiology, Boston University School of Medicine, Boston, MA, United States
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15
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Burtis JC, Bjork J, Johnson TL, Schiffman E, Neitzel D, Eisen RJ. Seasonal activity patterns of host-seeking Ixodes scapularis (Acari: Ixodidae) in Minnesota, 2015-2017. JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:769-777. [PMID: 37075475 PMCID: PMC10593201 DOI: 10.1093/jme/tjad048] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 03/13/2023] [Accepted: 04/05/2023] [Indexed: 05/03/2023]
Abstract
As the primary vector of Lyme disease spirochetes and several other medically significant pathogens, Ixodes scapularis presents a threat to public health in the United States. The incidence of Lyme disease is growing rapidly in upper midwestern states, particularly Michigan, Minnesota, and Wisconsin. The probability of a tick bite, acarological risk, is affected by the phenology of host-seeking I. scapularis. Phenology has been well-studied in northeastern states, but not in the Upper Midwest. We conducted biweekly drag sampling across 4 woodland sites in Minnesota between April and November from 2015 to 2017. The majority of ticks collected were I. scapularis (82%). Adults were active throughout our entire 8-month collection season, with sporadic activity during the summer, larger peaks in activity observed in April, and less consistent and lower peaks observed in October. Nymphs were most active from May through August, with continuing low-level activity in October, and peak activity most commonly observed in June. The observed nymphal peak corresponded with the typical peak in reported human Lyme disease and anaplasmosis cases. These findings are consistent with previous studies from the Upper Midwest and highlight a risk of human exposure to I. scapularis at least from April through November. This information may aid in communicating the seasonality of acarological risk for those living in Minnesota and other upper midwestern states as well as being relevant to the assessment of the ecoepidemiology of Lyme disease and the modeling of transmission dynamics.
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Affiliation(s)
- James C. Burtis
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA
| | - Jenna Bjork
- Minnesota Department of Health, 625 North Robert Street, Saint Paul, MN 55164, USA
| | - Tammi L. Johnson
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA
- Present address, Texas A&M AgriLife Research, Department of Rangeland, Wildlife and Fisheries Management, Texas A&M University, Uvalde, TX 78801, USA
| | - Elizabeth Schiffman
- Minnesota Department of Health, 625 North Robert Street, Saint Paul, MN 55164, USA
| | - David Neitzel
- Minnesota Department of Health, 625 North Robert Street, Saint Paul, MN 55164, USA
| | - Rebecca J. Eisen
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA
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16
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Burtis JC, Ford SL, Parise CM, Foster E, Eisen RJ, Eisen L. Comparison of in vitro and in vivo repellency bioassay methods for Ixodes scapularis nymphs. Parasit Vectors 2023; 16:228. [PMID: 37430360 DOI: 10.1186/s13071-023-05845-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/20/2023] [Indexed: 07/12/2023] Open
Abstract
BACKGROUND Numerous bioassay methods have been used to test the efficacy of repellents for ticks, but the comparability of results across different methods has only been evaluated in a single study. Of particular interest are comparisons between bioassays that use artificial containers (in vitro) with those conducted on a human subject (in vivo) for efficacy testing of new potential unregistered active ingredients, which most commonly use in vitro methods. METHODS We compared four different bioassay methods and evaluated three ingredients (DEET [N,N-Diethyl-meta-toluamide], peppermint oil and rosemary oil) and a negative control (ethanol) over a 6-h period. Two of the methods tested were in vivo bioassay methods in which the active ingredient was applied to human skin (finger and forearm bioassays), and the other two methods were in vitro methods using artificial containers (jar and petri dish bioassays). All four bioassays were conducted using Ixodes scapularis nymphs. We compared the results using nymphs from two different tick colonies that were derived from I. scapularis collected in the US states of Connecticut and Rhode Island (northern origin) and Oklahoma (southern origin), expecting that ticks of different origin would display differences in host-seeking behavior. RESULTS The results between bioassay methods did not differ significantly, even when comparing those that provide the stimulus of human skin with those that do not. We also found that tick colony source can impact the outcome of repellency bioassays due to differences in movement speed; behavioral differences were incorporated into the assay screening. DEET effectively repelled nymphs for the full 6-h duration of the study. Peppermint oil showed a similar repellent efficacy to DEET during the first hour, but it decreased sharply afterwards. Rosemary oil did not effectively repel nymphs across any of the time points. CONCLUSIONS The repellency results did not differ significantly between the four bioassay methods tested. The results also highlight the need to consider the geographic origin of ticks used in repellency bioassays in addition to species and life stage. Finally, our results indicate a limited repellent efficacy of the two essential oils tested, which highlights the need for further studies on the duration of repellency for similar botanically derived active ingredients and for evaluation of formulated products.
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Affiliation(s)
- James C Burtis
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA.
| | - Shelby L Ford
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Christina M Parise
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Erik Foster
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Lars Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
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17
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Bouchard C, Dumas A, Baron G, Bowser N, Leighton PA, Lindsay LR, Milord F, Ogden NH, Aenishaenslin C. Integrated human behavior and tick risk maps to prioritize Lyme disease interventions using a 'One Health' approach. Ticks Tick Borne Dis 2023; 14:102083. [PMID: 36435167 DOI: 10.1016/j.ttbdis.2022.102083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 10/25/2022] [Accepted: 11/09/2022] [Indexed: 11/21/2022]
Abstract
Lyme disease (LD) risk is emerging rapidly in Canada due to range expansion of its tick vectors, accelerated by climate change. The risk of contracting LD varies geographically due to variability in ecological characteristics that determine the hazard (the densities of infected host-seeking ticks) and vulnerability of the human population determined by their knowledge and adoption of preventive behaviors. Risk maps are commonly used to support public health decision-making on Lyme disease, but the ability of the human public to adopt preventive behaviors is rarely taken into account in their development, which represents a critical gap. The objective of this work was to improve LD risk mapping using an integrated social-behavioral and ecological approach to: (i) compute enhanced integrated risk maps for prioritization of interventions and (ii) develop a spatially-explicit assessment tool to examine the relative contribution of different risk factors. The study was carried out in the Estrie region located in southern Québec. The blacklegged tick, Ixodes scapularis, infected with the agent of LD is widespread in Estrie and as a result, regional LD incidence is the highest in the province. LD knowledge and behaviors in the population were measured in a cross-sectional health survey conducted in 2018 reaching 10,790 respondents in Estrie. These data were used to create an index for the social-behavioral component of risk in 2018. Local Empirical Bayes estimator technique were used to better quantify the spatial variance in the levels of adoption of LD preventive activities. For the ecological risk analysis, a tick abundance model was developed by integrating data from ongoing long-term tick surveillance programs from 2007 up to 2018. Social-behavioral and ecological components of the risk measures were combined to create vulnerability index maps and, with the addition of human population densities, prioritization index maps. Map predictions were validated by testing the association of high-risk areas with the current spatial distribution of human cases of LD and reported tick exposure. Our results demonstrated that social-behavioral and ecological components of LD risk have markedly different distributions within Estrie. The occurrence of human LD cases or reported tick exposure in a municipality was positively associated with tick density and the prioritization risk index (p < 0.001). This research is a second step towards a more comprehensive integrated LD risk assessment approach, examining social-behavioral risk factors that interact with ecological risk factors to influence the management of emerging tick-borne diseases, an approach that could be applied more widely to vector-borne and zoonotic diseases.
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Affiliation(s)
- Catherine Bouchard
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada; Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire (FMV), Université de Montréal, Saint-Hyacinthe, Québec, Canada.
| | - Ariane Dumas
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire (FMV), Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Geneviève Baron
- Direction de la santé publique de l'Estrie, CIUSSS de l'Estrie-CHUS, Sherbrooke, Québec, Canada
| | - Natasha Bowser
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire (FMV), Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de recherche en santé publique, Université de Montréal et CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - Patrick A Leighton
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire (FMV), Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de recherche en santé publique, Université de Montréal et CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - L Robbin Lindsay
- Zoonotic Diseases and Special Pathogens, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - François Milord
- Direction de santé publique de la Montérégie, Centre intégré de santé et de services sociaux Montérégie-Centre, Longueuil, Canada
| | - Nicholas H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada; Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire (FMV), Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de recherche en santé publique, Université de Montréal et CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - Cécile Aenishaenslin
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire (FMV), Université de Montréal, Saint-Hyacinthe, Québec, Canada; Centre de recherche en santé publique, Université de Montréal et CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
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Pelletier J, Rocheleau JP, Aenishaenslin C, Dimitri Masson G, Lindsay LR, Ogden NH, Bouchard C, Leighton PA. Fluralaner Baits Reduce the Infestation of Peromyscus spp. Mice (Rodentia: Cricetidae) by Ixodes scapularis (Acari: Ixodidae) Larvae and Nymphs in a Natural Environment. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:2080-2089. [PMID: 35980603 DOI: 10.1093/jme/tjac106] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Indexed: 06/15/2023]
Abstract
The development of interventions that reduce Lyme disease incidence remains a challenge. Reservoir-targeted approaches aiming to reduce tick densities or tick infection prevalence with Borrelia burgdorferi have emerged as promising ways to reduce the density of infected ticks. Acaricides of the isoxazoline family offer high potential for reducing infestation of ticks on small mammals as they have high efficacy at killing feeding ticks for a long period. Fluralaner baits were recently demonstrated as effective, in the laboratory, at killing Ixodes scapularis larvae infesting Peromyscus mice, the main reservoir for B. burgdorferi in northeastern North America. Here, effectiveness of this approach for reducing the infestation of small mammals by immature stages of I. scapularis was tested in a natural environment. Two densities of fluralaner baits (2.1 baits/1,000 m2 and 4.4 baits/1,000 m2) were used during three years in forest plots. The number of I. scapularis larvae and nymphs per mouse from treated and control plots were compared. Fluralaner baiting reduced the number of larvae per mouse by 68% (CI95: 51-79%) at 2.1 baits/1,000 m2 and by 86% (CI95: 77-92%) at 4.4 baits/1,000 m2. The number of nymphs per mouse was reduced by 72% (CI95: 22-90%) at 4.4 baits/1,000 m2 but was not significantly reduced at 2.1 baits/1,000 m2. Reduction of Peromyscus mouse infestation by immature stages of I. scapularis supports the hypothesis that an approach targeting reservoirs of B. burgdorferi with isoxazolines has the potential to reduce tick-borne disease risk by decreasing the density of infected ticks in the environment.
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Affiliation(s)
- Jérôme Pelletier
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - Jean-Philippe Rocheleau
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Département de santé animale, CÉGEP de Saint-Hyacinthe, Saint-Hyacinthe, Québec, Canada
| | - Cécile Aenishaenslin
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
| | - Gabrielle Dimitri Masson
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - L Robbin Lindsay
- One Health Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Nicholas H Ogden
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - Catherine Bouchard
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - Patrick A Leighton
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique de l'Université de Montréal et du CIUSSS du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
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Burtis JC, Foster E, Schwartz AM, Kugeler KJ, Maes SE, Fleshman AC, Eisen RJ. Predicting distributions of blacklegged ticks (Ixodes scapularis), Lyme disease spirochetes (Borrelia burgdorferi sensu stricto) and human Lyme disease cases in the eastern United States. Ticks Tick Borne Dis 2022; 13:102000. [PMID: 35785605 PMCID: PMC10591441 DOI: 10.1016/j.ttbdis.2022.102000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 06/22/2022] [Accepted: 06/25/2022] [Indexed: 11/27/2022]
Abstract
Lyme disease is the most commonly reported vector-borne disease in the United States (US), with approximately 300,000 -to- 40,000 cases reported annually. The blacklegged tick, Ixodes scapularis, is the primary vector of the Lyme disease-causing spirochete, Borrelia burgdorferi sensu stricto, in high incidence regions in the upper midwestern and northeastern US. Using county-level records of the presence of I. scapularis or presence of B. burgdorferi s.s. infected host-seeking I. scapularis, we generated habitat suitability consensus maps based on an ensemble of statistical models for both acarological risk metrics. Overall accuracy of these suitability models was high (AUC = 0.76 for I. scapularis and 0.86 for B. burgdorferi s.s. infected-I. scapularis). We sought to compare which acarological risk metric best described the distribution of counties reporting high Lyme disease incidence (≥10 confirmed cases/100,000 population) by setting the models to a fixed omission rate (10%). We compared the percent of high incidence counties correctly classified by the two models. The I. scapularis consensus map correctly classified 53% of high and low incidence counties, while the B. burgdorferi s.s. infected-I. scapularis consensus map classified 83% correctly. Counties classified as suitable by the B. burgdorferi s.s. map showed a 91% overlap with high Lyme disease incidence counties with over a 38-fold difference in Lyme disease incidence between high- and low-suitability counties. A total of 288 counties were classified as highly suitable for B. burgdorferi s.s., but lacked records of infected-I. scapularis and were not classified as high incidence. These counties were considered to represent a leading edge for B. burgdorferi s.s. infection in ticks and humans. They clustered in Illinois, Indiana, Michigan, and Ohio. This information can aid in targeting tick surveillance and prevention education efforts in counties where Lyme disease risk may increase in the future.
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Affiliation(s)
- James C Burtis
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States.
| | - Erik Foster
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States
| | - Amy M Schwartz
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States
| | - Kiersten J Kugeler
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States
| | - Sarah E Maes
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States
| | - Amy C Fleshman
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, United States
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Gregory N, Fernandez MP, Diuk-Wasser M. Risk of tick-borne pathogen spillover into urban yards in New York City. Parasit Vectors 2022; 15:288. [PMID: 35948911 PMCID: PMC9365221 DOI: 10.1186/s13071-022-05416-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/27/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The incidence of tick-borne disease has increased dramatically in recent decades, with urban areas increasingly recognized as high-risk environments for exposure to infected ticks. Green spaces may play a key role in facilitating the invasion of ticks, hosts and pathogens into residential areas, particularly where they connect residential yards with larger natural areas (e.g. parks). However, the factors mediating tick distribution across heterogeneous urban landscapes remain poorly characterized. METHODS Using generalized linear models in a multimodel inference framework, we determined the residential yard- and local landscape-level features associated with the presence of three tick species of current and growing public health importance in residential yards across Staten Island, a borough of New York City, in the state of New York, USA. RESULTS The amount and configuration of canopy cover immediately surrounding residential yards was found to strongly predict the presence of Ixodes scapularis and Amblyomma americanum, but not that of Haemaphysalis longicornis. Within yards, we found a protective effect of fencing against I. scapularis and A. americanum, but not against H. longicornis. For all species, the presence of log and brush piles strongly increased the odds of finding ticks in yards. CONCLUSIONS The results highlight a considerable risk of tick exposure in residential yards in Staten Island and identify both yard- and landscape-level features associated with their distribution. In particular, the significance of log and brush piles for all three species supports recommendations for yard management as a means of reducing contact with ticks.
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Affiliation(s)
- Nichar Gregory
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY USA
| | - Maria P. Fernandez
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY USA
- Earth Institute, Columbia University, New York, NY USA
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA USA
| | - Maria Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY USA
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Mechanical Acaricides Active against the Blacklegged Tick, Ixodes scapularis. INSECTS 2022; 13:insects13080672. [PMID: 35893027 PMCID: PMC9331188 DOI: 10.3390/insects13080672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/22/2022] [Accepted: 07/23/2022] [Indexed: 02/05/2023]
Abstract
Cases of Lyme disease in humans are on the rise in the United States and Canada. The vector of the bacteria that causes this disease is the blacklegged tick, Ixodes scapularis. Current control methods for I. scapularis mainly involve chemical acaricides. Unfortunately, ticks are developing resistance to these chemicals, and more and more, the public prefers non-toxic alternatives to chemical pesticides. We discovered that volcanic glass, ImergardTM WP, and other industrial minerals such as Celite 610 were efficacious mechanical insecticides against mosquitoes, filth flies, and agricultural pests. In this report, when 6-10- and 50-70-day old unfed I. scapularis nymphs were dipped for 1-2 s into Celite, the time to 50% mortality (LT50) was 66.8 and 81.7 min, respectively, at 30 °C and 50% relative humidity (RH). The LT50 was actually shorter at a higher 70% RH, 43.8 min. Scanning electron microscopy showed that the ticks were coated over most of their body surface, including partial to almost total coverage of the opening to their respiratory system. The other mechanical insecticide, Imergard, had similar efficacy against blacklegged unfed nymphs with an LT50 at 30 °C and 50% RH of 70.4 min. Although more research is needed, this study suggests that industrial minerals could be used as an alternative to chemical pesticides to control ticks and Lyme disease.
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Fleshman AC, Foster E, Maes SE, Eisen RJ. Reported County-Level Distribution of Seven Human Pathogens Detected in Host-Seeking Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the Contiguous United States. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1328-1335. [PMID: 35583265 DOI: 10.1093/jme/tjac049] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Indexed: 06/15/2023]
Abstract
Tickborne disease cases account for over 75% of reported vector-borne disease cases in the United States each year. In addition to transmitting the agents of Lyme disease (Borrelia burgdorferi sensu strict [Spirochaetales: Spirochaetaceae] and Borrelia mayonii [Spirochaetales: Spirochaetaceae]), the blacklegged tick, Ixodes scapularis, and the western blacklegged tick, Ixodes pacificus collectively transmit five additional human pathogens. By mapping the distributions of tickborne pathogens in host-seeking ticks, we can understand where humans are at risk of contracting tickborne diseases and devise targeted strategies to prevent them. Using publicly available tickborne pathogen surveillance databases, internal CDC pathogen testing databases, and SCOPUS search records published since 2000, we mapped the county-level distribution of Borrelia miyamotoi (Spirochaetales: Spirochaetaceae), Anaplasma phagocytophilum (Rickettsiales: Anaplasmataceae), Ehrlichia muris eauclairensis (Rickettsiales: Ehrlichiaceae), Babesia microti (Piroplasmida: Babesiidae), and Powassan virus (Flaviviridae) reported in host-seeking I. scapularis or I. pacificus in the contiguous United States. We also updated recently published maps of the distributions of Borrelia burgdorferi sensu stricto and Borrelia mayonii. All seven pathogen distributions were more limited than the distributions of vector ticks, with at least one of the seven pathogens detected in 30 states out of 41 total states (73.2% of states) where vector ticks are considered to be established. Prevention and diagnosis of tickborne diseases rely on an accurate understanding by the public and health care providers of where people are at risk for exposure to infected ticks. Our county-level pathogen distribution maps expand on previous efforts showing the distribution of Lyme disease spirochetes and highlight counties where further investigation may be warranted.
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Affiliation(s)
- Amy C Fleshman
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Erik Foster
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Sarah E Maes
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
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Jordan RA, Gable S, Egizi A. Relevance of Spatial and Temporal Trends in Nymphal Tick Density and Infection Prevalence for Public Health and Surveillance Practice in Long-Term Endemic Areas: A Case Study in Monmouth County, NJ. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1451-1466. [PMID: 35662344 DOI: 10.1093/jme/tjac073] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Indexed: 06/15/2023]
Abstract
Tick-borne diseases are a growing public health problem in the United States, and the US northeast has reported consistently high case rates for decades. Monmouth County, New Jersey, was one of the earliest jurisdictions to report Lyme disease cases in 1979 and reports several hundred cases per year nearly 40 yr later. In the time since, however, tick-borne health risks have expanded far beyond Lyme disease to include a variety of other bacterial pathogens and viruses, and additional vectors, necessitating a continually evolving approach to tick surveillance. In 2017, Monmouth County initiated an active surveillance program targeting sites across three ecological regions for collection of Ixodes scapularis Say (Acari: Ixodidae) and Amblyomma americanum L. (Acari: Ixodidae) as well as testing via qPCR for associated bacterial pathogens. During the first five years of this program (2017-2021), we report high levels of spatiotemporal variability in nymphal density and infection prevalence in both species, limiting the granularity with which human risk can be predicted from acarological data. Nonetheless, broader patterns emerged, including an ongoing trend of A. americanum dominance, risks posed by Borrelia miyamotoi, and the frequency of coinfected ticks. We present some of the first county-level, systematic surveillance of nymphal A. americanum density and infection prevalence in the northeastern US. We also documented a temporary decline in Borrelia burgdorferi that could relate to unmeasured trends in reservoir host populations. We discuss the implications of our findings for tick-borne disease ecology, public health communication, and tick surveillance strategies in endemic areas.
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Affiliation(s)
- Robert A Jordan
- Tick-borne Disease Program, Monmouth County Mosquito Control Division, 1901 Wayside Road, Tinton Falls, NJ 07724, USA
- Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ 08901, USA
| | - Sydney Gable
- Tick-borne Disease Program, Monmouth County Mosquito Control Division, 1901 Wayside Road, Tinton Falls, NJ 07724, USA
- Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ 08901, USA
| | - Andrea Egizi
- Tick-borne Disease Program, Monmouth County Mosquito Control Division, 1901 Wayside Road, Tinton Falls, NJ 07724, USA
- Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ 08901, USA
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O’Keeffe KR, Oppler ZJ, Prusinski M, Falco RC, Oliver J, Haight J, Sporn LA, Backenson PB, Brisson D. Phylogeographic dynamics of the arthropod vector, the blacklegged tick (Ixodes scapularis). Parasit Vectors 2022; 15:238. [PMID: 35765050 PMCID: PMC9241328 DOI: 10.1186/s13071-022-05304-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/15/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The emergence of vector-borne pathogens in novel geographic areas is regulated by the migration of their arthropod vectors. Blacklegged ticks (Ixodes scapularis) and the pathogens they vector, including the causative agents of Lyme disease, babesiosis and anaplasmosis, continue to grow in their population sizes and to expand in geographic range. Migration of this vector over the previous decades has been implicated as the cause of the re-emergence of the most prevalent infectious diseases in North America. METHODS We systematically collected ticks from across New York State (hereafter referred to as New York) from 2004 to 2017 as part of routine tick-borne pathogen surveillance in the state. This time frame corresponds with an increase in range and incidence of tick-borne diseases within New York. We randomly sampled ticks from this collection to explore the evolutionary history and population dynamics of I. scapularis. We sequenced the mitochondrial genomes of each tick to characterize their current and historical spatial genetic structure and population growth using phylogeographic methods. RESULTS We sequenced whole mitochondrial genomes from 277 ticks collected across New York between 2004 and 2017. We found evidence of population genetic structure at a broad geographic scale due to differences in the relative abundance, but not the composition, of haplotypes among sampled ticks. Ticks were often most closely related to ticks from the same and nearby collection sites. The data indicate that both short- and long-range migration events shape the population dynamics of blacklegged ticks in New York. CONCLUSIONS We detailed the population dynamics of the blacklegged tick (Ixodes scapularis) in New York during a time frame in which tick-borne diseases were increasing in range and incidence. Migration of ticks occurred at both coarse and fine scales in the recent past despite evidence of limits to gene flow. Past and current tick population dynamics have implications for further range expansion as habitat suitability for ticks changes due to global climate change. Analyses of mitochondrial genome sequencing data will expound upon previously identified drivers of tick presence and abundance as well as identify additional drivers. These data provide a foundation on which to generate testable hypotheses on the drivers of tick population dynamics occurring at finer scales.
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Affiliation(s)
| | - Zachary J. Oppler
- Department of Biology, University of Pennsylvania, Philadelphia, PA USA
| | | | | | - JoAnne Oliver
- Department of Health, Central New York Regional Office, Syracuse, NY 13202 USA
| | - Jamie Haight
- New York State Department of Health, Albany, NY USA
| | | | | | - Dustin Brisson
- Department of Biology, University of Pennsylvania, Philadelphia, PA USA
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Bourdin A, Bord S, Durand J, Galon C, Moutailler S, Scherer-Lorenzen M, Jactel H. Forest Diversity Reduces the Prevalence of Pathogens Transmitted by the Tick Ixodes ricinus. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.891908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tick-borne diseases represent the majority of vector-borne human diseases in Europe, with Ixodes ricinus, mostly present in forests, as the main vector. Studies show that vertebrate hosts diversification would decrease the prevalence of these pathogens. However, it is not well known whether habitat diversity can have similar impact on ticks and their infection rates. We measured the presence and abundance of different stages of I. ricinus, and the prevalence of associated pathogens in a large-scale forest experiment in which we manipulated tree diversity and moisture level. We showed that larval abundance was influenced by tree species identity, with larvae being more present in pine plots than in oak plots, while nymph abundance increased with canopy tree density. The proportion of Borrelia burgdorferi s.l.-infected nymphs decreased with increasing tree diversity. Our findings suggest that tree overstorey composition, structure and diversity, can affect tick abundance and pathogen prevalence. They support the idea that forest habitats may have “diluting” or “amplifying” effects on tick-borne diseases with direct relevance for human health.
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Sentinel Surveillance Contributes to Tracking Lyme Disease Spatiotemporal Risk Trends in Southern Quebec, Canada. Pathogens 2022; 11:pathogens11050531. [PMID: 35631052 PMCID: PMC9145942 DOI: 10.3390/pathogens11050531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/16/2022] Open
Abstract
Lyme disease (LD) is a tick-borne disease which has been emerging in temperate areas in North America, Europe, and Asia. In Quebec, Canada, the number of human LD cases is increasing rapidly and thus surveillance of LD risk is a public health priority. In this study, we aimed to evaluate the ability of active sentinel surveillance to track spatiotemporal trends in LD risk. Using drag flannel data from 2015–2019, we calculated density of nymphal ticks (DON), an index of enzootic hazard, across the study region (southern Quebec). A Poisson regression model was used to explore the association between the enzootic hazard and LD risk (annual number of human cases) at the municipal level. Predictions from models were able to track both spatial and interannual variation in risk. Furthermore, a risk map produced by using model predictions closely matched the official risk map published by provincial public health authorities, which requires the use of complex criteria-based risk assessment. Our study shows that active sentinel surveillance in Quebec provides a sustainable system to follow spatiotemporal trends in LD risk. Such a network can support public health authorities in informing the public about LD risk within their region or municipality and this method could be extended to support Lyme disease risk assessment at the national level in Canada.
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The Utility of a Maximum Entropy Species Distribution Model for Ixodes scapularis in Predicting the Public Health Risk of Lyme Disease in Ontario, Canada. Ticks Tick Borne Dis 2022; 13:101969. [DOI: 10.1016/j.ttbdis.2022.101969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/05/2022] [Accepted: 05/20/2022] [Indexed: 11/22/2022]
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Slatculescu AM, Duguay C, Ogden NH, Sander B, Desjardins M, Cameron DW, Kulkarni MA. Spatiotemporal trends and socioecological factors associated with Lyme disease in eastern Ontario, Canada from 2010-2017. BMC Public Health 2022; 22:736. [PMID: 35418084 PMCID: PMC9006558 DOI: 10.1186/s12889-022-13167-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/31/2022] [Indexed: 11/12/2022] Open
Abstract
Currently, there is limited knowledge about socioeconomic, neighbourhood, and local ecological factors that contribute to the growing Lyme disease incidence in the province of Ontario, Canada. In this study, we sought to identify these factors that play an important role at the local scale, where people are encountering ticks in their communities. We used reported human Lyme disease case data and tick surveillance data submitted by the public from 2010–2017 to analyze trends in tick exposure, spatiotemporal clusters of infection using the spatial scan statistic and Local Moran’s I statistic, and socioecological risk factors for Lyme disease using a multivariable negative binomial regression model. Data were analyzed at the smallest geographic unit, consisting of 400–700 individuals, for which census data are disseminated in Canada. We found significant heterogeneity in tick exposure patterns based on location of residence, with 65.2% of Lyme disease patients from the city of Ottawa reporting tick exposures outside their health unit of residence, compared to 86.1%—98.1% of patients from other, largely rural, health units, reporting peri-domestic exposures. We detected eight spatiotemporal clusters of human Lyme disease incidence in eastern Ontario, overlapping with three clusters of Borrelia burgdorferi-infected ticks. When adjusting for population counts, Lyme disease case counts increased with larger numbers of Borrelia burgdorferi-infected ticks submitted by the public, higher proportion of treed landcover, lower neighbourhood walkability due to fewer intersections, dwellings, and points of interest, as well as with regions of higher residential instability and lower ethnic concentration (Relative Risk [RR] = 1.25, 1.02, 0.67–0.04, 1.34, and 0.57, respectively, p < .0001). Our study shows that there are regional differences in tick exposure patterns in eastern Ontario and that multiple socioecological factors contribute to Lyme disease risk in this region.
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Affiliation(s)
- Andreea M Slatculescu
- School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, 600 Peter Morand Crescent, Ottawa, ON, K1G 5Z3, Canada.
| | - Claudia Duguay
- School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, 600 Peter Morand Crescent, Ottawa, ON, K1G 5Z3, Canada
| | - Nicholas H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, QC, Canada
| | - Beate Sander
- Toronto Health Economics and Technology Assessment Collaborative, University Health Network, Toronto, ON, Canada.,Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada.,Public Health Ontario, Toronto, ON, Canada.,ICES, Toronto, ON, Canada
| | - Marc Desjardins
- Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, ON, Canada.,Division of Microbiology, Eastern Ontario Regional Laboratory Association, Ottawa, ON, Canada
| | - D William Cameron
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.,Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Manisha A Kulkarni
- School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, 600 Peter Morand Crescent, Ottawa, ON, K1G 5Z3, Canada
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Dyczko D, Kiewra D, Kolanek A, Błażej P. The influence of local environmental factors in southwestern Poland on the abundance of Ixodes ricinus and prevalence of infection with Borrelia burgdorferi s.l. and B. miyamotoi. Parasitol Res 2022; 121:1575-1585. [PMID: 35347426 DOI: 10.1007/s00436-022-07493-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 03/10/2022] [Indexed: 10/18/2022]
Abstract
Ticks are important ectoparasites and vectors of pathogens that cause disease in humans and animals. The natural habitat of Ixodes ricinus ticks is forests, which are convenient habitats to search for hosts, including reservoir hosts, and therefore can be an important habitat source of tick-borne pathogens. The aim of the study was to assess the usefulness of detailed forest habitat-type maps to estimate the tick-borne risk at a local scale (Lower Silesia, SW Poland). For the purposes of estimating tick abundance, we used the land cover maps available from the Forest Data Bank. For I. ricinus collection, nine sites located in three forest habitat types were chosen: broadleaf forest, mixed broadleaf and coniferous forest and coniferous forest. Ticks were collected once a month from April to June 2018 and 2019 using the standard flagging method. At each of the nine sites, ticks were collected in four plots, of 100 m2 each. Tick abundance was analysed using general linear mixed models (GLMM). A total of 2196 (10.1/100 m2) ticks were collected, including 2093 Ixodes ricinus (95.3%; 9.6/100 m2), 46 Dermacentor reticulatus (2.1%; 0.2/100 m2) and 57 Haemaphysalis concinna (2.6%; 0.3/100 m2). Among the collected I. ricinus were 589 larvae (28.1%; 2.7/100 m2), 1261 nymphs (60.3%; 5.8/100 m2), 128 females (6.1%; 0.6/100 m2) and 115 males (5.5%; 0.5/100 m2). We found a highly significant effect of forest habitat type on the density of ticks for broadleaf forest (coefficient = 1.87267, p-value = 2.79e - 07). Additionally, a significant influence of air temperature and relative humidity on the abundance of ticks was observed. During spring, the peak activity of I. ricinus was recorded in May and June. For DNA amplification of Borrelia burgdorferi s.l., a nested PCR method was used. Out of 494 I. ricinus, 83 (16.8%) were positive for Borrelia spp. The RFLP method showed the occurrence of five species including four belonging to the B. burgdorferi s.l. complex: B. afzelii (30.1%), B. garinii (38.6%), B. valaisiana (2.4%) and B. lusitaniae (18.1%). Furthermore, B. miyamotoi (9.6%), a species belonging to bacteria that cause relapsing fever as well as co-infection of B. miyamotoi/B.lusitaniae (1.2%) were found. The differences in the infection level of Borrelia spp. between broadleaf forest and mixed broadleaf and coniferous forest were statistically significant.
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Affiliation(s)
- Dagmara Dyczko
- Department of Microbial Ecology and Acaroentomology, Faculty of Biological Sciences, University of Wroclaw, Przybyszewskiego 63/77, 51-148, Wroclaw, Poland.
| | - Dorota Kiewra
- Department of Microbial Ecology and Acaroentomology, Faculty of Biological Sciences, University of Wroclaw, Przybyszewskiego 63/77, 51-148, Wroclaw, Poland
| | - Aleksandra Kolanek
- Department of Geoinformatics and Cartography, Institute of Geography and Regional Development, University of Wroclaw, pl. Uniwersytecki 1, 50-137, Wroclaw, Poland
| | - Paweł Błażej
- Department of Bioinformatics and Genomics, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
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Schulze TL, Jordan RA. Daily Variation in Sampled Densities of Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) Nymphs at a Single Site-Implications for Assessing Acarological Risk. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:741-751. [PMID: 34994380 DOI: 10.1093/jme/tjab213] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Indexed: 06/14/2023]
Abstract
The public health challenge posed by tick-borne disease (TBD) has increased efforts to characterize the spatial and temporal distribution of ticks and associated pathogens to better focus tick control strategies and personal protection measures. We describe variability in nymphal Ixodes scapularis Say and Amblyomma americanum (L.) density derived from daily drag sampling at a single location in New Jersey over 4 yr and explore how observed differences in daily collections might affect the estimation of acarological risk. We found significant variability in the density of host-seeking nymphs that could suggest substantially different rates of human-tick encounters depending on sampling date, habitat, and ambient weather conditions. The spatial and temporal variability in the distribution of 2 sympatric tick species with different host preferences and questing strategies, suggests that to produce results that are comparable among sites across the area sampled, surveillance efforts may be limited to shorter collection seasons, fewer sites or less sampling effort (fewer plots or fewer visits) per site, and a geographic scope that minimizes the potential temporal and spatial biases indicated here. Our results illustrate that evaluation of models of tick distribution or relative acarological risk based on surveillance data requires a full description of the diversity of habitats sampled and the conditions under which sampling is performed. The array of factors that affect tick host-seeking and that could bias interpretation of sampling results emphasizes the need to standardize sampling protocols and for more caution when interpreting tick sampling data collected over large temporal and spatial scales.
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Affiliation(s)
- Terry L Schulze
- Terry L. Schulze, Ph.D., Inc., 9 Evergreen Court, Perrineville, NJ, USA
| | - Robert A Jordan
- Monmouth County Mosquito Control Division, 1901 Wayside Road, Tinton Falls, NJ, USA
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31
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Foster E, Burtis J, Sidge JL, Tsao JI, Bjork J, Liu G, Neitzel DF, Lee X, Paskewitz S, Caporale D, Eisen RJ. Inter-annual variation in prevalence of Borrelia burgdorferi sensu stricto and Anaplasma phagocytophilum in host-seeking Ixodes scapularis (Acari: Ixodidae) at long-term surveillance sites in the upper midwestern United States: Implications for public health practice. Ticks Tick Borne Dis 2022; 13:101886. [PMID: 34929604 PMCID: PMC10621653 DOI: 10.1016/j.ttbdis.2021.101886] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/10/2021] [Accepted: 12/03/2021] [Indexed: 02/04/2023]
Abstract
The geographic range of the blacklegged tick, Ixodes scapularis, and its associated human pathogens have expanded substantially over the past 20 years putting an increasing number of persons at risk for tick-borne diseases, particularly in the upper midwestern and northeastern United States. Prevention and diagnosis of tick-borne diseases rely on an accurate understanding by the public and health care providers of when and where persons may be exposed to infected ticks. While tracking changes in the distribution of ticks and tick-borne pathogens provides fundamental information on risk for tick-borne diseases, metrics that incorporate prevalence of infection in ticks better characterize acarological risk. However, assessments of infection prevalence are more labor intensive and costly than simple measurements of tick or pathogen presence. Our objective was to examine whether data derived from repeated sampling at longitudinal sites substantially influences public health recommendations for Lyme disease and anaplasmosis prevention, or if more constrained sampling is sufficient. Here, we summarize inter-annual variability in prevalence of the agents of Lyme disease (Borrelia burgdorferi s.s.) and anaplasmosis (Anaplasma phagocytophilum) in host-seeking I. scapularis nymphs and adults at 28 longitudinal sampling sites in the Upper Midwestern US (Michigan, Minnesota, and Wisconsin). Infection prevalence was highly variable among sites and among years within sites. We conclude that monitoring infection prevalence in ticks aids in describing coarse acarological risk trends, but setting a fixed prevalence threshold for prevention or diagnostic decisions is not feasible given the observed variability and lack of temporal trends. Reducing repeated sampling of the same sites had minimal impact on regional (Upper Midwest) estimates of average infection prevalence; this information should be useful in allocating scarce public health resources for tick and tick-borne pathogen surveillance, prevention, and control activities.
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Affiliation(s)
- Erik Foster
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA.
| | - James Burtis
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
| | - Jennifer L Sidge
- Comparative Medicine and Integrative Biology, Michigan State University, East Lansing, MI 48824, USA; Michigan Department of Agriculture and Rural Development, Lansing, MI 48933, USA
| | - Jean I Tsao
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA
| | - Jenna Bjork
- Vectorborne Diseases Unit, Minnesota Department of Health, St. Paul, MN 55164, USA
| | - Gongping Liu
- Vectorborne Diseases Unit, Minnesota Department of Health, St. Paul, MN 55164, USA
| | - David F Neitzel
- Vectorborne Diseases Unit, Minnesota Department of Health, St. Paul, MN 55164, USA
| | - Xia Lee
- Department of Entomology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Susan Paskewitz
- Department of Entomology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Diane Caporale
- Department of Biology, University of Wisconsin-Stevens Point, Stevens Point, WI 54481, USA
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
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32
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Kopsco HL, Duhaime RJ, Mather TN. Crowdsourced Tick Image-Informed Updates to U.S. County Records of Three Medically Important Tick Species. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:2412-2424. [PMID: 33973636 DOI: 10.1093/jme/tjab082] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Burgeoning cases of tick-borne disease present a significant public health problem in the United States. Passive tick surveillance gained traction as an effective way to collect epidemiologic data, and in particular, photograph-based tick surveillance can complement in-hand tick specimen identification to amass distribution data and related encounter demographics. We compared the Federal Information Processing Standards (FIPS) code of tick photos submitted to a free public identification service (TickSpotters) from 2014 to 2019 to published nationwide county reports for three tick species of medical concern: Ixodes scapularis Say (Ixodida: Ixodidae), Ixodes pacificus Cooley and Kohls (Ixodida: Ixodidae), and Amblyomma americanum Linneaus (Ixodida: Ixodidae). We tallied the number of TickSpotters submissions for each tick species according to "Reported" or "Established" criteria per county, and found that TickSpotters submissions represented more than half of the reported counties of documented occurrence, and potentially identified hundreds of new counties with the occurrence of these species. We detected the largest number of new county reports of I. scapularis presence in Michigan, North Carolina, and Texas. Tick image submissions revealed potentially nine new counties of occurrence for I. pacificus, and we documented the largest increase in new county reports of A. americanum in Kentucky, Illinois, Indiana, and Ohio. These findings demonstrate the utility of crowdsourced photograph-based tick surveillance as a complement to other tick surveillance strategies in documenting tick distributions on a nationwide scale, its potential for identifying new foci, and its ability to highlight at-risk localities that might benefit from tick-bite prevention education.
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Affiliation(s)
- Heather L Kopsco
- Department of Plant Sciences and Entomology, University of Rhode Island, Kingston, RI, USA
- TickEncounter Resource Center, University of Rhode Island, Kingston, RI, USA
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Roland J Duhaime
- TickEncounter Resource Center, University of Rhode Island, Kingston, RI, USA
- Environmental Data Center, University of Rhode Island, Kingston, RI, USA
| | - Thomas N Mather
- Department of Plant Sciences and Entomology, University of Rhode Island, Kingston, RI, USA
- TickEncounter Resource Center, University of Rhode Island, Kingston, RI, USA
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Reptile Host Associations of Ixodes scapularis in Florida and Implications for Borrelia spp. Ecology. Pathogens 2021; 10:pathogens10080999. [PMID: 34451463 PMCID: PMC8400089 DOI: 10.3390/pathogens10080999] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 12/13/2022] Open
Abstract
Host associations of the tick vector for Lyme Borreliosis, Ixodes scapularis, differ across its geographic range. In Florida, the primary competent mammalian host of Lyme disease is not present but instead has other small mammals and herpetofauna that I. scapularis can utilize. We investigated host–tick association for lizards, the abundance of ticks on lizards and the prevalence of Borrelia burgdorferi sensu lato (sl). To determine which lizard species I. scapularis associates with, we examined 11 native lizard species from historical herpetological specimens. We found that (294/5828) of the specimens had attached ticks. The most infested species were Plestiodon skinks (241/1228) and Ophisaurus glass lizards (25/572). These species were then targeted at six field sites across Florida and sampled from June to September 2020, using drift fence arrays, cover boards and fishing. We captured 125 lizards and collected 233 immature I. scapularis. DNA was extracted from ticks and lizard tissue samples, followed by PCR testing for Borrelia spp. Of the captured lizards, 69/125 were infested with immature I. scapularis. We did not detect Borrelia spp. from tick or lizard tissue samples. Overall, we found that lizards are commonly infested with I. scapularis. However, we did not detect Borrelia burgdorferi sl. These findings add to a growing body of evidence that lizards are poor reservoir species.
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Hook SA, Nawrocki CC, Meek JI, Feldman KA, White JL, Connally NP, Hinckley AF. Human-tick encounters as a measure of tickborne disease risk in lyme disease endemic areas. Zoonoses Public Health 2021; 68:384-392. [PMID: 33554467 PMCID: PMC10883354 DOI: 10.1111/zph.12810] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/17/2020] [Accepted: 01/05/2021] [Indexed: 12/22/2022]
Abstract
Entomological measures have long served as proxies for human risk of Lyme disease (LD) and other tickborne diseases (TBDs) in endemic areas of the United States, despite conflicting results regarding the correlation between these measures and human disease outcomes. Using data from a previous TBD intervention study in Connecticut, Maryland and New York, we evaluated whether human-tick encounters can serve as an accurate proxy for risk of TBDs in areas where LD and other Ixodes scapularis-transmitted infections are common. Among 2,590 households consisting of 4,210 individuals, experiencing a tick encounter was associated with an increased risk of both self-reported (RR = 3.17, 95% CI: 2.05, 4.91) and verified TBD (RR = 2.60, 95% CI: 1.39, 4.84) at the household level. Household characteristics associated with experiencing any tick encounter were residence in Connecticut (aOR = 1.86, 95% CI: 1.38, 2.51) or New York (aOR = 1.66, 95% CI: 1.25, 2.22), head of household having a graduate level education (aOR = 1.46, 95% CI: 1.04, 2.08), owning a pet (aOR = 1.80, 95% CI: 1.46, 2.23) and a property size of 2 acres or larger (aOR = 2.30, 95% CI: 1.42, 3.70). Results for individual characteristics were similar to those for households. Future prevention studies in LD endemic areas should consider using human-tick encounters as a robust proxy for TBD risk.
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Affiliation(s)
- Sarah A Hook
- Division of Vector-borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | - Courtney C Nawrocki
- Division of Vector-borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | - James I Meek
- Yale Emerging Infections Program, New Haven, CT, USA
| | | | | | | | - Alison F Hinckley
- Division of Vector-borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
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Diuk-Wasser MA, VanAcker MC, Fernandez MP. Impact of Land Use Changes and Habitat Fragmentation on the Eco-epidemiology of Tick-Borne Diseases. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:1546-1564. [PMID: 33095859 DOI: 10.1093/jme/tjaa209] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Indexed: 06/11/2023]
Abstract
The incidence of tick-borne diseases has increased in recent decades and accounts for the majority of vector-borne disease cases in temperate areas of Europe, North America, and Asia. This emergence has been attributed to multiple and interactive drivers including changes in climate, land use, abundance of key hosts, and people's behaviors affecting the probability of human exposure to infected ticks. In this forum paper, we focus on how land use changes have shaped the eco-epidemiology of Ixodes scapularis-borne pathogens, in particular the Lyme disease spirochete Borrelia burgdorferi sensu stricto in the eastern United States. We use this as a model system, addressing other tick-borne disease systems as needed to illustrate patterns or processes. We first examine how land use interacts with abiotic conditions (microclimate) and biotic factors (e.g., host community composition) to influence the enzootic hazard, measured as the density of host-seeking I. scapularis nymphs infected with B. burgdorferi s.s. We then review the evidence of how specific landscape configuration, in particular forest fragmentation, influences the enzootic hazard and disease risk across spatial scales and urbanization levels. We emphasize the need for a dynamic understanding of landscapes based on tick and pathogen host movement and habitat use in relation to human resource provisioning. We propose a coupled natural-human systems framework for tick-borne diseases that accounts for the multiple interactions, nonlinearities and feedbacks in the system and conclude with a call for standardization of methodology and terminology to help integrate studies conducted at multiple scales.
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Affiliation(s)
- Maria A Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York
| | - Meredith C VanAcker
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York
| | - Maria P Fernandez
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York
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Eisen RJ, Paddock CD. Tick and Tickborne Pathogen Surveillance as a Public Health Tool in the United States. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:1490-1502. [PMID: 32440679 PMCID: PMC8905548 DOI: 10.1093/jme/tjaa087] [Citation(s) in RCA: 105] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Indexed: 05/03/2023]
Abstract
In recent decades, tickborne disease (TBD) cases and established populations of medically important ticks have been reported over expanding geographic areas, and an increasing number of tickborne bacteria, viruses, and protozoans have been recognized as human pathogens, collectively contributing to an increasing burden of TBDs in the United States. The prevention and diagnosis of TBDs depend greatly on an accurate understanding by the public and healthcare providers of when and where persons are at risk for exposure to human-biting ticks and to the pathogens these ticks transmit. However, national maps showing the distributions of medically important ticks and the presence or prevalence of tickborne pathogens are often incomplete, outdated, or lacking entirely. Similar deficiencies exist regarding geographic variability in host-seeking tick abundance. Efforts to accurately depict acarological risk are hampered by lack of systematic and routine surveillance for medically important ticks and their associated human pathogens. In this review, we: 1) outline the public health importance of tick surveillance; 2) identify gaps in knowledge regarding the distributions and abundance of medically important ticks in the United States and the presence and prevalence of their associated pathogens; 3) describe key objectives for tick surveillance and review methods appropriate for addressing those goals; and 4) assess current capacity and barriers to implementation and sustainability of tick surveillance programs.
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Affiliation(s)
- Rebecca J. Eisen
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO
| | - Christopher D. Paddock
- Rickettsial Zoonoses Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA
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37
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Development of a capture sequencing assay for enhanced detection and genotyping of tick-borne pathogens. Sci Rep 2021; 11:12384. [PMID: 34117323 PMCID: PMC8196166 DOI: 10.1038/s41598-021-91956-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/31/2021] [Indexed: 02/05/2023] Open
Abstract
Inadequate sensitivity has been the primary limitation for implementing high-throughput sequencing for studies of tick-borne agents. Here we describe the development of TBDCapSeq, a sequencing assay that uses hybridization capture probes that cover the complete genomes of the eleven most common tick-borne agents found in the United States. The probes are used for solution-based capture and enrichment of pathogen nucleic acid followed by high-throughput sequencing. We evaluated the performance of TBDCapSeq to surveil samples that included human whole blood, mouse tissues, and field-collected ticks. For Borrelia burgdorferi and Babesia microti, the sensitivity of TBDCapSeq was comparable and occasionally exceeded the performance of agent-specific quantitative PCR and resulted in 25 to > 10,000-fold increase in pathogen reads when compared to standard unbiased sequencing. TBDCapSeq also enabled genome analyses directly within vertebrate and tick hosts. The implementation of TBDCapSeq could have major impact in studies of tick-borne pathogens by improving detection and facilitating genomic research that was previously unachievable with standard sequencing approaches.
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Chandra S, Harvey E, Emery D, Holmes EC, Šlapeta J. Unbiased Characterization of the Microbiome and Virome of Questing Ticks. Front Microbiol 2021; 12:627327. [PMID: 34054743 PMCID: PMC8153229 DOI: 10.3389/fmicb.2021.627327] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 04/16/2021] [Indexed: 11/30/2022] Open
Abstract
Due to their vector capacity, ticks are ectoparasites of medical and veterinary significance. Modern sequencing tools have facilitated tick-associated microbiota studies, but these have largely focused on bacterial pathogens and symbionts. By combining 16S rRNA gene sequencing with total RNA-sequencing methods, we aimed to determine the complete microbiome and virome of questing, female Ixodes holocyclus recovered from coastal, north-eastern New South Wales (NSW), Australia. We present, for the first time, a robust and unbiased method for the identification of novel microbes in ticks that enabled us to identify bacteria, viruses, fungi and eukaryotic pathogens. The dominant bacterial endosymbionts were Candidatus Midichloria sp. Ixholo1 and Candidatus Midichloria sp. Ixholo2. Candidatus Neoehrlichia australis and Candidatus Neoehrlichia arcana were also recovered, confirming that these bacteria encompass I. holocyclus’ core microbiota. In addition, seven virus species were detected—four previously identified in I. holocyclus and three novel species. Notably, one of the four previously identified virus species has pathogenic potential based on its phylogenetic relationship to other tick-associated pathogens. No known pathogenic eukaryotes or fungi were identified. This study has revealed the microbiome and virome of female I. holocyclus from the environment in north-eastern NSW. We propose that future tick microbiome and virome studies utilize equivalent methods to provide an improved representation of the microbial diversity in ticks globally.
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Affiliation(s)
- Shona Chandra
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, NSW, Australia
| | - Erin Harvey
- Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Life and Environmental Sciences and School of Medical Sciences, The University of Sydney, Sydney, NSW, Australia
| | - David Emery
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, NSW, Australia
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Life and Environmental Sciences and School of Medical Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, NSW, Australia
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Ratti V, Winter JM, Wallace DI. Dilution and amplification effects in Lyme disease: Modeling the effects of reservoir-incompetent hosts on Borrelia burgdorferi sensu stricto transmission. Ticks Tick Borne Dis 2021; 12:101724. [PMID: 33878571 DOI: 10.1016/j.ttbdis.2021.101724] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 11/19/2022]
Abstract
The literature on Lyme disease includes a lively debate about the paradoxical role of changing deer populations. A decrease in the number of deer will both (1) reduce the incidence of Lyme disease by decreasing the host populations for ticks and therefore tick populations, and (2) enhance the incidence of Lyme disease by offering fewer reservoir-incompetent hosts for ticks, forcing the vector to choose reservoir-competent, and therefore possibly diseased, hosts to feed on. A review of field studies exploring the net impact of changing deer populations shows mixed results. In this manuscript, we investigate the hypothesis that the balance of these two responses to changing deer populations depends on the relative population sizes of reservoir-competent vs. reservoir-incompetent hosts and the presence of host preference in larval and adult stages. A temperature driven seasonal model of Borrelia burgdorferi sensu stricto (cause of Lyme disease) transmission among three host types (reservoir-competent infected and uninfected hosts, and reservoir-incompetent hosts) is constructed as a system of nonlinear ordinary differential equations. The model, which produces biologically reasonable results for both the tick vector Ixodes scapularis Say 1921 and the hosts, is used to investigate the effects of reservoir-incompetent host removal on both tick populations and disease prevalence for various relative population sizes of reservoir-competent hosts vs. reservoir-incompetent hosts. In summary, the simulation results show that the model with host preference appears to be more accurate than the one with no host preference. Given these results, we found that removal of adult I. scapularis(Say) hosts is likely to reduce questing nymph populations. At very low levels questing adult abundance may rise with lack of adult hosts. There is a dilution effect at low reservoir-competent host populations and there is an amplification effect at high reservoir-competent host populations.
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Affiliation(s)
- Vardayani Ratti
- Department of Mathematics and Statistics, California State University Chico, CA, United States.
| | - Jonathan M Winter
- Department of Geography, Dartmouth College, Hanover, NH, United States
| | - Dorothy I Wallace
- Department of Mathematics, Dartmouth College, Hanover, NH, United States
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Zhang L, Zhu X, Hou X, Li H, Yang X, Chen T, Fu X, Miao G, Hao Q, Li S. Prevalence and prediction of Lyme disease in Hainan province. PLoS Negl Trop Dis 2021; 15:e0009158. [PMID: 33735304 PMCID: PMC8009380 DOI: 10.1371/journal.pntd.0009158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/30/2021] [Accepted: 01/18/2021] [Indexed: 11/23/2022] Open
Abstract
Lyme disease (LD) is one of the most important vector-borne diseases worldwide. However, there is limited information on the prevalence and risk analysis using correlated factors in the tropical areas. A total of 1583 serum samples, collected from five hospitals of Hainan Province, were tested by immunofluorescence assay (IFA) and western blot (WB) analyses using anti-Borrelia burgdorferi antibodies. Then, we mapped the distribution of positive rate (by IFA) and the spread of confirmed Lyme patients (by WB). Using ArcGIS, we compiled host-vector-human interactions and correlated data as risk factor layers to predict LD risk in Hainan Province. There are three LD hotspots, designated hotspot I, which is located in central Hainan, hotspot II, which contains Sanya district, and hotspot III, which lies in the Haikou-Qiongshan area. The positive rate (16.67% by IFA) of LD in Qiongzhong, located in hotspot I, was higher than that in four other areas. Of confirmed cases of LD, 80.77% of patients (42/52) whose results had been confirmed by WB were in hotspots I and III. Hotspot II, with unknowed prevalence of LD, need to be paid more attention considering human-vector interaction. Wuzhi and Limu mountains might be the most important areas for the prevalence of LD, as the severe host-vector and human-vector interactions lead to a potential origin site for LD. Qiongzhong is the riskiest area and is located to the east of Wuzhi Mountain. In the Sanya and Haikou-Qiongshan area, intervening in the human-vector interaction would help control the prevalence of LD.
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Affiliation(s)
- Lin Zhang
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiong Zhu
- People’s Hospital of Sanya, Hainan province, China
| | - Xuexia Hou
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Huan Li
- People’s Hospital of Sanya, Hainan province, China
| | - Xiaona Yang
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ting Chen
- People’s Hospital of Sanya, Hainan province, China
| | - Xiaoying Fu
- People’s Hospital of Sanya, Hainan province, China
| | - Guangqing Miao
- Affiliated Hospital of Hangzhou Normal University, Hangzhou, China
| | - Qin Hao
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Sha Li
- People’s Hospital of Sanya, Hainan province, China
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Seasonal patterns and spatial variation of Borrelia burgdorferi (sensu lato) infections in Ixodes ricinus in the Netherlands. Parasit Vectors 2021; 14:121. [PMID: 33627166 PMCID: PMC7905678 DOI: 10.1186/s13071-021-04607-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/23/2021] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The incidence of Lyme borreliosis varies over time and space through as yet incompletely understood mechanisms. In Europe, Lyme borreliosis is caused by infection with a Borrelia burgdorferi (s.l.) genospecies, which is primarily transmitted by a bite of Ixodes ricinus nymphs. The aim of this study was to investigate the spatial and temporal variation in nymphal infection prevalence of B. burgdorferi (s.l.) (NIP), density of questing nymphs (DON) and the resulting density of infected nymphs (DIN). METHODS We investigated the infection rates in I. ricinus nymphs that were collected monthly between 2009 and 2016 in 12 locations in the Netherlands. Using generalized linear mixed models, we explored how the NIP, DON and DIN varied during the seasons, between years and between locations. We also determined the genospecies of the Borrelia infections and investigated whether the genospecies composition differed between locations. RESULTS The overall NIP was 14.7%. A seasonal pattern in infection prevalence was observed, with higher estimated prevalences in the summer than in the spring and autumn. This, combined with higher nymphal densities in summer, resulted in a pronounced summer peak in the estimated DIN. Over the 7.5-year study period, a significant decrease in infection prevalence was found, as well as a significant increase in nymphal density. These two effects appear to cancel each other out; the density of infected nymphs, which is the product of NIP × DON, showed no significant trend over years. Mean infection prevalence (NIP, averaged over all years and all months) varied considerably between locations, ranging from 5 to 26%. Borrelia genospecies composition differed between locations: in some locations almost all infections consisted of B. afzelii, whereas other locations had more diverse genospecies compositions. CONCLUSION In the Netherlands, the summer peak in DIN is a result of peaks in both NIP and DON. No significant trend in DIN was observed over the years of the study, and variations in DIN between locations were mostly a result of the variation in DON. There were considerable differences in acarological risk between areas in terms of infection prevalence and densities of ticks as well as in Borrelia genospecies composition.
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Winter JM, Partridge TF, Wallace D, Chipman JW, Ayres MP, Osterberg EC, Dekker ER. Modeling the Sensitivity of Blacklegged Ticks (Ixodes scapularis) to Temperature and Land Cover in the Northeastern United States. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:416-427. [PMID: 32901803 DOI: 10.1093/jme/tjaa179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Indexed: 06/11/2023]
Abstract
The prevalence of Lyme disease and other tick-borne diseases is dramatically increasing across the United States. While the rapid rise in Lyme disease is clear, the causes of it are not. Modeling Ixodes scapularis Say (Acari: Ixodidae), the primary Lyme disease vector in the eastern United States, presents an opportunity to disentangle the drivers of increasing Lyme disease, including climate, land cover, and host populations. We improved upon a recently developed compartment model of ordinary differential equations that simulates I. scapularis growth, abundance, and infection with Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) by adding land cover effects on host populations, refining the representation of growth stages, and evaluating output against observed data. We then applied this model to analyze the sensitivity of simulated I. scapularis dynamics across temperature and land cover in the northeastern United States. Specifically, we ran an ensemble of 232 simulations with temperature from Hanover, New Hampshire and Storrs, Connecticut, and land cover from Hanover and Cardigan in New Hampshire, and Windsor and Danielson in Connecticut. Consistent with observations, simulations of I. scapularis abundance are sensitive to temperature, with the warmer Storrs climate significantly increasing the number of questing I. scapularis at all growth stages. While there is some variation in modeled populations of I. scapularis infected with B. burgdorferi among land cover distributions, our analysis of I. scapularis response to land cover is limited by a lack of observations describing host populations, the proportion of hosts competent to serve as B. burgdorferi reservoirs, and I. scapularis abundance.
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Affiliation(s)
- Jonathan M Winter
- Department of Geography, Dartmouth College, Hanover, NH
- Department of Earth Sciences, Dartmouth College, Hanover, NH
| | | | | | - Jonathan W Chipman
- Department of Geography, Dartmouth College, Hanover, NH
- Department of Earth Sciences, Dartmouth College, Hanover, NH
| | - Matthew P Ayres
- Department of Biological Sciences, Dartmouth College, Hanover, NH
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Porter WT, Barrand ZA, Wachara J, DaVall K, Mihaljevic JR, Pearson T, Salkeld DJ, Nieto NC. Predicting the current and future distribution of the western black-legged tick, Ixodes pacificus, across the Western US using citizen science collections. PLoS One 2021; 16:e0244754. [PMID: 33400719 PMCID: PMC7785219 DOI: 10.1371/journal.pone.0244754] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 12/15/2020] [Indexed: 01/04/2023] Open
Abstract
In the twenty-first century, ticks and tick-borne diseases have expanded their ranges and impact across the US. With this spread, it has become vital to monitor vector and disease distributions, as these shifts have public health implications. Typically, tick-borne disease surveillance (e.g., Lyme disease) is passive and relies on case reports, while disease risk is calculated using active surveillance, where researchers collect ticks from the environment. Case reports provide the basis for estimating the number of cases; however, they provide minimal information on vector population or pathogen dynamics. Active surveillance monitors ticks and sylvatic pathogens at local scales, but it is resource-intensive. As a result, data are often sparse and aggregated across time and space to increase statistical power to model or identify range changes. Engaging public participation in surveillance efforts allows spatially and temporally diverse samples to be collected with minimal effort. These citizen-driven tick collections have the potential to provide a powerful tool for tracking vector and pathogen changes. We used MaxEnt species distribution models to predict the current and future distribution of Ixodes pacificus across the Western US through the use of a nationwide citizen science tick collection program. Here, we present niche models produced through citizen science tick collections over two years. Despite obvious limitations with citizen science collections, the models are consistent with previously-predicted species ranges in California that utilized more than thirty years of traditional surveillance data. Additionally, citizen science allows for an expanded understanding of I. pacificus distribution in Oregon and Washington. With the potential for rapid environmental changes instigated by a burgeoning human population and rapid climate change, the development of tools, concepts, and methodologies that provide rapid, current, and accurate assessment of important ecological qualities will be invaluable for monitoring and predicting disease across time and space.
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Affiliation(s)
- W. Tanner Porter
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States of America
- Translational Genomics Research Institute, Flagstaff, AZ, United States of America
- * E-mail:
| | - Zachary A. Barrand
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States of America
| | - Julie Wachara
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States of America
| | - Kaila DaVall
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States of America
| | - Joseph R. Mihaljevic
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, United States of America
| | - Talima Pearson
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, AZ, United States of America
| | - Daniel J. Salkeld
- Department of Biology, Colorado State University, Fort Collins, CO, United States of America
| | - Nathan C. Nieto
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States of America
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Gardner AM, Pawlikowski NC, Hamer SA, Hickling GJ, Miller JR, Schotthoefer AM, Tsao JI, Allan BF. Landscape features predict the current and forecast the future geographic spread of Lyme disease. Proc Biol Sci 2020; 287:20202278. [PMID: 33352074 PMCID: PMC7779494 DOI: 10.1098/rspb.2020.2278] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/27/2020] [Indexed: 01/02/2023] Open
Abstract
Lyme disease, the most prevalent vector-borne disease in North America, is increasing in incidence and geographic distribution as the tick vector, Ixodes scapularis, spreads to new regions. We re-construct the spatial-temporal invasion of the tick and human disease in the Midwestern US, a major focus of Lyme disease transmission, from 1967 to 2018, to analyse the influence of spatial factors on the geographic spread. A regression model indicates that three spatial factors-proximity to a previously invaded county, forest cover and adjacency to a river-collectively predict tick occurrence. Validation of the predictive capability of this model correctly predicts counties invaded or uninvaded with 90.6% and 98.5% accuracy, respectively. Reported incidence increases in counties after the first report of the tick; based on this modelled relationship, we identify 31 counties where we suspect I. scapularis already occurs yet remains undetected. Finally, we apply the model to forecast tick establishment by 2021 and predict 42 additional counties where I. scapularis will probably be detected based upon historical drivers of geographic spread. Our findings leverage resources dedicated to tick and human disease reporting and provide the opportunity to take proactive steps (e.g. educational efforts) to prevent and limit transmission in areas of future geographic spread.
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Affiliation(s)
- Allison M. Gardner
- School of Biology and Ecology, University of Maine, 5722 Deering Hall, Orono, ME 04469, USA
| | - Natalie C. Pawlikowski
- School of Integrative Biology, University of Illinois, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - Sarah A. Hamer
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA
| | - Graham J. Hickling
- The Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN 37966, USA
| | - James R. Miller
- Department of Natural Resources and Environmental Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL 61801, USA
| | | | - Jean I. Tsao
- Department of Fisheries and Wildlife and Department of Large Animal Clinical Sciences, Michigan State University, 480 Wilson Rd., East Lansing, MI 48824, USA
| | - Brian F. Allan
- School of Integrative Biology, University of Illinois, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
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Abstract
Lyme disease (Lyme borreliosis) is a tick-borne, zoonosis of adults and children caused by genospecies of the Borrelia burgdorferi sensu lato complex. The ailment, widespread throughout the Northern Hemisphere, continues to increase globally due to multiple environmental factors, coupled with increased incursion of humans into habitats that harbor the spirochete. B. burgdorferi sensu lato is transmitted by ticks from the Ixodes ricinus complex. In North America, B. burgdorferi causes nearly all infections; in Europe, B. afzelii and B. garinii are most associated with human disease. The spirochete's unusual fragmented genome encodes a plethora of differentially expressed outer surface lipoproteins that play a seminal role in the bacterium's ability to sustain itself within its enzootic cycle and cause disease when transmitted to its incidental human host. Tissue damage and symptomatology (i.e., clinical manifestations) result from the inflammatory response elicited by the bacterium and its constituents. The deposition of spirochetes into human dermal tissue generates a local inflammatory response that manifests as erythema migrans (EM), the hallmark skin lesion. If treated appropriately and early, the prognosis is excellent. However, in untreated patients, the disease may present with a wide range of clinical manifestations, most commonly involving the central nervous system, joints, or heart. A small percentage (~10%) of patients may go on to develop a poorly defined fibromyalgia-like illness, post-treatment Lyme disease (PTLD) unresponsive to prolonged antimicrobial therapy. Below we integrate current knowledge regarding the ecologic, epidemiologic, microbiologic, and immunologic facets of Lyme disease into a conceptual framework that sheds light on the disorder that healthcare providers encounter.
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Affiliation(s)
- Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, CT 06030, USA
- Department of Pediatrics, UConn Health, Farmington, CT 06030, USA
- Departments of Genetics and Genome Sciences, UConn Health, Farmington, CT 06030, USA
- Departments of Molecular Biology and Biophysics, UConn Health, Farmington, CT 06030, USA
- Department of Immunology, UConn Health, Farmington, CT 06030, USA
| | - Klemen Strle
- Division of Infectious Diseases, Wadsworth Center, NY Department of Health, Albany NY, 12208, USA
| | - Jacob E. Lemieux
- Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Franc Strle
- Department of Infectious Diseases, University Medical Center Ljubljana, Ljubljana, Slovenia
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Kopsco HL, Xu G, Luo CY, Rich SM, Mather TN. Crowdsourced Photographs as an Effective Method for Large-Scale Passive Tick Surveillance. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:1955-1963. [PMID: 32812635 DOI: 10.1093/jme/tjaa140] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Indexed: 06/11/2023]
Abstract
As tick vector ranges expand and the number of tickborne disease cases rise, physicians, veterinarians, and the public are faced with diagnostic, treatment, and prevention challenges. Traditional methods of active surveillance (e.g., flagging) can be time-consuming, spatially limited, and costly, while passive surveillance can broadly monitor tick distributions and infection rates. However, laboratory testing can require service fees in addition to mailing and processing time, which can put a tick-bite victim outside the window of potential prophylactic options or under unnecessary antibiotic administration. We performed a retrospective analysis of a national photograph-based crowdsourced tick surveillance system to determine the accuracy of identifying ticks by photograph when compared to those same ticks identified by microscopy and molecular methods at a tick testing laboratory. Ticks identified by photograph were correct to species with an overall accuracy of 96.7% (CI: 0.9522, 0.9781; P < 0.001), while identification accuracy for Ixodes scapularis Say (Ixodida: Ixodidae), Amblyomma americanum Linnaeus (Ixodida: Ixodidae), and Dermacentor variabilis Say (Ixodida: Ixodidae), three ticks of medical importance, was 98.2% (Cohen's kappa [κ] = 0.9575; 95% CI: 0.9698, 0.9897), 98.8% (κ = 0.9466, 95% CI: 0.9776, 0.9941), and 98.8% (κ = 0.9515, 95% CI: 0.9776, 0.9941), respectively. Fitted generalized linear models revealed that tick species and stage were the most significant predictive factors that contributed to correct photograph-based tick identifications. Neither engorgement, season, nor location of submission affected identification ability. These results provide strong support for the utility of photograph-based tick surveillance as a tool for risk assessment and monitoring among commonly encountered ticks of medical concern.
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Affiliation(s)
- Heather L Kopsco
- Department of Plant Sciences and Entomology, University of Rhode Island, Kingston, RI
- TickEncounter Resource Center, University of Rhode Island, Kingston, RI
| | - Guang Xu
- Department of Microbiology, University of Massachusetts, Amherst, MA
| | - Chu-Yuan Luo
- Department of Microbiology, University of Massachusetts, Amherst, MA
| | - Stephen M Rich
- Department of Microbiology, University of Massachusetts, Amherst, MA
| | - Thomas N Mather
- Department of Plant Sciences and Entomology, University of Rhode Island, Kingston, RI
- TickEncounter Resource Center, University of Rhode Island, Kingston, RI
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Salomon J, Hamer SA, Swei A. A Beginner's Guide to Collecting Questing Hard Ticks (Acari: Ixodidae): A Standardized Tick Dragging Protocol. JOURNAL OF INSECT SCIENCE (ONLINE) 2020; 20:11. [PMID: 33135760 PMCID: PMC7604844 DOI: 10.1093/jisesa/ieaa073] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Indexed: 05/22/2023]
Abstract
Tick-borne diseases are emerging globally, necessitating increased research and coordination of tick surveillance practices. The most widely used technique for active collection of host-seeking, human-biting tick vectors is 'tick dragging', by which a cloth is dragged across the top of the vegetation or forest floor and regularly checked for the presence of ticks. Use of variable dragging protocols limits the ability of researchers to combine data sets for comparative analyses or determine patterns and trends across different spatial and temporal scales. Standardization of tick drag collection and reporting methodology will greatly benefit the field of tick-pathogen studies. Based on the recommendations of the Center for Disease Control and Prevention and other ecological considerations, we propose that tick dragging should be conducted to sample at least 750 m2 along linear transects when habitat allows in a manner that reduces bias in the sampled area, and report density of each tick species and life stage separately. A protocol for constructing a standard drag cloth, establishing linear transects, and drag sampling is presented, along with a downloadable datasheet that can be modified to suit the needs of different projects. Efforts to align tick surveillance according to these standard best practices will help generate robust data on tick population biology.
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Affiliation(s)
- Jordan Salomon
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Sarah A Hamer
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Andrea Swei
- Department of Biology, San Francisco State University, San Francisco, CA
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Sentinel surveillance of Lyme disease risk in Canada, 2019: Results from the first year of the Canadian Lyme Sentinel Network (CaLSeN). ACTA ACUST UNITED AC 2020; 46:354-361. [PMID: 33315999 DOI: 10.14745/ccdr.v46i10a08] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Background Lyme disease is an emerging vector-borne zoonotic disease of increasing public health importance in Canada. As part of its mandate, the Canadian Lyme Disease Research Network (CLyDRN) launched a pan-Canadian sentinel surveillance initiative, the Canadian Lyme Sentinel Network (CaLSeN), in 2019. Objectives To create a standardized, national sentinel surveillance network providing a real-time portrait of the evolving environmental risk of Lyme disease in each province. Methods A multicriteria decision analysis (MCDA) approach was used in the selection of sentinel regions. Within each sentinel region, a systematic drag sampling protocol was performed in selected sampling sites. Ticks collected during these active surveillance visits were identified to species, and Ixodes spp. ticks were tested for infection with Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum, Babesia microti and Powassan virus. Results In 2019, a total of 567 Ixodes spp. ticks (I. scapularis [n=550]; I. pacificus [n=10]; and I. angustus [n=7]) were collected in seven provinces: British Columbia, Manitoba, Ontario, Québec, New Brunswick, Nova Scotia and Prince Edward Island. The highest mean tick densities (nymphs/100 m2) were found in sentinel regions of Lunenburg (0.45), Montréal (0.43) and Granby (0.38). Overall, the Borrelia burgdorferi prevalence in ticks was 25.2% (0%-45.0%). One I. angustus nymph from British Columbia was positive for Babesia microti, a first for the province. The deer tick lineage of Powassan virus was detected in one adult I. scapularis in Nova Scotia. Conclusion CaLSeN provides the first coordinated national active surveillance initiative for tick-borne disease in Canada. Through multidisciplinary collaborations between experts in each province, the pilot year was successful in establishing a baseline for Lyme disease risk across the country, allowing future trends to be detected and studied.
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Biotic Factors Influence Microbiota of Nymph Ticks from Vegetation in Sydney, Australia. Pathogens 2020; 9:pathogens9070566. [PMID: 32668699 PMCID: PMC7400589 DOI: 10.3390/pathogens9070566] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/08/2020] [Accepted: 07/10/2020] [Indexed: 01/17/2023] Open
Abstract
Ticks are haematophagous ectoparasites of medical and veterinary significance due to their excellent vector capacity. Modern sequencing techniques enabled the rapid sequencing of bacterial pathogens and symbionts. This study’s aims were two-fold; to determine the nymph diversity in Sydney, and to determine whether external biotic factors affect the microbiota. Tick DNA was isolated, and the molecular identity was determined for nymphs at the cox1 level. The tick DNA was subjected to high throughput DNA sequencing to determine the bacterial profile and the impact of biotic factors on the microbiota. Four nymph tick species were recovered from Sydney, NSW: Haemaphysalis bancrofti, Ixodes holocyclus, Ixodes trichosuri and Ixodes tasmani. Biotic factors, notably tick species and geography, were found to have a significance influence on the microbiota. The microbial analyses revealed that Sydney ticks display a core microbiota. The dominating endosymbionts among all tick species were Candidatus Midichloria sp. Ixholo1 and Candidatus Midichloria sp. Ixholo2. A novel Candidatus Midichloria sp. OTU_2090 was only found in I. holocyclus ticks (nymph: 96.3%, adult: 75.6%). Candidatus Neoehrlichia australis and Candidatus Neoehrlichia arcana was recovered from I. holocyclus and one I. trichosuri nymph ticks. Borrelia spp. was absent from all ticks. This study has shown that nymph and adult ticks carry different bacteria, and a tick bite in Sydney, Australia will result in different bacterial transfer depending on tick life stage, tick species and geography.
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Gaff H, Eisen RJ, Eisen L, Nadolny R, Bjork J, Monaghan AJ. LYMESIM 2.0: An Updated Simulation of Blacklegged Tick (Acari: Ixodidae) Population Dynamics and Enzootic Transmission of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae). JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:715-727. [PMID: 32002549 PMCID: PMC9376966 DOI: 10.1093/jme/tjz252] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Indexed: 05/24/2023]
Abstract
Lyme disease is the most commonly reported vector-borne disease in the United States, and the number of cases reported each year continues to rise. The complex nature of the relationships between the pathogen (Borrelia burgdorferi sensu stricto), the tick vector (Ixodes scapularis Say), multiple vertebrate hosts, and numerous environmental factors creates challenges for understanding and predicting tick population and pathogen transmission dynamics. LYMESIM is a mechanistic model developed in the late 1990s to simulate the life-history of I. scapularis and transmission dynamics of B. burgdorferi s.s. Here we present LYMESIM 2.0, a modernized version of LYMESIM, that includes several modifications to enhance the biological realism of the model and to generate outcomes that are more readily measured under field conditions. The model is tested for three geographically distinct locations in New York, Minnesota, and Virginia. Model-simulated timing and densities of questing nymphs, infected nymphs, and abundances of nymphs feeding on hosts are consistent with field observations and reports for these locations. Sensitivity analysis highlighted the importance of temperature in host finding for the density of nymphs, the importance of transmission from small mammals to ticks on the density of infected nymphs, and temperature-related tick survival for both density of nymphs and infected nymphs. A key challenge for accurate modeling of these metrics is the need for regionally representative inputs for host populations and their fluctuations. LYMESIM 2.0 is a useful public health tool that downstream can be used to evaluate tick control interventions and can be adapted for other ticks and pathogens.
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Affiliation(s)
- Holly Gaff
- Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529
- School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, South Africa
| | - Rebecca J. Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521
| | - Lars Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521
| | - Robyn Nadolny
- Army Public Health Center, Aberdeen Proving Ground, MD 21010
| | - Jenna Bjork
- Minnesota Department of Health, St. Paul, MN 55164
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