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Ferguson LV, El Nabbout A, Adamo SA. Warming, but not infection with Borrelia burgdorferi, increases off-host winter activity in the ectoparasite, Ixodes scapularis. J Therm Biol 2024; 121:103853. [PMID: 38626664 DOI: 10.1016/j.jtherbio.2024.103853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 03/17/2024] [Indexed: 04/18/2024]
Abstract
Warming winters will change patterns of behaviour in temperate and polar arthropods, but we know little about the drivers of winter activity in animals such as ticks. Any changes in behaviour are likely to arise from a combination of both abiotic (e.g. temperature) and biotic (e.g. infection) drivers, and will have important consequences for survival and species interactions. Blacklegged ticks, Ixodes scapularis, have invaded Atlantic Canada and high proportions (30-50%) are infected with the bacteria causing Lyme disease, Borrelia burgdorferi. Infection is correlated with increased overwintering survival of adult females, and ticks are increasingly active in the winter, but it is unclear if infection is associated with activity. Further, we know little about how temperature drives the frequency of winter activity. Here, we exposed wild-caught, adult, female Ixodes scapularis ticks to three different winter temperature regimes (constant low temperatures, increased warming, and increased warming + variability) to determine the thermal and infection conditions that promote or suppress activity. We used automated behaviour monitors to track daily activity in individual ticks and repeated the study with fresh ticks over three years. Following exposure to winter conditions we determined whether ticks were infected with the bacteria B. burgdorferi and if infection was responsible for any patterns in winter activity. Warming conditions promoted increased activity throughout the overwintering period but infection with B. burgdorferi had no impact on the frequency or overall number of ticks active throughout the winter. Individual ticks varied in their levels of activity throughout the winter, such that some were largely dormant for several weeks, while others were active almost daily; however, we do not yet know the drivers behind this individual variation in behaviour. Overall, warming winters will heighten the risk of tick-host encounters.
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Affiliation(s)
- Laura V Ferguson
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, B3H 4J1, Canada.
| | - Amal El Nabbout
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, B3H 4J1, Canada
| | - Shelley A Adamo
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, B3H 4J1, Canada
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2
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Stokowski M, Allen D. IxPopDyMod: an R package to write, run, and analyze tick population and infection dynamics models. Parasit Vectors 2024; 17:90. [PMID: 38409067 PMCID: PMC10898031 DOI: 10.1186/s13071-024-06171-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/29/2024] [Indexed: 02/28/2024] Open
Abstract
Given the increasing prevalence of tick-borne diseases, such as Lyme disease, modeling the population and infection dynamics of tick vectors is an important public health tool. These models have applications for testing the effects of control methods or climate change on tick populations. There is an established history of tick population models, but code for them is rarely shared, especially not in a convenient format for others to modify and use. We present an R package, called IxPopDyMod, intended to function as a flexible and consistent framework for reproducible Ixodidae (hard-bodied ticks) population dynamics models. Here we focus on two key parts of the package: a function to create valid model configurations and a function to run a configured model and return the daily population over time. We provide three examples in appendices: one reproducing an existing Ixodes scapularis population model, one providing a novel Dermacentor albipictus model, and one showing Borrelia burgdorferi infection in ticks. Together these examples show the flexibility of the package to model scenarios of interest to tick researches.
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Affiliation(s)
- Myles Stokowski
- Department of Biology, Middlebury College, Middlebury, 05753, VT, USA
| | - David Allen
- Department of Biology, Middlebury College, Middlebury, 05753, VT, USA.
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3
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Valcárcel F, Elhachimi L, Vilá M, Tomassone L, Sánchez M, Selles SMA, Kouidri M, González MG, Martín-Hernández R, Valcárcel Á, Fernández N, Tercero JM, Sanchis J, Bellido-Blasco J, González-Coloma A, Olmeda AS. Emerging Hyalomma lusitanicum: From identification to vectorial role and integrated control. MEDICAL AND VETERINARY ENTOMOLOGY 2023; 37:425-459. [PMID: 37144688 DOI: 10.1111/mve.12660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 04/11/2023] [Indexed: 05/06/2023]
Abstract
In the Mediterranean basin, the tick species Hyalomma lusitanicum Koch stands out among other species of the Hyalomma genus due to its wide distribution, and there is great concern about its potential role as a vector and/or reservoir and its continuous expansion to new areas because of climate warming and human and other animal movements. This review aims to consolidate all the information on H. lusitanicum, including taxonomy and evolution, morphological and molecular identification, life cycle, sampling methods, rearing under laboratory conditions, ecology, hosts, geographical distribution, seasonality, vector role and control methods. The availability of adequate data is extremely relevant to the development of appropriate control strategies in areas where this tick is currently distributed as well as in new areas where it could become established in the near future.
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Affiliation(s)
- Félix Valcárcel
- Grupo de Parasitología Animal, Departamento de Reproducción Animal, INIA-CSIC, Madrid, Spain
| | - L Elhachimi
- Département de parasitologie et de Santé Publique, Institut Agronomique et Vétérinaire Hassan II, Rabat, Morocco
| | - M Vilá
- Grupo de Investigación COPAR (GI-2120; USC), Departamento de Patoloxia Animal, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - L Tomassone
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - M Sánchez
- Grupo de Parasitología Animal, Departamento de Reproducción Animal, INIA-CSIC, Madrid, Spain
- Villamagna S.A., Finca "La Garganta", Villanueva de Córdoba, Spain
- Facultad de Veterinaria, Universidad Alfonso X El Sabio (UAX), Madrid, Spain
| | - S M A Selles
- Institute of Veterinary Sciences, University of Tiaret, Tiaret, Algeria
- Laboratory of Research on Local Animal Products, University of Tiaret, Tiaret, Algeria
| | - M Kouidri
- Laboratory of Farm Animal Products, University of Tiaret, Tiaret, Algeria
| | - M G González
- Grupo de Parasitología Animal, Departamento de Reproducción Animal, INIA-CSIC, Madrid, Spain
- Villamagna S.A., Finca "La Garganta", Villanueva de Córdoba, Spain
| | - R Martín-Hernández
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), IRIAF-Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal, Marchamalo, 19180, Spain. Instituto de Recursos Humanos para la Ciencia y la Tecnología (INCRECYT-ESF/EC-FSE), Fundación Parque Científico y Tecnológico de Castilla-La Mancha, Albacete, Spain
| | - Á Valcárcel
- Lokimica S.L., c/ Valdemorillo, Madrid, Spain
- Veterinary Pathobiology section, University College Dublín, Dublin 4, Ireland
| | - N Fernández
- Facultad de Veterinaria, Universidad Alfonso X El Sabio (UAX), Madrid, Spain
| | - J M Tercero
- Villamagna S.A., Finca "La Garganta", Villanueva de Córdoba, Spain
| | - J Sanchis
- Facultad de Veterinaria, CENUR Litoral Norte, Universidad de la República, Uruguay
| | - J Bellido-Blasco
- Sección de Epidemiología, Centro de Salud Pública de Castelló, CIBER-ESP. Universitat Jaume I (UJI), Castelló, Spain
| | | | - A S Olmeda
- Departamento de Sanidad Animal, Facultad de Veterinaria, UCM, Madrid, Spain
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4
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Goren A, Viljugrein H, Rivrud IM, Jore S, Bakka H, Vindenes Y, Mysterud A. The emergence and shift in seasonality of Lyme borreliosis in Northern Europe. Proc Biol Sci 2023; 290:20222420. [PMID: 36809802 PMCID: PMC9943644 DOI: 10.1098/rspb.2022.2420] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Climate change has had a major impact on seasonal weather patterns, resulting in marked phenological changes in a wide range of taxa. However, empirical studies of how changes in seasonality impact the emergence and seasonal dynamics of vector-borne diseases have been limited. Lyme borreliosis, a bacterial infection spread by hard-bodied ticks, is the most common vector-borne disease in the northern hemisphere and has been rapidly increasing in both incidence and geographical distribution in many regions of Europe and North America. By analysis of long-term surveillance data (1995-2019) from across Norway (latitude 57°58'-71°08' N), we demonstrate a marked change in the within-year timing of Lyme borreliosis cases accompanying an increase in the annual number of cases. The seasonal peak in cases is now six weeks earlier than 25 years ago, exceeding seasonal shifts in plant phenology and previous model predictions. The seasonal shift occurred predominantly in the first 10 years of the study period. The concurrent upsurgence in case number and shift in case timing indicate a major change in the Lyme borreliosis disease system over recent decades. This study highlights the potential for climate change to shape the seasonal dynamics of vector-borne disease systems.
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Affiliation(s)
- Asena Goren
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, Oslo NO-0316, Norway
| | - Hildegunn Viljugrein
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, Oslo NO-0316, Norway.,Norwegian Veterinary Institute, PO Box 64, NO-1431 Ås, Norway
| | - Inger Maren Rivrud
- Norwegian Institute for Nature Research (NINA), Sognsveien 68, NO-0855 Oslo, Norway
| | - Solveig Jore
- Zoonotic, Food and Waterborne Infections, The Norwegian Public Health Institute, PO Box 4404 Nydalen, NO-0403 Oslo, Norway
| | - Haakon Bakka
- Norwegian Veterinary Institute, PO Box 64, NO-1431 Ås, Norway
| | - Yngvild Vindenes
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, Oslo NO-0316, Norway
| | - Atle Mysterud
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, Oslo NO-0316, Norway.,Norwegian Institute for Nature Research (NINA), PO Box 5685 Sluppen, NO-7485 Trondheim, Norway
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5
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Estrada-Peña A, Fernández-Ruiz N. An Agenda for Research of Uncovered Epidemiological Patterns of Tick-Borne Pathogens Affecting Human Health. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:2206. [PMID: 36767573 PMCID: PMC9915995 DOI: 10.3390/ijerph20032206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/11/2023] [Accepted: 01/22/2023] [Indexed: 06/18/2023]
Abstract
The panorama of ticks and tick-borne pathogens (TBP) is complex due to the many interactions among vertebrates, vectors, and habitats, occurring at different scales. At a broad spatial range, climate and host availability regulate most tick processes, including questing activity, development, and survival. At a local scale, interactions are obscured by a high indeterminacy, making it arduous to record in field surveys. A solid modelling framework could translate the local/regional empirical findings into larger scales, shedding light on the processes governing the circulation of TBP. In this opinion paper, we advocate for a re-formulation of some paradigms in the research of these outstanding cycles of transmission. We propose revisiting concepts that faced criticisms or lacked solid support, together with the development of a conceptual scheme exploring the circulation of TBP under a range of conditions. We encourage (i) an adequate interpretation of the niche concept of both ticks and vertebrate/reservoir hosts interpreting the (a)biotic components that shape the tick's niche, (ii) an assessment of the role played by the communities of wild vertebrates on the circulation of pathogens, and (iii) the development of new approaches, based on state-of-the-art epidemiological concepts, to integrate findings and modelling efforts on TBP over large regions.
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Affiliation(s)
- Agustín Estrada-Peña
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain
- Instituto Agroalimentario de Aragón (IA2), 50013 Zaragoza, Spain
| | - Natalia Fernández-Ruiz
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain
- Instituto Agroalimentario de Aragón (IA2), 50013 Zaragoza, Spain
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6
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Mangan MJ, Foré SA, Kim HJ. Seasonal changes in questing efficiency of wild Amblyomma americanum (Acari: Ixodidae) nymphs. Ticks Tick Borne Dis 2022; 13:101988. [PMID: 35763958 DOI: 10.1016/j.ttbdis.2022.101988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 10/18/2022]
Abstract
Understanding the factors which influence host-seeking behavior of ticks is essential to determine the risk they pose as a vector of pathogens. While many studies have evaluated the impact of environmental variables on tick behavior, few have examined how seasonal changes in physiological status may further modify patterns of activity. In this study, we measured differences in questing behavior of mid spring- and early summer-caught Amblyomma americanum nymphs held under standardized laboratory conditions. As both groups represent the same cohort of overwintered nymphs, we hypothesized that age-related changes in the older summer ticks may influence questing behavior. In each season, we collected nymphs from field and forest habitats in northeast Missouri, after which we placed each nymph individually in a desiccating vertical questing apparatus with a hydrating microenvironment at the base. On the day following collection, we recorded the height of each nymph in the apparatus bi-hourly from 04:00 to 22:00 and calculated the vertical displacement between consecutive observations. Despite displaying no differences in mean questing height throughout the experiment, active ticks collected in the summer group (n = 89) travelled greater cumulative distances between desiccating and hydrating microenvironments than those collected in the spring (n = 119). This suggests that questing efficiency decreases in summer nymphs to accommodate increased time allocation towards rehydration. While we observed no direct association between body size and distance travelled, body size of the nymphal population also decreased significantly from spring to summer. Overall, our results demonstrate that there are seasonal changes in how A. americanum responds to environmental conditions. To more accurately predict host-seeking behavior of ticks across seasons, models should incorporate physiological parameters of the active ticks in a given population.
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Affiliation(s)
- Madelyn J Mangan
- Centre for Planetary Health and Food Security, Griffith University, Southport, QLD, Australia; Department of Biology, Truman State University, Kirksville, MO, USA.
| | - Stephanie A Foré
- Department of Biology, Truman State University, Kirksville, MO, USA
| | - Hyun-Joo Kim
- Department of Statistics, Truman State University, Kirksville, MO USA
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7
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Payo-Payo A, Acker P, Bocedi G, Travis JMJ, Burthe SJ, Harris MP, Wanless S, Newell M, Daunt F, Reid JM. Modelling the responses of partially-migratory metapopulations to changing seasonal migration rates: from theory to data. J Anim Ecol 2022; 91:1781-1796. [PMID: 35633181 PMCID: PMC9545393 DOI: 10.1111/1365-2656.13748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 05/04/2022] [Indexed: 11/30/2022]
Abstract
Among‐individual and within‐individual variation in expression of seasonal migration versus residence is widespread in nature and could substantially affect the dynamics of partially migratory metapopulations inhabiting seasonally and spatially structured environments. However, such variation has rarely been explicitly incorporated into metapopulation dynamic models for partially migratory systems. We, therefore, lack general frameworks that can identify how variable seasonal movements, and associated season‐ and location‐specific vital rates, can control system persistence. We constructed a novel conceptual framework that captures full‐annual‐cycle dynamics and key dimensions of metapopulation structure for partially migratory species inhabiting seasonal environments. We conceptualize among‐individual variation in seasonal migration as two variable vital rates: seasonal movement probability and associated movement survival probability. We conceptualize three levels of within‐individual variation (i.e. plasticity), representing seasonal or annual variation in seasonal migration or lifelong fixed strategies. We formulate these concepts as a general matrix model, which is customizable for diverse life‐histories and seasonal landscapes. To illustrate how variable seasonal migration can affect metapopulation growth rate, demographic structure and vital rate elasticities, we parameterize our general models for hypothetical short‐ and longer‐lived species. Analyses illustrate that elasticities of seasonal movement probability and associated survival probability can sometimes equal or exceed those of vital rates typically understood to substantially influence metapopulation dynamics (i.e. seasonal survival probability or fecundity), that elasticities can vary non‐linearly, and that metapopulation outcomes depend on the level of within‐individual plasticity. We illustrate how our general framework can be applied to evaluate the consequences of variable and changing seasonal movement probability by parameterizing our models for a real partially migratory metapopulation of European shags Gulosus aristotelis assuming lifelong fixed strategies. Given observed conditions, metapopulation growth rate was most elastic to breeding season adult survival of the resident fraction in the dominant population. However, given doubled seasonal movement probability, variation in survival during movement would become the primary driver of metapopulation dynamics. Our general conceptual and matrix model frameworks, and illustrative analyses, thereby highlight complex ways in which structured variation in seasonal migration can influence dynamics of partially migratory metapopulations, and pave the way for diverse future theoretical and empirical advances.
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Affiliation(s)
- Ana Payo-Payo
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK
| | - Paul Acker
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK.,Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway
| | - Greta Bocedi
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK
| | - Justin M J Travis
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK
| | - Sarah J Burthe
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - Michael P Harris
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - Sarah Wanless
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - Mark Newell
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - Francis Daunt
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - Jane M Reid
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK.,Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway
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8
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Sentinel Surveillance Contributes to Tracking Lyme Disease Spatiotemporal Risk Trends in Southern Quebec, Canada. Pathogens 2022; 11:pathogens11050531. [PMID: 35631052 PMCID: PMC9145942 DOI: 10.3390/pathogens11050531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/16/2022] Open
Abstract
Lyme disease (LD) is a tick-borne disease which has been emerging in temperate areas in North America, Europe, and Asia. In Quebec, Canada, the number of human LD cases is increasing rapidly and thus surveillance of LD risk is a public health priority. In this study, we aimed to evaluate the ability of active sentinel surveillance to track spatiotemporal trends in LD risk. Using drag flannel data from 2015–2019, we calculated density of nymphal ticks (DON), an index of enzootic hazard, across the study region (southern Quebec). A Poisson regression model was used to explore the association between the enzootic hazard and LD risk (annual number of human cases) at the municipal level. Predictions from models were able to track both spatial and interannual variation in risk. Furthermore, a risk map produced by using model predictions closely matched the official risk map published by provincial public health authorities, which requires the use of complex criteria-based risk assessment. Our study shows that active sentinel surveillance in Quebec provides a sustainable system to follow spatiotemporal trends in LD risk. Such a network can support public health authorities in informing the public about LD risk within their region or municipality and this method could be extended to support Lyme disease risk assessment at the national level in Canada.
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9
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Jensen PM, Danielsen F, Skarphedinsson S. Monitoring Temporal Trends in Internet Searches for “Ticks” across Europe by Google Trends: Tick–Human Interaction or General Interest? INSECTS 2022; 13:insects13020176. [PMID: 35206749 PMCID: PMC8877544 DOI: 10.3390/insects13020176] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/03/2022] [Accepted: 02/04/2022] [Indexed: 02/01/2023]
Abstract
Simple Summary It is notoriously difficult to track the spread of vector-borne diseases, and to determine the underlying causes of change in disease occurrence. Importantly, public health representatives have limited access to information, which permit them to assess trends and changes in vector–human contact. Exposed individuals may, however, seek information on the Internet and thereby deliver input to a search record for the given vector. The variation in search-frequencies may reflect the variation in contact rates, but varying general interest could also influence the data. We here investigated records for search terms synonymous with “tick(s)”, and found that the records reflect the seasonal variation, which one would expect when these result from tick encounters. Albeit, variable use of search terminology suggest that these records should not be used to make comparisons between years. Abstract Monitoring vector–human interaction is pivotal for assessing potential transmission rates of vector borne diseases and their associated public health impact. People often seek information following an insect bite in order to identify hematophagous arthropods, which in recent years often is done using Internet resources. Through this activity, a record of net searches is generated, which include information that reflect local human–arthropod interaction, e.g., for the common tick (Ixodes ricinus) in European countries. Such records could in principle provide low cost real-time monitoring data, if indeed Internet search activities adequately reflect tick–human interaction. We here explore Google Trends records for within-year and between-year trends, for four different Danish search terms for “tick(s)”. We further assess the relationship between monthly search-frequencies and local weather conditions (temperatures and precipitation from 2007 to 2016) in nine European countries. Our findings point to significant limitations in the records due to changes in search-term preferences over the given years. However, the seasonal dynamics are comparable among search-terms. Moreover, the seasonal pattern in search terms vary across Europe in tune with changes in temperature and precipitation. We conclude that, the within-year variation for given search-terms provide credible information, which systematically vary with local weather patterns. We are not convinced that these records merely reflect general interest. It will, however, require a more in-depth analysis by researchers that have specific insight into local language practices to fully assess the strength and weaknesses of this approach
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Affiliation(s)
- Per M. Jensen
- Department of Plants and Environmental Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
- Correspondence:
| | - Finn Danielsen
- Nordic Foundation for Development and Ecology (NORDECO), Skindergade 23, 3rd Floor, 1159 Copenhagen, Denmark;
| | - Sigurdur Skarphedinsson
- Clinical Center for Emerging and Vector-borne Infections, Department of Infectious Diseases, Odense University Hospital, Winsloews vej 4, 5000 Odense, Denmark;
- Research Unit of Infectious Diseases, Department of Clinical Research, Faculty of Health Science, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
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10
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Tick bite risk resulting from spatially heterogeneous hazard, exposure and coping capacity. ECOLOGICAL COMPLEXITY 2021. [DOI: 10.1016/j.ecocom.2021.100967] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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11
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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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12
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Zhang X, Wu J. Synchronized Tick Population Oscillations Driven by Host Mobility and Spatially Heterogeneous Developmental Delays Combined. Bull Math Biol 2021; 83:61. [PMID: 33870474 PMCID: PMC8053666 DOI: 10.1007/s11538-021-00874-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/23/2021] [Indexed: 12/05/2022]
Abstract
We consider a coupled system of delay differential equations for a single-species tick population dynamics, assuming feeding adult ticks are distributed by their hosts in a spatially heterogeneous environment consisting of two patches where egg ticks produced will complete their life cycles with different, normal and diapause, developmental delays. We show that the mobility of adult tick host and the diapause developmental delay combined drive a synchronized oscillation in the total tick populations around a uniquely defined positive equilibrium, and this synchronization makes the oscillatory patterns much simpler in comparison with multi-peak oscillations exhibited in the absence of host mobility.
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Affiliation(s)
- Xue Zhang
- College of Science, Northeastern University, Shenyang, 110819 Liaoning China
| | - Jianhong Wu
- Laboratory for Industrial and Applied Mathematics, York University, Toronto, ON M3J 1P3 Canada
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13
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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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14
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Keyte S, Abdullah S, James K, Newbury H, Helps C, Tasker S, Wall R. Prevalence and distribution of Anaplasma phagocytophilum in ticks collected from dogs in the United Kingdom. Vet Rec 2021; 188:e12. [PMID: 33818768 DOI: 10.1002/vetr.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/07/2020] [Accepted: 11/09/2020] [Indexed: 12/30/2022]
Abstract
BACKGROUND Anaplasma phagocytophilum is the etiological agent of canine granulocytic anaplasmosis in dogs and causes human granulocytic anaplasmosis (HGA). Tick-borne anaplasmosis has been recognised as an emerging zoonotic health concern worldwide. The aim of the present study was to determine the prevalence of A. phagocytophilum in ticks collected from dogs in the UK and map its distribution. Routine surveillance of tick-borne disease is essential as part of a "One Health" approach to infectious disease management. METHODS Tick DNA samples collected in 2015 as part of a large-scale tick surveillance programme were analysed using a previously validated diagnostic quantitative PCR for A. phagocytophilum. RESULTS PCR analysis indicated that 138 out of 2994 tick DNA samples analysed were positive for A. phagocytophilum, a prevalence of 4.6% (95% CI: 3.89-5.42). Among these 138 tick DNA samples, 131 were from Ixodes ricinus, six were from Ixodes hexagonus and one was from Ixodes canisuga. Three of the I. ricinus tick DNA samples positive for A. phagocytophilum DNA were also positive for Borrelia spp. DNA and one was positive for Babesia spp. DNA, indicating co-infection. The ticks positive for the pathogen DNA were found widely distributed throughout the UK. CONCLUSIONS These data provide important information on the prevalence and wide distribution of A. phagocytophilum in ticks infesting dogs within the UK.
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Affiliation(s)
- Sophie Keyte
- Bristol Veterinary School, University of Bristol, Bristol, UK
| | - Swaid Abdullah
- School of Biological Sciences, University of Bristol, Bristol, UK.,School of Veterinary Science, University of Queensland, Queensland, Australia
| | - Kate James
- Molecular Diagnostic Unit, Diagnostic Laboratories, Langford Vets, University of Bristol, Bristol, UK
| | | | - Chris Helps
- Molecular Diagnostic Unit, Diagnostic Laboratories, Langford Vets, University of Bristol, Bristol, UK
| | - Séverine Tasker
- Bristol Veterinary School, University of Bristol, Bristol, UK.,Molecular Diagnostic Unit, Diagnostic Laboratories, Langford Vets, University of Bristol, Bristol, UK
| | - Richard Wall
- School of Biological Sciences, University of Bristol, Bristol, UK
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15
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Perveen N, Muzaffar SB, Al-Deeb MA. Ticks and Tick-Borne Diseases of Livestock in the Middle East and North Africa: A Review. INSECTS 2021; 12:83. [PMID: 33477991 PMCID: PMC7835866 DOI: 10.3390/insects12010083] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 01/18/2023]
Abstract
Ticks are important vectors of an array of viral, bacterial and protozoan pathogens resulting in a wide range of animal and human diseases. There is limited information in the literature about tick species in the Middle East and North Africa (MENA) countries, even though they have suitable climate and vegetation for ticks and their hosts. We reviewed the occurrence of tick species and the pathogens they transmit from the MENA on published papers from 1901-2020. We found taxonomic records of 55 tick species infesting livestock representing the following eight genera: Ornithodoros, Otobius, Amblyomma, Dermacentor, Haemaphysalis, Hyalomma, Ixodes, and Rhipicephalus. In addition, 15 pathogens were recorded causing diseases of significance, with Crimean-Congo hemorrhagic fever, theileriosis, babesiosis and anaplasmosis being widely distributed diseases in the region. In recent decades, there has been increasing trends in disease occurrence and movement associated with global movement of humans and global trade of animals. We suggest that disease control and prevention could be achieved effectively through good integration between public health, veterinary medicine and animal management, and ecological approaches. We recommend further research in the areas of tick ecology and tick born-disease transmission. Furthermore, we suggest evaluation and improvement of disease control policies in the region.
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Affiliation(s)
| | | | - Mohammad Ali Al-Deeb
- Department of Biology, United Arab Emirates University, Al-Ain 15551, UAE; (N.P.); (S.B.M.)
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16
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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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17
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Bacterial community profiling highlights complex diversity and novel organisms in wildlife ticks. Ticks Tick Borne Dis 2020; 11:101407. [PMID: 32051105 DOI: 10.1016/j.ttbdis.2020.101407] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/24/2020] [Accepted: 02/04/2020] [Indexed: 10/25/2022]
Abstract
Ticks Acari:Ixodida transmit a greater variety of pathogens than any other blood-feeding group of arthropods. While numerous microbes have been identified inhabiting Australian Ixodidae, some of which are related to globally important tick-borne pathogens, little is known about the bacterial communities within ticks collected from Australian wildlife. In this study, 1,019 ticks were identified on 221 hosts spanning 27 wildlife species. Next-generation sequencing was used to amplify the V1-2 hypervariable region of the bacterial 16S rRNA gene from 238 ticks; Amblyomma triguttatum (n = 6), Bothriocroton auruginans (n = 11), Bothriocroton concolor (n = 20), Haemaphysalis bancrofti (n = 10), Haemaphysalis bremneri (n = 4), Haemaphysalis humerosa (n = 13), Haemaphysalis longicornis (n = 4), Ixodes antechini (n = 29), Ixodes australiensis (n = 26), Ixodes fecialis (n = 13), Ixodes holocyclus (n = 37), Ixodes myrmecobii (n = 1), Ixodes ornithorhynchi (n = 10), Ixodes tasmani (n = 51) and Ixodes trichosuri (n = 3). After bioinformatic analyses, over 14 million assigned bacterial sequences revealed the presence of recently described bacteria 'Candidatus Borrelia tachyglossi', 'Candidatus Neoehrlichia australis', 'Candidatus Neoehrlichia arcana' and 'Candidatus Ehrlichia ornithorhynchi'. Furthermore, three novel Anaplasmataceae species were identified in the present study including; a Neoehrlichia sp. in I. australiensis and I. fecialis collected from quenda (Isoodon fusciventer) (Western Australia), an Anaplasma sp. from one B. concolor from echidna (Tachyglossus aculeatus) (New South Wales), and an Ehrlichia sp. from a single I. fecialis parasitising a quenda (WA). This study highlights the diversity of bacterial genera harboured within wildlife ticks, which may prove to be of medical and/or veterinary importance in the future.
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18
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Jung Kjær L, Soleng A, Edgar KS, Lindstedt HEH, Paulsen KM, Andreassen ÅK, Korslund L, Kjelland V, Slettan A, Stuen S, Kjellander P, Christensson M, Teräväinen M, Baum A, Klitgaard K, Bødker R. Predicting the spatial abundance of Ixodes ricinus ticks in southern Scandinavia using environmental and climatic data. Sci Rep 2019; 9:18144. [PMID: 31792296 PMCID: PMC6889419 DOI: 10.1038/s41598-019-54496-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/15/2019] [Indexed: 01/24/2023] Open
Abstract
Recently, focus on tick-borne diseases has increased as ticks and their pathogens have become widespread and represent a health problem in Europe. Understanding the epidemiology of tick-borne infections requires the ability to predict and map tick abundance. We measured Ixodes ricinus abundance at 159 sites in southern Scandinavia from August-September, 2016. We used field data and environmental variables to develop predictive abundance models using machine learning algorithms, and also tested these models on 2017 data. Larva and nymph abundance models had relatively high predictive power (normalized RMSE from 0.65–0.69, R2 from 0.52–0.58) whereas adult tick models performed poorly (normalized RMSE from 0.94–0.96, R2 from 0.04–0.10). Testing the models on 2017 data produced good results with normalized RMSE values from 0.59–1.13 and R2 from 0.18–0.69. The resulting 2016 maps corresponded well with known tick abundance and distribution in Scandinavia. The models were highly influenced by temperature and vegetation, indicating that climate may be an important driver of I. ricinus distribution and abundance in Scandinavia. Despite varying results, the models predicted abundance in 2017 with high accuracy. The models are a first step towards environmentally driven tick abundance models that can assist in determining risk areas and interpreting human incidence data.
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Affiliation(s)
- Lene Jung Kjær
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark. .,Department for Diagnostics and Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark.
| | - Arnulf Soleng
- Department of Pest Control, Norwegian Institute of Public Health, Oslo, Norway
| | | | | | - Katrine Mørk Paulsen
- Department of Virology, Norwegian Institute of Public Health, Oslo, Norway.,Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | | | - Lars Korslund
- Department of Natural Sciences, University of Agder, Kristiansand, Norway
| | - Vivian Kjelland
- Department of Natural Sciences, University of Agder, Kristiansand, Norway.,Sørlandet Hospital Health Enterprise, Research Unit, Kristiansand, Norway
| | - Audun Slettan
- Department of Natural Sciences, University of Agder, Kristiansand, Norway
| | - Snorre Stuen
- Department of Production Animal Clinical Sciences, Section of Small Ruminant Research, Norwegian University of Life Sciences, Sandnes, Norway
| | - Petter Kjellander
- Department of Ecology, Wildlife Ecology Unit, Swedish University of Agricultural Sciences, Grimsö, Sweden
| | - Madeleine Christensson
- Department of Ecology, Wildlife Ecology Unit, Swedish University of Agricultural Sciences, Grimsö, Sweden
| | - Malin Teräväinen
- Department of Ecology, Wildlife Ecology Unit, Swedish University of Agricultural Sciences, Grimsö, Sweden
| | - Andreas Baum
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark
| | - Kirstine Klitgaard
- Department for Diagnostics and Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark
| | - René Bødker
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.,Department for Diagnostics and Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark
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19
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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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20
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Nah K, Magpantay FMG, Bede-Fazekas Á, Röst G, Trájer AJ, Wu X, Zhang X, Wu J. Assessing systemic and non-systemic transmission risk of tick-borne encephalitis virus in Hungary. PLoS One 2019; 14:e0217206. [PMID: 31163042 PMCID: PMC6548428 DOI: 10.1371/journal.pone.0217206] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 05/07/2019] [Indexed: 01/28/2023] Open
Abstract
Estimating the tick-borne encephalitis (TBE) infection risk under substantial uncertainties of the vector abundance, environmental condition and human-tick interaction is important for evidence-informed public health intervention strategies. Estimating this risk is computationally challenging since the data we observe, i.e., the human incidence of TBE, is only the final outcome of the tick-host transmission and tick-human contact processes. The challenge also increases since the complex TBE virus (TBEV) transmission cycle involves the non-systemic route of transmission between co-feeding ticks. Here, we describe the hidden Markov transition process, using a novel TBEV transmission-human case reporting cascade model that couples the susceptible-infected compartmental model describing the TBEV transmission dynamics among ticks, animal hosts and humans, with the stochastic observation process of human TBE reporting given infection. By fitting human incidence data in Hungary to the transmission model, we estimate key parameters relevant to the tick-host interaction and tick-human transmission. We then use the parametrized cascade model to assess the transmission potential of TBEV in the enzootic cycle with respect to the climate change, and to evaluate the contribution of non-systemic transmission. We show that the TBEV transmission potential in the enzootic cycle has been increasing along with the increased temperature though the TBE human incidence has dropped since 1990s, emphasizing the importance of persistent public health interventions. By demonstrating that non-systemic transmission pathway is a significant factor in the transmission of TBEV in Hungary, we conclude that the risk of TBE infection will be highly underestimated if the non-systemic transmission route is neglected in the risk assessment.
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Affiliation(s)
- Kyeongah Nah
- Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | | | - Ákos Bede-Fazekas
- Institute of Ecology and Botany, MTA Centre for Ecological Research, Vácrátót, Hungary
- GINOP Sustainable Ecosystems Group, MTA Centre for Ecological Research, Tihany, Hungary
| | - Gergely Röst
- Wolfson Centre for Mathematical Biology, University of Oxford, Oxford, United Kingdom
- Bolyai Institute, University of Szeged, Szeged, Hungary
| | - Attila János Trájer
- Department of Limnology, University of Pannonia, Veszprém, Hungary
- Institute of Environmental Engineering, University of Pannonia, Veszprém, Hungary
| | - Xiaotian Wu
- College of Arts and Sciences, Shanghai Maritime University, Shanghai, China
| | - Xue Zhang
- Department of Mathematics, Northeastern University, Shenyang, China
| | - Jianhong Wu
- Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
- * E-mail:
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21
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Li S, Gilbert L, Vanwambeke SO, Yu J, Purse BV, Harrison PA. Lyme Disease Risks in Europe under Multiple Uncertain Drivers of Change. ENVIRONMENTAL HEALTH PERSPECTIVES 2019; 127:67010. [PMID: 31232609 PMCID: PMC6792373 DOI: 10.1289/ehp4615] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
BACKGROUND Debates over whether climate change could lead to the amplification of Lyme disease (LD) risk in the future have received much attention. Although recent large-scale disease mapping studies project an overall increase in Lyme disease risk as the climate warms, such conclusions are based on climate-driven models in which other drivers of change, such as land-use/cover and host population distribution, are less considered. OBJECTIVES The main objectives were to project the likely future ecological risk patterns of LD in Europe under different assumptions about future socioeconomic and climate conditions and to explore similarity and uncertainty in the projected risks. METHODS An integrative, spatially explicit modeling study of the ecological risk patterns of LD in Europe was conducted by applying recent advances in process-based modeling of tick-borne diseases, species distribution mapping, and scenarios of land-use/cover change. We drove the model with stakeholder-driven, integrated scenarios of plausible future socioeconomic and climate change [the Shared Socioeconomic Pathway (SSPs) combined with the Representative Concentration Pathways (RCPs)]. RESULTS The model projections suggest that future temperature increases may not always amplify LD risk: Low emissions scenarios (RCP2.6) combined with a sustainability socioeconomic scenario (SSP1) resulted in reduced LD risk. The greatest increase in risk was projected under intermediate (RCP4.5) rather than high-end (RCP8.5) climate change scenarios. Climate and land-use change were projected to have different roles in shaping the future regional dynamics of risk, with climate warming being likely to cause risk expansion in northern Europe and conversion of forest to agriculture being likely to limit risk in southern Europe. CONCLUSIONS Projected regional differences in LD risk resulted from mixed effects of temperature, land use, and host distributions, suggesting region-specific and cross-sectoral foci for LD risk management policy. The integrated model provides an improved explanatory tool for the system mechanisms of LD pathogen transmission and how pathogen transmission could respond to combined socioeconomic and climate changes. https://doi.org/10.1289/EHP4615.
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Affiliation(s)
- Sen Li
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, P.R. China
- Centre for Ecology & Hydrology, Wallingford, UK
- Environmental Change Institute, University of Oxford, Oxford, UK
| | - Lucy Gilbert
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Sophie O. Vanwambeke
- Georges Lemaître Centre for Earth and Climate Research, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Jianjun Yu
- Environmental Change Institute, University of Oxford, Oxford, UK
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22
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McClure M, Diuk-Wasser MA. Climate impacts on blacklegged tick host-seeking behavior. Int J Parasitol 2018; 49:37-47. [PMID: 30447202 DOI: 10.1016/j.ijpara.2018.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/04/2018] [Accepted: 08/13/2018] [Indexed: 11/26/2022]
Abstract
The nymph of the blacklegged tick (Ixodes scapularis), the primary North American vector of the causative agent of Lyme disease, must attach to a host by the end of its questing season in order to feed and subsequently molt into an adult. The proper timing of this behavior is critical both for the tick's survival and for perpetuating the transmission of tick-borne pathogens. Questing also depletes limited nymphal lipid reserves and increases desiccation risk. Given this tradeoff, questing behavior and its environmental influences can be expressed in a dynamic state variable model. We develop what we believe to be the first such model for a tick, and investigate the influence of climate on nymph fitness predictions. We apply these results to the hypothesized inland migration of I. scapularis from island refugia, evaluating fitness under suboptimal questing strategies and uncertain environmental conditions.
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Affiliation(s)
- Max McClure
- Vagelos College of Physicians & Surgeons, Columbia University, New York City, NY 10032, USA
| | - Maria A Diuk-Wasser
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York City, NY 10027, USA.
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23
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Selmi M, Tomassone L, Ceballos LA, Crisci A, Ragagli C, Pintore MD, Mignone W, Pautasso A, Ballardini M, Casalone C, Mannelli A. Analysis of the environmental and host-related factors affecting the distribution of the tick Dermacentor marginatus. EXPERIMENTAL & APPLIED ACAROLOGY 2018; 75:209-225. [PMID: 29713917 DOI: 10.1007/s10493-018-0257-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 04/19/2018] [Indexed: 06/08/2023]
Abstract
Understanding and responding to the ecological, social and economic conditions that facilitate disease emergence and transmission represents a substantial challenge for epidemiologists and health professionals. In this article we integrate knowledge about the human and the vector population, to provide a context from which to examine the underlying causal factors of D. marginatus-borne diseases emergence in the study area. Within this framework we analyse the biotic and abiotic factors that drive D. marginatus population dynamics and the role of its typical host for dispersal. These investigations suggest that D. marginatus is a tick species prone to spatially overlap its presence with human population presence. Then we consider the public health implications for the residents, when simply carrying out trivial outdoor activities may increase the risk to contact an infected tick.
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Affiliation(s)
- Marco Selmi
- Department of Prevention, Observatory for Vector Borne Diseases, Piazza Aldo Moro, Capannori, 55012, Lucca, Italy.
| | - Laura Tomassone
- Department of Veterinary Sciences, University of Turin, Via L. da Vinci 44, 10095, Grugliasco, Turin, Italy
| | - Leonardo A Ceballos
- Department of Veterinary Sciences, University of Turin, Via L. da Vinci 44, 10095, Grugliasco, Turin, Italy
| | - Alfonso Crisci
- Institute of Biometeorology, Italian National Research Council, Via G. Caproni 8, Florence, Italy
| | | | - Maria D Pintore
- Experimental Zooprophylactic Institute of Piedmont Liguria and Aosta Valley, Turin, Italy
| | - Walter Mignone
- Experimental Zooprophylactic Institute of Piedmont Liguria and Aosta Valley, Turin, Italy
| | - Alessandra Pautasso
- Experimental Zooprophylactic Institute of Piedmont Liguria and Aosta Valley, Turin, Italy
| | - Marco Ballardini
- Experimental Zooprophylactic Institute of Piedmont Liguria and Aosta Valley, Turin, Italy
| | - Cristina Casalone
- Experimental Zooprophylactic Institute of Piedmont Liguria and Aosta Valley, Turin, Italy
| | - Alessandro Mannelli
- Department of Veterinary Sciences, University of Turin, Via L. da Vinci 44, 10095, Grugliasco, Turin, Italy
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24
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Furness RW, Furness EN. Ixodes ricinus parasitism of birds increases at higher winter temperatures. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2018; 43:59-62. [PMID: 29757511 DOI: 10.1111/jvec.12283] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 11/19/2017] [Indexed: 06/08/2023]
Abstract
Increasing winter temperatures are expected to cause seasonal activity of Ixodes ricinus ticks to extend further into the winter. We caught birds during winter months (November to February) at a site in the west of Scotland over a period of 24 years (1993-1994 to 2016-2017) to quantify numbers of attached I. ricinus and to relate these to monthly mean temperature. No adult ticks were found on any of the 21,731 bird captures, but 946 larvae and nymphs were found, with ticks present in all winter months, on 16 different species of bird hosts. All ticks identified to species were I. ricinus. I. ricinus are now active throughout the year in this area providing temperature permits. No I. ricinus were present in seven out of eight months when the mean temperature was below 3.5º C. Numbers of I. ricinus attached to birds increased rapidly with mean monthly temperatures above 7º C. Winter temperatures in Scotland have been above the long-term average in most years in the last two decades, and this is likely to increase risk of tick-borne disease.
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Affiliation(s)
- Robert W Furness
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Euan N Furness
- Clare College, University of Cambridge, Cambridge CB2 1TL, UK
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25
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Rosà R, Andreo V, Tagliapietra V, Baráková I, Arnoldi D, Hauffe HC, Manica M, Rosso F, Blaňarová L, Bona M, Derdáková M, Hamšíková Z, Kazimírová M, Kraljik J, Kocianová E, Mahríková L, Minichová L, Mošanský L, Slovák M, Stanko M, Špitalská E, Ducheyne E, Neteler M, Hubálek Z, Rudolf I, Venclikova K, Silaghi C, Overzier E, Farkas R, Földvári G, Hornok S, Takács N, Rizzoli A. Effect of Climate and Land Use on the Spatio-Temporal Variability of Tick-Borne Bacteria in Europe. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15040732. [PMID: 29649132 PMCID: PMC5923774 DOI: 10.3390/ijerph15040732] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/29/2018] [Accepted: 04/10/2018] [Indexed: 11/29/2022]
Abstract
The incidence of tick-borne diseases caused by Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Rickettsia spp. has been rising in Europe in recent decades. Early pre-assessment of acarological hazard still represents a complex challenge. The aim of this study was to model Ixodes ricinus questing nymph density and its infection rate with B. burgdorferi s.l., A. phagocytophilum and Rickettsia spp. in five European countries (Italy, Germany, Czech Republic, Slovakia, Hungary) in various land cover types differing in use and anthropisation (agricultural, urban and natural) with climatic and environmental factors (Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Land Surface Temperature (LST) and precipitation). We show that the relative abundance of questing nymphs was significantly associated with climatic conditions, such as higher values of NDVI recorded in the sampling period, while no differences were observed among land use categories. However, the density of infected nymphs (DIN) also depended on the pathogen considered and land use. These results contribute to a better understanding of the variation in acarological hazard for Ixodes ricinus transmitted pathogens in Central Europe and provide the basis for more focused ecological studies aimed at assessing the effect of land use in different sites on tick–host pathogens interaction.
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Affiliation(s)
- Roberto Rosà
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
| | - Veronica Andreo
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
- Department of Earth Observation Science, Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, 7500 AE Enschede, The Netherlands.
| | - Valentina Tagliapietra
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
| | - Ivana Baráková
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Daniele Arnoldi
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
| | - Heidi Christine Hauffe
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
| | - Mattia Manica
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
| | - Fausta Rosso
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
| | - Lucia Blaňarová
- Parasitological Institute, Slovak Academy of Sciences, 04001 Košice, Slovakia.
| | - Martin Bona
- Department of Anatomy, Pavol Jozef Šafárik University, 04001 Košice, Slovakia.
| | - Marketa Derdáková
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Zuzana Hamšíková
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Maria Kazimírová
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Jasna Kraljik
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Elena Kocianová
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia.
| | - Lenka Mahríková
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Lenka Minichová
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia.
| | - Ladislav Mošanský
- Parasitological Institute, Slovak Academy of Sciences, 04001 Košice, Slovakia.
| | - Mirko Slovák
- Institute of Zoology, Slovak Academy of Sciences, 84506 Bratislava, Slovakia.
| | - Michal Stanko
- Parasitological Institute, Slovak Academy of Sciences, 04001 Košice, Slovakia.
| | - Eva Špitalská
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia.
| | - Els Ducheyne
- Avia-GIS, Risschotlei 33, 2980 Zoersel, Belgium.
| | | | - Zdenek Hubálek
- Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, 60365 Brno, Czech Republic.
| | - Ivo Rudolf
- Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, 60365 Brno, Czech Republic.
| | - Kristyna Venclikova
- Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, 60365 Brno, Czech Republic.
- Institute of Macromolecular Chemistry CAS, 16206 Prague 6, Czech Republic.
| | - Cornelia Silaghi
- Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität, 80802 Munich, Germany.
- Institute of Parasitology, National Centre for Vector Entomology, Vetsuisse-Faculty, University of Zurich, 8057 Zürich, Switzerland.
- Institute of Infectology, Friedrich-Loeffler-Institut, 17493 Greifswald, Germany.
| | - Evelyn Overzier
- Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität, 80802 Munich, Germany.
| | - Robert Farkas
- Department of Parasitology and Zoology, University of Veterinary Medicine, 1078 Budapest, Hungary.
| | - Gábor Földvári
- Department of Parasitology and Zoology, University of Veterinary Medicine, 1078 Budapest, Hungary.
| | - Sándor Hornok
- Department of Parasitology and Zoology, University of Veterinary Medicine, 1078 Budapest, Hungary.
| | - Nóra Takács
- Department of Parasitology and Zoology, University of Veterinary Medicine, 1078 Budapest, Hungary.
| | - Annapaola Rizzoli
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all'Adige, Italy.
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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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Boehnke D, Gebhardt R, Petney T, Norra S. On the complexity of measuring forests microclimate and interpreting its relevance in habitat ecology: the example of Ixodes ricinus ticks. Parasit Vectors 2017; 10:549. [PMID: 29110691 PMCID: PMC5674834 DOI: 10.1186/s13071-017-2498-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/25/2017] [Indexed: 02/07/2023] Open
Abstract
Background Ecological field research on the influence of meteorological parameters on a forest inhabiting species is confronted with the complex relations between measured data and the real conditions the species is exposed to. This study highlights this complexity for the example of Ixodes ricinus. This species lives mainly in forest habitats near the ground, but field research on impacts of meteorological conditions on population dynamics is often based on data from nearby official weather stations or occasional in situ measurements. In addition, studies use very different data approaches to analyze comparable research questions. This study is an extensive examination of the methodology used to analyze the impact of meteorological parameters on Ixodes ricinus and proposes a methodological approach that tackles the underlying complexity. Methods Our specifically developed measurement concept was implemented at 25 forest study sites across Baden-Württemberg, Germany. Meteorological weather stations recorded data in situ and continuously between summer 2012 and autumn 2015, including relative humidity measures in the litter layer and different heights above it (50 cm, 2 m). Hourly averages of relative humidity were calculated and compared with data from the nearest official weather station. Results Data measured directly in the forest can differ dramatically from conditions recorded at official weather stations. In general, data indicate a remarkable relative humidity decrease from inside to outside the forest and from ground to atmosphere. Relative humidity measured in the litter layer were, on average, 24% higher than the official data and were much more balanced, especially in summer. Conclusions The results illustrate the need for, and benefit of, continuous in situ measurements to grasp the complex relative humidity conditions in forests. Data from official weather stations do not accurately represent actual humidity conditions in forest stands and the explanatory power of short period and fragmentary in situ measurements is extremely limited. However, it is still an open question to what kind of meteorological data are necessary to answer specific questions in tick research. The comparison of research findings was hindered by the variety of information provided, which is why we propose details for future reporting.
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Affiliation(s)
- Denise Boehnke
- Institute of Regional Science, Karlsruhe Institute of Technology, Reinhard-Baumeister-Platz 1, 76131, Karlsruhe, Germany.
| | - Reiner Gebhardt
- Institute of Geography and Geoecology, Karlsruhe Institute of Technology, Reinhard-Baumeister-Platz 1, 76131, Karlsruhe, Germany
| | - Trevor Petney
- Institute of Zoology, Department of Ecology and Parasitology, Karlsruhe Institute of Technology, Kornblumen Strasse 13, 76131, Karlsruhe, Germany
| | - Stefan Norra
- Institute of Geography and Geoecology, Karlsruhe Institute of Technology, Reinhard-Baumeister-Platz 1, 76131, Karlsruhe, Germany.,Institute of Applied Geosciences, Karlsruhe Institute of Technology, Adenauerring 20, 76131, Karlsruhe, Germany
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28
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Hofmeester TR, Rowcliffe JM, Jansen PA. Quantifying the Availability of Vertebrate Hosts to Ticks: A Camera-Trapping Approach. Front Vet Sci 2017; 4:115. [PMID: 28770219 PMCID: PMC5515830 DOI: 10.3389/fvets.2017.00115] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/03/2017] [Indexed: 11/13/2022] Open
Abstract
The availability of vertebrate hosts is a major determinant of the occurrence of ticks and tick-borne zoonoses in natural and anthropogenic ecosystems and thus drives disease risk for wildlife, livestock, and humans. However, it remains challenging to quantify the availability of vertebrate hosts in field settings, particularly for medium-sized to large-bodied mammals. Here, we present a method that uses camera traps to quantify the availability of warm-bodied vertebrates to ticks. The approach is to deploy camera traps at questing height at a representative sample of random points across the study area, measure the average photographic capture rate for vertebrate species, and then correct these rates for the effective detection distance. The resulting "passage rate" is a standardized measure of the frequency at which vertebrates approach questing ticks, which we show is proportional to contact rate. A field test across twenty 1-ha forest plots in the Netherlands indicated that this method effectively captures differences in wildlife assemblage composition between sites. Also, the relative abundances of three life stages of the sheep tick Ixodes ricinus from drag sampling were correlated with passage rates of deer, which agrees with the known association with this group of host species, suggesting that passage rate effectively reflects the availability of medium- to large-sized hosts to ticks. This method will facilitate quantitative studies of the relationship between densities of questing ticks and the availability of different vertebrate species-wild as well as domesticated species-in natural and anthropogenic settings.
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Affiliation(s)
- Tim R. Hofmeester
- Department of Environmental Sciences, Wageningen University, Wageningen, Netherlands
| | | | - Patrick A. Jansen
- Department of Environmental Sciences, Wageningen University, Wageningen, Netherlands
- Center for Tropical Forest Science, Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
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29
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Lou Y, Wu J. Modeling Lyme disease transmission. Infect Dis Model 2017; 2:229-243. [PMID: 29928739 PMCID: PMC6001969 DOI: 10.1016/j.idm.2017.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/12/2017] [Accepted: 05/12/2017] [Indexed: 01/25/2023] Open
Abstract
Lyme disease, a typical tick-borne disease, imposes increasing global public health challenges. A growing body of theoretical models have been proposed to better understand various factors determining the disease risk, which not only enrich our understanding on the ecological cycle of disease transmission but also promote new theoretical developments on model formulation, analysis and simulation. In this paper, we provide a review about the models and results we have obtained recently on modeling and analyzing Lyme disease transmission, with the purpose to highlight various aspects in the ecological cycle of disease transmission to be incorporated, including the growth of ticks with different stages in the life cycle, the seasonality, host diversity, spatial disease pattern due to host short distance movement and bird migration, co-infection with other tick-borne pathogens, and climate change impact.
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Affiliation(s)
- Yijun Lou
- Department of Applied Mathematics, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Jianhong Wu
- Department of Mathematics and Statistics, York University, Toronto, Ontario, M3J 1P3, Canada
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Cayol C, Koskela E, Mappes T, Siukkola A, Kallio ER. Temporal dynamics of the tick Ixodes ricinus in northern Europe: epidemiological implications. Parasit Vectors 2017; 10:166. [PMID: 28359294 PMCID: PMC5374616 DOI: 10.1186/s13071-017-2112-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/24/2017] [Indexed: 11/10/2022] Open
Abstract
Background Tick-borne pathogens pose an increasing threat to human and veterinary health across the northern hemisphere. While the seasonal activity of ticks is largely determined by climatic conditions, host-population dynamics are also likely to affect tick abundance. Consequently, abundance fluctuations of rodents in northern Europe are expected to be translated into tick dynamics, and can hence potentially affect the circulation of tick-borne pathogens. We quantified and explained the temporal dynamics of the tick Ixodes ricinus in the northernmost part of its European geographical range, by estimating (i) abundance in vegetation and (ii) infestation load in the most common rodent species in the study area, the bank vole Myodes glareolus. Results Ixodes ricinus nymphs and adult females, the life stages responsible for the most of tick bites in humans, peaked in May-June and August-September. Larvae and nymphs were simultaneously active in June and abundance of questing larvae and nymphs in the vegetation showed a positive association with bank vole abundance. Moreover, infesting larvae and nymphs were aggregated on bank voles, and the infestation of bank voles with I. ricinus larvae and nymphs was positively associated with bank vole abundance. Conclusion Our results indicate early summer and early autumn as periods of increased risk for humans to encounter I. ricinus ticks in boreal urban forests and suggest a 2 years life-cycle for I. ricinus with two cohorts of ticks during the same year. Moreover, we identified a simultaneous activity of larvae and nymphs which allows co-feeding on the rodent host, which in turn supports the transmission of several important zoonotic tick-borne pathogens. Finally, we showed that a high density of the rodent host may enhance the risk that ticks and, potentially, tick-borne pathogens pose to human health. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2112-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Claire Cayol
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland.
| | - Esa Koskela
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
| | - Tapio Mappes
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
| | - Anja Siukkola
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
| | - Eva R Kallio
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
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31
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Cat J, Beugnet F, Hoch T, Jongejan F, Prangé A, Chalvet-Monfray K. Influence of the spatial heterogeneity in tick abundance in the modeling of the seasonal activity of Ixodes ricinus nymphs in Western Europe. EXPERIMENTAL & APPLIED ACAROLOGY 2017; 71:115-130. [PMID: 28127642 DOI: 10.1007/s10493-016-0099-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/09/2016] [Indexed: 05/28/2023]
Abstract
The seasonal weather-driven activity of the tick Ixodes ricinus is frequently explored using multisite surveys. This study aimed to investigate the statistical modeling of seasonal trends in the activity of I. ricinus nymphs when both the influence of abiotic factors and spatial heterogeneity were taken into account. Time series data of abiotic covariates (temperature, relative humidity, rainfall and photoperiod) and nymphal tick counts were recorded on several sites in The Netherlands, Belgium and in France in 2008 and 2009. The sites were divided into two subsets which were used for model construction or model validation. A generalized linear mixed model was set up, with aggregated abiotic covariates as fixed effects, and the collection site as a random effect to account for the site-varying density in nymphs. A linear regression model was developed to estimate the site effect against the observed local abundance on each site. The activity patterns simulated from the weather and photoperiod covariates realistically reproduced the observed seasonal trends in nymphal tick activity. The fit between observed and simulated nymphal count time series was greatly improved when the site-specific local abundance in nymphs was included. Our modeling approach allows indicators of local tick abundance and the temporal modeling of I. ricinus activity to be combined. The model presented here can also be used to study scenarios on the temporal patterns of I. ricinus activity in the present and in the context of climate change.
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Affiliation(s)
- Julie Cat
- EPIA, INRA, 63122, Saint Genès Champanelle, France.
- Université de Lyon, VetAgroSup, 1 av Bourgelat, 69280, Marcy-l'Etoile, France.
| | | | - Thierry Hoch
- BIOEPAR, INRA, Oniris, La Chantrerie, 44307, Nantes, France
| | - Frans Jongejan
- Utrecht Centre for Tick-borne Diseases (UCTD), FAO Reference Centre for Ticks and Tick-borne Diseases, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, Utrecht, The Netherlands
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Medicine, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Aurélie Prangé
- Direction interarmées du service de santé en Nouvelle Calédonie (DIASS-NC), 38 - 98843, Nouméa cedex, New Caledonia, France
| | - Karine Chalvet-Monfray
- EPIA, INRA, 63122, Saint Genès Champanelle, France
- Université de Lyon, VetAgroSup, 1 av Bourgelat, 69280, Marcy-l'Etoile, France
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Li S, Gilbert L, Harrison PA, Rounsevell MDA. Modelling the seasonality of Lyme disease risk and the potential impacts of a warming climate within the heterogeneous landscapes of Scotland. J R Soc Interface 2016; 13:rsif.2016.0140. [PMID: 27030039 DOI: 10.1098/rsif.2016.0140] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 03/04/2016] [Indexed: 12/22/2022] Open
Abstract
Lyme disease is the most prevalent vector-borne disease in the temperate Northern Hemisphere. The abundance of infected nymphal ticks is commonly used as a Lyme disease risk indicator. Temperature can influence the dynamics of disease by shaping the activity and development of ticks and, hence, altering the contact pattern and pathogen transmission between ticks and their host animals. A mechanistic, agent-based model was developed to study the temperature-driven seasonality of Ixodes ricinus ticks and transmission of Borrelia burgdorferi sensu lato across mainland Scotland. Based on 12-year averaged temperature surfaces, our model predicted that Lyme disease risk currently peaks in autumn, approximately six weeks after the temperature peak. The risk was predicted to decrease with increasing altitude. Increases in temperature were predicted to prolong the duration of the tick questing season and expand the risk area to higher altitudinal and latitudinal regions. These predicted impacts on tick population ecology may be expected to lead to greater tick-host contacts under climate warming and, hence, greater risks of pathogen transmission. The model is useful in improving understanding of the spatial determinants and system mechanisms of Lyme disease pathogen transmission and its sensitivity to temperature changes.
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Affiliation(s)
- Sen Li
- Environmental Change Institute, University of Oxford, South Parks Road, Oxford OX1 3QY, UK
| | - Lucy Gilbert
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
| | - Paula A Harrison
- Environmental Change Institute, University of Oxford, South Parks Road, Oxford OX1 3QY, UK Centre for Ecology and Hydrology, Library Avenue, Lancaster LA1 4AP, UK
| | - Mark D A Rounsevell
- School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK
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Gray JS, Kahl O, Lane RS, Levin ML, Tsao JI. Diapause in ticks of the medically important Ixodes ricinus species complex. Ticks Tick Borne Dis 2016; 7:992-1003. [PMID: 27263092 PMCID: PMC5659180 DOI: 10.1016/j.ttbdis.2016.05.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/09/2016] [Accepted: 05/16/2016] [Indexed: 11/22/2022]
Abstract
Four members of the Ixodes ricinus species complex, Ixodes pacificus, Ixodes persulcatus, Ixodes ricinus and Ixodes scapularis, have, between them, a worldwide distribution within the northern hemisphere. They are responsible for the transmission of several animal and human pathogens, including the causal agents of Lyme borreliosis, tick-borne encephalitis, human granulocytic anaplasmosis and human babesiosis. Despite the importance of these ticks as vectors, the knowledge and understanding of the role that diapause plays in their complex life cycles are confused and incomplete. In view of the continuing geographic spread of these tick species, as well as the effects of climate change on vector-borne diseases, it is timely to encourage research on diapause phenomena to improve understanding of their biology and of pathogen transmission dynamics. In our review we seek to clarify thinking on the topic and to address gaps in our knowledge that require the attention of researchers.
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Affiliation(s)
- Jeremy S Gray
- School of Biology and Environmental Science, University College Dublin, Ireland.
| | | | - Robert S Lane
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA
| | - Michael L Levin
- Medical Entomology Laboratory, Rickettsial Zoonoses Branch, DVBD, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-13, Atlanta, GA 30333, USA
| | - Jean I Tsao
- Department of Fisheries & Wildlife and Large Animal Clinical Sciences, Michigan State University, USA
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Grigoryeva LA, Stanyukovich MK. Life cycle of the taiga tick Ixodes persulcatus (Acari: Ixodidae) in the North-West of Russia. EXPERIMENTAL & APPLIED ACAROLOGY 2016; 69:347-357. [PMID: 26979586 DOI: 10.1007/s10493-016-0038-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 03/09/2016] [Indexed: 06/05/2023]
Abstract
The life cycle of Ixodes persulcatus lasts 3 years in the conditions of the Leningrad province (North-West Russia), the development of each phase taking a year. The normal age of the taiga tick is 3 years. The calendar age of larvae and nymphs reaches 11-12 months under favorable abiotic and biotic factors, while the calendar age of adults does not exceed 11 months. At the preimaginal phases of development the ticks that breed in August can feed before or after winter. However, their metamorphosis begins and reaches completion within the same timeframes (from late June to early August) and lasts for about 30-50 (60) days. The survival rate of hungry and engorged larvae and nymphs after wintering is quite high (88.6-100 %). We explain the low activity of larvae and nymphs in late summer and autumn by incomplete development. Morphogenetic diapause of engorged larvae and nymphs interrupts digestion but not metamorphosis which starts only in late June and July after the complete absorption of blood from the gut cavity.
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Affiliation(s)
- L A Grigoryeva
- Zoological Institute of RAS, Saint Petersburg, Russia, 199034.
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Estrada-Peña A, Alexander N, Wint GRW. Perspectives on modelling the distribution of ticks for large areas: so far so good? Parasit Vectors 2016; 9:179. [PMID: 27030357 PMCID: PMC4815247 DOI: 10.1186/s13071-016-1474-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/23/2016] [Indexed: 11/10/2022] Open
Abstract
Background This paper aims to illustrate the steps needed to produce reliable correlative modelling for arthropod vectors, when process-driven models are unavailable. We use ticks as examples because of the (re)emerging interest in the pathogens they transmit. We argue that many scientific publications on the topic focus on: (i) the use of explanatory variables that do not adequately describe tick habitats; (ii) the automatic removal of variables causing internal (statistical) problems in the models without considering their ecological significance; and (iii) spatial pattern matching rather than niche mapping, therefore losing information that could be used in projections. Methods We focus on extracting information derived from modelling the environmental niche of ticks, as opposed to pattern matching exercises, as a first step in the process of identifying the ecological determinants of tick distributions. We perform models on widely reported species of ticks in Western Palaearctic to derive a set of covariates, describing the climate niche, reconstructing a Fourier transformation of remotely-sensed information. Results We demonstrate the importance of assembling ecological information that drives the distribution of ticks before undertaking any mapping exercise, from which this kind of information is lost. We also show how customised covariates are more relevant to tick ecology than the widely used set of “Bioclimatic Indicators” (“Biovars”) derived from interpolated datasets, and provide programming scripts to easily calculate them. We demonstrate that standard pre-tailored vegetation categories also fail to describe tick habitats and are best used to describe absence rather than presence of ticks, but could be used in conjunction with the climate based suitability models. Conclusions We stress the better performance of climatic covariates obtained from remotely sensed information as opposed to interpolated explanatory variables derived from ground measurements which are flawed with internal issues affecting modelling performance. Extracting ecological conclusions from modelling projections is necessary to gain information about the variables driving the distribution of arthropod vectors. Mapping exercises should be a secondary aim in the study of the distribution of health threatening arthropods. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1474-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Agustín Estrada-Peña
- Department of Animal Pathology, Faculty of Veterinary Medicine, Miguel Servet 177, 50013, Zaragoza, Spain.
| | - Neil Alexander
- Environmental Research Group Oxford, Department of Zoology, South Parks Road, Oxford, OX1 3PS, UK
| | - G R William Wint
- Environmental Research Group Oxford, Department of Zoology, South Parks Road, Oxford, OX1 3PS, UK
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Hartemink N, Takken W. Trends in tick population dynamics and pathogen transmission in emerging tick-borne pathogens in Europe: an introduction. EXPERIMENTAL & APPLIED ACAROLOGY 2016; 68:269-78. [PMID: 26782278 DOI: 10.1007/s10493-015-0003-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/10/2015] [Indexed: 05/26/2023]
Affiliation(s)
- Nienke Hartemink
- Theoretical Ecology group, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands.
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, PO Box 8031, 6700 EH, Wageningen, The Netherlands
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Hoch T, Breton E, Josse M, Deniz A, Guven E, Vatansever Z. Identifying main drivers and testing control strategies for CCHFV spread. EXPERIMENTAL & APPLIED ACAROLOGY 2016; 68:347-359. [PMID: 26174420 DOI: 10.1007/s10493-015-9937-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 06/05/2015] [Indexed: 06/04/2023]
Abstract
Crimean Congo Haemorrhagic Fever (CCHF) is an emerging zoonotic disease. The causative agent is a virus (CCHFV), mainly transmitted by ticks of the species Hyalomma marginatum in Eastern Europe and Turkey. In order to test potential scenarios for the control of pathogen spread, the basic reproduction number (R0) for CCHF was calculated. This calculation was based on a population dynamics model and parameter values from the literature for pathogen transmission. The tick population dynamics model takes into account the major processes involved and gives estimates for tick survival from one stage to the other and number of feeding ticks. It also considers the influence of abiotic (meteorological variables) and biotic factors (host densities) on model outputs, which were compared with data collected in Central Anatolia (Turkey). R0 computation was thereafter used to test control strategies and especially the effect of acaricide treatment. Simulation results indicate that such treatments could have valuable effects provided that the acaricide is applied regularly throughout the spring and summer, and over several years. Furthermore, a sensitivity analysis to abiotic and biotic factors showed that, even though temperature has a strong impact on model outputs, host (mainly hare) densities also play a role. The kind of model we have developed provides insight into the ability of different strategies to prevent and control disease spread and has proved its relevance when associated with field trials.
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Affiliation(s)
- T Hoch
- INRA, UMR1300 Biologie, Epidémiologie et Analyse de Risque en santé animale, 44307, Nantes, France.
- LUNAM Université, ONIRIS, UMR1300 Biologie, Epidémiologie et Analyse de Risque en santé animale, 44307, Nantes, France.
| | - E Breton
- INRA, UMR1300 Biologie, Epidémiologie et Analyse de Risque en santé animale, 44307, Nantes, France
- LUNAM Université, ONIRIS, UMR1300 Biologie, Epidémiologie et Analyse de Risque en santé animale, 44307, Nantes, France
| | - M Josse
- INRA, UMR1300 Biologie, Epidémiologie et Analyse de Risque en santé animale, 44307, Nantes, France
- LUNAM Université, ONIRIS, UMR1300 Biologie, Epidémiologie et Analyse de Risque en santé animale, 44307, Nantes, France
| | - A Deniz
- Etlik Central Veterinary Control and Research Institute, Ankara, Turkey
| | - E Guven
- Department of Parasitology, Faculty of Veterinary Medicine, Ataturk University, Erzurum, Turkey
| | - Z Vatansever
- Department of Parasitology, Faculty of Veterinary Medicine, Kafkas University, Kars, Turkey
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Dobson ADM, Auld SKJR. Epidemiological Implications of Host Biodiversity and Vector Biology: Key Insights from Simple Models. Am Nat 2016; 187:405-22. [PMID: 27028070 DOI: 10.1086/685445] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Models used to investigate the relationship between biodiversity change and vector-borne disease risk often do not explicitly include the vector; they instead rely on a frequency-dependent transmission function to represent vector dynamics. However, differences between classes of vector (e.g., ticks and insects) can cause discrepancies in epidemiological responses to environmental change. Using a pair of disease models (mosquito- and tick-borne), we simulated substitutive and additive biodiversity change (where noncompetent hosts replaced or were added to competent hosts, respectively), while considering different relationships between vector and host densities. We found important differences between classes of vector, including an increased likelihood of amplified disease risk under additive biodiversity change in mosquito models, driven by higher vector biting rates. We also draw attention to more general phenomena, such as a negative relationship between initial infection prevalence in vectors and likelihood of dilution, and the potential for a rise in density of infected vectors to occur simultaneously with a decline in proportion of infected hosts. This has important implications; the density of infected vectors is the most valid metric for primarily zoonotic infections, while the proportion of infected hosts is more relevant for infections where humans are a primary host.
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Valcárcel F, González J, Pé rez Sánchez JL, Olmeda AS. Long-Term Ecological Study of Host-Seeking Adults of Hyalomma lusitanicum (Acari: Ixodidae) in a Meso-Mediterranean Climate. JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:221-224. [PMID: 26477051 DOI: 10.1093/jme/tjv152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
From January 2007 to December 2014, three representative meso-Mediterranean bioclimatic environment types were sampled monthly using blanket-dragging techniques to determine the tick abundance rate. Hyalomma lusitanicum Koch, 1844 was the most prevalent species (96.58%) followed by Dermacentor marginatus Sulzer, 1776; Rhipicephalus pusillus Gil Collado, 1936; and Rhipicephalus bursa Canestrini and Fanzago, 1878. H. lusitanicum adults begin questing activity around March, numbers rising quickly reaching their peak in May–June and then diminishing until the end of the year, with a small increase in September–October. This pattern was clear and constant throughout the years, irrespective of the microclimate or biotope tested.
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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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Diuk-Wasser MA, Vannier E, Krause PJ. Coinfection by Ixodes Tick-Borne Pathogens: Ecological, Epidemiological, and Clinical Consequences. Trends Parasitol 2015; 32:30-42. [PMID: 26613664 DOI: 10.1016/j.pt.2015.09.008] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 09/25/2015] [Accepted: 09/28/2015] [Indexed: 12/13/2022]
Abstract
Ixodes ticks maintain a large and diverse array of human pathogens in the enzootic cycle, including Borrelia burgdorferi and Babesia microti. Despite the poor ecological fitness of B. microti, babesiosis has recently emerged in areas endemic for Lyme disease. Studies in ticks, reservoir hosts, and humans indicate that coinfection with B. burgdorferi and B. microti is common, promotes transmission and emergence of B. microti in the enzootic cycle, and causes greater disease severity and duration in humans. These interdisciplinary studies may serve as a paradigm for the study of other vector-borne coinfections. Identifying ecological drivers of pathogen emergence and host factors that fuel disease severity in coinfected individuals will help guide the design of effective preventative and therapeutic strategies.
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Affiliation(s)
| | - Edouard Vannier
- Tufts Medical Center and Tufts University School of Medicine, Boston, MA, USA
| | - Peter J Krause
- Yale School of Public Health and Yale School of Medicine, New Haven, CT, USA.
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Alonso-Carné J, García-Martín A, Estrada-Peña A. Modelling the Phenological Relationships of Questing ImmatureIxodes Ricinus(Ixodidae) Using Temperature and NDVI Data. Zoonoses Public Health 2015; 63:40-52. [DOI: 10.1111/zph.12203] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Indexed: 11/29/2022]
Affiliation(s)
- J. Alonso-Carné
- Department of Geography and Territorial Planning; University of Zaragoza; Zaragoza Spain
- GEOFOREST group - Instituto Universitario de Ciencias Ambientales (IUCA); University of Zaragoza; Zaragoza Spain
- Department of Animal Pathology; University of Zaragoza; Zaragoza Spain
| | - A. García-Martín
- GEOFOREST group - Instituto Universitario de Ciencias Ambientales (IUCA); University of Zaragoza; Zaragoza Spain
- Centro Universitario de la Defensa de Zaragoza; Zaragoza Spain
| | - A. Estrada-Peña
- Department of Animal Pathology; University of Zaragoza; Zaragoza Spain
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Estrada-Peña A, de la Fuente J, Latapia T, Ortega C. The Impact of Climate Trends on a Tick Affecting Public Health: A Retrospective Modeling Approach for Hyalomma marginatum (Ixodidae). PLoS One 2015; 10:e0125760. [PMID: 25955315 PMCID: PMC4425654 DOI: 10.1371/journal.pone.0125760] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 03/26/2015] [Indexed: 11/23/2022] Open
Abstract
The impact of climate trends during the period 1901–2009 on the life cycle of Hyalomma marginatum in Europe was modeled to assess changes in the physiological processes of this threat to public health. Monthly records of temperature and water vapour at a resolution of 0.5° and equations describing the life cycle processes of the tick were used. The climate in the target region affected the rates of the life cycle processes of H. marginatum: development rates increased, mortality rates in molting stages decreased, and the survival rates of questing ticks decreased in wide territories of the Mediterranean basin. The modeling framework indicated the existence of critical areas in the Balkans, central Europe, and the western coast of France, where the physiological processes of the tick improved to extents that are consistent with the persistence of populations if introduced. A spatially explicit risk assessment was performed to detect candidate areas where active surveys should be performed to monitor changes in tick density or persistence after a hypothetical introduction. We detected areas where the critical abiotic (climate) and biotic (host density) factors overlap, including most of the Iberian peninsula, the Mediterranean coast of France, eastern Turkey, and portions of the western Black Sea region. Wild ungulate densities are unavailable for large regions of the territory, a factor that might affect the outcome of the study. The risk of successfully establishing H. marginatum populations at northern latitudes of its current colonization range seems to be still low, even if the climate has improved the performance of the tick in these areas.
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Affiliation(s)
- Agustín Estrada-Peña
- Department of Animal Pathology, Faculty of Veterinary Medicine, Miguel Servet 177, 50013, Zaragoza, Spain
- * E-mail:
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, 3 Ronda de Toledo s/n, 13005, Ciudad Real, Spain
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, United States of America
| | - Tamara Latapia
- Department of Animal Pathology, Faculty of Veterinary Medicine, Miguel Servet 177, 50013, Zaragoza, Spain
| | - Carmelo Ortega
- Department of Animal Pathology, Faculty of Veterinary Medicine, Miguel Servet 177, 50013, Zaragoza, Spain
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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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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: 17] [Impact Index Per Article: 1.7] [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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46
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Mysterud A, Hatlegjerde IL, Sørensen OJ. Attachment site selection of life stages of Ixodes ricinus ticks on a main large host in Europe, the red deer (Cervus elaphus). Parasit Vectors 2014; 7:510. [PMID: 25391754 PMCID: PMC4233035 DOI: 10.1186/s13071-014-0510-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 10/29/2014] [Indexed: 11/25/2022] Open
Abstract
Background Ticks and tick-borne diseases are increasing in many areas of Europe and North America due to climate change, while land use and the increased abundances of large hosts play a more controversial role. The pattern of host selection involves a crucial component for tick abundance. While the larvae and nymphs feed on a wide range of different sized hosts, the adult female ticks require blood meal from a large host (>1 kg), typically a deer, to fulfil the life cycle. Understanding the role of different hosts for abundances of ticks is therefore important, and also the extent to which different life stages attach to large hosts. Findings We studied attachment site selection of life stages of I. ricinus ticks on a main large host in Europe, the red deer (Cervus elaphus). We collected from 33 felled red deer pieces of skin from five body parts: leg, groin, neck, back and ear. We counted the number of larval, nymphal, adult male and adult female ticks. Nymphs (42.2%) and adult (48.7%) ticks dominated over larvae (9.1%). There were more larvae on the legs (40.9%), more nymphs on the ears (83.7%), while adults dominated in the groins (89.2%) and neck (94.9%). Conclusions Large mammalian hosts are thus a diverse habitat suitable for different life stages of ticks. The attachment site selection reflected the life stages differing ability to move. The spatial separation of life stages may partly limit the role of deer in co-feeding transmission cycles.
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Affiliation(s)
- Atle Mysterud
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, NO-0316, Oslo, Norway.
| | - Idar Lauge Hatlegjerde
- Nord-Trøndelag University College, Faculty of Nature Resource Sciences, P.O. Box 2501, NO-7729, Steinkjer, Norway.
| | - Ole Jakob Sørensen
- Nord-Trøndelag University College, Faculty of Nature Resource Sciences, P.O. Box 2501, NO-7729, Steinkjer, Norway.
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Towards an evolutionary understanding of questing behaviour in the tick Ixodes ricinus. PLoS One 2014; 9:e110028. [PMID: 25333919 PMCID: PMC4198204 DOI: 10.1371/journal.pone.0110028] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 09/04/2014] [Indexed: 11/29/2022] Open
Abstract
The tick Ixodes ricinus finds its hosts by climbing vegetation and adopting a sit-and-wait tactic. This “questing” behaviour is known to be temperature-dependent, such that questing increases with temperature up to a point where the vapor pressure deficit (drying effect) forces ticks down to rehydrate in the soil or mat layer. Little if any attention has been paid to understanding the questing of ticks from an evolutionary perspective. Here we ask whether populations from colder climatic conditions respond differently in terms of the threshold temperature for questing and the rate of response to a fixed temperature. We find significant variation between populations in the temperature sensitivity of questing, with populations from cooler climates starting questing at lower temperatures than populations from warmer temperatures. Cool climate populations also quest sooner when the temperature is held constant. These patterns are consistent with local adaptation to temperature either through direct selection or acclimation and challenge the use of fixed thresholds for questing in modeling the spread of tick populations. Our results also show how both time and temperature play a role in questing, but we are unable to explain the relationship in terms of degree-time used to model Arthropod development. We find that questing in response to temperature fits well with a quantitative genetic model of the conditional strategy, which reveals how selection on questing may operate and hence may be of value in understanding the evolutionary ecology of questing.
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Verschave SH, Vercruysse J, Claerebout E, Rose H, Morgan ER, Charlier J. The parasitic phase of Ostertagia ostertagi: quantification of the main life history traits through systematic review and meta-analysis. Int J Parasitol 2014; 44:1091-104. [PMID: 25229178 DOI: 10.1016/j.ijpara.2014.08.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
Predictive models of parasite life cycles increase our understanding of how parasite epidemiology is influenced by global changes and can be used to support decisions for more targeted worm control. Estimates of parasite population dynamics are needed to parameterize such models. The aim of this study was to quantify the main life history traits of Ostertagia ostertagi, economically the most important nematode of cattle in temperate regions. The main parameters determining parasite density during the parasitic phase of O. ostertagi are (i) the larval establishment rate, (ii) hypobiosis rate, (iii) adult mortality and (iv) female fecundity (number of eggs laid per day per female). A systematic review was performed covering studies from 1962 to 2007, in which helminth-naïve calves were artificially infected with O. ostertagi. The database was further extended with results of unpublished trials conducted at the Laboratory for Parasitology of Ghent University, Belgium. Overall inverse variance weighted estimates were computed for each of the traits through random effects models. An average establishment rate (±S.E.) of 0.269±0.022 was calculated based on data of 27 studies (46 experiments). The establishment rate declined when infection dose increased and was lower in younger animals. An average proportion of larvae entering hypobiosis (±S.E.) of 0.041 (±0.009) was calculated based on 27 studies (54 experiments). The proportion of ingested larvae that went into hypobiosis was higher in animals that received concomitant infections with nematode species other than O. ostertagi (mixed infections). An average daily adult mortality (±S.E.) of 0.028 (±0.002) was computed based on data from 28 studies (70 experiments). Adult mortality was positively correlated with infection dose. A daily fecundity (±S.E.) of 284 (±45) eggs per female was found based on nine studies (10 experiments). The average female sex ratio of O. ostertagi based on individual animal data (n=75) from six different studies was estimated to be 0.55. We believe that this systematic review is the first to summarise the available data on the main life history traits of the parasitic phase of O. ostertagi. In conclusion, this meta-analysis provides novel estimates for the parameterization of life cycle-based transmission models, explicitly reports measures of variance around these estimates, gives evidence for density dependence of larval establishment and adult mortality, shows that host age affects larval establishment and, to our knowledge, provides the first evidence for O. ostertagi of a female-biased sex ratio.
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Affiliation(s)
- S H Verschave
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
| | - J Vercruysse
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - E Claerebout
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - H Rose
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, United Kingdom; Cabot Institute, University of Bristol, Cantocks Close, Bristol BS8 1TS, United Kingdom
| | - E R Morgan
- Cabot Institute, University of Bristol, Cantocks Close, Bristol BS8 1TS, United Kingdom; School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom
| | - J Charlier
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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Estrada-Peña A, de la Fuente J. The ecology of ticks and epidemiology of tick-borne viral diseases. Antiviral Res 2014; 108:104-28. [DOI: 10.1016/j.antiviral.2014.05.016] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 02/08/2014] [Accepted: 05/24/2014] [Indexed: 12/30/2022]
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50
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Dobson ADM. History and complexity in tick-host dynamics: discrepancies between 'real' and 'visible' tick populations. Parasit Vectors 2014; 7:231. [PMID: 24885852 PMCID: PMC4038084 DOI: 10.1186/1756-3305-7-231] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/06/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Numerical responses of ticks to changes in densities of their hosts can be complex and apparently unpredictable. Manipulations even of deterministic models can produce counter-intuitive results, including tick populations that either rise or fall under increasing host densities, depending on initial conditions. METHODS In this paper I use an established simulation model to demonstrate a wide range of numerical responses to different scenarios of host changes, and to examine the basic mechanisms that drive them. RESULTS The rate and direction of change of host densities affects the extent to which questing tick numbers reflect those of their hosts. Numerical responses differ profoundly between dynamic tick-host systems and those allowed to reach equilibrium. CONCLUSIONS The key to understanding tick-host dynamics is to understand the difference between 'real' and 'visible' tick populations. An appreciation of the implications of this difference - and of the conditions that influence it - will benefit the effective interpretation of field data.
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Affiliation(s)
- Andrew D M Dobson
- School of Biological and Environmental Sciences, University of Stirling, Cottrell Building, Stirling FK9 4LA, UK.
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