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Hubálek Z. History of Arbovirus Research in the Czech Republic. Viruses 2021; 13:2334. [PMID: 34835140 PMCID: PMC8622538 DOI: 10.3390/v13112334] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 01/07/2023] Open
Abstract
The aim of this review is to follow the history of studies on endemiv arboviruses and the diseases they cause which were detected in the Czech lands (Bohemia, Moravia and Silesia (i.e., the Czech Republic)). The viruses involve tick-borne encephalitis, West Nile and Usutu flaviviruses; the Sindbis alphavirus; Ťahyňa, Batai, Lednice and Sedlec bunyaviruses; the Uukuniemi phlebovirus; and the Tribeč orbivirus. Arboviruses temporarily imported from abroad to the Czech Republic have been omitted. This brief historical review includes a bibliography of all relevant papers.
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Affiliation(s)
- Zdenek Hubálek
- Institute of Vertebrate Biology, Czech Academy of Sciences, Květná 8, 60365 Brno, Czech Republic
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Management Options for Ixodes ricinus-Associated Pathogens: A Review of Prevention Strategies. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17061830. [PMID: 32178257 PMCID: PMC7143654 DOI: 10.3390/ijerph17061830] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/03/2020] [Accepted: 03/05/2020] [Indexed: 12/16/2022]
Abstract
Ticks are important human and animal parasites and vectors of many infectious disease agents. Control of tick activity is an effective tool to reduce the risk of contracting tick-transmitted diseases. The castor bean tick (Ixodes ricinus) is the most common tick species in Europe. It is also a vector of the causative agents of Lyme borreliosis and tick-borne encephalitis, which are two of the most important arthropod-borne diseases in Europe. In recent years, increases in tick activity and incidence of tick-borne diseases have been observed in many European countries. These increases are linked to many ecological and anthropogenic factors such as landscape management, climate change, animal migration, and increased popularity of outdoor activities or changes in land usage. Tick activity is driven by many biotic and abiotic factors, some of which can be effectively managed to decrease risk of tick bites. In the USA, recommendations for landscape management, tick host control, and tick chemical control are well-defined for the applied purpose of reducing tick presence on private property. In Europe, where fewer studies have assessed tick management strategies, the similarity in ecological factors influencing vector presence suggests that approaches that work in USA may also be applicable. In this article we review key factors driving the tick exposure risk in Europe to select those most conducive to management for decreased tick-associated risk.
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Liddell C, Morgan ER, Bull K, Ioannou CC. Response to resources and parasites depends on health status in extensively grazed sheep. Proc Biol Sci 2020; 287:20192905. [PMID: 32019442 PMCID: PMC7031671 DOI: 10.1098/rspb.2019.2905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 01/14/2020] [Indexed: 11/30/2022] Open
Abstract
A fundamental question in animal ecology is how an individual's internal state and the external environment together shape species distributions across habitats. The increasing availability of biologgers is driving a revolution in answering this question in a wide range of species. In this study, the position of sheep (Ovis aries) from Global Positioning System collars was integrated with remote sensing data, field sampling of parasite distributions, and parasite load and health measures for each tagged individual. This allowed inter-individual variation in habitat use to be examined. Once controlling for a positive relationship between vegetation productivity and tick abundance, healthier individuals spent more of their time at sites with higher vegetation productivity, while less healthy individuals showed a stronger (negative) response to tick abundance. These trends are likely to represent a trade-off in foraging decisions that vary between individuals based on their health status. Given the rarity of studies that explore how animal distributions are affected by health and external factors, we demonstrate the value of integrating biologging technology with remote sensing data, traditional ecological sampling and individual measures of animal health. Our study, using extensively grazed sheep as a model system, opens new possibilities to study free-living grazing systems.
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Affiliation(s)
- Caroline Liddell
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Eric R. Morgan
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- School of Biological Sciences, Queen's University Belfast, Belfast BT9 5BL, UK
| | - Katie Bull
- Bristol Veterinary School, University of Bristol, Bristol BS40 5DU, UK
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Hönig V, Švec P, Marek L, Mrkvička T, Dana Z, Wittmann MV, Masař O, Szturcová D, Růžek D, Pfister K, Grubhoffer L. Model of Risk of Exposure to Lyme Borreliosis and Tick-Borne Encephalitis Virus-Infected Ticks in the Border Area of the Czech Republic (South Bohemia) and Germany (Lower Bavaria and Upper Palatinate). INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16071173. [PMID: 30986900 PMCID: PMC6479554 DOI: 10.3390/ijerph16071173] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/22/2019] [Accepted: 03/26/2019] [Indexed: 01/26/2023]
Abstract
In Europe, Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are the two vector-borne diseases with the largest impact on human health. Based on data on the density of host-seeking Ixodes ricinus ticks and pathogen prevalence and using a variety of environmental data, we have created an acarological risk model for a region where both diseases are endemic (Czech Republic-South Bohemia and Germany-Lower Bavaria, Upper Palatinate). The data on tick density were acquired by flagging 50 sampling sites three times in a single season. Prevalence of the causative agents of LB and TBE was determined. Data on environmental variables (e.g., altitude, vegetation cover, NDVI, land surface temperature) were obtained from various sources and processed using geographical information systems. Generalized linear models were used to estimate tick density, probability of tick infection, and density of infected ticks for the whole area. A significantly higher incidence of human TBE cases was recorded in South Bohemia compared to Bavarian regions, which correlated with a lower tick density in Bavaria. However, the differences in pathogen prevalence rates were not significant. The model outputs were made available to the public in the form of risk maps, indicating the distribution of tick-borne disease risk in space.
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Affiliation(s)
- Václav Hönig
- Institute of Parasitology, Biology Centre, Academy of Sciences of Czech Republic, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
- Faculty of Science, University of South Bohemia, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
- Veterinary Research Institute, Hudcova 296, 621 00 Brno, Czech Republic.
| | - Pavel Švec
- Department of Geoinformatics, VSB-Technical University of Ostrava, 17. listopadu 15, 708 00 Ostrava, Czech Republic.
| | - Lukáš Marek
- GeoHealth Laboratory, Geospatial Research Institute, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
| | - Tomáš Mrkvička
- Faculty of Economics, University of South Bohemia, Studentska 13, 370 05 Ceske Budejovice, Czech Republic.
| | - Zubriková Dana
- Institute of Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Leopoldstr. 5, 80802 Munich, Germany.
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, 040 01 Kosice, Slovakia.
| | - Maria Vögerl Wittmann
- Institute of Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Leopoldstr. 5, 80802 Munich, Germany.
| | - Ondřej Masař
- Department of Geoinformatics, VSB-Technical University of Ostrava, 17. listopadu 15, 708 00 Ostrava, Czech Republic.
| | - Daniela Szturcová
- Department of Geoinformatics, VSB-Technical University of Ostrava, 17. listopadu 15, 708 00 Ostrava, Czech Republic.
| | - Daniel Růžek
- Institute of Parasitology, Biology Centre, Academy of Sciences of Czech Republic, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
- Faculty of Science, University of South Bohemia, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
- Veterinary Research Institute, Hudcova 296, 621 00 Brno, Czech Republic.
| | - Kurt Pfister
- Institute of Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Leopoldstr. 5, 80802 Munich, Germany.
| | - Libor Grubhoffer
- Institute of Parasitology, Biology Centre, Academy of Sciences of Czech Republic, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
- Faculty of Science, University of South Bohemia, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
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Sympatric Ixodes-tick species: pattern of distribution and pathogen transmission within wild rodent populations. Sci Rep 2018; 8:16660. [PMID: 30413762 PMCID: PMC6226450 DOI: 10.1038/s41598-018-35031-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/25/2018] [Indexed: 11/19/2022] Open
Abstract
The generalist tick Ixodes ricinus is the most important vector for tick-borne pathogens (TBP), including Borrelia burgdorferi sensu lato, in Europe. However, the involvement of other sympatric Ixodes ticks, such as the specialist vole tick I. trianguliceps, in the enzootic circulations of TBP remains unclear. We studied the distribution of I. ricinus and I. trianguliceps in Central Finland and estimated the TBP infection likelihood in the most common rodent host in relation with the abundance of the two tick species. Ixodes trianguliceps was encountered in all 16 study sites whereas I. ricinus was frequently observed only at a quarter of the study sites. The abundance of I. ricinus was positively associated with open water coverage and human population density around the study sites. Borrelia burgdorferi s. l.-infected rodents were found only in sites where I. ricinus was abundant, whereas the occurrence of other TBP was independent of I. ricinus presence. These results suggest that I. trianguliceps is not sufficient, at least alone, in maintaining the circulation of B. burgdorferi s. l. in wild hosts. In addition, anthropogenic factors might affect the distribution of I. ricinus ticks and, hence, their pathogens, thus shaping the landscape of tick-borne disease risk for humans.
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Mierzejewska EJ, Estrada-Peña A, Bajer A. Spread of Dermacentor reticulatus is associated with the loss of forest area. EXPERIMENTAL & APPLIED ACAROLOGY 2017; 72:399-413. [PMID: 28831655 PMCID: PMC5583311 DOI: 10.1007/s10493-017-0160-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 07/22/2017] [Indexed: 05/14/2023]
Abstract
Changes in tick distribution and abundance are among the main drivers of the (re)emergence of transmitted pathogens. We aimed to uncover the reasons of the reported spread of Dermacentor reticulatus in Poland using a variety of proxies of environmental features, ground-measured temperature and remotely-sensed data of temperature and vegetation. Ground-measured temperature was recorded in 2013-2014, in sites where D. reticulatus presence (n = 16) or absence (n = 16) was confirmed. We specifically aimed to test whether changes in phenology of vegetation and the length of the growing season were correlated with field-derived data regarding the presence/absence of D. reticulatus. We also used categorical descriptions of the habitat to capture the vegetation patterns that might delineate the distribution of the tick. We demonstrated that temperature, phenology of vegetation and length of growing season have no correlation with the occurrence of D. reticulatus in Poland. There is, however, a clear association between the trends of the loss of forests and the presence of the tick. This parameter was two times higher at sites colonized by D. reticulatus in comparison to the sites where the population of the tick is not yet established. A spatial analysis demonstrated that the preferred territories for D. reticulatus are those of a highly fragmented landscape within a large patch of homogeneous vegetation, in the vicinity of permanent water courses or reservoirs.
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Affiliation(s)
- Ewa J Mierzejewska
- Department of Parasitology, Faculty of Biology, University of Warsaw, Warsaw, Poland.
| | - Agustín Estrada-Peña
- Department of Animal Health, Faculty of Veterinary Medicine, University of Zaragoza, Zaragoza, Spain
| | - Anna Bajer
- Department of Parasitology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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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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Estrada-Peña A, de la Fuente J, Cabezas-Cruz A. A comparison of the performance of regression models of Amblyomma americanum (L.) (Ixodidae) using life cycle or landscape data from administrative divisions. Ticks Tick Borne Dis 2016; 7:624-30. [PMID: 26826973 DOI: 10.1016/j.ttbdis.2016.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 12/27/2015] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
Abstract
The distribution of Amblyomma americanum (L.) in the continental United States has been modelled using the reported distribution in counties as "established" (six or more ticks or two or more life stages were recorded during a specified time period), "reported" (fewer than six ticks of a single life stage were recorded), or "absent" (neither of the above categories were met) and a set of environmental and biotic explanatory variables. Categorical (vegetation, climate, and habitat suitability for the main host of the tick) or continuous variables (raw data on temperature, vegetation, and habitat fragmentation), as well as the processes of the tick's life cycle, were tested to build models using multiple logistic regression. The best results were obtained when the life cycle processes were used as descriptors of regressions. Better models derived from life cycle processes were obtained after inclusion of habitat suitability for the white tailed deer (the main host of the tick) and landscape fragmentation. Using this approach, 86% of "absent" and 83% of "established" counties were classified correctly, but all "reported" counties were erroneously classified. Modelling life cycle processes with descriptions of host abundance and habitat fragmentation produced the best outcome when coordinates were missing. When only standard categorical descriptors of climate or vegetation were included in models, results produced poor outcomes. Models were improved with remotely sensed information on temperature and vegetation but produced high rates of misclassification for 14% of "absent", 37% of "established", and 100% of "reported" counties. Modelling produced poor results in the absence of point distributions (coordinates). Therefore, "reported" counties cannot be handled adequately by modelling procedures, probably because this category does not reflect the true status of the tick distribution. We conclude that standard categorical classifications of the distribution of an organism can not be reliably used as input for modelling procedures.
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Affiliation(s)
- Agustín Estrada-Peña
- Department of Animal Pathology, Faculty of Veterinary Medicine, University of Zaragoza, Spain
| | - José de la Fuente
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA; SaBio, Instituto de Investigación en Recursos Cinegéticos (IREC)-Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Castilla-La Mancha (UCLM)-Junta de Comunidades de Castilla-La Mancha (JCCM), Ronda de Toledo s/n, 13005 Ciudad Real, Spain
| | - Alejandro Cabezas-Cruz
- Center for Infection and Immunity of Lille (CIIL), INSERM U1019-CNRS UMR 8204, Université Lille Nord de France, Institut Pasteur de Lille, Lille, France
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Corley CD, Pullum LL, Hartley DM, Benedum C, Noonan C, Rabinowitz PM, Lancaster MJ. Disease prediction models and operational readiness. PLoS One 2014; 9:e91989. [PMID: 24647562 PMCID: PMC3960139 DOI: 10.1371/journal.pone.0091989] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 02/19/2014] [Indexed: 11/18/2022] Open
Abstract
The objective of this manuscript is to present a systematic review of biosurveillance models that operate on select agents and can forecast the occurrence of a disease event. We define a disease event to be a biological event with focus on the One Health paradigm. These events are characterized by evidence of infection and or disease condition. We reviewed models that attempted to predict a disease event, not merely its transmission dynamics and we considered models involving pathogens of concern as determined by the US National Select Agent Registry (as of June 2011). We searched commercial and government databases and harvested Google search results for eligible models, using terms and phrases provided by public health analysts relating to biosurveillance, remote sensing, risk assessments, spatial epidemiology, and ecological niche modeling. After removal of duplications and extraneous material, a core collection of 6,524 items was established, and these publications along with their abstracts are presented in a semantic wiki at http://BioCat.pnnl.gov. As a result, we systematically reviewed 44 papers, and the results are presented in this analysis. We identified 44 models, classified as one or more of the following: event prediction (4), spatial (26), ecological niche (28), diagnostic or clinical (6), spread or response (9), and reviews (3). The model parameters (e.g., etiology, climatic, spatial, cultural) and data sources (e.g., remote sensing, non-governmental organizations, expert opinion, epidemiological) were recorded and reviewed. A component of this review is the identification of verification and validation (V&V) methods applied to each model, if any V&V method was reported. All models were classified as either having undergone Some Verification or Validation method, or No Verification or Validation. We close by outlining an initial set of operational readiness level guidelines for disease prediction models based upon established Technology Readiness Level definitions.
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Affiliation(s)
- Courtney D. Corley
- Pacific Northwest National Laboratory, Richland, Washington, United States of America
- * E-mail:
| | - Laura L. Pullum
- Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - David M. Hartley
- Georgetown University Medical Center, Washington, DC, United States of America
| | - Corey Benedum
- Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Christine Noonan
- Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Peter M. Rabinowitz
- Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Mary J. Lancaster
- Pacific Northwest National Laboratory, Richland, Washington, United States of America
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Steigedal HH, Loe LE, Grøva L, Mysterud A. The effect of sheep ( Ovis aries) presence on the abundance of ticks ( Ixodes ricinus). ACTA AGR SCAND A-AN 2013. [DOI: 10.1080/09064702.2013.823236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Lauterbach R, Wells K, O'Hara RB, Kalko EKV, Renner SC. Variable strength of forest stand attributes and weather conditions on the questing activity of Ixodes ricinus ticks over years in managed forests. PLoS One 2013; 8:e55365. [PMID: 23372852 PMCID: PMC3555926 DOI: 10.1371/journal.pone.0055365] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 12/21/2012] [Indexed: 11/21/2022] Open
Abstract
Given the ever-increasing human impact through land use and climate change on the environment, we crucially need to achieve a better understanding of those factors that influence the questing activity of ixodid ticks, a major disease-transmitting vector in temperate forests. We investigated variation in the relative questing nymph densities of Ixodes ricinus in differently managed forest types for three years (2008-2010) in SW Germany by drag sampling. We used a hierarchical Bayesian modeling approach to examine the relative effects of habitat and weather and to consider possible nested structures of habitat and climate forces. The questing activity of nymphs was considerably larger in young forest successional stages of thicket compared with pole wood and timber stages. Questing nymph density increased markedly with milder winter temperatures. Generally, the relative strength of the various environmental forces on questing nymph density differed across years. In particular, winter temperature had a negative effect on tick activity across sites in 2008 in contrast to the overall effect of temperature across years. Our results suggest that forest management practices have important impacts on questing nymph density. Variable weather conditions, however, might override the effects of forest management practices on the fluctuations and dynamics of tick populations and activity over years, in particular, the preceding winter temperatures. Therefore, robust predictions and the detection of possible interactions and nested structures of habitat and climate forces can only be quantified through the collection of long-term data. Such data are particularly important with regard to future scenarios of forest management and climate warming.
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Affiliation(s)
- Ralf Lauterbach
- Institute of Experimental Ecology, University of Ulm, Ulm, Germany
| | - Konstans Wells
- Institute of Experimental Ecology, University of Ulm, Ulm, Germany
- Biodiversity and Climate Research Centre, Frankfurt, Germany
| | | | | | - Swen C. Renner
- Institute of Experimental Ecology, University of Ulm, Ulm, Germany
- Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, United States of America
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Stefanoff P, Rosinska M, Samuels S, White DJ, Morse DL, Randolph SE. A national case-control study identifies human socio-economic status and activities as risk factors for tick-borne encephalitis in Poland. PLoS One 2012; 7:e45511. [PMID: 23029063 PMCID: PMC3446880 DOI: 10.1371/journal.pone.0045511] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 08/21/2012] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Tick-borne encephalitis (TBE) is endemic to Europe and medically highly significant. This study, focused on Poland, investigated individual risk factors for TBE symptomatic infection. METHODS AND FINDINGS In a nation-wide population-based case-control study, of the 351 TBE cases reported to local health departments in Poland in 2009, 178 were included in the analysis. For controls, of 2704 subjects (matched to cases by age, sex, district of residence) selected at random from the national population register, two were interviewed for each case and a total of 327 were suitable for the analysis. Questionnaires yielded information on potential exposure to ticks during the six weeks (maximum incubation period) preceding disease onset in each case. Independent associations between disease and socio-economic factors and occupational or recreational exposure were assessed by conditional logistic regression, stratified according to residence in known endemic and non-endemic areas. Adjusted population attributable fractions (PAF) were computed for significant variables. In endemic areas, highest TBE risk was associated with spending ≥10 hours/week in mixed forests and harvesting forest foods (adjusted odds ratio 19.19 [95% CI: 1.72-214.32]; PAF 0.127 [0.064-0.193]), being unemployed (11.51 [2.84-46.59]; 0.109 [0.046-0.174]), or employed as a forester (8.96 [1.58-50.77]; 0.053 [0.011-0.100]) or non-specialized worker (5.39 [2.21-13.16]; 0.202 [0.090-0.282]). Other activities (swimming, camping and travel to non-endemic regions) reduced risk. Outside TBE endemic areas, risk was greater for those who spent ≥10 hours/week on recreation in mixed forests (7.18 [1.90-27.08]; 0.191 [0.065-0.304]) and visited known TBE endemic areas (4.65 [0.59-36.50]; 0.058 [-0.007-0.144]), while travel to other non-endemic areas reduced risk. CONCLUSIONS These socio-economic factors and associated human activities identified as risk factors for symptomatic TBE in Poland are consistent with results from previous correlational studies across eastern Europe, and allow public health interventions to be targeted at particularly vulnerable sections of the population.
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Affiliation(s)
- Pawel Stefanoff
- Department of Epidemiology, National Institute of Public Health – National Institute of Hygiene, Warsaw, Poland
| | - Magdalena Rosinska
- Department of Epidemiology, National Institute of Public Health – National Institute of Hygiene, Warsaw, Poland
| | - Steven Samuels
- State University of New York at Albany, School of Public Health, Rensselaer, New York, United States of America
| | - Dennis J. White
- State University of New York at Albany, School of Public Health, Rensselaer, New York, United States of America
- New York State Department of Health, Albany, New York, United States of America
| | - Dale L. Morse
- National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Hausermann H, Tschakert P, Smithwick EAH, Ferring D, Amankwah R, Klutse E, Hagarty J, Kromel L. Contours of risk: spatializing human behaviors to understand disease dynamics in changing landscapes. ECOHEALTH 2012; 9:251-255. [PMID: 22805769 DOI: 10.1007/s10393-012-0780-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 06/14/2012] [Accepted: 06/14/2012] [Indexed: 06/01/2023]
Abstract
We echo viewpoints presented in recent publications from EcoHealth and other journals arguing for the need to understand linkages between human health, disease ecology, and landscape change. We underscore the importance of incorporating spatialities of human behaviors and perceptions in such analyses to further understandings of socio-ecological interactions mediating human health. We use Buruli ulcer, an emerging necrotizing skin infection and serious health concern in central Ghana, to illustrate our argument.
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Affiliation(s)
- Heidi Hausermann
- Department of Human Ecology, Rutgers University, New Brunswick, NJ 08901-8520, USA.
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15
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El-Seedi HR, Khalil NS, Azeem M, Taher EA, Göransson U, Pålsson K, Borg-Karlson AK. Chemical composition and repellency of essential oils from four medicinal plants against Ixodes ricinus nymphs (Acari: Ixodidae). JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:1067-1075. [PMID: 23025188 DOI: 10.1603/me11250] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In our search for effective tick repellents from plant origin, we investigated the effect of essential oils of four medicinal and culinary plants belonging to the family Lamiaceae on nymphs of the tick Ixodes ricinus (L.). The essential oils of the dry leaves of Rosmarinus officinalis (Rosemary) (L.), Mentha spicata (Spearmint) (L.), Origanum majorana (Majoram) (L.), and Ocimum basilicum (Basil) (L.) were isolated by steam distillation and 15 microg/cm2 concentration of oils was tested against ticks in a laboratory bioassay. The oils of R. officinalis, M. spicata, and O. majorana showed strong repellency against the ticks 100, 93.2, and 84.3%, respectively, whereas O. basilicum only showed 64.5% repellency. When tested in the field, the oils of R. officinalis and M. spicata showed 68.3 and 59.4% repellency at a concentration of 6.5 microg/cm2 on the test cloths. The oils were analyzed by gas chromatography mass spectrometry and the major compounds from the most repellent oils were 1,8-cineole, camphor, linalool, 4-terpineol, borneol, and carvone.
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Affiliation(s)
- Hesham R El-Seedi
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123, Biomedical Centre, Uppsala, Sweden.
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16
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Gilbert L, Maffey GL, Ramsay SL, Hester AJ. The effect of deer management on the abundance of Ixodes ricinus in Scotland. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2012; 22:658-667. [PMID: 22611862 DOI: 10.1890/11-0458.1] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The management of wildlife hosts for controlling parasites and disease has a history of mixed success. Deer can be important hosts for ticks, such as Ixodes ricinus, which is the primary vector of disease-causing zoonotic pathogens in Europe. Deer are generally managed by culling and fencing for forestry protection, habitat conservation, and commercial hunting, and in this study we test whether these deer management methods can be useful for controlling ticks, with implications for tick-borne pathogens. At different spatial scales and habitats we tested the hypotheses that tick abundance is reduced by (1) culling deer and (2) deer exclusion using fencing. We compared abundance indices of hosts and questing I. ricinus nymphs using a combination of small-scale fencing experiments on moorland, a large-scale natural experiment of fenced and unfenced pairs of forests, and cross-sectional surveys of forest and moorland areas with varying deer densities. As predicted, areas with fewer deer had fewer ticks, and fenced exclosures had dramatically fewer ticks in both large-scale forest and small-scale moorland plots. Fencing and reducing deer density were also associated with higher ground vegetation. The implications of these results on other hosts, pathogen prevalence, and disease risk are discussed. This study provides evidence of how traditional management methods of a keystone species can reduce a generalist parasite, with implications for disease risk mitigation.
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Affiliation(s)
- L Gilbert
- James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, United Kingdom.
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17
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Agoulon A, Malandrin L, Lepigeon F, Vénisse M, Bonnet S, Becker CAM, Hoch T, Bastian S, Plantard O, Beaudeau F. A Vegetation Index qualifying pasture edges is related to Ixodes ricinus density and to Babesia divergens seroprevalence in dairy cattle herds. Vet Parasitol 2011; 185:101-9. [PMID: 22079425 DOI: 10.1016/j.vetpar.2011.10.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 10/12/2011] [Accepted: 10/18/2011] [Indexed: 11/25/2022]
Abstract
Babesia divergens, transmitted by the tick Ixodes ricinus, is the main agent of bovine piroplasmosis in France. This Apicomplexa often is present in asymptomatic carriers; however, clinical cases are rare. While numerous factors are known to influence tick density, no risk factor of contact with B. divergens has been identified for cattle. Our study aimed to explore whether a Vegetation Index could serve as an indirect indicator of within-herd B. divergens seroprevalence. In February 2007, blood samples were taken from all of the cows in 19 dairy cattle herds in Western France and IFAT serology was performed individually to measure B. divergens seroprevalence. The following spring, I. ricinus nymphs were collected by drag sampling along transects on the vegetation of each farm's pasture perimeters. Tick density was related significantly to a Vegetation Index (V.I., ranging from 1 to 5) that took into account the abundance of trees and bushes on the edge of pastures: most ticks (57%) were found in transects with the highest V.I. (covering 15% of the explored surface in the study area). At the farm level, the proportion of transects presenting I. ricinus nymphs was significantly related to B. divergens seroprevalence: the farms with more than 15% of transects with I. ricinus had a significantly higher risk of high seroprevalence. The proportion of pasture perimeters where the V.I.=5 also was significantly related to B. divergens seroprevalence: the farms where more than 20% of transects had a V.I.=5 had a significantly higher risk of high seroprevalence. Given that the Vegetation Index is a steady indicator of the potential I. ricinus density in the biotope, we recommend that the risk of high B. divergens seroprevalence in cows be evaluated using this tool rather than drag samplings.
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Affiliation(s)
- Albert Agoulon
- LUNAM Université, Oniris, UMR 1300 Bio-Agression, Epidémiologie et Analyse de Risque, Nantes, F-44307, France.
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18
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Lambin EF, Tran A, Vanwambeke SO, Linard C, Soti V. Pathogenic landscapes: interactions between land, people, disease vectors, and their animal hosts. Int J Health Geogr 2010; 9:54. [PMID: 20979609 PMCID: PMC2984574 DOI: 10.1186/1476-072x-9-54] [Citation(s) in RCA: 211] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 10/27/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Landscape attributes influence spatial variations in disease risk or incidence. We present a review of the key findings from eight case studies that we conducted in Europe and West Africa on the impact of land changes on emerging or re-emerging vector-borne diseases and/or zoonoses. The case studies concern West Nile virus transmission in Senegal, tick-borne encephalitis incidence in Latvia, sandfly abundance in the French Pyrenees, Rift Valley Fever in the Ferlo (Senegal), West Nile Fever and the risk of malaria re-emergence in the Camargue, and rodent-borne Puumala hantavirus and Lyme borreliosis in Belgium. RESULTS We identified general principles governing landscape epidemiology in these diverse disease systems and geographic regions. We formulated ten propositions that are related to landscape attributes, spatial patterns and habitat connectivity, pathways of pathogen transmission between vectors and hosts, scale issues, land use and ownership, and human behaviour associated with transmission cycles. CONCLUSIONS A static view of the "pathogenecity" of landscapes overlays maps of the spatial distribution of vectors and their habitats, animal hosts carrying specific pathogens and their habitat, and susceptible human hosts and their land use. A more dynamic view emphasizing the spatial and temporal interactions between these agents at multiple scales is more appropriate. We also highlight the complementarity of the modelling approaches used in our case studies. Integrated analyses at the landscape scale allows a better understanding of interactions between changes in ecosystems and climate, land use and human behaviour, and the ecology of vectors and animal hosts of infectious agents.
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Affiliation(s)
- Eric F Lambin
- Georges Lemaître Centre for Earth and Climate Research, Earth and Life Institute, University of Louvain, 3 place Pasteur, Louvain-la-Neuve, B-1348, Belgium
- School of Earth Sciences and Woods Institute, Stanford University, 473 Via Ortega, Stanford, CA 94305-4216, USA
| | - Annelise Tran
- CIRAD, Animal et gestion intégrée des risques (Agirs), CIRAD, Montpellier, France
- CIRAD, UMR Territoires, environnement, télédétection et information spatiale (TETIS), CIRAD, Montpellier, France
- SAS Nevantropic, Cayenne, French Guiana, France
| | - Sophie O Vanwambeke
- Georges Lemaître Centre for Earth and Climate Research, Earth and Life Institute, University of Louvain, 3 place Pasteur, Louvain-la-Neuve, B-1348, Belgium
| | - Catherine Linard
- Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford, OX1 3PS, UK
| | - Valérie Soti
- CIRAD, Animal et gestion intégrée des risques (Agirs), CIRAD, Montpellier, France
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Vanwambeke SO, Sumilo D, Bormane A, Lambin EF, Randolph SE. Landscape predictors of tick-borne encephalitis in Latvia: land cover, land use, and land ownership. Vector Borne Zoonotic Dis 2010; 10:497-506. [PMID: 19877818 DOI: 10.1089/vbz.2009.0116] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although the presence of tick-borne encephalitis (TBE) virus circulating in tick populations depends on large-scale patterns of climate, and the local density of infected ticks depends on the abundance of mammalian hosts, the risk of human infection depends on the access and use by human populations of tick-infested habitats, particularly forests, at the landscape level. We investigated the incidence of reported TBE cases in rural parishes (i.e., municipalities) in Latvia. The following major characteristics of parishes were considered: whether their environment is suitable for tick and tick-host populations (depending on land cover); whether the local human population is likely to enter the forest on a regular base (depending on land use); and whether the spatial distributions of these two aspects are likely to intersect, through access rules (as a function of land ownership). The results indicated that all three aspects are important in explaining and predicting the spatial distribution of TBE cases in the rural areas of Latvia. The concept of landscape is here given new depth by consideration of its physical structure, its use by human populations, and its accessibility as modulated by ownership.
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Affiliation(s)
- Sophie O Vanwambeke
- Department of Geography, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
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20
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Hansmann Y, Pierre Gut J, Remy V, Martinot M, Allard Witz M, Christmann D. Tick-borne encephalitis in eastern France. ACTA ACUST UNITED AC 2009; 38:520-6. [PMID: 16798704 DOI: 10.1080/00365540600585073] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Each y a few cases of TBE infection are described in Alsace, France which lies at the occidental limit of the endemic zone of tick-borne encephalitis (TBE). Hence we carried out a retrospective epidemiological and clinical study of TBE infection in Alsace. Data were collected from serological results sent to the Institut de Virologie (Université Louis Pasteur) in Strasbourg. All samples positive for specific IgM against TBE were retained. The physician in charge of each patient was asked to provide clinical, epidemiological and biological data and with his agreement the medical file was referred to us. Since 1968, 64 cases of TBE infection, occurring between April and November, had been described. In 56% of cases, flu-like symptoms preceded neurological symptoms. Most patients had meningitis (54%) or meningoencephalitis (34%). There was no death due to TBE. Two areas were more highly endemic for the disease: the Guebwiller valley in low mountain country and the Neuhof forest, near Strasbourg in the plain of Alsace. In the last 2 y of the study, a third zone seemed to emerge, in the Munster valley. This epidemiological survey revealed the existence in Alsace of 2 endemic zones of TBE with a third zone possibly emerging in the last few y. The survey must be continued to follow the evolution of the disease.
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Affiliation(s)
- Yves Hansmann
- Clinique Médicale A-Hôpital Civil, Hôpitaux Universitaires de Strasbourg, Colmar, France
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21
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Schwarz A, Maier WA, Kistemann T, Kampen H. Analysis of the distribution of the tick Ixodes ricinus L. (Acari: Ixodidae) in a nature reserve of western Germany using Geographic Information Systems. Int J Hyg Environ Health 2008; 212:87-96. [PMID: 18262840 DOI: 10.1016/j.ijheh.2007.12.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2007] [Revised: 11/09/2007] [Accepted: 12/18/2007] [Indexed: 11/19/2022]
Abstract
From May to November 2003, at five selected sites of the 'Siebengebirge', a nature reserve near Bonn, Germany, data on microclimate, pedology, plant sociology and tick abundance were collected weekly and correlated. A total of 2832 host-seeking Ixodes ricinus (2660 nymphs and 172 adults) were collected, with maximal abundance in June and a minor second increase in abundance in August. The spatial and temporal variation in tick abundance was closely related to the air temperature, relative humidity, soil water content and specific vegetation type. Increases in tick abundances in individual habitats were most likely caused by climate change and/or anthropogenic interventions such as increased numbers of wild boar, a host of I. ricinus. When combined with data from previous investigations a correlation of plant communities with six semi-qualitative tick abundance categories (ranging from 'no ticks' to 'very high tick abundance') was revealed, and GIS analysis indicated that 56.5% of the 'Siebengebirge' is made up of plant communities belonging to the three highest tick abundance categories. Therefore, the risk of visitors in the 'Siebengebirge' of being exposed to tick bites and being infected by Borrelia burgdorferi sensu lato had increased.
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Affiliation(s)
- Alexandra Schwarz
- Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Germany.
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22
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Linard C, Lamarque P, Heyman P, Ducoffre G, Luyasu V, Tersago K, Vanwambeke SO, Lambin EF. Determinants of the geographic distribution of Puumala virus and Lyme borreliosis infections in Belgium. Int J Health Geogr 2007; 6:15. [PMID: 17474974 PMCID: PMC1867807 DOI: 10.1186/1476-072x-6-15] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Accepted: 05/02/2007] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Vector-borne and zoonotic diseases generally display clear spatial patterns due to different space-dependent factors. Land cover and land use influence disease transmission by controlling both the spatial distribution of vectors or hosts, and the probability of contact with susceptible human populations. The objective of this study was to combine environmental and socio-economic factors to explain the spatial distribution of two emerging human diseases in Belgium, Puumala virus (PUUV) and Lyme borreliosis. Municipalities were taken as units of analysis. RESULTS Negative binomial regressions including a correction for spatial endogeneity show that the spatial distribution of PUUV and Lyme borreliosis infections are associated with a combination of factors linked to the vector and host populations, to human behaviours, and to landscape attributes. Both diseases are associated with the presence of forests, which are the preferred habitat for vector or host populations. The PUUV infection risk is higher in remote forest areas, where the level of urbanisation is low, and among low-income populations. The Lyme borreliosis transmission risk is higher in mixed landscapes with forests and spatially dispersed houses, mostly in wealthy peri-urban areas. The spatial dependence resulting from a combination of endogenous and exogenous processes could be accounted for in the model on PUUV but not for Lyme borreliosis. CONCLUSION A large part of the spatial variation in disease risk can be explained by environmental and socio-economic factors. The two diseases not only are most prevalent in different regions but also affect different groups of people. Combining these two criteria may increase the efficiency of information campaigns through appropriate targeting.
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Affiliation(s)
- Catherine Linard
- Department of Geography, Université Catholique de Louvain, Place Pasteur 3, B-1348 Louvain-la-Neuve, Belgium
| | - Pénélope Lamarque
- Department of Geography, Université Catholique de Louvain, Place Pasteur 3, B-1348 Louvain-la-Neuve, Belgium
| | - Paul Heyman
- Research Laboratory and Reference Laboratory for Vector-borne Diseases, Queen Astrid Military Hospital, B-1120 Brussels, Belgium
| | - Geneviève Ducoffre
- Scientific Institute of Public Health (IPH), Unit of Epidemiology, B-1050 Brussels, Belgium
| | - Victor Luyasu
- Research Group and Information on tick-borne diseases (RILY), Centre de Vaccinations, Clinique St-Pierre, B-1340 Ottignies, Belgium
| | - Katrien Tersago
- Research group of Evolutionary Biology, University of Antwerp, B-2020 Antwerp, Belgium
| | - Sophie O Vanwambeke
- Department of Geography, Université Catholique de Louvain, Place Pasteur 3, B-1348 Louvain-la-Neuve, Belgium
| | - Eric F Lambin
- Department of Geography, Université Catholique de Louvain, Place Pasteur 3, B-1348 Louvain-la-Neuve, Belgium
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23
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Garboui SS, Jaenson TGT, Borg-Karlson AK, Pålsson K. Repellency of methyl jasmonate to Ixodes ricinus nymphs (Acari: Ixodidae). EXPERIMENTAL & APPLIED ACAROLOGY 2007; 42:209-15. [PMID: 17611808 DOI: 10.1007/s10493-007-9066-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 03/04/2007] [Indexed: 05/16/2023]
Abstract
In our search for tick repellents of plant origin, to be used as alternatives to commercial arthropod repellents, we investigated the effect of the well known plant signaling compound methyl jasmonate (MJ) using nymphs of the tick Ixodes ricinus. In laboratory tests, pieces of cloth with MJ at 0.075, 0.15, 0.30 and 0.75 mg/cm2 yielded increasing repellencies against the nymphs: 57%, 71%, 92% and 99%, respectively, of the nymphs did not cling to the cloth. Repellency of MJ was also investigated in a tick-infested woodland area in central Sweden. Cotton flannel cloths sprayed with 0.05, 0.1 or 0.2 mg/cm2 MJ dissolved in acetone were dragged over the ground vegetation. The numbers of nymphs on the treated cloths were significantly lower than those on the untreated cloth. Thus, MJ has, at the concentrations tested, significant repellent activity against I. ricinus nymphs.
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Affiliation(s)
- Samira S Garboui
- Medical Entomology Unit, Department of Systematic Zoology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden
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24
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Rácz GR, Bán E, Ferenczi E, Berencsi G. A Simple Spatial Model to Explain the Distribution of Human Tick-Borne Encephalitis Cases in Hungary. Vector Borne Zoonotic Dis 2006; 6:369-78. [PMID: 17187571 DOI: 10.1089/vbz.2006.6.369] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Tick-borne encephalitis (TBE) is a common medical problem in Hungary and throughout much of Europe and Asia. This paper develops a geographic model that helps to predict the distribution of human tick-borne encephalitis cases in Hungary. The model is tested on a dataset of serologically confirmed TBE cases mapped by patients' residences. Case densities (incidence rates) are compared to predicted distributions of TBE derived from digital land-cover data. Maps are analyzed at the county level and on a smaller spatial scale. The analyses identified three major factors that shape the geographic distribution of human TBE cases in Hungary. The most important component is the distribution of forest habitat. TBE incidence correlates positively with the amount of forested habitat in each county. On a finer scale, the amount of forests within a 2500-meter radius of each town and village correlated significantly with TBE incidence rate. Based on these data, about 30% of the variation in TBE incidence is accounted for by the specific distribution of forest habitats in Hungary. Besides the distribution of forests, differences in human land-use practices among regions also affect the distribution of TBE cases. Additionally, because of the low transmission rate of the virus to humans, the perceived distribution of TBE cases is affected by random stochastic events. As a consequence of stochastic variation, meaningful patterns in the distribution of TBE cases can be only recognized when data are analyzed over broader temporal and spatial scales.
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Affiliation(s)
- Gábor R Rácz
- Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
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25
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Abstract
Geographic information systems (GIS), their fundamental components and technologies are described. GIS is a computer-based system enabling the storage, integration, query, display and analysis of data using information on data location. Further, remote sensing (RS) methods and their application in landscape characterization are described. Landscape pattern analysis, combined with statistical analysis, allows the determination of landscape predictors of disease risk. This makes RS/GIS a powerful set of tools for disease surveillance, enabling the prediction of potential disease outbreaks and targeting intervention programs. The 'pre-GIS era' is briefly described including the early mapping of tick distribution, analyses and the display of biogeographical and medical data. The theory of natural focality of diseases (NFD) is explained and its significance in tick-borne diseases (TBD) research is discussed. Many problems of tick ecology and TBD epidemiology and epizootology have been addressed by means of GIS and examples of these studies are presented and discussed.
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Affiliation(s)
- M Daniel
- School of Public Health, Institute of Postgraduate Medical Education, Prague, Czech Republic.
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26
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Odiit M, Bessell PR, Fèvre EM, Robinson T, Kinoti J, Coleman PG, Welburn SC, McDermott J, Woolhouse MEJ. Using remote sensing and geographic information systems to identify villages at high risk for rhodesiense sleeping sickness in Uganda. Trans R Soc Trop Med Hyg 2006; 100:354-62. [PMID: 16246384 DOI: 10.1016/j.trstmh.2005.04.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 04/01/2005] [Accepted: 04/12/2005] [Indexed: 11/25/2022] Open
Abstract
Geographic information systems (GIS) and remote sensing were used to identify villages at high risk for sleeping sickness, as defined by reported incidence. Landsat Enhanced Thematic Mapper (ETM) satellite data were classified to obtain a map of land cover, and the Normalised Difference Vegetation Index (NDVI) and Landsat band 5 were derived as unclassified measures of vegetation density and soil moisture, respectively. GIS functions were used to determine the areas of land cover types and mean NDVI and band 5 values within 1.5 km radii of 389 villages where sleeping sickness incidence had been estimated. Analysis using backward binary logistic regression found proximity to swampland and low population density to be predictive of reported sleeping sickness presence, with distance to the sleeping sickness hospital as an important confounding variable. These findings demonstrate the potential of remote sensing and GIS to characterize village-level risk of sleeping sickness in endemic regions.
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Affiliation(s)
- Martin Odiit
- Sleeping Sickness Programme, National Agricultural Research Organization, LIRI Hospital, P.O. Box 96, Tororo, Uganda
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27
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Daniel M, Zitek K, Danielová V, Kríz B, Valter J, Kott I. Risk assessment and prediction of Ixodes ricinus tick questing activity and human tick-borne encephalitis infection in space and time in the Czech Republic. Int J Med Microbiol 2006; 296 Suppl 40:41-7. [PMID: 16567128 DOI: 10.1016/j.ijmm.2006.02.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Present risk assessment and prediction of future risk of humans exposed to Ixodes (I.) ricinus tick attacks and, consequently, to tick-borne encephalitis (TBE) virus infection as one of the basic preconditions for successful TBE prevention has been intensively studied in the Czech Republic. An atlas of TBE in the Czech Republic containing predictive maps of I. ricinus high-incidence habitats and TBE risk sites identified by satellite data (Landsat 5 TM with spatial resolution 30 m) at a scale of 1:200,000 over a territory of 52,000 km(2) and maps of human TBE case distribution (1971-2000) has been prepared using remote sensing and geographical information systems technologies. The influence of climate changes on a forest ecosystem inhabited by I. ricinus has been studied in the southern region of the Czech Republic. The analysis of long-term series (1931-2000) of climatologic and phenological characteristics has been carried out. The results are compared with the long-term series of TBE incidence. The influence of weather condition on day-to-day changes of I. ricinus host-seeking activities was studied in 2001-2004. Field observations were realized in the south-eastern periphery of Prague where the experimental plots for tick monitoring were established in a relevant type of forest growth (Querceto-carpinetum). I. ricinus activities were investigated by the flagging method on three plots (200 m(2) each) in weekly intervals (March to November) during 2001-2004. The instruments for micrometeorological observations were installed between the experimental plots. Macrometeorological data were used from the nearby Czech Hydrometeorological Institute first class meteorological observatory. Simple and multiple linear regression and quadratic regression were used to test the relation between weather modification and I. ricinus host-seeking activity. Two preliminary most suitable 'models' are demonstrated.
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Affiliation(s)
- Milan Daniel
- National Institute of Public Health, Prague, Czech Republic.
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28
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Estrada-Peña A, Quílez J, del Cacho E, Acedo CS. A framework to map abundance of tick metapopulations. Ecol Modell 2006. [DOI: 10.1016/j.ecolmodel.2005.09.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Pietzsch ME, Medlock JM, Jones L, Avenell D, Abbott J, Harding P, Leach S. Distribution of Ixodes ricinus in the British Isles: investigation of historical records. MEDICAL AND VETERINARY ENTOMOLOGY 2005; 19:306-14. [PMID: 16134979 DOI: 10.1111/j.1365-2915.2005.00575.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Ixodes ricinus Linnaeus (Acari: Ixodidae) is the most abundant and widely distributed tick in the British Isles, and is a vector for a number of bacterial, viral and protozoal pathogens of both medical and veterinary importance. This report provides an update to the historical distribution data of I. ricinus, published by the Biological Records Centre (BRC), Monks Wood in The Provisional Atlas of the Ticks (Ixodidae) of the British Isles by K. P. Martyn (1988), and is supplemented with additional BRC records since 1988, additional data from published scientific literature and unpublished field studies, and enhanced with spatial and temporal information on tick stages collected and their host associations. Records have been mapped at 10 km resolution and enhanced to 5 km, 1 km and 0.1 km. Differentiation between records representing one-off collections from those representing populations of I. ricinus has been achieved through the classification of the records into either reported or established populations. Detailed seasonality and host associations of records are investigated, highlighting the value in obtaining additional detailed contemporary data to aid risk assessments and research within this field.
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Affiliation(s)
- M E Pietzsch
- Microbial Risk Assessment, Health Protection Agency, Centre for Emergency Preparedness & Response, Porton Down, Salisbury, Wiltshire SP4 0JG, U.K.
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Foley JE, Queen EV, Sacks B, Foley P. GIS-facilitated spatial epidemiology of tick-borne diseases in coyotes (Canis latrans) in northern and coastal California. Comp Immunol Microbiol Infect Dis 2005; 28:197-212. [PMID: 15857659 DOI: 10.1016/j.cimid.2005.01.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2005] [Indexed: 11/15/2022]
Abstract
Ixodes pacificus is the main tick vector for transmission of Anaplasma phagocytophilum and Borrelia burgdorferi to large vertebrates in California. The present study was undertaken in I. pacificus-infested counties in California to examine spatial and temporal relationships among A. phagocytophilum and B. burgdorferi-exposed coyotes with vegetation type and climate. The overall A. phagocytophilum and B. burgdorferi seroprevalences were 39.5% (N=215) and 18.9% (N=148), respectively, with no association with sex. PCR for A. phagocytophilum and B. burgdorferi was negative in all blood and kidney samples. Increased seroprevalence was a positive function of rainfall. Ehrlichial seropositivity was increased in blue-oak foothill pine, montane hardwood, and redwood vegetation regions, and decreased in coastal sagebrush and cropland. Increased exposure to B. burgdorferi occurred in blue oak woodland.
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Affiliation(s)
- Janet E Foley
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Randolph SE. Tick ecology: processes and patterns behind the epidemiological risk posed by ixodid ticks as vectors. Parasitology 2005; 129 Suppl:S37-65. [PMID: 15938504 DOI: 10.1017/s0031182004004925] [Citation(s) in RCA: 293] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The population ecology of ticks is fundamental to the spatial and temporal variation in the risk of infection by tick-borne pathogens. Tick population dynamics can only be fully understood by quantifying the rates of the demographic processes, which are influenced by both abiotic (climatic) factors acting on the free-living tick stages and biotic (host) responses to the tick as a parasite. Within the framework of a population model, I review methods and results of attempts to quantify (1) rates of tick development and the probability of diapause, (2) the probability of questing for hosts by unfed ticks, (3) the probability of ticks attaching to a host, and (4) tick mortality rates. Biologically, these processes involve the physiological and behavioural response of ticks to temperature, moisture stress and day length that result in specific patterns of seasonal population dynamics and host relationships. Temperate and tropical patterns will be illustrated with reference mostly toIxodes ricinusandRhipicephalus appendiculatus, respectively.
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Affiliation(s)
- S E Randolph
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Barrera R, Torres N, Freier JE, Navarro JC, García CZ, Salas R, Vasquez C, Weaver SC. Characterization of enzootic foci of Venezuelan equine encephalitis virus in western Venezuela. Vector Borne Zoonotic Dis 2003; 1:219-30. [PMID: 12653150 DOI: 10.1089/153036601753552585] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The distribution of the sylvatic subtype ID Venezuelan equine encephalitis (VEE) viruses in the lowland tropical forests of western Venezuela was investigated using remote sensing and geographic information system technologies. Landsat 5 Thematic Mapper satellite imagery was used to study the reflectance patterns of VEE endemic foci and to identify other locations with similar reflectance patterns. Enzootic VEE virus variants isolated during this study are the closest genetic relatives of the epizootic viruses that emerged in western Venezuela during 1992-1993. VEE virus surveillance was conducted by exposing sentinel hamsters to mosquito bites and trapping wild vertebrates in seven forests identified and located by means of the satellite image. We isolated VEE viruses from 48 of a total of 1,363 sentinel hamsters in two of the forests on six occasions, in both dry and wet seasons. None of the 12 small vertebrates captured in 8,190 trap-nights showed signs of previous VEE virus infection. The satellite image was classified into 13 validated classes of land use/vegetation using unsupervised and supervised techniques. Data derived from the image consisted of the raw digital values of near- and mid-infrared bands 4, 5, and 7, derived Tasseled Cap indices of wetness, greenness, and brightness, and the Normalized Difference Vegetation Index. Digitized maps provided ancillary data of elevation and soil geomorphology. Image enhancement was applied using Principal Component Analysis. A digital layer of roads together with georeferenced images was used to locate the study sites. A cluster analysis using the above data revealed two main groups of dense forests separated by spectral properties, altitude, and soil geomorphology. Virus was isolated more frequently from the forest type identified on flat flood plains of main rivers rather than the forest type found on the rolling hills of the study area. The spatial analysis suggests that mosquitoes carrying the enzootic viruses would reach 82-97% of the total land area by flying only 1-3 km from forests. We hypothesize that humans within that area are at risk of severe disease caused by enzootic ID VEE viruses. By contrast, equines could actually become naturally vaccinated, thus preventing the local emergence of epizootic IC VEE virus strains and protecting humans indirectly.
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Affiliation(s)
- R Barrera
- Instituto de Zoología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela.
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Randolph SE, Green RM, Hoodless AN, Peacey MF. An empirical quantitative framework for the seasonal population dynamics of the tick Ixodes ricinus. Int J Parasitol 2002; 32:979-89. [PMID: 12076627 DOI: 10.1016/s0020-7519(02)00030-9] [Citation(s) in RCA: 231] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The wide geographic and climatic range of the tick Ixodes ricinus, and the consequent marked variation in its seasonal population dynamics, have a direct impact on the transmission dynamics of the many pathogens vectored by this tick species. We use long-term observations on the seasonal abundance and fat contents (a marker of physiological ageing) of ticks, and contemporaneous microclimate at three field sites in the UK, to establish a simple quantitative framework for the phenology (i.e. seasonal cycle of development) of I. ricinus as a foundation for a generic population model. An hour-degree tick inter-stadial development model, driven by soil temperature and including diapause, predicts the recruitment (i.e. emergence from the previous stage) of a single cohort of each stage of ticks each year in the autumn. The timing of predicted emergence coincides exactly with the new appearance of high-fat nymphs and adults in the autumn. Thereafter, fat contents declined steadily until unfed ticks with very low energy reserves disappeared from the questing population within about 1 year from their recruitment. Very few newly emerged ticks were counted on the vegetation in the autumn, but they appeared in increasing numbers through the following spring. Larger ticks became active and subsequently left the questing population before smaller ones. Questing tick population dynamics are determined by seasonal patterns of tick behaviour, host-contact rates and mortality rates, superimposed on a basal phenology that is much less complex than has hitherto been portrayed.
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Affiliation(s)
- Sarah E Randolph
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Guerra M, Walker E, Jones C, Paskewitz S, Cortinas MR, Stancil A, Beck L, Bobo M, Kitron U. Predicting the risk of Lyme disease: habitat suitability for Ixodes scapularis in the north central United States. Emerg Infect Dis 2002; 8:289-97. [PMID: 11927027 PMCID: PMC2732460 DOI: 10.3201/eid0803.010166] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The distribution and abundance of Ixodes scapularis were studied in Wisconsin, northern Illinois, and portions of the Upper Peninsula of Michigan by inspecting small mammals for ticks and by collecting questing ticks at 138 locations in state parks and natural areas. Environmental data were gathered at a local level (i.e., micro and meso levels), and a geographic information system (GIS) was used with several digitized coverages of environmental data to create a habitat profile for each site and a grid map for Wisconsin and Illinois. Results showed that the presence and abundance of I. scapularis varied, even when the host population was adequate. Tick presence was positively associated with deciduous, dry to mesic forests and alfisol-type soils of sandy or loam-sand textures overlying sedimentary rock. Tick absence was associated with grasslands, conifer forests, wet to wet/mesic forests, acidic soils of low fertility and a clay soil texture, and Precambrian bedrock. We performed a discriminant analysis to determine environmental differences between positive and negative tick sites and derived a regression equation to examine the probability of I. scapularis presence per grid. Both analyses indicated that soil order and land cover were the dominant contributors to tick presence. We then constructed a risk map indicating suitable habitats within areas where I. scapularis is already established. The risk map also shows areas of high probability the tick will become established if introduced. Thus, this risk analysis has both explanatory power and predictive capability.
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Affiliation(s)
- Marta Guerra
- University of Illinois College of Veterinary Medicine, Urbana, Illinois, USA
| | - Edward Walker
- Michigan State University, East Lansing, Michigan, USA
| | - Carl Jones
- University of Illinois College of Veterinary Medicine, Urbana, Illinois, USA
| | | | - M. Roberto Cortinas
- University of Illinois College of Veterinary Medicine, Urbana, Illinois, USA
| | | | - Louisa Beck
- NASA Ames Research Center, Moffett Field, California
| | - Matthew Bobo
- NASA Ames Research Center, Moffett Field, California
| | - Uriel Kitron
- University of Illinois College of Veterinary Medicine, Urbana, Illinois, USA
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Randolph SE. The shifting landscape of tick-borne zoonoses: tick-borne encephalitis and Lyme borreliosis in Europe. Philos Trans R Soc Lond B Biol Sci 2001; 356:1045-56. [PMID: 11516382 PMCID: PMC1088499 DOI: 10.1098/rstb.2001.0893] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The two major vector-borne diseases of northern temperate regions, tick-borne encephalitis (TBE) and Lyme borreliosis (LB), show very different epidemiological patterns, but both have increased significantly in incidence since the 1980s. Insight into the temporal dynamics of TBE, gained from statistical analysis of spatial patterns integrated with biological explanation, suggests that the recent increases in TBE cases in Central Europe and the Baltic States may have arisen largely from changes in human behaviour that have brought more people into contact with infected ticks. Under forecast climate change scenarios, it is predicted that enzootic cycles of TBE virus may not survive along the southern edge of their present range, e.g. in Slovenia, Croatia and Hungary, where case numbers are indeed decreasing. New foci, however, are predicted and have been observed in Scandinavia. At the same time, human impact on the landscape, increasing both the habitat and wildlife hosts of ticks, has allowed tick populations to multiply significantly. This probably accounts for a genuine emergence of LB, with its high potential transmission rate, in both the USA and Europe, although the rate of emergence has been exaggerated by improved surveillance and diagnosis.
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Affiliation(s)
- S E Randolph
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Abstract
Climate and vegetation are the major factors affecting the distribution of ticks. Consequently, spatial distributions can be analysed by statistical methods that look for correlations between abiotic factors and known data about tick presence/absence. Remote sensing features can be obtained from a wide database of sensors with different characteristics, then applied to the problem of mapping prediction of tick distribution. Some studies had demonstrated that the use of these abiotic variables from satellite imagery has biological significance, therefore statistical accuracy of these distribution models can be interpreted under an ecological framework. Furthermore, models can be linked to these predictive maps, enabling the forecast of spatial and temporal dynamics of ticks, looking for seasonal patterns of activity and accurate use of acaricide treatments.
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Affiliation(s)
- A Estrada-Peña
- Department of Parasitology, Veterinary Faculty, Miguel Servet, 177, 50013, Zaragoza, Spain.
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Estrada-Peña A. Distribution, abundance, and habitat preferences of Ixodes ricinus (Acari: Ixodidae) in northern Spain. JOURNAL OF MEDICAL ENTOMOLOGY 2001; 38:361-370. [PMID: 11372959 DOI: 10.1603/0022-2585-38.3.361] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ixodes ricinus (L.) was collected by standard dragging in 2,082 different sites in 18 broad vegetation categories in northern Spain to explore the influence of vegetation on its abundance. Of these, 785 sites were surveyed in 1995, 636 in 1996, and 661 in 1997. The impact of habitat features on differences in tick numbers is addressed. The tick was present in low numbers in areas of old, heterogeneous coniferous forests. Ticks appeared to prefer sites that had substantial secondary plant growth such as river canopies, heterogeneous Pinus uncinata forests, mixed forests, and deciduous heterogeneous woods. Highest tick abundance was recorded for sites that contained Quercus spp., as well as for mixed old forests that had many ecotones. I. ricinus was absent in open habitats, homogeneous young coniferous forests, and open hillsides. These differences were attributed to greater shrub cover and litter depth, which created more favorable microclimatic conditions for tick survival. The abundance of I. ricinus nymphs was not homogeneous in sites within the same habitat category and vegetation physiognomy at these sites did not appear to cause differences in tick abundance. Analysis of variance (ANOVA) indicated that variation in tick abundance could be explained by the exposure of the sampled site, at least for some zones within deciduous forest categories. However, this factor did not explain the variation observed in other habitats. Temperature and vegetation (normalized derived vegetation index) features were recorded daily by remotely sensed imagery throughout the study period and the data were used to obtain long-term mean and maximum values of the physical parameters considered. Multiple regression analysis performed between these long-term abiotic factors and nymphal abundance in positive sites showed high relationship (R2 coefficients) for every habitat category and explained >50% of the variation in tick abundance.
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Affiliation(s)
- A Estrada-Peña
- Unidad de Parasitología, Facultad de Veterinaria, Miguel Servet, Zaragoza, Spain
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Abstract
Analyses within geographical information systems (GISs) indicate that small- and large-scale ranges of hard tick species (Ixodidae) are determined more by climate and vegetation than by host-related factors. Spatial distributions of ticks may therefore be analysed by statistical methods that seek correlations between known tick presence/absence and ground- or remotely-sensed (RS) environmental factors. In this way, local habitats of Amblyomma variegatum in the Caribbean and Ixodes ricinus in Europe have been mapped using Landsat RS imagery, while regional and continental distributions of African and temperate tick species have been predicted using multi-temporal information from the National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer (NOAA-AVHRR) imagery. These studies illustrate ways of maximizing statistical accuracy, whose interpretation is then discussed in a biological framework. Methods such as discriminant analysis are biologically transparent and interpretable, while others, such as logistic regression and tree-based classifications, are less so. Furthermore, the most consistently significant variable for predicting tick distributions, the RS Normalized Difference Vegetation Index (NDVI), has a sound biological basis in that it is related to moisture availability to free-living ticks and correlated with tick mortality rates. The development of biological process-based models for predicting the spatial dynamics of ticks is a top priority, especially as the risk of tick-borne infections is commonly related not simply to the vector's density, but to its seasonal population dynamics. Nevertheless, using statistical pattern-matching, the combination of RS temperature indices and NDVI successfully predicts certain temporal features essential for the transmission of tick-borne encephalitis virus, which translate into a spatial pattern of disease foci on a continental scale.
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Labuda M, Randolph SE. Survival strategy of tick-borne encephalitis virus: cellular basis and environmental determinants. ZENTRALBLATT FUR BAKTERIOLOGIE : INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY 1999; 289:513-24. [PMID: 10652718 DOI: 10.1016/s0934-8840(99)80005-x] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although TBE virus can be transmitted in the laboratory by a wide variety of ixodid tick species to a wide variety of vertebrate host species, nevertheless in nature endemic cycles of TBE virus depend principally on just two tick species, Ixodes ricinus in the western and I. persulcatus in the eastern Palaearctic. A complete transmission cycle, from tick to tick via vertebrates, occurs most efficiently between co-feeding ticks in the absence of a systemic viraemia. This non-systemic route depends on TBE virus replication within particular immunocompetent cells in the skin, and only certain vertebrate species, notably Apodemus mice, are susceptible to this. Amongst the potential tick vectors in Europe, only I. ricinus has the correct host relationships and appropriate natural life cycle to support such non-systemic transmission cycles. Within the wide European distribution of this tick-host relationship, only in certain places do larval and nymphal ticks feed together on the same hosts with sufficient coincidence to ensure TBE virus survival. The environmental factors that determine this seasonal coincidence are being identified with the help of remotely-sensed meteorological satellite imagery to create predictive risk maps of TBE foci.
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Affiliation(s)
- M Labuda
- Institute of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia
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Manguin S, Boussinesq M. Apport de la télédétection en santé publique: l'exemple du paludisme et autres perspectives. Med Mal Infect 1999. [DOI: 10.1016/s0399-077x(99)80065-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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