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Husar K, Pittman DC, Rajala J, Mostafa F, Allen LJS. Lyme Disease Models of Tick-Mouse Dynamics with Seasonal Variation in Births, Deaths, and Tick Feeding. Bull Math Biol 2024; 86:25. [PMID: 38294562 DOI: 10.1007/s11538-023-01248-y] [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: 05/10/2023] [Accepted: 12/19/2023] [Indexed: 02/01/2024]
Abstract
Lyme disease is the most common vector-borne disease in the United States impacting the Northeast and Midwest at the highest rates. Recently, it has become established in southeastern and south-central regions of Canada. In these regions, Lyme disease is caused by Borrelia burgdorferi, which is transmitted to humans by an infected Ixodes scapularis tick. Understanding the parasite-host interaction is critical as the white-footed mouse is one of the most competent reservoir for B. burgdorferi. The cycle of infection is driven by tick larvae feeding on infected mice that molt into infected nymphs and then transmit the disease to another susceptible host such as mice or humans. Lyme disease in humans is generally caused by the bite of an infected nymph. The main aim of this investigation is to study how diapause delays and demographic and seasonal variability in tick births, deaths, and feedings impact the infection dynamics of the tick-mouse cycle. We model tick-mouse dynamics with fixed diapause delays and more realistic Erlang distributed delays through delay and ordinary differential equations (ODEs). To account for demographic and seasonal variability, the ODEs are generalized to a continuous-time Markov chain (CTMC). The basic reproduction number and parameter sensitivity analysis are computed for the ODEs. The CTMC is used to investigate the probability of Lyme disease emergence when ticks and mice are introduced, a few of which are infected. The probability of disease emergence is highly dependent on the time and the infected species introduced. Infected mice introduced during the summer season result in the highest probability of disease emergence.
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Affiliation(s)
- Kateryna Husar
- Department of Statistical Science, Duke University, Durham, NC, 27705, USA.
| | - Dana C Pittman
- Department of Epidemiology and Biostatistics, Texas A &M University, College Station, TX, 77843, USA
| | - Johnny Rajala
- Department of Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - Fahad Mostafa
- Department of Mathematics and Statistics, Texas Tech University, Lubbock, TX, 79409, USA
| | - Linda J S Allen
- Department of Mathematics and Statistics, Texas Tech University, Lubbock, TX, 79409, USA
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2
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VanAcker MC, DeNicola VL, DeNicola AJ, Aucoin SG, Simon R, Toal KL, Diuk-Wasser MA, Cagnacci F. Resource selection by New York City deer reveals the effective interface between wildlife, zoonotic hazards and humans. Ecol Lett 2023; 26:2029-2042. [PMID: 37882483 DOI: 10.1111/ele.14326] [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: 10/25/2022] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 10/27/2023]
Abstract
Although the role of host movement in shaping infectious disease dynamics is widely acknowledged, methodological separation between animal movement and disease ecology has prevented researchers from leveraging empirical insights from movement data to advance landscape scale understanding of infectious disease risk. To address this knowledge gap, we examine how movement behaviour and resource utilization by white-tailed deer (Odocoileus virginianus) determines blacklegged tick (Ixodes scapularis) distribution, which depend on deer for dispersal in a highly fragmented New York City borough. Multi-scale hierarchical resource selection analysis and movement modelling provide insight into how deer's movements contribute to the risk landscape for human exposure to the Lyme disease vector-I. scapularis. We find deer select highly vegetated and accessible residential properties which support blacklegged tick survival. We conclude the distribution of tick-borne disease risk results from the individual resource selection by deer across spatial scales in response to habitat fragmentation and anthropogenic disturbances.
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Affiliation(s)
- Meredith C VanAcker
- Ecology, Evolution and Environmental Biology, Columbia University, New York, New York, USA
- Global Health Program, Smithsonian's National Zoo and Conservation Biology Institute, District of Columbia, Washington, USA
| | | | | | | | - Richard Simon
- City of New York Parks & Recreation, New York, New York, USA
| | - Katrina L Toal
- City of New York Parks & Recreation, New York, New York, USA
| | - Maria A Diuk-Wasser
- Ecology, Evolution and Environmental Biology, Columbia University, New York, New York, USA
| | - Francesca Cagnacci
- Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy
- National Biodiversity Future Centre, Palermo, Italy
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3
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Combs MA, Tufts DM, Adams B, Lin YP, Kolokotronis SO, Diuk-Wasser MA. Host adaptation drives genetic diversity in a vector-borne disease system. PNAS NEXUS 2023; 2:pgad234. [PMID: 37559749 PMCID: PMC10408703 DOI: 10.1093/pnasnexus/pgad234] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 05/18/2023] [Accepted: 07/07/2023] [Indexed: 08/11/2023]
Abstract
The range of hosts a pathogen can infect is a key trait, influencing human disease risk and reservoir host infection dynamics. Borrelia burgdorferi sensu stricto (Bb), an emerging zoonotic pathogen, causes Lyme disease and is widely considered a host generalist, commonly infecting mammals and birds. Yet the extent of intraspecific variation in Bb host breadth, its role in determining host competence, and potential implications for human infection remain unclear. We conducted a long-term study of Bb diversity, defined by the polymorphic ospC locus, across white-footed mice, passerine birds, and tick vectors, leveraging long-read amplicon sequencing. Our results reveal strong variation in host breadth across Bb genotypes, exposing a spectrum of genotype-specific host-adapted phenotypes. We found support for multiple niche polymorphism, maintaining Bb diversity in nature and little evidence of temporal shifts in genotype dominance, as would be expected under negative frequency-dependent selection. Passerine birds support the circulation of several human-invasive strains (HISs) in the local tick population and harbor greater Bb genotypic diversity compared with white-footed mice. Mouse-adapted Bb genotypes exhibited longer persistence in individual mice compared with nonadapted genotypes. Genotype communities infecting individual mice preferentially became dominated by mouse-adapted genotypes over time. We posit that intraspecific variation in Bb host breadth and adaptation helps maintain overall species fitness in response to transmission by a generalist vector.
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Affiliation(s)
- Matthew A Combs
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
- Department of Epidemiology and Biostatistics, School of Public Health, SUNY Downstate Health Sciences University, Brooklyn, NY 11203-2098, USA
- Institute for Genomics in Health, SUNY Downstate Health Sciences University, Brooklyn, NY 11203-2098, USA
| | - Danielle M Tufts
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
- Infectious Diseases and Microbiology Department, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Ben Adams
- Department of Mathematical Sciences, University of Bath, Bath, BA27AY, UK
| | - Yi-Pin Lin
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
- Department of Biomedical Sciences, University at Albany, Albany, NY 12203, USA
| | - Sergios-Orestis Kolokotronis
- Department of Epidemiology and Biostatistics, School of Public Health, SUNY Downstate Health Sciences University, Brooklyn, NY 11203-2098, USA
- Institute for Genomics in Health, SUNY Downstate Health Sciences University, Brooklyn, NY 11203-2098, USA
- Division of Infectious Diseases, Department of Medicine, College of Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY 11203-2098, USA
- Department of Cell Biology, College of Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY 11203-2098, USA
| | - Maria A Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
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4
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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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Tardy O, Acheson ES, Bouchard C, Chamberland É, Fortin A, Ogden NH, Leighton PA. Mechanistic movement models to predict geographic range expansions of ticks and tick-borne pathogens: Case studies with Ixodes scapularis and Amblyomma americanum in eastern North America. Ticks Tick Borne Dis 2023; 14:102161. [PMID: 36996508 DOI: 10.1016/j.ttbdis.2023.102161] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/30/2023]
Abstract
The geographic range of the blacklegged tick, Ixodes scapularis, is expanding northward from the United States into southern Canada, and studies suggest that the lone star tick, Amblyomma americanum, will follow suit. These tick species are vectors for many zoonotic pathogens, and their northward range expansion presents a serious threat to public health. Climate change (particularly increasing temperature) has been identified as an important driver permitting northward range expansion of blacklegged ticks, but the impacts of host movement, which is essential to tick dispersal into new climatically suitable regions, have received limited investigation. Here, a mechanistic movement model was applied to landscapes of eastern North America to explore 1) relationships between multiple ecological drivers and the speed of the northward invasion of blacklegged ticks infected with the causative agent of Lyme disease, Borrelia burgdorferi sensu stricto, and 2) its capacity to simulate the northward range expansion of infected blacklegged ticks and uninfected lone star ticks under theoretical scenarios of increasing temperature. Our results suggest that the attraction of migratory birds (long-distance tick dispersal hosts) to resource-rich areas during their spring migration and the mate-finding Allee effect in tick population dynamics are key drivers for the spread of infected blacklegged ticks. The modeled increases in temperature extended the climatically suitable areas of Canada for infected blacklegged ticks and uninfected lone star ticks towards higher latitudes by up to 31% and 1%, respectively, and with an average predicted speed of the range expansion reaching 61 km/year and 23 km/year, respectively. Differences in the projected spatial distribution patterns of these tick species were due to differences in climate envelopes of tick populations, as well as the availability and attractiveness of suitable habitats for migratory birds. Our results indicate that the northward invasion process of lone star ticks is primarily driven by local dispersal of resident terrestrial hosts, whereas that of blacklegged ticks is governed by long-distance migratory bird dispersal. The results also suggest that mechanistic movement models provide a powerful approach for predicting tick-borne disease risk patterns under complex scenarios of climate, socioeconomic and land use/land cover changes.
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6
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Yuan P, Tan Y, Yang L, Aruffo E, Ogden NH, Bélair J, Heffernan J, Arino J, Watmough J, Carabin H, Zhu H. Assessing transmission risks and control strategy for monkeypox as an emerging zoonosis in a metropolitan area. J Med Virol 2023; 95:e28137. [PMID: 36089815 DOI: 10.1002/jmv.28137] [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: 07/05/2022] [Revised: 08/11/2022] [Accepted: 08/26/2022] [Indexed: 01/11/2023]
Abstract
To model the spread of monkeypox (MPX) in a metropolitan area for assessing the risk of possible outbreaks, and identifying essential public health measures to contain the virus spread. The animal reservoir is the key element in the modeling of zoonotic disease. Using a One Health approach, we model the spread of the MPX virus in humans considering potential animal hosts such as rodents (e.g., rats, mice, squirrels, chipmunks, etc.) and emphasize their role and transmission of the virus in a high-risk group, including gay and bisexual men-who-have-sex-with-men (gbMSM). From model and sensitivity analysis, we identify key public health factors and present scenarios under different transmission assumptions. We find that the MPX virus may spill over from gbMSM high-risk groups to broader populations if the efficiency of transmission increases in the higher-risk group. However, the risk of outbreak can be greatly reduced if at least 65% of symptomatic cases can be isolated and their contacts traced and quarantined. In addition, infections in an animal reservoir will exacerbate MPX transmission risk in the human population. Regions or communities with a higher proportion of gbMSM individuals need greater public health attention. Tracing and quarantine (or "effective quarantine" by postexposure vaccination) of contacts with MPX cases in high-risk groups would have a significant effect on controlling the spreading. Also, monitoring for animal infections would be prudent.
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Affiliation(s)
- Pei Yuan
- Laboratory of Mathematical Parallel Systems (LAMPS), Department of Mathematics and Statistics, Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Centre for Diseases Modeling (CDM), York University, Toronto, Canada
| | - Yi Tan
- Laboratory of Mathematical Parallel Systems (LAMPS), Department of Mathematics and Statistics, Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Centre for Diseases Modeling (CDM), York University, Toronto, Canada
| | - Liu Yang
- Laboratory of Mathematical Parallel Systems (LAMPS), Department of Mathematics and Statistics, Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,School of Mathematics and Statistics, Northeast Normal University, Changchun, Jilin, China
| | - Elena Aruffo
- Laboratory of Mathematical Parallel Systems (LAMPS), Department of Mathematics and Statistics, Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Centre for Diseases Modeling (CDM), York University, Toronto, Canada
| | - Nicholas H Ogden
- Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Ottawa, Canada
| | - Jacques Bélair
- Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Département de Mathématiques et de Statistique, Université de Montréal, Montréal, Québec, Canada
| | - Jane Heffernan
- Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Department of Mathematics and Statistics, York University, Toronto, Canada
| | - Julien Arino
- Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Department of Mathematics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - James Watmough
- Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Department of Mathematics and Statistics, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Hélène Carabin
- Département de Pathologie et Microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.,Département de médecine sociale et préventive, École de santé publique de l'université de Montréal, Montréal, Québec, Canada.,Centre de Recherche en Santé Publique (CReSP), de l'université de Montréal et du CIUSS du Centre Sud de Montréal, Montréal, Québec, Canada.,Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Huaiping Zhu
- Laboratory of Mathematical Parallel Systems (LAMPS), Department of Mathematics and Statistics, Centre for Diseases Modeling (CDM), York University, Toronto, Canada.,Centre for Diseases Modeling (CDM), York University, Toronto, Canada
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7
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Morris CN, Gaff HD, Berghaus RD, Wilson CM, Gleim ER. Tick Species Composition, Collection Rates, and Phenology Provide Insights into Tick-Borne Disease Ecology in Virginia. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1993-2005. [PMID: 35996864 PMCID: PMC9667727 DOI: 10.1093/jme/tjac121] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Indexed: 06/12/2023]
Abstract
To better understand tick ecology in Virginia and the increasing Lyme disease incidence in western Virginia, a comparative phenological study was conducted in which monthly collections were performed at twelve sampling locations in southwestern Virginia (high Lyme disease incidence) and 18 equivalent sampling locations in southeastern Virginia (low Lyme disease incidence) for one year. In western Virginia, we also explored the effect of elevation on collection rates of Ixodes scapularis Say (Acari: Ixodidae) and Amblyomma americanum (L.) (Acari: Ixodidae). In total, 35,438 ticks were collected (33,106 A. americanum; 2,052 I. scapularis; 134 Ixodes affinis Neumann [Acari: Ixodidae]; 84 Dermacentor variabilis [Say] [Acari: Ixodidae]; 49 Dermacentor albipictus [Packard] [Acari: Ixodidae]; 10 Haemaphysalis leporispalustris [Packard] [Acari: Ixodidae]; 2 Ixodes brunneus Koch [Acari: Ixodidae]; 1 Haemaphysalis longicornis Neumann [Acari: Ixodidae]). Within southwestern Virginia, Ixodes scapularis collection rates were not influenced by elevation, unlike A. americanum which were collected more frequently at lower elevations (e.g., below 500 m). Notably, I. scapularis larvae and nymphs were commonly collected in southwestern Virginia (indicating that they were questing on or above the leaf litter) but not in southeastern Virginia. Questing on or above the leaf litter is primarily associated with northern populations of I. scapularis. These findings may support the hypothesis that I. scapularis from the northeastern United States are migrating into western Virginia and contributing to the higher incidence of Lyme disease in this region. This comparative phenological study underscores the value of these types of studies and the need for additional research to further understand the rapidly changing tick-borne disease dynamics in Virginia.
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Affiliation(s)
- Ciera N Morris
- Department of Biology, Hollins University, Roanoke, VA 24020, USA
| | - Holly D Gaff
- Department of Biological Sciences, Old Dominion University, Norfolk, VA 23508, USA
- University of KwaZulu-Natal, School of Mathematics, Statistics, and Computer Sciences, Durban, South Africa
| | - Roy D Berghaus
- Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - C Morgan Wilson
- Department of Biology, Hollins University, Roanoke, VA 24020, USA
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8
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A climate-based model for tick life cycle: positive semigroup theory on Cauchy problem approach. J Math Biol 2022; 84:52. [DOI: 10.1007/s00285-022-01755-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/10/2022] [Accepted: 04/03/2022] [Indexed: 10/18/2022]
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Ackleh AS, Veprauskas A. Modeling the invasion and establishment of a tick-borne pathogen. Ecol Modell 2022; 467. [PMID: 35663375 PMCID: PMC9161809 DOI: 10.1016/j.ecolmodel.2022.109915] [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] [Indexed: 12/03/2022]
Abstract
We develop a discrete-time tick–host–pathogen model to describe the spread of a disease in a hard-bodied tick species. This model incorporates the developmental stages for a tick, the dependence of the tick life-cycle and disease transmission on host availability, and three sources of pathogen transmission. We first establish the global dynamics of the disease-free system. We then apply the model to two pathogens, Borellia burgdorferi and Anaplasma phagocytophila, using Ixodes ricinus as the tick species to study properties of the invasion and establishment of a disease numerically. In particular, we consider the basic reproduction number, which determines whether a disease can invade the tick-host system, as well as disease prevalence and time to establishment in the case of successful disease invasion. Using Monte Carlo simulations, we calculate the means of each of these disease metrics and their elasticities with respect to various model parameters. We find that increased tick survival may help enable disease invasion, decrease the time to disease establishment, and increase disease prevalence once established. In contrast, though disease invasion is sensitive to tick-to-host transmission and tick searching efficiencies, neither disease prevalence nor time to disease establishment is sensitive to these parameters. These differences emphasize the importance of developing approaches, such as the one highlighted here, that can be used to study disease dynamics beyond just pathogen invasion, including transitional and long-term dynamics.
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10
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Occhibove F, Kenobi K, Swain M, Risley C. An eco-epidemiological modeling approach to investigate dilution effect in two different tick-borne pathosystems. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2550. [PMID: 35092122 PMCID: PMC9286340 DOI: 10.1002/eap.2550] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 10/20/2021] [Accepted: 10/27/2021] [Indexed: 05/05/2023]
Abstract
Disease (re)emergence appears to be driven by biodiversity decline and environmental change. As a result, it is increasingly important to study host-pathogen interactions within the context of their ecology and evolution. The dilution effect is the concept that higher biodiversity decreases pathogen transmission. It has been observed especially in zoonotic vector-borne pathosystems, yet evidence against it has been found. In particular, it is still debated how the community (dis)assembly assumptions and the degree of generalism of vectors and pathogens affect the direction of the biodiversity-pathogen transmission relationship. The aim of this study was to use empirical data and mechanistic models to investigate dilution mechanisms in two rodent-tick-pathogen systems differing in their vector degree of generalism. A community was assembled to include ecological interactions that expand from purely additive to purely substitutive. Such systems are excellent candidates to analyze the link between vector ecology, community (dis)assembly dynamics, and pathogen transmission. To base our mechanistic models on empirical data, rodent live-trapping, including tick sampling, was conducted in Wales across two seasons for three consecutive years. We have developed a deterministic single-vector, multi-host compartmental model that includes ecological relationships with non-host species, uniquely integrating theoretical and observational approaches. To describe pathogen transmission across a gradient of community diversity, the model was populated with parameters describing five different scenarios differing in ecological complexity; each based around one of the pathosystems: Ixodes ricinus (generalist tick)-Borrelia burgdorferi and I. trianguliceps (small mammals specialist tick)-Babesia microti. The results suggested that community composition and interspecific dynamics affected pathogen transmission with different dilution outcomes depending on the vector degree of generalism. The model provides evidence that dilution and amplification effects are not mutually exclusive in the same community but depend on vector ecology and the epidemiological output considered (i.e., the "risk" of interest). In our scenarios, more functionally diverse communities resulted in fewer infectious rodents, supporting the dilution effect. In the pathosystem with generalist vector we identified a hump shaped relationship between diversity and infections in hosts, while for that characterized by specialist tick, this relationship was more complex and more dependent upon specific parameter values.
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Affiliation(s)
- Flavia Occhibove
- IBERS, Aberystwyth UniversityAberystwythUK
- UK Centre for Ecology & HydrologyWallingfordUK
| | - Kim Kenobi
- Department of MathematicsAberystwyth UniversityAberystwythUK
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11
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Elias SP, Witham JW, Schneider EF, Rand PW, Hunter ML, Lubelczyk C, Smith RP. Emergence of Ixodes scapularis (Acari: Ixodidae) in a Small Mammal Population in a Coastal Oak-Pine Forest, Maine, USA. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:725-740. [PMID: 34958101 DOI: 10.1093/jme/tjab209] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Indexed: 06/14/2023]
Abstract
In the United States, surveillance has been key to tracking spatiotemporal emergence of blacklegged ticks [Ixodes scapularis Say (Ixodida:Ixodidae)] and their pathogens such as Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner (Spirochaetales: Spirochaetaceae), the agent of Lyme disease. On the Holt Research Forest in midcoastal Maine, collection of feeding ticks from live-trapped small mammal hosts allowed us to track the emergence and establishment of I. scapularis, 1989-2019. From 1989-1995, we collected only I. angustus Neumann (Ixodida: Ixodidae)(vole tick), Dermacentor variabilis Say (Ixodida: Ixodidae) (American dog tick), and I. marxi Banks (Ixodida: Ixodidae) (squirrel tick) from seven species of small mammals. The most abundant tick host was the white-footed mouse [Peromyscus leucopus Rafinesque (Rodentia:Cricetidae)] followed by the red-backed vole (Myodes gapperi Vigors (Rodentia: Cricetidae)). Emergence of I. scapularis was signaled via the appearance of subadult I. scapularis in 1996. Emergence of B. burgdorferi was signaled through its appearance in I. scapularis feeding on mice in 2005. There was a substantial increase in I. scapularis prevalence (proportion of hosts parasitized) and burdens (ticks/host) on white-footed mice and red-backed voles in 2007. The ~11-yr time-to-establishment for I. scapularis was consistent with that seen in other studies. White-footed mice comprised 65.9% of all captures and hosted 94.1% of the total I. scapularis burden. The white-footed mouse population fluctuated interannually, but did not trend up as did I. scapularis prevalence and burdens. There were concurrent declines in I. angustus and D. variabilis. We discuss these results in the broader context of regional I. scapularis range expansion.
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Affiliation(s)
- Susan P Elias
- Maine Medical Center Research Institute, Lyme & Vector-Borne Disease Laboratory, 81 Research Drive, Scarborough, ME 04074, USA
| | - Jack W Witham
- Center for Research on Sustainable Forests, University of Maine, 5755 Nutting Hall, Orono, ME 04469, USA
| | - Elizabeth F Schneider
- Maine Medical Center Research Institute, Lyme & Vector-Borne Disease Laboratory, 81 Research Drive, Scarborough, ME 04074, USA
| | - Peter W Rand
- Maine Medical Center Research Institute, Lyme & Vector-Borne Disease Laboratory, 81 Research Drive, Scarborough, ME 04074, USA
| | - Malcolm L Hunter
- Department of Wildlife, Fisheries, and Conservation Biology, University of Maine, 5755 Nutting Hall, Orono, ME 04469, USA
| | - Charles Lubelczyk
- Maine Medical Center Research Institute, Lyme & Vector-Borne Disease Laboratory, 81 Research Drive, Scarborough, ME 04074, USA
| | - Robert P Smith
- Maine Medical Center Research Institute, Lyme & Vector-Borne Disease Laboratory, 81 Research Drive, Scarborough, ME 04074, USA
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12
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Hromníková D, Furka D, Furka S, Santana JAD, Ravingerová T, Klöcklerová V, Žitňan D. Prevention of tick-borne diseases: challenge to recent medicine. Biologia (Bratisl) 2022; 77:1533-1554. [PMID: 35283489 PMCID: PMC8905283 DOI: 10.1007/s11756-021-00966-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 11/10/2021] [Indexed: 12/14/2022]
Abstract
Abstract Ticks represent important vectors and reservoirs of pathogens, causing a number of diseases in humans and animals, and significant damage to livestock every year. Modern research into protection against ticks and tick-borne diseases focuses mainly on the feeding stage, i.e. the period when ticks take their blood meal from their hosts during which pathogens are transmitted. Physiological functions in ticks, such as food intake, saliva production, reproduction, development, and others are under control of neuropeptides and peptide hormones which may be involved in pathogen transmission that cause Lyme borreliosis or tick-borne encephalitis. According to current knowledge, ticks are not reservoirs or vectors for the spread of COVID-19 disease. The search for new vaccination methods to protect against ticks and their transmissible pathogens is a challenge for current science in view of global changes, including the increasing migration of the human population. Highlights • Tick-borne diseases have an increasing incidence due to climate change and increased human migration • To date, there is no evidence of transmission of coronavirus COVID-19 by tick as a vector • To date, there are only a few modern, effective, and actively- used vaccines against ticks or tick-borne diseases • Neuropeptides and their receptors expressed in ticks may be potentially used for vaccine design
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Affiliation(s)
- Dominika Hromníková
- Department of Molecular Physiology, Slovak Academy of Sciences, Institute of Zoology, Dúbravská cesta 9, 84506 Bratislava, Slovakia
| | - Daniel Furka
- Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Comenius University, Mlynská dolina, Ilkovičova 6, 84104 Bratislava, SK Slovakia
- Department of Cardiovascular Physiology and Pathophysiology, Slovak Academy of Sciences, Institute of Heart Research, Dúbravská cesta 9, SK 84005 Bratislava, Slovakia
| | - Samuel Furka
- Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Comenius University, Mlynská dolina, Ilkovičova 6, 84104 Bratislava, SK Slovakia
- Department of Cardiovascular Physiology and Pathophysiology, Slovak Academy of Sciences, Institute of Heart Research, Dúbravská cesta 9, SK 84005 Bratislava, Slovakia
| | - Julio Ariel Dueñas Santana
- Chemical Engineering Department, University of Matanzas, Km 3 Carretera a Varadero, 44740 Matanzas, CU Cuba
| | - Táňa Ravingerová
- Department of Cardiovascular Physiology and Pathophysiology, Slovak Academy of Sciences, Institute of Heart Research, Dúbravská cesta 9, SK 84005 Bratislava, Slovakia
| | - Vanda Klöcklerová
- Department of Molecular Physiology, Slovak Academy of Sciences, Institute of Zoology, Dúbravská cesta 9, 84506 Bratislava, Slovakia
| | - Dušan Žitňan
- Department of Molecular Physiology, Slovak Academy of Sciences, Institute of Zoology, Dúbravská cesta 9, 84506 Bratislava, Slovakia
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13
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Zinck CB, Lloyd VK. Borrelia burgdorferi and Borrelia miyamotoi in Atlantic Canadian wildlife. PLoS One 2022; 17:e0262229. [PMID: 35061805 PMCID: PMC8782396 DOI: 10.1371/journal.pone.0262229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/20/2021] [Indexed: 11/23/2022] Open
Abstract
Borrelia burgdorferi and Borrelia miyamotoi are tick-vectored zoonotic pathogens maintained in wildlife species. Tick populations are establishing in new areas globally in response to climate change and other factors. New Brunswick is a Canadian maritime province at the advancing front of tick population establishment and has seen increasing numbers of ticks carrying B. burgdorferi, and more recently B. miyamotoi. Further, it is part of a region of Atlantic Canada with wildlife species composition differing from much of continental North America and little information exists as to the presence and frequency of infection of Borrelia spp. in wildlife in this region. We used a citizen science approach to collect a wide range of animals including migratory birds, medium-sized mammals, and small mammals. In total we tested 339 animals representing 20 species for the presence of B. burgdorferi and B. miyamotoi. We have developed new nested PCR primers and a protocol with excellent specificity for detecting both of these Borrelia species, both single and double infections, in tissues and organs of various wildlife species. The positive animals were primarily small non-migratory mammals, approximately twice as many were infected with B. burgdorferi than B. miyamotoi and one animal was found infected with both. In addition to established reservoir species, the jumping mouse (Napaeozapus insignis) was found frequently infected; this species had the highest infection prevalence for both B. burgdorferi and B. miyamotoi and has not previously been identified as an important carrier for either Borrelia species. Comprehensive testing of tissues found that all instances of B. burgdorferi infection were limited to one tissue within the host, whereas two of the five B. miyamotoi infections were diffuse and found in multiple systems. In the one coinfected specimen, two fetuses were also recovered and found infected with B. miyamotoi. This presumptive transplacental transmission suggests that vertical transmission in mammals is possible. This finding implies that B. miyamotoi could rapidly spread into wildlife populations, as well as having potential human health implications.
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Affiliation(s)
- Christopher B. Zinck
- Western College of Veterinary Medicine, University of Saskatchewan, Saskatchewan, Canada
| | - Vett K. Lloyd
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada
- * E-mail:
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14
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Tsao JI, Hamer SA, Han S, Sidge JL, Hickling GJ. The Contribution of Wildlife Hosts to the Rise of Ticks and Tick-Borne Diseases in North America. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:1565-1587. [PMID: 33885784 DOI: 10.1093/jme/tjab047] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Indexed: 05/09/2023]
Abstract
Wildlife vertebrate hosts are integral to enzootic cycles of tick-borne pathogens, and in some cases have played key roles in the recent rise of ticks and tick-borne diseases in North America. In this forum article, we highlight roles that wildlife hosts play in the maintenance and transmission of zoonotic, companion animal, livestock, and wildlife tick-borne pathogens. We begin by illustrating how wildlife contribute directly and indirectly to the increase and geographic expansion of ticks and their associated pathogens. Wildlife provide blood meals for tick growth and reproduction; serve as pathogen reservoirs; and can disperse ticks and pathogens-either through natural movement (e.g., avian migration) or through human-facilitated movement (e.g., wildlife translocations and trade). We then discuss opportunities to manage tick-borne disease through actions directed at wildlife hosts. To conclude, we highlight key gaps in our understanding of the ecology of tick-host interactions, emphasizing that wildlife host communities are themselves a very dynamic component of tick-pathogen-host systems and therefore complicate management of tick-borne diseases, and should be taken into account when considering host-targeted approaches. Effective management of wildlife to reduce tick-borne disease risk further requires consideration of the 'human dimensions' of wildlife management. This includes understanding the public's diverse views and values about wildlife and wildlife impacts-including the perceived role of wildlife in fostering tick-borne diseases. Public health agencies should capitalize on the expertise of wildlife agencies when developing strategies to reduce tick-borne disease risks.
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Affiliation(s)
- Jean I Tsao
- Department of Fisheries and Wildlife, Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA
| | - Sarah A Hamer
- Department of Veterinary Integrative Biosciences, and Schubot Center for Avian Health, Department of Veterinary Pathology, Texas A&M University, College Station, TX, USA
| | - Seungeun Han
- Department of Disease Control and Epidemiology, National Veterinary Institute (SVA), Uppsala, Sweden
| | - Jennifer L Sidge
- Michigan Department of Agriculture and Rural Development, Lansing, MI, USA
| | - Graham J Hickling
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, TN, USA
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15
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Infection with Borrelia afzelii and manipulation of the egg surface microbiota have no effect on the fitness of immature Ixodes ricinus ticks. Sci Rep 2021; 11:10686. [PMID: 34021230 PMCID: PMC8140075 DOI: 10.1038/s41598-021-90177-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 04/29/2021] [Indexed: 12/20/2022] Open
Abstract
Arthropod vectors carry vector-borne pathogens that cause infectious disease in vertebrate hosts, and arthropod-associated microbiota, which consists of non-pathogenic microorganisms. Vector-borne pathogens and the microbiota can both influence the fitness of their arthropod vectors, and hence the epidemiology of vector-borne diseases. The bacterium Borrelia afzelii, which causes Lyme borreliosis in Europe, is transmitted among vertebrate reservoir hosts by Ixodes ricinus ticks, which also harbour a diverse microbiota of non-pathogenic bacteria. The purpose of this controlled study was to test whether B. afzelii and the tick-associated microbiota influence the fitness of I. ricinus. Eggs obtained from field-collected adult female ticks were surface sterilized (with bleach and ethanol), which reduced the abundance of the bacterial microbiota in the hatched I. ricinus larvae by 28-fold compared to larvae that hatched from control eggs washed with water. The dysbiosed and control larvae were subsequently fed on B. afzelii-infected or uninfected control mice, and the engorged larvae were left to moult into nymphs under laboratory conditions. I. ricinus larvae that fed on B. afzelii-infected mice had a significantly faster larva-to-nymph moulting time compared to larvae that fed on uninfected control mice, but the effect was small (2.4% reduction) and unlikely to be biologically significant. We found no evidence that B. afzelii infection or reduction of the larval microbiota influenced the four other life history traits of the immature I. ricinus ticks, which included engorged larval weight, unfed nymphal weight, larva-to-nymph moulting success, and immature tick survival. A retrospective power analysis found that our sampling effort had sufficient power (> 80%) to detect small effects (differences of 5% to 10%) of our treatments. Under the environmental conditions of this study, we conclude that B. afzelii and the egg surface microbiota had no meaningful effects on tick fitness and hence on the R0 of Lyme borreliosis.
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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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17
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Burrows H, Talbot B, McKay R, Slatculescu A, Logan J, Thickstun C, Lindsay LR, Dibernardo A, Koffi JK, Ogden NH, Kulkarni MA. A multi-year assessment of blacklegged tick (Ixodes scapularis) population establishment and Lyme disease risk areas in Ottawa, Canada, 2017-2019. PLoS One 2021; 16:e0246484. [PMID: 33539458 PMCID: PMC7861446 DOI: 10.1371/journal.pone.0246484] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 01/19/2021] [Indexed: 11/20/2022] Open
Abstract
Canadians face an emerging threat of Lyme disease due to the northward expansion of the tick vector, Ixodes scapularis. We evaluated the degree of I. scapularis population establishment and Borrelia burgdorferi occurrence in the city of Ottawa, Ontario, Canada from 2017–2019 using active surveillance at 28 sites. We used a field indicator tool developed by Clow et al. to determine the risk of I. scapularis establishment for each tick cohort at each site using the results of drag sampling. Based on results obtained with the field indicator tool, we assigned each site an ecological classification describing the pattern of tick colonization over two successive cohorts (cohort 1 was comprised of ticks collected in fall 2017 and spring 2018, and cohort 2 was collected in fall 2018 and spring 2019). Total annual site-specific I. scapularis density ranged from 0 to 16.3 ticks per person-hour. Sites with the highest density were located within the Greenbelt zone, in the suburban/rural areas in the western portion of the city of Ottawa, and along the Ottawa River; the lowest densities occurred at sites in the suburban/urban core. B. burgdorferi infection rates exhibited a similar spatial distribution pattern. Of the 23 sites for which data for two tick cohorts were available, 11 sites were classified as “high-stable”, 4 were classified as “emerging”, 2 were classified as “low-stable”, and 6 were classified as “non-zero”. B. burgdorferi-infected ticks were found at all high-stable sites, and at one emerging site. These findings suggest that high-stable sites pose a risk of Lyme disease exposure to the community as they have reproducing tick populations with consistent levels of B. burgdorferi infection. Continued surveillance for I. scapularis, B. burgdorferi, and range expansion of other tick species and emerging tick-borne pathogens is important to identify areas posing a high risk for human exposure to tick-borne pathogens in the face of ongoing climate change and urban expansion.
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Affiliation(s)
- Holly Burrows
- Yale School of Public Health, Yale University, New Haven, Connecticut, United States of America
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
| | - Benoit Talbot
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
| | - Roman McKay
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
| | - Andreea Slatculescu
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
| | - James Logan
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
| | - Charles Thickstun
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
| | - L. Robbin Lindsay
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Antonia Dibernardo
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Jules K. Koffi
- Centre for Foodborne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - Nicholas H. Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - Manisha A. Kulkarni
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
- * E-mail:
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18
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Almazán C, Šimo L, Fourniol L, Rakotobe S, Borneres J, Cote M, Peltier S, Mayé J, Versillé N, Richardson J, Bonnet SI. Multiple Antigenic Peptide-Based Vaccines Targeting Ixodes ricinus Neuropeptides Induce a Specific Antibody Response but Do Not Impact Tick Infestation. Pathogens 2020; 9:pathogens9110900. [PMID: 33126686 PMCID: PMC7693490 DOI: 10.3390/pathogens9110900] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/22/2020] [Accepted: 10/27/2020] [Indexed: 02/06/2023] Open
Abstract
Synthetic peptide vaccines were designed to target the neuropeptides innervating Ixodes ricinus salivary glands and hindgut and they were tested for their capacity to afford protective immunity against nymphs or larvae and Anaplasma phagocytophilum-infected nymph infestation, in mice and sheep, respectively. In both models, the assembly of SIFamide (SIFa) or myoinhibitory peptide (MIP) neuropeptides into multiple antigenic peptide constructs (MAPs) elicited a robust IgG antibody response following immunization. Nevertheless, no observable detrimental impact on nymphs was evidenced in mice, and, unfortunately, the number of engorged nymphs on sheep was insufficient for firm conclusions to be drawn, including for bacterial transmission. Regarding larvae, while vaccination of the sheep did not globally diminish tick feeding success or development, analyses of animals at the individual level revealed a negative correlation between anti-SIFa and MIP antibody levels and larva-to-nymph molting success for both antigens. Our results provide a proof of principle and precedent for the use of MAPs for the induction of immunity against tick peptide molecules. Although the present study did not provide the expected level of protection, it inaugurates a new strategy for protection against ticks based on the immunological targeting of key components of their nervous system.
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Affiliation(s)
- Consuelo Almazán
- UMR BIPAR 0956, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France; (C.A.); (L.Š.); (L.F.); (S.R.); (M.C.)
| | - Ladislav Šimo
- UMR BIPAR 0956, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France; (C.A.); (L.Š.); (L.F.); (S.R.); (M.C.)
| | - Lisa Fourniol
- UMR BIPAR 0956, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France; (C.A.); (L.Š.); (L.F.); (S.R.); (M.C.)
| | - Sabine Rakotobe
- UMR BIPAR 0956, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France; (C.A.); (L.Š.); (L.F.); (S.R.); (M.C.)
| | - Jérémie Borneres
- SEPPIC Paris La Défense, 92250 La Garenne Colombes, France; (J.B.); (S.P.); (J.M.); (N.V.)
| | - Martine Cote
- UMR BIPAR 0956, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France; (C.A.); (L.Š.); (L.F.); (S.R.); (M.C.)
| | - Sandy Peltier
- SEPPIC Paris La Défense, 92250 La Garenne Colombes, France; (J.B.); (S.P.); (J.M.); (N.V.)
| | - Jennifer Mayé
- SEPPIC Paris La Défense, 92250 La Garenne Colombes, France; (J.B.); (S.P.); (J.M.); (N.V.)
| | - Nicolas Versillé
- SEPPIC Paris La Défense, 92250 La Garenne Colombes, France; (J.B.); (S.P.); (J.M.); (N.V.)
| | - Jennifer Richardson
- UMR Virologie 1161, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France;
| | - Sarah I. Bonnet
- UMR BIPAR 0956, INRAE, National Veterinary School of Alfort, ANSES, Paris-Est University, 94700 Maisons-Alfort, France; (C.A.); (L.Š.); (L.F.); (S.R.); (M.C.)
- Correspondence:
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19
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Han S, Hickling GJ, Ogden NH, Ginsberg HS, Kobbekaduwa V, Rulison EL, Beati L, Tsao JI. Seasonality of acarological risk of exposure to Borrelia miyamotoi from questing life stages of Ixodes scapularis collected from Wisconsin and Massachusetts, USA. Ticks Tick Borne Dis 2020; 12:101556. [PMID: 33035757 DOI: 10.1016/j.ttbdis.2020.101556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 08/29/2020] [Accepted: 08/31/2020] [Indexed: 11/28/2022]
Abstract
Measures of acarological risk of exposure to Ixodes scapularis-borne disease agents typically focus on nymphs; however, the relapsing fever group spirochete Borrelia miyamotoi can be passed transovarially, and I. scapularis larvae are capable of transmitting B. miyamotoi to their hosts. To quantify the larval contribution to acarological risk, relative to nymphs and adults, we collected questing I. scapularis for 3 yr at Fort McCoy, Wisconsin (WI, n = 23,367 ticks), and Cape Cod, Massachusetts (MA, n = 4190) in the United States. Borrelia miyamotoi infection prevalence was estimated for I. scapularis larvae, nymphs, females, and males, respectively, as 0.88, 2.05, 0.63, and 1.22 % from the WI site and 0.33, 2.32, 2.83, and 2.11 % from the MA site. Densities of B. miyamotoi-infected ticks (DIT, per 1000 m2) were estimated for larvae, nymphs, females, and males, respectively, as 0.36, 0.14, 0.01, and 0.03 from the WI site and 0.05, 0.06, 0.03, and 0.02 from the MA site. Thus, although larval infection prevalence with B. miyamotoi was significantly lower than that of nymphs and similar to that of adults, because of their higher abundance, the larval contribution to the overall DIT was similar to that of nymphs and trended towards a greater contribution than adults. Assuming homogenous contact rates with humans, these results suggest that eco-epidemiological investigations of B. miyamotoi disease in North America should include larvae. A fuller appreciation of the epidemiological implications of these results, therefore, requires an examination of the heterogeneity in contact rates with humans among life stages.
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Affiliation(s)
- Seungeun Han
- Comparative Medicine and Integrative Biology program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, United States.
| | - Graham J Hickling
- Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN 37996, United States.
| | - Nicholas H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC J2S 2M2, Canada.
| | - Howard S Ginsberg
- U.S. Geological Survey, Patuxent Wildlife Research Center, Kingston, RI 02881, United States.
| | - Vishvapali Kobbekaduwa
- Comparative Medicine and Integrative Biology program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, United States.
| | - Eric L Rulison
- California Department of Transportation, Redding, CA 96001, United States.
| | - Lorenza Beati
- Department of Biology, Georgia Southern University, Statesboro, GA 30460, United States.
| | - Jean I Tsao
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, 48824, United States; Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI, 48824, United States.
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20
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Cost analysis of vaccination in tick-mouse transmission of Lyme disease. J Theor Biol 2020; 494:110245. [DOI: 10.1016/j.jtbi.2020.110245] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 03/08/2020] [Accepted: 03/10/2020] [Indexed: 11/22/2022]
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21
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Elias SP, Maasch KA, Anderson NT, Rand PW, Lacombe EH, Robich RM, Lubelczyk CB, Smith RP. Decoupling of Blacklegged Tick Abundance and Lyme Disease Incidence in Southern Maine, USA. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:755-765. [PMID: 31808817 DOI: 10.1093/jme/tjz218] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Indexed: 06/10/2023]
Abstract
Lyme disease is caused by the bacterial spirochete Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt, and Brenner (Spirocheatales: Spirochaetaceae) which is transmitted through the bite of an infected blacklegged tick Ixodes scapularis Say (Ixodida: Ixodidae). Maine, USA, is a high Lyme disease incidence state, with rising incidence of Lyme disease and other tick-borne illnesses associated with increasing I. scapularis abundance and northward range expansion. Members of the public submitted ticks to a tick identification program (1990-2013). From these passive surveillance data, we characterized temporal trends in I. scapularis submission rate (an index of abundance), comparing Maine's northern tier (seven counties) versus southern tier (nine counties). In the northern tier, the I. scapularis submission rate increased throughout the duration of the time series, suggesting I. scapularis was emergent but not established. By contrast, in the southern tier, submission rate increased initially but leveled off after 10-14 yr, suggesting I. scapularis was established by the mid-2000s. Active (field) surveillance data from a site in the southern tier-bird tick burdens and questing adult tick collections-corroborated this leveling pattern. Lyme disease incidence and I. scapularis submission rate were temporally correlated in the northern but not southern tier. This suggested a decoupling of reported disease incidence and entomological risk.
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Affiliation(s)
- Susan P Elias
- Maine Medical Center Research Institute, Vector-borne Disease Research Laboratory, Scarborough, Maine
| | - Kirk A Maasch
- School of Earth and Climate Sciences, University of Maine, Orono, Maine
| | | | - Peter W Rand
- Maine Medical Center Research Institute, Vector-borne Disease Research Laboratory, Scarborough, Maine
| | - Eleanor H Lacombe
- Maine Medical Center Research Institute, Vector-borne Disease Research Laboratory, Scarborough, Maine
| | - Rebecca M Robich
- Maine Medical Center Research Institute, Vector-borne Disease Research Laboratory, Scarborough, Maine
| | - Charles B Lubelczyk
- Maine Medical Center Research Institute, Vector-borne Disease Research Laboratory, Scarborough, Maine
| | - Robert P Smith
- Maine Medical Center Research Institute, Vector-borne Disease Research Laboratory, Scarborough, Maine
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22
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Zikeli S, Zohdy S. Why Research on Lyme Disease and Ixodes scapularis Needs Wildlife Ecology without Taxonomic Bias: A Review. SOUTHEAST NAT 2020. [DOI: 10.1656/058.019.0101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Shelby Zikeli
- Auburn University School of Forestry and Wildlife Science, 602 Duncan Drive Auburn AL, 36830
| | - Sarah Zohdy
- Auburn University School of Forestry and Wildlife Science, 602 Duncan Drive Auburn AL, 36830
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Effect of Rising Temperature on Lyme Disease: Ixodes scapularis Population Dynamics and Borrelia burgdorferi Transmission and Prevalence. CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2019; 2019:9817930. [PMID: 31636771 PMCID: PMC6766261 DOI: 10.1155/2019/9817930] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/11/2019] [Accepted: 07/07/2019] [Indexed: 01/06/2023]
Abstract
Warmer temperatures are expected to increase the incidence of Lyme disease through enhanced tick maturation rates and a longer season of transmission. In addition, there could be an increased risk of disease export because of infected mobile hosts, usually birds. A temperature-driven seasonal model of Borrelia burgdorferi (Lyme disease) transmission among four host types is constructed as a system of nonlinear ordinary differential equations. The model is developed and parametrized based on a collection of lab and field studies. The model is shown to produce biologically reasonable results for both the tick vector (Ixodes scapularis) and the hosts when compared to a different set of studies. The model is used to predict the response of Lyme disease risk to a mean annual temperature increase, based on current temperature cycles in Hanover, NH. Many of the risk measures suggested by the literature are shown to change with increased mean annual temperature. The most straightforward measure of disease risk is the abundance of infected questing ticks, averaged over a year. Compared to this measure, which is difficult and resource-intensive to track in the field, all other risk measures considered underestimate the rise of risk with rise in mean annual temperature. The measure coming closest was “degree days above zero.” Disease prevalence in ticks and hosts showed less increase with rising temperature. Single field measurements at the height of transmission season did not show much change at all with rising temperature.
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24
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Nguyen A, Mahaffy J, Vaidya NK. Modeling transmission dynamics of lyme disease: Multiple vectors, seasonality, and vector mobility. Infect Dis Model 2019; 4:28-43. [PMID: 30997436 PMCID: PMC6453107 DOI: 10.1016/j.idm.2019.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/16/2019] [Accepted: 03/24/2019] [Indexed: 10/27/2022] Open
Abstract
Lyme disease is the most prevalent tick-borne disease in the United States, which humans acquire from an infected tick of the genus Ixodes (primarily Ixodes scapularis). While previous studies have provided useful insights into various aspects of Lyme disease, the tick's host preference in the presence of multiple hosts has not been considered in the existing models. In this study, we develop a transmission dynamics model that includes the interactions between the primary vectors involved: blacklegged ticks (I. scapularis), white-footed mice (Peromyscus leucopus), and white-tailed deer (Odocoileus virginianus). Our model shows that the presence of multiple vectors may have a significant impact on the dynamics and spread of Lyme disease. Based on our model, we also calculate the basic reproduction number, R 0 , a threshold value that predicts whether a disease exists or dies out. Subsequent extensions of the model consider seasonality of the tick's feeding period and mobility of deer between counties. Our results suggest that a longer tick peak feeding period results in a higher infection prevalence. Moreover, while the deer mobility may not be a primary factor for short-term emergence of Lyme disease epidemics, in the long-run it can significantly contribute to local infectiousness in neighboring counties, which eventually reach the endemic steady state.
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Affiliation(s)
- Aileen Nguyen
- Department of Mathematics and Statistics, San Diego State University, California, 92182, USA
| | - Joseph Mahaffy
- Department of Mathematics and Statistics, San Diego State University, California, 92182, USA
| | - Naveen K Vaidya
- Department of Mathematics and Statistics, San Diego State University, California, 92182, USA.,Computational Science Research Center, San Diego State University, California, 92182, USA.,Viral Information Institute, San Diego State University, California, 92182, USA
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25
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Ogden NH, Pang G, Ginsberg HS, Hickling GJ, Burke RL, Beati L, Tsao JI. Evidence for Geographic Variation in Life-Cycle Processes Affecting Phenology of the Lyme Disease Vector Ixodes scapularis (Acari: Ixodidae) in the United States. JOURNAL OF MEDICAL ENTOMOLOGY 2018; 55:1386-1401. [PMID: 29986046 DOI: 10.1093/jme/tjy104] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Indexed: 06/08/2023]
Abstract
The seasonal activity pattern of immature Ixodes scapularis Say (Acari: Ixodidae) varies geographically in the United States, which may affect the efficiency of transmission cycles of pathogens transmitted by this species. To study the factors that determine seasonality, a multiyear study at seven sites across the geographic range of I. scapularis systematically collected questing ticks by flagging/dragging, and feeding ticks by capture of their hosts. The observed phenology patterns were consistent with previous studies reporting geographic variation in seasonal tick activity. Predictions of seasonal activity for each site were obtained from an I. scapularis simulation model calibrated using contemporaneous weather data. A range of scenarios for life-cycle processes-including different regimes of temperature-independent behavioral and developmental diapause, variations in temperature-development rate relationships, and temperature-dependent tick activity-were used in model formulations. These formulations produced a range of simulations of seasonal activity for each site and were compared against the field observed tick data using negative binomial regression models. Best fit scenarios were chosen for each site on the basis of Akaike's information criterion and regression model parameters. This analysis suggests that temperature-independent diapause mechanisms explain some key observed variations in I. scapularis seasonality, and are responsible in part for geographic variations in I. scapularis seasonality in the United States. However, diapause appears to operate in idiosyncratic ways in different regions of the United States, so further studies on populations in different regions will be needed to enable predictive modeling of climatic and climate change effects on I. scapularis seasonal activity and pathogen transmission.
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Affiliation(s)
- Nicholas H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC, Canada
- South African Centre for Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, Western Cape, South Africa
| | - Genevieve Pang
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI
| | - Howard S Ginsberg
- USGS Patuxent Wildlife Research Center Coastal Field Station, Kingston, RI
| | - Graham J Hickling
- Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN
| | | | - Lorenza Beati
- Department of Biology, Georgia Southern University, Statesboro, GA
| | - Jean I Tsao
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI
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26
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Mendoza EJ, Warner B, Kobinger G, Ogden NH, Safronetz D. Baited vaccines: A strategy to mitigate rodent-borne viral zoonoses in humans. Zoonoses Public Health 2018; 65:711-727. [PMID: 29931738 DOI: 10.1111/zph.12487] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 06/05/2018] [Accepted: 05/21/2018] [Indexed: 11/27/2022]
Abstract
Rodents serve as the natural reservoir and vector for a variety of pathogens, some of which are responsible for severe and life-threatening disease in humans. Despite the significant impact in humans many of these viruses, including Old and New World hantaviruses as well as Arenaviruses, most have no specific vaccine or therapeutic to treat or prevent human infection. The recent success of wildlife vaccines to mitigate rabies in animal populations offers interesting insight into the use of similar strategies for other zoonotic agents of human disease. In this review, we discuss the notion of using baited vaccines as a means to interrupt the transmission of viral pathogens between rodent reservoirs and to susceptible human hosts.
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Affiliation(s)
- Emelissa J Mendoza
- Zoonotic Diseases and Special Pathogens, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Bryce Warner
- Zoonotic Diseases and Special Pathogens, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.,Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Gary Kobinger
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania.,Centre Hospitalier de l'Université Laval, Quebec City, Quebec, Canada
| | - Nicholas H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, Quebec, Canada
| | - David Safronetz
- Zoonotic Diseases and Special Pathogens, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.,Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
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27
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Campagnolo ER, Tewari D, Farone TS, Livengood JL, Mason KL. Evidence of Powassan/deer tick virus in adult black-legged ticks (Ixodes scapularis) recovered from hunter-harvested white-tailed deer (Odocoileus virginianus) in Pennsylvania: A public health perspective. Zoonoses Public Health 2018; 65:589-594. [PMID: 29707917 DOI: 10.1111/zph.12476] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Indexed: 11/29/2022]
Abstract
Studies reporting tick infection rates for Powassan virus (POWV), an emerging zoonotic arthropod-borne pathogen responsible for POWV disease in the Commonwealth of Pennsylvania, are limited. To determine the presence and ascertain a statewide prevalence of POWV, ticks were collected from 9,912 hunter-harvested white-tailed deer (Odocoileus virginianus) heads presented to six regional Pennsylvania Game Commission Chronic Wasting Disease sampling stations in early December of 2013, 2014 and 2015. Of the 2,973 ticks recovered, 1,990 (66.9%) were identified as adult Ixodes scapularis (black-legged tick). The 1,990 I. scapularis ticks were PCR-tested for the presence of POWV. The ticks had a statewide Powassan/deer tick virus infection rate of 0.05%, providing evidence of this pathogen in Pennsylvania's adult I. scapularis ticks and supporting the need for more comprehensive pathogen prevalence assessment strategies, as well as increased public health awareness for this emerging zoonotic arthropod-borne pathogen of public health concern.
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Affiliation(s)
- E R Campagnolo
- Pennsylvania Department of Health, Bureau of Epidemiology, Harrisburg, Pennsylvania.,Division of State and Local Readiness, Centers for Disease Control and Prevention, Office of Public Health Preparedness and Response, Atlanta, Georgia
| | - D Tewari
- Pennsylvania Department of Agriculture, Pennsylvania Veterinary Laboratory, Harrisburg, Pennsylvania
| | - T S Farone
- Department of Biology, Grove City College, Grove City, Pennsylvania
| | - J L Livengood
- Pennsylvania Department of Agriculture, Pennsylvania Veterinary Laboratory, Harrisburg, Pennsylvania
| | - K L Mason
- Pennsylvania Department of Health, Bureau of Epidemiology, Harrisburg, Pennsylvania
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28
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Clow KM, Ogden NH, Lindsay LR, Russell CB, Michel P, Pearl DL, Jardine CM. A field-based indicator for determining the likelihood of Ixodes scapularis establishment at sites in Ontario, Canada. PLoS One 2018; 13:e0193524. [PMID: 29486007 PMCID: PMC5828431 DOI: 10.1371/journal.pone.0193524] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 02/13/2018] [Indexed: 12/15/2022] Open
Abstract
The emergence of the vector Ixodes scapularis in Ontario, Canada poses a significant public health risk. Both passive and active surveillance approaches have been employed by public health professionals (i.e., government employees) to monitor for the range expansion of this tick. Field surveillance using drag sampling for questing ticks is a recognized and effective method to identify reproducing tick populations. The degree of effort (i.e., number of visits per site) can enhance the sensitivity and specificity of surveillance, but increased effort conflicts with the cost to public health for field surveillance. Here we developed an indicator to determine the likelihood of I. scapularis establishment based on field sampling results. Field data from two established populations of I. scapularis in Ontario were incorporated with previous analyses of surveillance data to create the indicator, which is in the form of a scoring system. The life stage(s) collected, overall abundance and past surveillance findings from a site are all considered and a level is assigned for the likelihood of I. scapularis establishment based on current field sampling results. The likelihood levels are non-zero (i.e., no I. scapularis detected, but risk still present due to adventitious ticks), low, medium or high, and recommendations for future surveillance and public health measures are provided. The indicator was validated against field sampling results from five other established sites in the province and correctly categorized all five areas as high likelihood of establishment. The indicator was also applied to field sampling results from 36 sites of unknown status that were visited twice during the period of 2014-2016. There was substantial agreement of levels between measurements, as calculated using a weighted kappa. The indicator can assist public health professionals with the interpretation of field sampling results and direct their efforts for ongoing surveillance and public health interventions for I. scapularis-borne diseases, including Lyme disease.
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Affiliation(s)
- Katie M. Clow
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Nicholas H. Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - L. Robbin Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Curtis B. Russell
- Enteric, Zoonotic and Vector-Borne Diseases, Communicable and Infectious Disease Prevention and Control, Public Health Ontario, Toronto, Ontario, Canada
| | - Pascal Michel
- Office of the Chief Science Officer, Public Health Agency of Canada, Ottawa, Ontario, Canada
| | - David L. Pearl
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Claire M. Jardine
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
- Canadian Wildlife Health Cooperative, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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29
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Kilpatrick AM, Dobson ADM, Levi T, Salkeld DJ, Swei A, Ginsberg HS, Kjemtrup A, Padgett KA, Jensen PM, Fish D, Ogden NH, Diuk-Wasser MA. Lyme disease ecology in a changing world: consensus, uncertainty and critical gaps for improving control. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0117. [PMID: 28438910 DOI: 10.1098/rstb.2016.0117] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2016] [Indexed: 11/12/2022] Open
Abstract
Lyme disease is the most common tick-borne disease in temperate regions of North America, Europe and Asia, and the number of reported cases has increased in many regions as landscapes have been altered. Although there has been extensive work on the ecology and epidemiology of this disease in both Europe and North America, substantial uncertainty exists about fundamental aspects that determine spatial and temporal variation in both disease risk and human incidence, which hamper effective and efficient prevention and control. Here we describe areas of consensus that can be built on, identify areas of uncertainty and outline research needed to fill these gaps to facilitate predictive models of disease risk and the development of novel disease control strategies. Key areas of uncertainty include: (i) the precise influence of deer abundance on tick abundance, (ii) how tick populations are regulated, (iii) assembly of host communities and tick-feeding patterns across different habitats, (iv) reservoir competence of host species, and (v) pathogenicity for humans of different genotypes of Borrelia burgdorferi Filling these knowledge gaps will improve Lyme disease prevention and control and provide general insights into the drivers and dynamics of this emblematic multi-host-vector-borne zoonotic disease.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
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Affiliation(s)
- A Marm Kilpatrick
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
| | | | - Taal Levi
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA
| | - Daniel J Salkeld
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Andrea Swei
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
| | - Howard S Ginsberg
- USGS Patuxent Wildlife Research Center, RI Field Station, University of Rhode Island, Kingston, RI 02881, USA
| | - Anne Kjemtrup
- Vector-Borne Disease Section, Division of Communicable Disease Control, California Department of Public Health, Center for Infectious Diseases, Sacramento, CA 95814, USA
| | - Kerry A Padgett
- Vector-Borne Disease Section, Division of Communicable Disease Control, California Department of Public Health, Center for Infectious Diseases, Sacramento, CA 95814, USA
| | - Per M Jensen
- Department of Plant and Environmental Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Durland Fish
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Nick H Ogden
- Public Health Risk Sciences, National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Quebec, J2S 7C6, Canada
| | - Maria A Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
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30
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Kada S, McCoy KD, Boulinier T. Impact of life stage-dependent dispersal on the colonization dynamics of host patches by ticks and tick-borne infectious agents. Parasit Vectors 2017; 10:375. [PMID: 28778181 PMCID: PMC5544987 DOI: 10.1186/s13071-017-2261-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/22/2017] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND When colonization and gene flow depend on host-mediated dispersal, a key factor affecting vector dispersal potential is the time spent on the host for the blood meal, a characteristic that can vary strongly among life history stages. Using a 2-patch vector-pathogen population model and seabird ticks as biological examples, we explore how vector colonization rates and the spread of infectious agents may be shaped by life stage-dependent dispersal. We contrast hard (Ixodidae) and soft (Argasidae) tick systems, which differ strongly in blood- feeding traits. RESULTS We find that vector life history characteristics (i.e. length of blood meal) and demographic constraints (Allee effects) condition the colonization potential of ticks; hard ticks, which take a single, long blood meal per life stage, should have much higher colonization rates than soft ticks, which take repeated short meals. Moreover, this dispersal potential has direct consequences for the spread of vector-borne infectious agents, in particular when transmission is transovarial. CONCLUSIONS These results have clear implications for predicting the dynamics of vector and disease spread in the context of large-scale environmental change. The findings highlight the need to include life-stage dispersal in models that aim to predict species and disease distributions, and provide testable predictions related to the population genetic structure of vectors and pathogens along expansion fronts.
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Affiliation(s)
- Sarah Kada
- Centre d’Ecologie Fonctionnelle et Evolutive (CEFE) - CNRS Université Montpellier UMR 5175, 1919 route de Mende, 34293 Montpellier, France
| | - Karen D. McCoy
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, UMR CNRS 5290 - UR IRD 224 - Université Montpellier, Centre IRD, 34394 Montpellier, France
| | - Thierry Boulinier
- Centre d’Ecologie Fonctionnelle et Evolutive (CEFE) - CNRS Université Montpellier UMR 5175, 1919 route de Mende, 34293 Montpellier, France
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31
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Belli A, Sarr A, Rais O, Rego ROM, Voordouw MJ. Ticks infected via co-feeding transmission can transmit Lyme borreliosis to vertebrate hosts. Sci Rep 2017; 7:5006. [PMID: 28694446 PMCID: PMC5503982 DOI: 10.1038/s41598-017-05231-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 05/25/2017] [Indexed: 11/09/2022] Open
Abstract
Vector-borne pathogens establish systemic infections in host tissues to maximize transmission to arthropod vectors. Co-feeding transmission occurs when the pathogen is transferred between infected and naive vectors that feed in close spatiotemporal proximity on a host that has not yet developed a systemic infection. Borrelia afzelii is a tick-borne spirochete bacterium that causes Lyme borreliosis (LB) and is capable of co-feeding transmission. Whether ticks that acquire LB pathogens via co-feeding are actually infectious to vertebrate hosts has never been tested. We created nymphs that had been experimentally infected as larvae with B. afzelii via co-feeding or systemic transmission, and compared their performance over one complete LB life cycle. Co-feeding nymphs had a spirochete load that was 26 times lower than systemic nymphs but both nymphs were highly infectious to mice (i.e., probability of nymph-to-host transmission of B. afzelii was ~100%). The mode of transmission had no effect on the other infection phenotypes of the LB life cycle. Ticks that acquire B. afzelii via co-feeding transmission are highly infectious to rodents, and the resulting rodent infection is highly infectious to larval ticks. This is the first study to show that B. afzelii can use co-feeding transmission to complete its life cycle.
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Affiliation(s)
- Alessandro Belli
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Anouk Sarr
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Olivier Rais
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Ryan O M Rego
- Institute of Parasitology, ASCR, Biology Centre, Ceske Budejovice, Czech Republic
| | - Maarten J Voordouw
- Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
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32
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Watson SC, Liu Y, Lund RB, Gettings JR, Nordone SK, McMahan CS, Yabsley MJ. A Bayesian spatio-temporal model for forecasting the prevalence of antibodies to Borrelia burgdorferi, causative agent of Lyme disease, in domestic dogs within the contiguous United States. PLoS One 2017; 12:e0174428. [PMID: 28472096 PMCID: PMC5417420 DOI: 10.1371/journal.pone.0174428] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/08/2017] [Indexed: 01/12/2023] Open
Abstract
This paper models the prevalence of antibodies to Borrelia burgdorferi in domestic dogs in the United States using climate, geographic, and societal factors. We then use this model to forecast the prevalence of antibodies to B. burgdorferi in dogs for 2016. The data available for this study consists of 11,937,925 B. burgdorferi serologic test results collected at the county level within the 48 contiguous United States from 2011-2015. Using the serologic data, a baseline B. burgdorferi antibody prevalence map was constructed through the use of spatial smoothing techniques after temporal aggregation; i.e., head-banging and Kriging. In addition, several covariates purported to be associated with B. burgdorferi prevalence were collected on the same spatio-temporal granularity, and include forestation, elevation, water coverage, temperature, relative humidity, precipitation, population density, and median household income. A Bayesian spatio-temporal conditional autoregressive (CAR) model was used to analyze these data, for the purposes of identifying significant risk factors and for constructing disease forecasts. The fidelity of the forecasting technique was assessed using historical data, and a Lyme disease forecast for dogs in 2016 was constructed. The correlation between the county level model and baseline B. burgdorferi antibody prevalence estimates from 2011 to 2015 is 0.894, illustrating that the Bayesian spatio-temporal CAR model provides a good fit to these data. The fidelity of the forecasting technique was assessed in the usual fashion; i.e., the 2011-2014 data was used to forecast the 2015 county level prevalence, with comparisons between observed and predicted being made. The weighted (to acknowledge sample size) correlation between 2015 county level observed prevalence and 2015 forecasted prevalence is 0.978. A forecast for the prevalence of B. burgdorferi antibodies in domestic dogs in 2016 is also provided. The forecast presented from this model can be used to alert veterinarians in areas likely to see above average B. burgdorferi antibody prevalence in dogs in the upcoming year. In addition, because dogs and humans can be exposed to ticks in similar habitats, these data may ultimately prove useful in predicting areas where human Lyme disease risk may emerge.
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Affiliation(s)
- Stella C. Watson
- Department of Mathematical Sciences, Clemson University, Clemson, SC, United States of America
| | - Yan Liu
- Department of Mathematical Sciences, Clemson University, Clemson, SC, United States of America
| | - Robert B. Lund
- Department of Mathematical Sciences, Clemson University, Clemson, SC, United States of America
| | - Jenna R. Gettings
- Department of Mathematical Sciences, Clemson University, Clemson, SC, United States of America
| | - Shila K. Nordone
- Department of Molecular and Biomedical Sciences, Comparative Medicine Institute, North Carolina State University, College of Veterinary Medicine, Raleigh, NC, United States of America
| | - Christopher S. McMahan
- Department of Mathematical Sciences, Clemson University, Clemson, SC, United States of America
| | - Michael J. Yabsley
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, United States of America
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33
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The influence of abiotic and biotic factors on the invasion of Ixodes scapularis in Ontario, Canada. Ticks Tick Borne Dis 2017; 8:554-563. [PMID: 28359751 DOI: 10.1016/j.ttbdis.2017.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/06/2017] [Accepted: 03/15/2017] [Indexed: 01/06/2023]
Abstract
In northeastern North America, the blacklegged tick, Ixodes scapularis, is the vector of numerous tick-borne pathogens, including the agent of Lyme disease, Borrelia burgdorferi sensu stricto. Since 1990, there has been a rapid spread of I. scapularis northward into the province of Ontario, Canada. Climate change has been implicated as one of the driving factors for the spread of this vector. Other ecological factors also influence survival of I. scapularis populations and may facilitate invasion. The objective of this study was to identify local abiotic and biotic factors of significance for the invasion of I. scapularis in Ontario. The presence of ticks was determined by drag sampling at 154 sites in southern, eastern and central Ontario from May to October in 2014 and 2015. At each site, data on site aspect, forest cover, understory density and composition, soil moisture and composition, and the depth of litter layer were collected. Cumulative degree days above zero °C, total precipitation and elevation were attributed to each site using a geographic information system. A mixed multi-variable logistic regression model was created to assess the impact of the ecological factors on the presence of I. scapularis. In total, I. scapularis was found at 29 sites (18.8%) across the study area. The density of the understory, the presence of shrubs and the interaction of these two ecological factors were statistically significant, as well as longitude and cumulative degree days above zero. Our findings illustrate that local ecological factors are of importance for the invasion of I. scapularis into Ontario, and may be used to enhance local public health interventions and current predictive models and risk maps for I. scapularis.
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34
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Ginsberg HS, Lee C, Volson B, Dyer MC, Lebrun RA. Relationships Between Maternal Engorgement Weight and the Number, Size, and Fat Content of Larval Ixodes scapularis (Acari: Ixodidae). JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:275-280. [PMID: 28028139 DOI: 10.1093/jme/tjw191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Indexed: 06/06/2023]
Abstract
The relationship between engorgement weight of female Ixodes scapularis Say and characteristics of offspring was studied using field-collected females fed on rabbits in the laboratory. The number of eggs laid was positively related to maternal engorgement weight in one trial, and larval size (estimated by scutal area) was positively related to maternal engorgement weight in the other. These results suggest a trade-off in number of eggs produced versus average size of offspring, possibly determined during late engorgement. The adults for the two trials were collected from different sites in southern Rhode Island and in different seasons (the fall adults were newly emerged, while the spring adults had presumably lived through the winter), so it is not clear whether these results reflect genetic differences or subtle environmental differences between trials. Percent egg hatch and average fat content of larvae were not related to female engorgement weight. We present a modified method to measure lipid content of pooled larval ticks.
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Affiliation(s)
- Howard S Ginsberg
- USGS Patuxent Wildlife Research Center, Woodward Hall-PSE, University of Rhode Island, Kingston, RI 02881
- Department of Plant Sciences and Entomology, Woodward Hall, University of Rhode Island, Kingston, RI 02881 (; )
| | - Chong Lee
- Department of Nutrition and Food Sciences, FSN Research Center, University of Rhode Island, Kingston, RI 02881 (; )
| | - Barry Volson
- Department of Nutrition and Food Sciences, FSN Research Center, University of Rhode Island, Kingston, RI 02881 (; )
| | - Megan C Dyer
- Department of Plant Sciences and Entomology, Woodward Hall, University of Rhode Island, Kingston, RI 02881 (; )
| | - Roger A Lebrun
- Department of Plant Sciences and Entomology, Woodward Hall, University of Rhode Island, Kingston, RI 02881 (; )
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Lynn GE, Oliver JD, Cornax I, O'Sullivan MG, Munderloh UG. Experimental evaluation of Peromyscus leucopus as a reservoir host of the Ehrlichia muris-like agent. Parasit Vectors 2017; 10:48. [PMID: 28129781 PMCID: PMC5273795 DOI: 10.1186/s13071-017-1980-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/12/2017] [Indexed: 11/10/2022] Open
Abstract
Background The Ehrlichia muris-like agent (EMLA) is a newly recognized human pathogen in the North Central United States. Although blacklegged ticks (Ixodes scapularis) have been identified as capable vectors, wild reservoirs have not yet been established for EMLA. As key hosts for I. scapularis, white-footed mice (Peromyscus leucopus) are important reservoirs for various tick-borne pathogens, and potentially, for EMLA. The objective of this study was to evaluate reservoir competence in P. leucopus using a natural vector. Results Mice acquired EMLA infection from feeding ticks and were able to transmit infection to naïve ticks. Transmission between simultaneously feeding tick life stages was also demonstrated. Infections in mice were acute and severe, with systemic dissemination. Limited host survival and clearance of infection among survivors resulted in a narrow interval where EMLA could be acquired by feeding ticks. Conclusions Peromyscus leucopus is a competent reservoir of EMLA and likely to play a role in its enzootic transmission cycle. The duration and severity of EMLA infection in these hosts suggests that tick phenology is a critical factor determining the geographic distribution of EMLA in North America.
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Affiliation(s)
- Geoffrey E Lynn
- Entomology Department, University of Minnesota - Twin Cities, 1980 Folwell Ave, St. Paul, MN, USA.
| | - Jonathan D Oliver
- Entomology Department, University of Minnesota - Twin Cities, 1980 Folwell Ave, St. Paul, MN, USA
| | - Ingrid Cornax
- Masonic Cancer Center Comparative Pathology Shared Resource, Masonic Cancer Center, University of Minnesota - Twin Cities, 420 Delaware St. SE, Minneapolis, MN, USA
| | - M Gerard O'Sullivan
- Masonic Cancer Center Comparative Pathology Shared Resource, Masonic Cancer Center, University of Minnesota - Twin Cities, 420 Delaware St. SE, Minneapolis, MN, USA
| | - Ulrike G Munderloh
- Entomology Department, University of Minnesota - Twin Cities, 1980 Folwell Ave, St. Paul, MN, USA
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Ogden NH, Lindsay LR. Effects of Climate and Climate Change on Vectors and Vector-Borne Diseases: Ticks Are Different. Trends Parasitol 2016; 32:646-656. [PMID: 27260548 DOI: 10.1016/j.pt.2016.04.015] [Citation(s) in RCA: 156] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/19/2016] [Accepted: 04/21/2016] [Indexed: 01/05/2023]
Abstract
There has been considerable debate as to whether global risk from vector-borne diseases will be impacted by climate change. This has focussed on important mosquito-borne diseases that are transmitted by the vectors from infected to uninfected humans. However, this debate has mostly ignored the biological diversity of vectors and vector-borne diseases. Here, we review how climate and climate change may impact those most divergent of arthropod disease vector groups: multivoltine insects and hard-bodied (ixodid) ticks. We contrast features of the life cycles and behaviour of these arthropods, and how weather, climate, and climate change may have very different impacts on the spatiotemporal occurrence and abundance of vectors, and the pathogens they transmit.
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Affiliation(s)
- Nick H Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 7C6, Canada; Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; National Microbiology Laboratory, Public Health Agency of Canada, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba, R3E 3R2, Canada.
| | - L Robbin Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba, R3E 3R2, Canada
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Springer YP, Hoekman D, Johnson PTJ, Duffy PA, Hufft RA, Barnett DT, Allan BF, Amman BR, Barker CM, Barrera R, Beard CB, Beati L, Begon M, Blackmore MS, Bradshaw WE, Brisson D, Calisher CH, Childs JE, Diuk‐Wasser M, Douglass RJ, Eisen RJ, Foley DH, Foley JE, Gaff HD, Gardner SL, Ginsberg HS, Glass GE, Hamer SA, Hayden MH, Hjelle B, Holzapfel CM, Juliano SA, Kramer LD, Kuenzi AJ, LaDeau SL, Livdahl TP, Mills JN, Moore CG, Morand S, Nasci RS, Ogden NH, Ostfeld RS, Parmenter RR, Piesman J, Reisen WK, Savage HM, Sonenshine DE, Swei A, Yabsley MJ. Tick‐, mosquito‐, and rodent‐borne parasite sampling designs for the National Ecological Observatory Network. Ecosphere 2016. [DOI: 10.1002/ecs2.1271] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Yunik MEM, Galloway TD, Lindsay LR. Assessment of prevalence and distribution of spotted fever group rickettsiae in Manitoba, Canada, in the American dog tick, Dermacentor variabilis (Acari: Ixodidae). Vector Borne Zoonotic Dis 2016; 15:103-8. [PMID: 25700040 DOI: 10.1089/vbz.2014.1692] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Little is known about the distribution and prevalence of the spotted fever group rickettsiae in Canada. We conducted active surveillance for tick-associated rickettsiae in 10 localities in Manitoba. A total of 1044 adult American dog ticks, Dermacentor variabilis (Acari: Ixodidae), were collected and screened for spotted fever group rickettsiae. Rickettsia montanensis was the only species of rickettsia detected. The mean prevalence of infection was 9.8% (range, 0.00-21.74% among localities). The proportion of infected male and female ticks was not significantly different; however, tick populations near the northern limit of D. variabilis distribution in Manitoba had a lower prevalence of infection compared to tick populations from more southern localities in the province.
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Affiliation(s)
- Matthew E M Yunik
- 1 Department of Entomology, University of Manitoba , Winnipeg, Manitoba, Canada
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Eisen RJ, Eisen L, Ogden NH, Beard CB. Linkages of Weather and Climate With Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae), Enzootic Transmission of Borrelia burgdorferi, and Lyme Disease in North America. JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:250-61. [PMID: 26681789 PMCID: PMC4844560 DOI: 10.1093/jme/tjv199] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Lyme disease has increased both in incidence and geographic extent in the United States and Canada over the past two decades. One of the underlying causes is changes during the same time period in the distribution and abundance of the primary vectors: Ixodes scapularis Say and Ixodes pacificus Cooley and Kohls in eastern and western North America, respectively. Aside from short periods of time when they are feeding on hosts, these ticks exist in the environment where temperature and relative humidity directly affect their development, survival, and host-seeking behavior. Other important factors that strongly influence tick abundance as well as the proportion of ticks infected with the Lyme disease spirochete, Borrelia burgdorferi, include the abundance of hosts for the ticks and the capacity of tick hosts to serve as B. burgdorferi reservoirs. Here, we explore the linkages between climate variation and: 1) duration of the seasonal period and the timing of peak activity; 2) geographic tick distributions and local abundance; 3) enzootic B. burgdorferi transmission cycles; and 4) Lyme disease cases. We conclude that meteorological variables are most influential in determining host-seeking phenology and development, but, while remaining important cofactors, additional variables become critical when exploring geographic distribution and local abundance of ticks, enzootic transmission of B. burgdorferi, and Lyme disease case occurrence. Finally, we review climate change-driven projections for future impact on vector ticks and Lyme disease and discuss knowledge gaps and research needs.
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Affiliation(s)
- Rebecca J. Eisen
- Bacterial Diseases Branch, Division of Vectorborne Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO
- Corresponding author,
| | - Lars Eisen
- Bacterial Diseases Branch, Division of Vectorborne Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO
| | - Nicholas H. Ogden
- Zoonoses Division, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
| | - Charles B. Beard
- Bacterial Diseases Branch, Division of Vectorborne Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO
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Mechai S, Margos G, Feil EJ, Barairo N, Lindsay LR, Michel P, Ogden NH. Evidence for Host-Genotype Associations of Borrelia burgdorferi Sensu Stricto. PLoS One 2016; 11:e0149345. [PMID: 26901761 PMCID: PMC4763156 DOI: 10.1371/journal.pone.0149345] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/29/2016] [Indexed: 11/18/2022] Open
Abstract
Different genotypes of the agent of Lyme disease in North America, Borrelia burgdorferi sensu stricto, show varying degrees of pathogenicity in humans. This variation in pathogenicity correlates with phylogeny and we have hypothesized that the different phylogenetic lineages in North America reflect adaptation to different host species. In this study, evidence for host species associations of B. burgdorferi genotypes was investigated using 41 B. burgdorferi-positive samples from five mammal species and 50 samples from host-seeking ticks collected during the course of field studies in four regions of Canada: Manitoba, northwestern Ontario, Quebec, and the Maritimes. The B. burgdorferi genotypes in the samples were characterized using three established molecular markers (multi-locus sequence typing [MLST], 16S-23S rrs-rrlA intergenic spacer, and outer surface protein C sequence [ospC] major groups). Correspondence analysis and generalized linear mixed effect models revealed significant associations between B. burgdorferi genotypes and host species (in particular chipmunks, and white-footed mice and deer mice), supporting the hypotheses that host adaptation contributes to the phylogenetic structure and possibly the observed variation in pathogenicity in humans.
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Affiliation(s)
- Samir Mechai
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Gabriele Margos
- National Reference Centre for Borrelia, Oberschleissheim, Germany
- Bavarian Health and Food Safety Authority, Oberschleissheim, Germany
| | - Edward J. Feil
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Nicole Barairo
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - L. Robbin Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Pascal Michel
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, 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
- National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
- * E-mail:
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Abstract
SUMMARYTicks are vectors of pathogens which are important both with respect to human health and economically. They have a complex life cycle requiring several blood meals throughout their life. These blood meals take place on different individual hosts and potentially on different host species. Their life cycle is also dependent on environmental conditions such as the temperature and habitat type. Mathematical models have been used for the more than 30 years to help us understand how tick dynamics are dependent on these environmental factors and host availability. In this paper, we review models of tick dynamics and summarize the main results. This summary is split into two parts, one which looks at tick dynamics and one which looks at tick-borne pathogens. In general, the models of tick dynamics are used to determine when the peak in tick densities is likely to occur in the year and how that changes with environmental conditions. The models of tick-borne pathogens focus more on the conditions under which the pathogen can persist and how host population densities might be manipulated to control these pathogens. In the final section of the paper, we identify gaps in the current knowledge and future modelling approaches. These include spatial models linked to environmental information and Geographic Information System maps, and development of new modelling techniques which model tick densities per host more explicitly.
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Abstract
The evidence that climate warming is changing the distribution of Ixodes ticks and the pathogens they transmit is reviewed and evaluated. The primary approaches are either phenomenological, which typically assume that climate alone limits current and future distributions, or mechanistic, asking which tick-demographic parameters are affected by specific abiotic conditions. Both approaches have promise but are severely limited when applied separately. For instance, phenomenological approaches (e.g. climate envelope models) often select abiotic variables arbitrarily and produce results that can be hard to interpret biologically. On the other hand, although laboratory studies demonstrate strict temperature and humidity thresholds for tick survival, these limits rarely apply to field situations. Similarly, no studies address the influence of abiotic conditions on more than a few life stages, transitions or demographic processes, preventing comprehensive assessments. Nevertheless, despite their divergent approaches, both mechanistic and phenomenological models suggest dramatic range expansions of Ixodes ticks and tick-borne disease as the climate warms. The predicted distributions, however, vary strongly with the models' assumptions, which are rarely tested against reasonable alternatives. These inconsistencies, limited data about key tick-demographic and climatic processes and only limited incorporation of non-climatic processes have weakened the application of this rich area of research to public health policy or actions. We urge further investigation of the influence of climate on vertebrate hosts and tick-borne pathogen dynamics. In addition, testing model assumptions and mechanisms in a range of natural contexts and comparing their relative importance as competing models in a rigorous statistical framework will significantly advance our understanding of how climate change will alter the distribution, dynamics and risk of tick-borne disease.
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Affiliation(s)
- Richard S Ostfeld
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545, USA
| | - Jesse L Brunner
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
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Voordouw MJ, Lachish S, Dolan MC. The lyme disease pathogen has no effect on the survival of its rodent reservoir host. PLoS One 2015; 10:e0118265. [PMID: 25688863 PMCID: PMC4331372 DOI: 10.1371/journal.pone.0118265] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/07/2015] [Indexed: 01/06/2023] Open
Abstract
Zoonotic pathogens that cause devastating morbidity and mortality in humans may be relatively harmless in their natural reservoir hosts. The tick-borne bacterium Borrelia burgdorferi causes Lyme disease in humans but few studies have investigated whether this pathogen reduces the fitness of its reservoir hosts under natural conditions. We analyzed four years of capture-mark-recapture (CMR) data on a population of white-footed mice, Peromyscus leucopus, to test whether B. burgdorferi and its tick vector affect the survival of this important reservoir host. We used a multi-state CMR approach to model mouse survival and mouse infection rates as a function of a variety of ecologically relevant explanatory factors. We found no effect of B. burgdorferi infection or tick burden on the survival of P. leucopus. Our estimates of the probability of infection varied by an order of magnitude (0.051 to 0.535) and were consistent with our understanding of Lyme disease in the Northeastern United States. B. burgdorferi establishes a chronic avirulent infection in their rodent reservoir hosts because this pathogen depends on rodent mobility to achieve transmission to its sedentary tick vector. The estimates of B. burgdorferi infection risk will facilitate future theoretical studies on the epidemiology of Lyme disease.
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Affiliation(s)
- Maarten J. Voordouw
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| | - Shelly Lachish
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, United Kingdom
| | - Marc C. Dolan
- Division of Vector-Borne Diseases, National Center for Enteric and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
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44
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Impact of biodiversity and seasonality on Lyme-pathogen transmission. Theor Biol Med Model 2014; 11:50. [PMID: 25432469 PMCID: PMC4396072 DOI: 10.1186/1742-4682-11-50] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/22/2014] [Indexed: 12/30/2022] Open
Abstract
Lyme disease imposes increasing global public health challenges. To better understand the joint effects of seasonal temperature variation and host community composition on the pathogen transmission, a stage-structured periodic model is proposed by integrating seasonal tick development and activity, multiple host species and complex pathogen transmission routes between ticks and reservoirs. Two thresholds, one for tick population dynamics and the other for Lyme-pathogen transmission dynamics, are identified and shown to fully classify the long-term outcomes of the tick invasion and disease persistence. Seeding with the realistic parameters, the tick reproduction threshold and Lyme disease spread threshold are estimated to illustrate the joint effects of the climate change and host community diversity on the pattern of Lyme disease risk. It is shown that climate warming can amplify the disease risk and slightly change the seasonality of disease risk. Both the "dilution effect" and "amplification effect" are observed by feeding the model with different possible alternative hosts. Therefore, the relationship between the host community biodiversity and disease risk varies, calling for more accurate measurements on the local environment, both biotic and abiotic such as the temperature and the host community composition.
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45
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Abstract
This review examines the phenomenon of co-feeding transmission in tick-borne pathogens. This mode of transmission is critical for the epidemiology of several tick-borne viruses but its importance for Borrelia burgdorferi sensu lato, the causative agents of Lyme borreliosis, is still controversial. The molecular mechanisms and ecological factors that facilitate co-feeding transmission are therefore examined with particular emphasis on Borrelia pathogens. Comparison of climate, tick ecology and experimental infection work suggests that co-feeding transmission is more important in European than North American systems of Lyme borreliosis, which potentially explains why this topic has gained more traction in the former continent than the latter. While new theory shows that co-feeding transmission makes a modest contribution to Borrelia fitness, recent experimental work has revealed new ecological contexts where natural selection might favour co-feeding transmission. In particular, co-feeding transmission might confer a fitness advantage in the Darwinian competition among strains in mixed infections. Future studies should investigate the ecological conditions that favour the evolution of this fascinating mode of transmission in tick-borne pathogens.
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46
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Vuong HB, Canham CD, Fonseca DM, Brisson D, Morin PJ, Smouse PE, Ostfeld RS. Occurrence and transmission efficiencies of Borrelia burgdorferi ospC types in avian and mammalian wildlife. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2014; 27:594-600. [PMID: 24382473 PMCID: PMC4180015 DOI: 10.1016/j.meegid.2013.12.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 12/18/2013] [Accepted: 12/20/2013] [Indexed: 12/11/2022]
Abstract
Borrelia burgdorferi s.s., the bacterium that causes Lyme disease in North America, circulates among a suite of vertebrate hosts and their tick vector. The bacterium can be differentiated at the outer surface protein C (ospC) locus into 25 genotypes. Wildlife hosts can be infected with a suite of ospC types but knowledge on the transmission efficiencies of these naturally infected hosts to ticks is still lacking. To evaluate the occupancy and detection of ospC types in wildlife hosts, we adapted a likelihood-based species patch occupancy model to test for the occurrence probabilities (ψ - "occupancy") and transmission efficiencies (ε - "detection") of each ospC type. We detected differences in ospC occurrence and transmission efficiencies from the null models with HIS (human invasive strains) types A and K having the highest occurrence estimates, but both HIS and non-HIS types having high transmission efficiencies. We also examined ospC frequency patterns with respect to strains known to be invasive in humans across the host species and phylogenetic groups. We found that shrews and to a lesser extent, birds, were important host groups supporting relatively greater frequencies of HIS to non-HIS types. This novel method of simultaneously assessing occurrence and transmission of ospC types provides a powerful tool in assessing disease risk at the genotypic level in naturally infected wildlife hosts and offers the opportunity to examine disease risk at the community level.
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Affiliation(s)
- Holly B Vuong
- Rutgers University, Ecology and Evolution Graduate Program, Cook Campus, ENR 1st Floor, New Brunswick, NJ 08901, USA; Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike, Millbrook, NY 12545, USA.
| | - Charles D Canham
- Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike, Millbrook, NY 12545, USA.
| | - Dina M Fonseca
- Rutgers University, Ecology and Evolution Graduate Program, Cook Campus, ENR 1st Floor, New Brunswick, NJ 08901, USA; Rutgers University, Center for Vector Biology, 180 Jones Ave., New Brunswick, NJ 08901, USA.
| | - Dustin Brisson
- University of Pennsylvania, Department of Biology, 209 Leidy Laboratories, Philadelphia, PA 19104, USA.
| | - Peter J Morin
- Rutgers University, Ecology and Evolution Graduate Program, Cook Campus, ENR 1st Floor, New Brunswick, NJ 08901, USA.
| | - Peter E Smouse
- Rutgers University, Ecology and Evolution Graduate Program, Cook Campus, ENR 1st Floor, New Brunswick, NJ 08901, USA.
| | - Richard S Ostfeld
- Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike, Millbrook, NY 12545, USA.
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Ogden NH, Radojevic M, Wu X, Duvvuri VR, Leighton PA, Wu J. Estimated effects of projected climate change on the basic reproductive number of the Lyme disease vector Ixodes scapularis. ENVIRONMENTAL HEALTH PERSPECTIVES 2014; 122:631-8. [PMID: 24627295 PMCID: PMC4050516 DOI: 10.1289/ehp.1307799] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 03/10/2014] [Indexed: 05/03/2023]
Abstract
BACKGROUND The extent to which climate change may affect human health by increasing risk from vector-borne diseases has been under considerable debate. OBJECTIVES We quantified potential effects of future climate change on the basic reproduction number (R0) of the tick vector of Lyme disease, Ixodes scapularis, and explored their importance for Lyme disease risk, and for vector-borne diseases in general. METHODS We applied observed temperature data for North America and projected temperatures using regional climate models to drive an I. scapularis population model to hindcast recent, and project future, effects of climate warming on R0. Modeled R0 increases were compared with R0 ranges for pathogens and parasites associated with variations in key ecological and epidemiological factors (obtained by literature review) to assess their epidemiological importance. RESULTS R0 for I. scapularis in North America increased during the years 1971-2010 in spatio-temporal patterns consistent with observations. Increased temperatures due to projected climate change increased R0 by factors (2-5 times in Canada and 1.5-2 times in the United States), comparable to observed ranges of R0 for pathogens and parasites due to variations in strains, geographic locations, epidemics, host and vector densities, and control efforts. CONCLUSIONS Climate warming may have co-driven the emergence of Lyme disease in northeastern North America, and in the future may drive substantial disease spread into new geographic regions and increase tick-borne disease risk where climate is currently suitable. Our findings highlight the potential for climate change to have profound effects on vectors and vector-borne diseases, and the need to refocus efforts to understand these effects.
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Affiliation(s)
- Nicholas H Ogden
- Zoonoses Division, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada
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48
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Simon JA, Marrotte RR, Desrosiers N, Fiset J, Gaitan J, Gonzalez A, Koffi JK, Lapointe FJ, Leighton PA, Lindsay LR, Logan T, Milord F, Ogden NH, Rogic A, Roy-Dufresne E, Suter D, Tessier N, Millien V. Climate change and habitat fragmentation drive the occurrence of Borrelia burgdorferi, the agent of Lyme disease, at the northeastern limit of its distribution. Evol Appl 2014; 7:750-64. [PMID: 25469157 PMCID: PMC4227856 DOI: 10.1111/eva.12165] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 04/05/2014] [Indexed: 12/15/2022] Open
Abstract
Lyme borreliosis is rapidly emerging in Canada, and climate change is likely a key driver of the northern spread of the disease in North America. We used field and modeling approaches to predict the risk of occurrence of Borrelia burgdorferi, the bacteria causing Lyme disease in North America. We combined climatic and landscape variables to model the current and future (2050) potential distribution of the black-legged tick and the white-footed mouse at the northeastern range limit of Lyme disease and estimated a risk index for B. burgdorferi from these distributions. The risk index was mostly constrained by the distribution of the white-footed mouse, driven by winter climatic conditions. The next factor contributing to the risk index was the distribution of the black-legged tick, estimated from the temperature. Landscape variables such as forest habitat and connectivity contributed little to the risk index. We predict a further northern expansion of B. burgdorferi of approximately 250–500 km by 2050 – a rate of 3.5–11 km per year – and identify areas of rapid rise in the risk of occurrence of B. burgdorferi. Our results will improve understanding of the spread of Lyme disease and inform management strategies at the most northern limit of its distribution.
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Affiliation(s)
- Julie A Simon
- Redpath Museum, McGill University Montreal, QC, Canada
| | - Robby R Marrotte
- Redpath Museum, McGill University Montreal, QC, Canada ; Department of Biology, McGill University Montreal, QC, Canada
| | - Nathalie Desrosiers
- Ministère du Développement Durable, de l'Environnement, de la Faune et des Parcs du Québec City, QC, Canada
| | - Jessica Fiset
- Département des Sciences Biologiques, Université de Montréal Montréal, QC, Canada
| | - Jorge Gaitan
- Redpath Museum, McGill University Montreal, QC, Canada
| | - Andrew Gonzalez
- Department of Biology, McGill University Montreal, QC, Canada
| | - Jules K Koffi
- Zoonoses Division, Centre for Food-Borne, Environmental & Zoonotic Infectious Diseases, Public Health Agency of Canada Saint-Hyacinthe, QC, Canada
| | | | - Patrick A Leighton
- Groupe de recherche en épidémiologie des zoonoses et santé publique Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
| | - Lindsay R Lindsay
- Zoonoses & Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada Winnipeg, MB, Canada
| | | | - Francois Milord
- Institut National de Santé Publique du Québec Longueuil, QC, Canada
| | - Nicholas H Ogden
- Groupe de recherche en épidémiologie des zoonoses et santé publique Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
| | - Anita Rogic
- Redpath Museum, McGill University Montreal, QC, Canada ; Département des Sciences Biologiques, Université de Montréal Montréal, QC, Canada
| | | | - Daniel Suter
- Redpath Museum, McGill University Montreal, QC, Canada
| | - Nathalie Tessier
- Département des Sciences Biologiques, Université de Montréal Montréal, QC, Canada
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The prevalence of Borrelia miyamotoi infection, and co-infections with other Borrelia spp. in Ixodes scapularis ticks collected in Canada. Parasit Vectors 2014; 7:183. [PMID: 24731287 PMCID: PMC4001108 DOI: 10.1186/1756-3305-7-183] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/02/2014] [Indexed: 11/15/2022] Open
Abstract
Background Blacklegged ticks, Ixodes scapularis are vectors of the tick-borne pathogens Borrelia burgdorferi, Anaplasma phagocytophilum and Babesia microti. Recently, the I. scapularis-borne bacterium Borrelia miyamotoi has been linked to human illness in North America. The range of this tick is expanding in Canada which may increase the potential for human exposure to these agents. Methods In this study, 4938 I. scapularis ticks collected in 2012 were tested following a newly developed PCR-based testing protocol to determine the prevalence of infection with B. miyamotoi and other pathogens in I. scapularis in Canada. Results Borrelia miyamotoi was detected in blacklegged ticks from all provinces except Newfoundland, although the infection prevalence was low (<1%). There was significant variation among provinces in the prevalence of infection of ticks with B. burgdorferi and A. phagocytophilum, but not with B. miyamotoi. Conclusions Given the widespread distribution of B. miyamotoi, infection due to this agent should be considered in patients who have been exposed to blacklegged ticks in Canada.
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Ogden NH, Mechai S, Margos G. Changing geographic ranges of ticks and tick-borne pathogens: drivers, mechanisms and consequences for pathogen diversity. Front Cell Infect Microbiol 2013; 3:46. [PMID: 24010124 PMCID: PMC3756306 DOI: 10.3389/fcimb.2013.00046] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/04/2013] [Indexed: 12/30/2022] Open
Abstract
The geographic ranges of ticks and tick-borne pathogens are changing due to global and local environmental (including climatic) changes. In this review we explore current knowledge of the drivers for changes in the ranges of ticks and tick-borne pathogen species and strains via effects on their basic reproduction number (R0), and the mechanisms of dispersal that allow ticks and tick-borne pathogens to invade suitable environments. Using the expanding geographic distribution of the vectors and agent of Lyme disease as an example we then investigate what could be expected of the diversity of tick-borne pathogens during the process of range expansion, and compare this with what is currently being observed. Lastly we explore how historic population and range expansions and contractions could be reflected in the phylogeography of ticks and tick-borne pathogens seen in recent years, and conclude that combined study of currently changing tick and tick-borne pathogen ranges and diversity, with phylogeographic analysis, may help us better predict future patterns of invasion and diversity.
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Affiliation(s)
- Nick H Ogden
- Zoonoses Division, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, QC, Canada. nicholas.ogden@ phac-aspc.gc.ca
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