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Abstract

Zoonotic diseases are major causes of infection related morbidity and mortality worldwide. Of the various arthropods capable of transmitting pathogens that cause such diseases to humans, ticks, which are vectors of more kinds of pathogens than any other group of invertebrate, have become an increasing focus of attention. This is particularly the case in the temperate northern hemisphere where they are a significant vector of human disease. Here, we provide an overview of the complex ecological systems defining the various epidemiological cycles of tick-borne diseases. We highlight the abiotic and biotic factors influencing the establishment and persistence of tick populations and their associated pathogens. Furthermore, we emphasize the dynamic nature of such systems, especially when they are under the influence of both small and large-scale anthropogenic changes to the environment. Although a great deal of work has been done on ticks and the diseases which they transmit, the very dynamism of the system means that new factors are continually arising which shift the epidemiological pattern within specific areas. We therefore consider that more detailed, long-term (i.e. at least 10 years), multidisciplinary studies need to be carried out to define why and how these pattern shifts take place and to determine their public health significance.

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... Several organisms act as vectors and transmit or cause diseases in the agriculture sector, humans, wildlife, and livestock. Ticks (Acari: Ixodida) are bloodsucking ectoparasites and act as vectors of pathogens infecting livestock, wildlife, and humans across the world (Bente et al., 2013;Pfäffle et al., 2013;Guglielmone et al., 2014;Monfared et al., 2015;de la Fuente et al., 2016;Sajid et al., 2017;Ghafar et al., 2020). Ticks and tick-borne diseases (hereafter abbreviated as TBDs) are known to decrease production below the genetic potential of livestock (Sajid et al., 2007). ...
... It is a proven fact that ticks act as biological vectors of a wide range of causative agents of protozoal (e.g., babesiosis and theileriosis), bacterial (ehrlichiosis, borreliosis, Rocky Mountain spotted fever, and Q fever), viral (e.g., Crimean Congo hemorrhagic fever, and Powassan), and rickettsial (e.g., anaplasmosis) diseases and Lyme disease (Dantas-Torres et al., 2012;Mccoy et al., 2013;Pfäffle et al., 2013;Gharbi and Aziz Darghouth, 2014;Ghosh and Nagar, 2014;Guglielmone et al., 2014;Pantchev et al., 2015;Solano-Gallego et al., 2016;Rashid et al., 2019;Siddique et al., 2020). Ticks are known to infest a wide range of hosts, including humans, livestock, pets, and wildlife, and are considered the second most widely used vector for disease transmission among arthropods on the planet (again behind mosquitoes) (Monfared et al., 2015). ...
... Resurgence, the emergence of new diseases, is also influenced by population growth, shifting, grazing, and transboundary transportation of animals for the economy and politics. Intrinsic changes and extrinsic factors both are enabling factors for tickborne diseases (Pfäffle et al., 2013;Baneth, 2014;Dantas-Torres, 2015). Ticks are very susceptible to climate. ...
... Dans une autre étude, l'effet du climat au niveau de la survie de la tique a été étudié et modélisé par Jaenson et Lindgren (2011). Cette modélisation suggère que les changements prédits vont induire une augmentation de la répartition de la tique I. ricinus qui est infectée par des pathogènes, car la présence d'une végétation abondante accueillant les hôtes « réservoirs » va jouer un rôle dans l'augmentation de la densité et du nombre de tiques infectées (Jaenson and Lindgren 2011 (Pfäffle et al. 2013). ...
... On peut également parler de la fragmentation des habitats (création de patchs d'environnements différents) qui va jouer sur les populations vivant dans ces milieux modifiés. Malgré des effets divers sur les espèces présentes, la création de bordures à l'interface des différents milieux est bénéfique pour les populations de tiques(Pfäffle et al. 2013) et pour la dispersion des pathogènes présents dans les hôtes et les tiques(Mechai et al. 2018). Les modifications de ce type permettent d'augmenter la prédation et également le parasitisme(Pfäffle et al. 2013). ...
... Malgré des effets divers sur les espèces présentes, la création de bordures à l'interface des différents milieux est bénéfique pour les populations de tiques(Pfäffle et al. 2013) et pour la dispersion des pathogènes présents dans les hôtes et les tiques(Mechai et al. 2018). Les modifications de ce type permettent d'augmenter la prédation et également le parasitisme(Pfäffle et al. 2013). Toutes ces modifications de paysages possèdent des effets multiples, pouvant être positifs ou négatifs sur les différents types d'organismes étudiés, comme les tiques, les hôtes et les pathogènes(Medlock et al. 2013).etc.), cela peut augmenter les contacts des parasites avec les humains(Pfäffle et al. 2013). ...
Thesis
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L’augmentation des populations de tiques dans le monde, due au changement climatique et au développement de résistance aux acaricides, met en évidence le besoin de nouvelles méthodes de contrôle. La caractérisation de nouvelles cibles moléculaires aux acaricides est donc nécessaire. Les récepteurs à l’acétylcholine de type nicotinique (ou nAChRs) sont des cibles pour les pesticides (comme les néonicotinoïdes) chez les arthropodes et sont peu étudiés chez la tique. Ce sont des protéines transmembranaires formées de cinq sous-unités et qui sont impliquées dans la neurotransmission synaptique rapide. Les objectifs de cette thèse sont de caractériser les profils pharmacologiques des nAChRs neuronaux chez la tique Ixodes ricinus et d’identifier de nouvelles molécules acaricides qui pourront être utilisées dans la prévention et la lutte contre les tiques. Pour accomplir ces objectifs de thèse, une nouvelle technique a été mise au point sur cette espèce de tique, la microtransplantation de membranes purifiées provenant du cerveau (ou synganglion) de la tique et leur expression en système hétérologue. Cette technique inédite a permis pour la première fois de caractériser les nAChRs natifs de la tique I. ricinus. Nous avons démontré la sensibilité des nAChRs à différents agonistes (acétylcholine et nicotine), antagonistes (alpha-bungarotoxine et méthyllycaconitine), ainsi que la faible sensibilité à des néonicotinoïdes. Néanmoins, l’utilisation d’un modulateur allostérique positif (le PNU-120596) a permis d’augmenter la sensibilité des nAChRs natifs à ces molécules. De plus, nous avons identifié plusieurs sous-unités de nAChRs chez la tique I. ricinus. En particulier, nous avons réalisé le clonage de sous-unité de nAChRs. En complément de ces études in-vitro, nous avons mené de nouvelles expériences comportementales sur des tiques adultes pour observer l’effet répulsifs de composés. Pour conclure, ces travaux ont mis en évidence la présence de nAChRs au sein du synganglion de la tique I. ricinus. Les résultats obtenus grâce à leur caractérisation moléculaire, électrophysiologique ainsi que l’approche comportementale sont encourageant pour le développement de nouvelles molécules acaricides et répulsives contre I. ricinus.
... Where the collection of environmental data on Lyme borreliosis risk can be achieved, such studies can provide useful insights into the ecological factors affecting the ecology of the disease (van den Wijngaard et al., 2017), as well as supplementing disease risk data. NIP and DIN are influenced by various environmental factors, including climate (Zintl et al., 2017;Hvidsten et al., 2015), habitat type (Gilbert, 2016;Pfäffle et al., 2013;Estrada-Peña et al., 2015), habitat fragmentation (Kilpatrick et al., 2017;LoGiudice et al., 2008;Gilbert, 2016;Pfäffle et al., 2013), and the vertebrate host community (LoGiudice et al., 2008;Ostfeld and Keesing, 2000;Pfäffle et al., 2013;Keesing et al., 2010). Studies from North America, for example, have found that smaller woodland fragments are associated with higher tick densities (Ostfeld and Keesing, 2000), and that woodland size is inversely correlated with Lyme borreliosis risk (Ostfeld and Keesing, 2000;Pfäffle et al., 2013;Allan et al., 2003). ...
... Where the collection of environmental data on Lyme borreliosis risk can be achieved, such studies can provide useful insights into the ecological factors affecting the ecology of the disease (van den Wijngaard et al., 2017), as well as supplementing disease risk data. NIP and DIN are influenced by various environmental factors, including climate (Zintl et al., 2017;Hvidsten et al., 2015), habitat type (Gilbert, 2016;Pfäffle et al., 2013;Estrada-Peña et al., 2015), habitat fragmentation (Kilpatrick et al., 2017;LoGiudice et al., 2008;Gilbert, 2016;Pfäffle et al., 2013), and the vertebrate host community (LoGiudice et al., 2008;Ostfeld and Keesing, 2000;Pfäffle et al., 2013;Keesing et al., 2010). Studies from North America, for example, have found that smaller woodland fragments are associated with higher tick densities (Ostfeld and Keesing, 2000), and that woodland size is inversely correlated with Lyme borreliosis risk (Ostfeld and Keesing, 2000;Pfäffle et al., 2013;Allan et al., 2003). ...
... Where the collection of environmental data on Lyme borreliosis risk can be achieved, such studies can provide useful insights into the ecological factors affecting the ecology of the disease (van den Wijngaard et al., 2017), as well as supplementing disease risk data. NIP and DIN are influenced by various environmental factors, including climate (Zintl et al., 2017;Hvidsten et al., 2015), habitat type (Gilbert, 2016;Pfäffle et al., 2013;Estrada-Peña et al., 2015), habitat fragmentation (Kilpatrick et al., 2017;LoGiudice et al., 2008;Gilbert, 2016;Pfäffle et al., 2013), and the vertebrate host community (LoGiudice et al., 2008;Ostfeld and Keesing, 2000;Pfäffle et al., 2013;Keesing et al., 2010). Studies from North America, for example, have found that smaller woodland fragments are associated with higher tick densities (Ostfeld and Keesing, 2000), and that woodland size is inversely correlated with Lyme borreliosis risk (Ostfeld and Keesing, 2000;Pfäffle et al., 2013;Allan et al., 2003). ...
Article
Full-text available
Lyme borreliosis is a vector-borne disease of concern in Europe. While neuroborreliosis data are reportable at EU level, it can nevertheless be difficult to make comparisons of disease risk between neighbouring countries. This study used proportion meta-analyses to compare environmental markers of disease risk between woodland sites in two countries in North-Western Europe (Ireland, Scotland). 73 site-visits from 12 publications were analysed, resulting in a significantly higher pooled nymphal infection prevalence (NIP) in Ireland (8.2% (95% CI: 5.9–11.4%)) than Scotland (1.7%(95% CI 1.1–2.5%)). All other analysed parameters of disease risk were also higher in Ireland than Scotland. Subgroup-meta-analyses and meta-regressions were used to assess the influence of environmental variables on NIP. NIP increased significantly with increasing woodland size in Ireland, but not Scotland, which may be accounted for by Ireland's highly fragmented landscape. Assuming the application of strict inclusion/exclusion criteria and control of variables, proportion meta-analysis can provide useful insights in disease ecology, as it allows for the achievement of high study powers incorporating samples collected across multiple sites, which is otherwise often a prohibitively difficult and resource-heavy feat in environmental studies in disease ecology. A standardised approach to data collection is recommended to achieve more robust meta-analyses in future in conjunction with additional research on environmental factors affecting Lyme borreliosis risk in Europe, particularly pertaining to the impact of host species on NIP.
... Several organisms act as vectors and transmit or cause diseases in the agriculture sector, humans, wildlife, and livestock. Ticks (Acari: Ixodida) are bloodsucking ectoparasites and act as vectors of pathogens infecting livestock, wildlife, and humans across the world (Bente et al., 2013;Pfäffle et al., 2013;Guglielmone et al., 2014;Monfared et al., 2015;de la Fuente et al., 2016;Sajid et al., 2017;Ghafar et al., 2020). Ticks and tick-borne diseases (hereafter abbreviated as TBDs) are known to decrease production below the genetic potential of livestock (Sajid et al., 2007). ...
... It is a proven fact that ticks act as biological vectors of a wide range of causative agents of protozoal (e.g., babesiosis and theileriosis), bacterial (ehrlichiosis, borreliosis, Rocky Mountain spotted fever, and Q fever), viral (e.g., Crimean Congo hemorrhagic fever, and Powassan), and rickettsial (e.g., anaplasmosis) diseases and Lyme disease (Dantas-Torres et al., 2012;Mccoy et al., 2013;Pfäffle et al., 2013;Gharbi and Aziz Darghouth, 2014;Ghosh and Nagar, 2014;Guglielmone et al., 2014;Pantchev et al., 2015;Solano-Gallego et al., 2016;Rashid et al., 2019;Siddique et al., 2020). Ticks are known to infest a wide range of hosts, including humans, livestock, pets, and wildlife, and are considered the second most widely used vector for disease transmission among arthropods on the planet (again behind mosquitoes) (Monfared et al., 2015). ...
... Resurgence, the emergence of new diseases, is also influenced by population growth, shifting, grazing, and transboundary transportation of animals for the economy and politics. Intrinsic changes and extrinsic factors both are enabling factors for tickborne diseases (Pfäffle et al., 2013;Baneth, 2014;Dantas-Torres, 2015). Ticks are very susceptible to climate. ...
Article
Full-text available
Ticks (Acari; Ixodidae) are the second most important vector for transmission of pathogens to humans, livestock, and wildlife. Ticks as vectors for viruses have been reported many times over the last 100 years. Tick-borne viruses (TBVs) belong to two orders (Bunyavirales and Mononegavirales) containing nine families (Bunyaviridae, Rhabdoviridae, Asfarviridae, Orthomyxovirida, Reoviridae, Flaviviridae, Phenuviridae, Nyamiviridae, and Nairoviridae). Among these TBVs, some are very pathogenic, causing huge mortality, and hence, deserve to be covered under the umbrella of one health. About 38 viral species are being transmitted by <10% of the tick species of the families Ixodidae and Argasidae. All TBVs are RNA viruses except for the African swine fever virus from the family Asfarviridae. Tick-borne viral diseases have also been classified as an emerging threat to public health and animals, especially in resource-poor communities of the developing world. Tick-host interaction plays an important role in the successful transmission of pathogens. The ticks' salivary glands are the main cellular machinery involved in the uptake, settlement, and multiplication of viruses, which are required for successful transmission into the final host. Furthermore, tick saliva also participates as an augmenting tool during the physiological process of transmission. Tick saliva is an important key element in the successful transmission of pathogens and contains different antimicrobial proteins, e.g., defensin, serine, proteases, and cement protein, which are key players in tick-virus interaction. While tick-virus interaction is a crucial factor in the propagation of tick-borne viral diseases, other factors (physiological, immunological, and gut flora) are also involved. Some immunological factors, e.g., toll-like receptors, scavenger receptors, Janus-kinase (JAK-STAT) pathway, and immunodeficiency (IMD) Maqbool et al. Transmission of the Tick-Borne Viruses at the Virus-Tick Interface pathway are involved in tick-virus interaction by helping in virus assembly and acting to increase transmission. Ticks also harbor some endogenous viruses as internal microbial faunas, which also play a significant role in tick-virus interaction. Studies focusing on tick saliva and its role in pathogen transmission, tick feeding, and control of ticks using functional genomics all point toward solutions to this emerging threat. Information regarding tick-virus interaction is somewhat lacking; however, this information is necessary for a complete understanding of transmission TBVs and their persistence in nature. This review encompasses insight into the ecology and vectorial capacity of tick vectors, as well as our current understanding of the predisposing, enabling, precipitating, and reinforcing factors that influence TBV epidemics. The review explores the cellular, biochemical, and immunological tools which ensure and augment successful evading of the ticks' defense systems and transmission of the viruses to the final hosts at the virus-vector interface. The role of functional genomics, proteomics, and metabolomics in profiling tick-virus interaction is also discussed. This review is an initial attempt to comprehensively elaborate on the epidemiological determinants of TBVs with a focus on intra-vector physiological processes involved in the successful execution of the docking, uptake, settlement, replication, and transmission processes of arboviruses. This adds valuable data to the existing bank of knowledge for global stakeholders, policymakers, and the scientific community working to devise appropriate strategies to control ticks and TBVs.
... Ticks and tick-borne diseases (TBDs) have spread since the mid-twentieth century, to a large extent due to major anthropogenic changes impacting natural ecosystems [1][2][3][4]. In the northern hemisphere, these diseases have expanded mostly due to rural desertification, land use modifications including forest culture (deforestation/afforestation) and agricultural practices, and modifications in hunting leading to an expansion in certain hosts such as deer [3,5,6]. In addition, greater awareness of clinicians and the public and improved diagnosis methods might explain the increase in TBDs [5,7]. ...
... In addition, greater awareness of clinicians and the public and improved diagnosis methods might explain the increase in TBDs [5,7]. Lyme borreliosis is the best example of diseases affected at least in part by these changes in Europe [5,6,8] and in the USA [9][10][11], constituting the first vector-borne disease of temperate regions, with the number of reported cases globally increasing [6,12,13] [Réseau Sentinelles France (sentiweb.fr), accessed on 18 January 2022]. ...
... In addition, greater awareness of clinicians and the public and improved diagnosis methods might explain the increase in TBDs [5,7]. Lyme borreliosis is the best example of diseases affected at least in part by these changes in Europe [5,6,8] and in the USA [9][10][11], constituting the first vector-borne disease of temperate regions, with the number of reported cases globally increasing [6,12,13] [Réseau Sentinelles France (sentiweb.fr), accessed on 18 January 2022]. ...
Article
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Ticks and tick-borne diseases have spread over the last decades. In parallel, the incidence in humans, accidental hosts for most of these zoonotic diseases, has increased. This epidemiological intensification can be associated with anthropogenic alterations of forest ecosystems and animal biodiversity, but also with socioeconomic changes. Their proliferation is largely due to human-induced effects on the factors that favor the circulation of these infectious agents. We selected different types of anthropogenic environments in Alsace, a region endemic for tick-borne diseases in France, to better understand the impact of human interventions on tick populations and tick-borne disease incidence. Ticks were collected in one golf course, three urban parks, one mid-mountain forest, and one alluvial forest that is currently part of a protected natural area. Ixodes ricinus was found primarily in humid vegetation, which is favorable for tick survival, such as grounds populated with trees and covered with leaf litter. We also observed that reforestation and high animal biodiversity in a protected area such as the alluvial forest led to a greater number of ticks, including both Ixodes ricinus and Dermacentor reticulatus, as well as to a higher prevalence of pathogens such as Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Borrelia miyamotoi, and Rickettsia raoulti.
... These factors are also increasing human exposure to animal reservoirs and arthropod vectors, including increased transmission of pathogens to naïve human populations [1,2]. Ticks transmit the highest number of pathogen species to vertebrates of any blood-feeding arthropod and are a growing threat to public health and agricultural systems worldwide [3,4]. ...
... While shared borders have historically suffered from shared pests and diseases [24], the globalization of trade and travel has increased the frequency of imported pests and associated diseases to new locations [23,61]. Additionally, increased habitat fragmentation due to urbanization, agricultural intensification, and other land-use changes can increase tick burdens at habitat edges due to complex interactions between wildlife diversity and the availability of anthropogenic food sources for generalist hosts such as white-tailed deer [3]. These spatiotemporal challenges highlight the critical importance of continued and increased surveillance of imported animals at borders, as well as education initiatives for travelers to check for "hitchhikers" while traveling and upon return [23], and for continued research on wildlife and environmental movement of ticks [39,62,72,104,105]. ...
Article
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Ticks are able to transmit the highest number of pathogen species of any blood-feeding arthropod and represent a growing threat to public health and agricultural systems worldwide. While there are numerous and varied causes and effects of changes to tick-borne disease (re)emergence, three primary challenges to tick control were identified in this review from a U.S. borders perspective. (1) Climate change is implicated in current and future alterations to geographic ranges and population densities of tick species, pathogens they can transmit, and their host and reservoir species, as highlighted by Ixodes scapularis and its expansion across southern Canada. (2) Modern technological advances have created an increasingly interconnected world, contributing to an increase in invasive tick species introductions through the increased speed and frequency of trade and travel. The introduction of the invasive Haemaphysalis longicornis in the eastern U.S. exemplifies the challenges with control in a highly interconnected world. (3) Lastly, while not a new challenge, differences in disease surveillance, control, and management strategies in bordering countries remains a critical challenge in managing ticks and tick-borne diseases. International inter-agency collaborations along the U.S.–Mexico border have been critical in control and mitigation of cattle fever ticks (Rhipicephalus spp.) and highlight the need for continued collaboration and research into integrated tick management strategies. These case studies were used to identify challenges and opportunities for tick control and mitigation efforts through a One Health framework.
... To identify how changes in climate might affect ticks in different regions and habitats of Britain in different ways, separate logistic regression models were used to test for two-way interaction effects between selected variables and model year, in predicting tick presence. Two-way interactions with model year were tested for the variables; northing (the cartesian equivalent of latitude), altitude, and percentage of upland habitat, because these variables act as proxies for ecological region (Estrada-Peña et al., 2006), and therefore affect which climatic factors limit I. ricinus survival (Pfäffle et al., 2013). ...
... Shifts in tick distribution to higher altitudes and latitudes have been predicted by other European models (Williams et al., 2015), and empirical evidence for these shifts have also been recorded in some countries (Medlock and Leach, 2015), such as Sweden (Lindgren et al., 2000) and Norway (Jore et al., 2014). These changes are likely to be driven by interactions between region and the climatic conditions which limit I. ricinus survival, with future higher temperatures at higher altitudes and latitudes, where low temperatures are currently the limiting factor in tick survival, and larger saturation deficits at lower latitudes, where low summer humidity currently limits I. ricinus survival (Jenkins et al., 2009;Pfäffle et al., 2013). ...
Article
The most abundant tick species in northern Europe, Ixodes ricinus, transmits a range of pathogens that cause disease in livestock. As I. ricinus distribution is influenced by climate, tick-borne disease risk is expected to change in the future. The aims of this work were to build a spatial model to predict current and future risk of ticks on livestock farms across Britain. Variables relating both to tick hazard and livestock exposure were included, to capture a niche which may be missed by broader scale models. A random forest machine learning model was used due to its ability to cope with correlated variables and interactions. Data on tick presence and absence on sheep and cattle farms was obtained from a retrospective questionnaire survey of 926 farmers. The ROC of the final model was 0.80. The model outputs matched observed patterns of tick distribution, with areas of highest tick risk in southwest and northwest England, Wales, and west Scotland. Overall, the probability of tick presence on livestock farms was predicted to increase by 5-7% across Britain under future climate scenarios. The predicted increase is greater at higher altitudes and latitudes, further increasing the risk of tick-borne disease on farms in these areas.
... felis, C. burnetii and T. gondii) in cats from Murcia municipality (Southeast Spain). We assume that there are high densities of wild and synanthropic hosts species increasing the risk of tick infestations and amplifying the sources of C. burnetii (Barbu et al., 2013;Meredith et al., 2014;Pfäffle et al., 2013;Rizzoli et al., 2014), T. gondii Barros et al., 2018;Hill & Dubey, 2002) and C. felis (Halánová et al., 2019). The high environmental stability of C. burnetii, which allows it to survive in soil for long periods (Eldin et al., 2017), the route of infection via inhalation (Angelakis & Raoult, 2010) and the possibility of wind currents spreading from manure accumulates (King et al., 2011;Tissot-Dupont et al., 2004) influence the prevalence of infection in agricultural landscapes with small ruminant farms (De Lange et al., 2014;Eldin et al., 2017;van der Hoek et al., 2010). ...
... In urban and peri-urban habitats in Europe, rodents, hedgehogs, shrews, birds, lizards and pets (dogs and cats), as well as red foxes (Vulpes vulpes), roe deer (Capreolus capreolus) and wild boar (Sus scrofa) in peri-urban areas, play a major role as hosts and reservoirs of tick-borne pathogens (Pfäffle et al., 2013). Some authors have also claimed that ticks may play an important role in the maintenance of C. burnetii infection in rodents and lagomorphs (Marrie et al., 1993), and thus, a very complex network of transmission could be present in an urban area. ...
Article
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Despite public concern on the role of free-roaming cats as reservoirs of zoonotic agents, little is known about the influence of urban and peri-urban landscapes on the exposure risk. We evaluated the seroprevalence of three zoonotic agents (Chlamydia felis, Coxiella burnetii and Toxoplasma gondii) in domestic cats (Felis catus). Two hundred and ninety-one free-roaming cats were trapped in Murcia municipality (Southeast Spain), and their sera were tested for specific antibodies against T. gondii using a modified agglutination test (MAT), and for C. felis, C. burnetii and feline immunode-ficiency virus (FIV) antibodies with ELISA technique. Pathogen seroprevalence at 95% CI was calculated for each sex and age category (up to and over 12 months) and compared with a chi-squared test. The role of human population density and urban landscape characteristics on the risk of pathogen exposure in the cat population was explored using generalized linear models. Seropositivity against a single pathogen was found in 60% of the cats, while 19% was seropositive for two or three pathogens. Seroprevalence of C. felis was 8% (CI 95% : 5-11), 37% (CI 95% : 31-42) for C. burnetii and 42% (CI 95% : 36-47) for T. gondii. In addition to these three pathogens, FIV seropositiv-ity was low (1%, CI 95% : −0.1 to 2) and adult cats were more likely to be seropositive to C. burnetii than young individuals (OR: 2.3, CI 95% : 1.2-4.2). No sex or age class differences in seroprevalence were observed for the rest of the pathogens. Seropositivity was correlated with water surface areas for C. felis, and not with crop areas. Coxiella burnetii seropositivity was correlated with the percentage of urban areas (continuous with only buildings and discontinuous, that include buildings, parks, and pedestrian and urban green areas), human population size and peri-urban areas with shrubs, and not correlated with other agricultural landscapes (orchards and crop areas). However, the seroprevalence of T. gondii was only associated with agricultural landscapes such as orchards. The detection of hotspot areas of high pathogen exposure risk is the basis for municipal services to implement surveillance and risk factor control campaigns in specific-risk areas, including (a) efficient health management of urban cat colonies by geographical location, population census and health status monitoring of the components of each cat colony, (b) improvement of hygiene and sanitary conditions
... The number of TBD cases in humans thus primarily depends on the abundance of tick species, the frequency of contact between humans and ticks and the prevalence of the pathogens. The higher the number of ticks, the higher the risk for humans to be bitten; the higher the prevalence of pathogens, the higher the risk of becoming infected through a tick bite (Randolph, 2008;Pfäffle et al., 2013;Wikel, 2018;Escobar, 2020). ...
... In particular, it is assumed that the abundance of small rodents depends on the availability of food (depending on the fructification of forest trees) and weather conditions (Klempa, 2009;Reil et al., 2015). In spatial terms, land cover may play an important role (e.g., forest cover) (Randolph, 2010;Pfäffle et al., 2013). Human behaviour depends on the weather situation and on land cover (Randolph, 2010): People spend more time outside in good weather than in bad weather and forested regions may be more crowded than other land cover types. ...
Article
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Background In the face of ongoing climate warming, vector-borne diseases are expected to increase in Europe, including tick-borne diseases (TBD). The most abundant tick-borne diseases in Germany are Tick-Borne Encephalitis (TBE) and Lyme Borreliosis (LB), with Ixodes ricinus as the main vector. Methods In this study, we display and compare the spatial and temporal patterns of reported cases of human TBE and LB in relation to some associated factors. The comparison may help with the interpretation of observed spatial and temporal patterns. Results The spatial patterns of reported TBE cases show a clear and consistent pattern over the years, with many cases in the south and only few and isolated cases in the north of Germany. The identification of spatial patterns of LB disease cases is more difficult due to the different reporting practices in the individual federal states. Temporal patterns strongly fluctuate between years, and are relatively synchronized between both diseases, suggesting common driving factors. Based on our results we found no evidence that weather conditions affect the prevalence of both diseases. Both diseases show a gender bias with LB bing more commonly diagnosed in females, contrary to TBE being more commonly diagnosed in males. Conclusion For a further investigation of of the underlying driving factors and their interrelations, longer time series as well as standardised reporting and surveillance system would be required.
... Ticks are obligate, bloodsucking, ectoparasitic arthropods that transmit disease-causing pathogens to a wide range of hosts (Dantas-Torres et al., 2012;Pfäffle et al., 2013). They are of (which was not certified by peer review) is the author/funder. ...
Preprint
Worldwide, ticks are blood-feeding arthropods responsible for the transmission of disease-causing pathogens to a wide range of vertebrate hosts, including livestock and humans. Tick-borne diseases have been implicated in significant economic losses to livestock production, and this threat will increase as these obligate parasites widen their geographical ranges. Just like in other ectotherms, thermal stress due to changing global temperatures has been shown to influence tick survival and distribution. However, the influence of extreme temperatures in ticks focused on advanced, mobile stages, ignoring stages that are immobile and cannot move to more favorable microhabitats. In this study, low- and high-temperature regimens were assessed in relation to egg viability for hard tick species. Tick eggs exposed early in development were significantly more susceptible to thermal stress when compared with those exposed later in development. In our tested models, treatment was more important for egg hatching than species differences. Lastly, there was evidence of extreme thermal exposure significantly altering the hatching times of tick eggs for specific treatments. These results provide insights into the critical period for tick egg viability and potential tick control strategies as the globe continues to experience climate change.
... Ticks are more likely than other blood-feeding arthropods to transmit pathogenic species, affecting humans and livestock [3]. Knowledge of the intricate relationship between ticks and their hosts, the environment, and the pathogens they transmit, is critical to understanding the epidemiology of tick-borne zoonotic diseases [4]. Ticks transmit various zoonotic diseases, including Lyme disease, Ehrlichiosis, and Rocky Mountain Spotted Fever (RMSF) [5]. ...
Article
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Tick-borne zoonotic diseases pose a threat to public health; hence, identifying the pathogenic agents associated with them is critical. The prevalence of Bartonella and Rickettsia in Iran is unknown. This study aimed to detect Rickettsia spp. and Bartonella species in ticks in northeast Iran and conduct phylogenetic analysis on these bacteria. Ticks from the sample bank in the Research Center for Emerging and Re-emerging Diseases were included in this study. The ticks were collected in 2017 and 2018 from domestic animals (sheep, goats, cows, camels, horses, dogs, and donkeys) and rodents in Golestan, Mazandaran, and Guilan provinces. Molecular methods were used to examine the DNA extracted from these samples to detect Rickettsia spp. and Bartonella species. The study examined a total of 3999 ticks. Ixodes ricinus (46.4%), Rhipicephalus turanicus (26.3%), and Rhipicephalus sanguineus (17.1%) were the most prevalent species. Among 638 DNA pools, real-time-PCR detected Rickettsia spp. in 161 (25.2%), mostly belonging to Rh . sanguineus (48.9%) and Rh . turanicus (41.9%). Golestan Province had the highest number of positive pools (29.7%). No positive samples for Bartonella were detected in a 638 pooled samples. Eight distinct Rickettsia species were detected in 65 sequenced samples, the majority of which were R . massiliae (n = 32, 49.2%) and R . sibirica (n = 20, 30.8%). Other species included R . rhipicephali (n = 3), R . aeschlimannii (n = 5), R . helvetica (n = 5), R . asiatica (n = 4), R . monacensis (n = 6), and R . raoultii (n = 1). The research findings may provide helpful information about tick-borne Rickettsiae in Iran and help to clarify the role of these arthropods in maintaining these agents. Rickettsia species were found to be circulating in three Northern provinces; thus, it is recommended that this disease be considered in the differential diagnosis of febrile diseases caused by tick bites and febrile diseases with skin rashes such as Crimean–Congo hemorrhagic fever (CCHF).
... Ticks are hematophagous ectoparasites that feed on the blood of a variety of vertebrate hosts and play an important role in the transmission of zoonotic diseases caused by viruses, bacteria, and protozoans (Pfäffle et al., 2013;de la Fuente et al., 2017). They attack a wide range of animals including humans. ...
... It is also apparent that our model had relatively high sensitivity to the habitat scaling factor compared to other parameters included in the model. It is well established that the survival, abundance and distribution of ticks is dependent on the overlap of suitable off-host environmental conditions and the distributions and movements of hosts (Diuk-Wasser et al., 2021;Leal et al., 2020;Pfäffle et al., 2013). There have been many studies in Europe that have found that habitat type or composition can influence the abundance of different tick species and prevalence of associated pathogens such as B. burgdorferi and Anaplasma phagocytophilum (Ehrmann et al., 2017(Ehrmann et al., , 2018Rosà et al., 2018;Tack et al., 2012). ...
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The risk of spillover of zoonotic diseases to humans is changing in response to multiple environmental and societal drivers, particularly in tropical regions where the burden of neglected zoonotic diseases is highest and land use change and forest conversion is occurring most rapidly. In these regions, neglected zoonotic diseases can have significant impacts on poor and marginalised populations in low-resource settings but ultimately receive less attention and funding for research and interventions. As such, effective control measures and interventions are often hindered by a limited ecological evidence base, which results in a limited understanding of epidemiologically relevant hosts or vectors and the processes that contribute to the maintenance of pathogens and spillover to humans. Here, we develop a generalisable next generation matrix modelling framework to better understand the transmission processes and hosts that have the greatest contribution to the maintenance of tick-borne diseases with the aim of improving the ecological evidence base and framing future research priorities for tick-borne diseases. Using this model we explore the relative contribution of different host groups and transmission routes to the maintenance of a neglected zoonotic tick-borne disease, Kyasanur Forest Disease Virus (KFD). The results highlight the potential importance of transovarial transmission and small mammals and birds in maintaining this disease. This contradicts previous hypotheses that primates play an important role influencing the distribution of infected ticks. There is also a suggestion that risk could vary across different habitat types. In light of these results we outline the key knowledge gaps for this system and future research priorities that would aid in informing effective interventions and control measures.
... Ixodes ricinus are most abundant in woodlands, which provide adequate environmental conditions compared to other less suitable habitats (Estrada-Peña, 2001;Pfäffle et al., 2013) so spatial expansion could be linked to increase in woodland cover and connectivity, which has been widely promoted in the UK (Forestry-Commission, 2022). ...
Article
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The tick Ixodes ricinus (Ixodida: Ixodidae, Linnaeus) is the main vector of several pathogens including Borrelia burgdorferi s.l. (agent of Lyme borreliosis) and tick-borne encephalitis virus. Its distribution depends on many factors including suitable habitat, climate and presence of hosts. In this study, we present records of I. ricinus bites on humans, dogs (Canis lupus familiaris; Carnivora: Canidae, L.) and cats (Felis catus; Carnivora: Felidiae, L.) in the United Kingdom (UK) obtained through the Tick Surveillance Scheme between 2013 and 2020. We divided the UK into 20 km x 20 km grids and 9.2% (range 1.2%–30%) of grids had at least one record every year since 2013. Most regions reported a yearly increase in the percentage of grids reporting I. ricinus since 2013 and the highest changes occurred in the South and East England with 5%–6.7% of new grids reporting I. ricinus bites each year in areas that never reported ticks before. Spatiotemporal analyses suggested that, while all regions recorded I. ricinus in new areas every year, there was a yearly decline in the percentage of new areas covered, except for Scotland. We discuss potential drivers of tick expansion, including reforestation and increase in deer populations.
... Furthermore, amphibians are globally threatened by pathogens such as Emerging Infectious Diseases (Wake and Vredenburg, 2008;Scheele et al., 2019). Among ectoparasites, ticks are associated with the highest diversity of pathogens (Pfäffle et al., 2013). Members of the genus Amblyomma specialized on ectothermic hosts are known vectors for different bacteria of the genus Rickettsia and several viruses (Miranda et al., 2012;Luz et al., 2018;Sameroff et al., 2021). ...
... Ixodes ticks mainly infest small ruminants, rodents, birds, carnivores and humans in cold deciduous, mixed forests and vegetative regions where rainfall is abundant and relatively more humid (> 80% relative humidity) [1,[6][7][8][9][10][11][12][13][14][15]. Environmental fluctuations, such as low temperature at high latitudes have been considered to limit the spread of Ixodes ticks and to a certain extent become a severe threat to novel hosts [4,5,16,17]. ...
Article
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Background: Hard ticks (Ixodidae) are hematophagous ectoparasites that transmit various pathogens to a variety of hosts including humans. Transhumant herds have been involved in the spread of ticks and associated Rickettsia spp. and studies on this neglected topic have been unexplored in many regions including Pakistan. This study aimed to investigate ticks infesting transhumant herds of sheep (Ovis aries) and goats (Capra hircus) in district Shangla, Khyber Pakhtunkhwa, Pakistan. Methods: Out of the 144 examined animals, 112 hosts (68 sheep and 44 goats) of transhumant herds were infested by 419 ticks of different life stages including nymphs (105; 25%), males (58; 14%) and females (256; 61%). For molecular analyses, DNA was extracted from 64 collected ticks and subjected to PCR for the amplification of tick 16S rDNA and ITS2 partial sequences and for the amplification of rickettsial gltA and ompA gene sequences. Results: All tick specimens were identified as Ixodes kashmiricus based on morphological features. The obtained 16S rDNA and ITS2 sequences showed 95.7% and 95.3% identity, respectively, with Ixodes kazakstani reported from Kyrgyzstan. In the phylogenetic tree, the sequences clustered with members of the Ixodes ricinus species complex, including I. kazakstani and Ixodes apronophorus. Additionally, rickettsial gltA and ompA partial sequences were 99.7% identical to Rickettsia sp. endosymbiont of Ixodes spp. from Panama and Costa Rica and 99.2% with Rickettsia endosymbiont from USA. Phylogenetically, the rickettsial gltA and ompA partial sequences from I. kashmiricus clustered with various haplotypes of Rickettsia endosymbiont, which were sister cladded to Rickettsia monacensis. Conclusions: This is the first genetic report of I. kashmiricus and associated Rickettsia sp. Large-scale tick surveillance studies across the country are needed to investigate Ixodes ticks and associated pathogens.
... Camel, Camelus dromedaries, is raised for milk and meat production, tourism, and transportation and has a significant role in the economy, especially in the Arabian cultures. Ticks are major vectors of diseases of economic importance as they transmit a variety of pathogens affecting humans, livestock, and domestic animals [1,2]. Ticks also cause discomfort through annoying bites, anorexia, skin spoilage, blood loss, and growth reduction [3]. ...
Article
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The control of the camel tick, Hyalomma dromedarii is very crucial. This study evaluated the novel toxicity of photosensitizers and Phoxim insecticide against H. dromedarii males using the adult immersion tests. Ticks were subjected to sunlight for 10 min post-treatment (PT). The optical characters of the applied materials were determined by UV–Vis spectroscopy (250–900 nm wavelengths). The intensity of spectra decreased as dye concentration decreased. The optical bandgap energies of the dyes at different concentrations were not changed as the concentration changed and decreased as the absorption peak of individual dyes red-shifted. The mortalities 72 h PT reached 42.2%, 44.4%, 51.1%, 71.1%, 46.7%, 48.9%, 44.4%, and 55.6% for chlorophyllin, echinochrome, field stain, methylene blue, phthalocyanine, rhodamine 6G, riboflavin, and safranin, respectively. Methylene blue recorded the highest median lethal concentration (LC 50 = 127 ppm) followed by safranin, field stain, rhodamine 6G, phthalocyanine, echinochrome riboflavin, and chlorophyllin (LC 50 = 209, 251, 271, 303, 324, 332, and 362 ppm, respectively, 72 h PT). Their median lethal time, LT 50 , values PT with 240 ppm were 45, 87, 96, 72, 129, 115, 131, and 137 h, respectively. The relative toxicities of the LC 50 values 72 h PT showed that chlorophyllin, echinochrome, field stain, methylene blue, phthalocyanine, rhodamine 6G, riboflavin, and safranin were 3.2, 3.6, 4.6, 9.1, 3.8, 4.3, 3.5, and 5.6 times, respectively, more effective than Phoxim. Methylene blue, safranin, and field stain showed a broad absorbance area indicating a large photoactivity and better phototoxicity and could be used as alternative agents to synthetic acaricides. Graphical Abstract
... Factors influencing geographic range and population size are dynamic and dependent upon the complex interplay among micro and macro climate variations, vegetation patterns, land use, land fragmentation, habitat or landscape modification (agricultural, residential, recreational), host animal diversity (domestic, wild and exotic species), human behavior, travel, commerce, economics, government policies, human and animal population growth, population movement, and evolutionary changes in ticks and tick-borne pathogens [1,2,9,12,14,45,49]. Each of these continually evolving factors, to differing degrees, influences tick and pathogen ecology, enzootic cycles of tick-transmitted infectious agents, disease incidence, epidemiology, and selection of appropriate control approaches [2,3,40]. ...
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Ticks and tick-borne pathogens are increasing public health threats due to emergence of novel pathogens, expanding geographic ranges of tick vectors, changing ecology of tick communities, as well as abiotic and biotic influences on tick–host–pathogen interactions. This review examines the major human-biting ixodid tick species and transmitted pathogens of North America. Topics addressed include current and projected tick geographic ranges, potential risks for introduction of tick transmitted microbes into those regions, and drivers for these events. Health care providers, public health authorities, and the general public need to be aware of existing, resurging, and emerging tick and tick-borne disease threats. Knowing which ticks and tick-borne pathogens are present is foundational to understanding and responding to these threats. Dominant tick species and pathogens remain major foci of research, while limited attention has been directed to other human-biting ticks for decades, resulting in questions about current distributions, population sizes, and diversity of infectious agents they are capable of transmitting. Significant threats due to invasive ticks are considered. Recommendations are made for establishment of a sustained North America network for surveillance of ticks, characterization of their microbiomes and viromes, and for support of tick and tick-borne disease ecology research.
... Ticks, which are vectors of more pathogens than any other group of invertebrates, have become a growing focus of attention among the different arthropods capable of transmitting pathogens that can cause serious diseases in animals and humans [13,14]. While the Middle East and North Africa (MENA) have suitable climates and favorable conditions for the propagation and spread of ticks, reports on TTBPs in this area are scarce [15]. ...
Article
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Ticks and tick-borne pathogens (TTBPs) are listed among the most serious concerns harming Egyptian livestock’s productivity. Several reports on tick-borne pathogens (TBPs) from various geographical regions in the country were published. However, data on the molecular characterization of TBPs are the most beneficial for understanding the epidemiology of this important group of pathogens. In this study, we present the first meta-analysis on the molecular epidemiology and species diversity of TBPs infecting animals in Egypt. All published studies on TBPs were systematically collected from various databases (PubMed, Scopus, ScienceDirect, the Egyptian Knowledge Bank, and Google Scholar). Data from eligible papers were extracted and subjected to various analyses. Seventy-eight studies were found to be eligible for inclusion. Furthermore, ticks infesting animals that were molecularly screened for their associated pathogens were also included in this study to display high species diversity and underline the high infection risk to animals. Theileria annulata was used as parasite model of TBPs to study the genetic diversity and transmission dynamics across different governorates of Egypt. This study extends cross-comparisons between all published molecular data on TBPs in Egypt and provides resources from Egyptian data in order to better understand parasite epidemiology, species diversity, and disease outcome as well as the development and implementation of prevention and control methods for public health, veterinary care practitioners, and animal owners all over the country.
... Here, new epidemiological studies are required to identify and understand the pathogens involved in the host-vector-pathogen interactions in the natural foci of TBPs. These types of studies can provide important epidemiological information that will serve as the one health concept in terms of both animal and human health (Dantas-Torres et al., 2012;Estrada-Peña et al., 2015; Estrada-Peña and de la Fuente, 2014; Pfäffle et al., 2013). Therefore, this study aimed to determine the tick species that parasitize grazing domestic ruminants in different ecosystems of the Asian part of Turkey (Anatolia) and to reveal the circulating tick-borne microorganisms in these ticks using a broad range of molecular screening techniques. ...
Article
Grazing domestic ruminants serve as important reservoirs and/or amplificatory hosts in the ecology of tick-borne pathogens (TBPs) and tick vectors in the natural foci; however, many enzootic life cycles including ruminants and ticks are still unknown. This study investigated a wide range of TBPs circulating among ticks and grazing ruminants in the natural foci of Anatolia, Turkey. Tick specimens (n = 1815) were collected from cattle, sheep, and goats in three ecologically distinct areas (wooded, transitional, and semi-arid zones) of Anatolia and identified by species: Dermacentor marginatus, Dermacentor reticulatus, Hyalomma anatolicum, Hyalomma excavatum, Hyalomma marginatum, Hyalomma scupense, Haemaphysalis inermis, Haemaphysalis parva, Haemaphysalis punctata, Haemaphysalis sulcata, Ixodes ricinus, Rhipicephalus bursa, and Rhipicephalus turanicus. PCR-sequencing analyses revealed TBPs of great diversity, with 32 different agents identified in the ticks: six Babesia spp. (Babesia occultans, Babesia crassa, Babesia microti, Babesia rossi, Babesia sp. tavsan1, and Babesia sp. Ucbas); four Theileria spp., including one putative novel species (Theileria annulata, Theileria orientalis, Theileria ovis, and Theileria sp.); one Hepatozoon sp.; four Anaplasma spp., including one novel genotype (Anaplasma phagocytophilum, Anaplasma marginale, Anaplasma ovis, and Anaplasma sp.); six unnamed Ehrlichia spp. genotypes; Neoehrlichia mikurensis; nine spotted fever group rickettsiae, including one putative novel species (Rickettsia aeschlimannii, Rickettsia slovaca, Rickettsia hoogstraalii, Rickettsia monacensis with strain IRS3, Rickettsia mongolitimonae, Rickettsia raoultii, Candidatus Rickettsia goldwasserii, Candidatus Rickettsia barbariae, and Rickettsia sp.); and Borrelia valaisiana. Detailed phylogenetic analyses showed that some of the detected pathogens represent more than one haplotype, potentially relating to the tick species or the host. Additionally, the presence of Neoehrlichia mikurensis, an emerging pathogen for humans, was reported for the first time in Turkey, expanding its geographical distribution. Consequently, this study describes some previously unknown tick-borne protozoan and bacterial species/genotypes and provides informative epidemiological data on TBPs, which are related to animal and human health, serving the one health concept.
... Adult stages of the three tick species considered here, are known to be exophilic. But the early stages of Dermacentor ticks are rarely or not at all found on vegetation which could indicate an endophilic behavior of these stages, i.e., nymphs remain within their host's nest or burrow between blood meals (Immler 1973;Pfäffle et al. 2013), where they are less exposed to extreme climatic conditions. At higher temperatures, water balance becomes important. ...
Article
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Tick-borne diseases are a major health problem worldwide and could become even more important in Europe in the future. Due to changing climatic conditions, ticks are assumed to be able to expand their ranges in Europe towards higher latitudes and altitudes, which could result in an increased occurrence of tick-borne diseases. There is a great interest to identify potential (new) areas of distribution of vector species in order to assess the future infection risk with vector-borne diseases, improve surveillance, to develop more targeted monitoring program, and, if required, control measures. Based on an ecological niche modelling approach we project the climatic suitability for the three tick species Ixodes ricinus , Dermacentor reticulatus and Dermacentor marginatus under current and future climatic conditions in Europe. These common tick species also feed on humans and livestock and are vector competent for a number of pathogens. For niche modelling, we used a comprehensive occurrence data set based on several databases and publications and six bioclimatic variables in a maximum entropy approach. For projections, we used the most recent IPCC data on current and future climatic conditions including four different scenarios of socio-economic developments. Our models clearly support the assumption that the three tick species will benefit from climate change with projected range expansions towards north-eastern Europe and wide areas in central Europe with projected potential co-occurrence. A higher tick biodiversity and locally higher abundances might increase the risk of tick-borne diseases, although other factors such as pathogen prevalence and host abundances are also important.
... Nowadays, ticks and tick-borne diseases are considered a growing concern and a main problem not only for humans but also for domestic animals in production and health situations [2]. In cattle, tick infestations and tick-borne diseases (e.g., babesiosis, theileriosis, and anaplasmosis) lead to serious complications such as considerable damage in meat, milk, and leather production [3,4]. ...
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Background: In this experimental study, we aimed to assess the acaricidal effects of Elettaria cardamomum L. essential oil (ECEO) against Hyalomma anatolicum tick in cattle from Saudi Arabia. Methods: Gas chromatography-mass spectrometry (GC-MS) was performed to identify the chemical composition of ECEO. The acaricidal, larvicidal, and repellent activity of ECEO against H. anatolicum was studied through the adult immersion test (AIT), the larval packet test (LPT), the vertical movement behavior of tick's larvae technique, anti-acetylcholinesterase (AChE) activity, and oxidative enzyme activity. Results: By GC/MS, the most compounds were 1,8-cineole (34.3%), α-terpinyl acetate (23.3%), and α-pinene (17.7%), respectively. ECEO significantly (p < 0.001) increased the mortality rate as a dose-dependent response. After ECEO Treatment, number of eggs, egg weight, and hatchability significantly declined as a dose-dependent response. ECEO at concentrations of 5 µL/mL and above completely killed the larva. The LC50 and LC90 values for ECEO were 1.46 and 2.68 µL/mL, respectively. ECEO at concentrations of 10, 20, and 40 µL/mL showed 100% repellency activity up to 60, 120, and 360 min incubation, respectively. ECEO, especially at ½ LC50 and LC50, significantly inhibited GST and AChE activities of H. anatolicum larvae compared to the control group. Conclusions: We found promising adulticidal, larvicidal, and repellent effects of ECEO against H. anatolicum as a vector of theileriosis in Saudi Arabia. We also found that ECEO displayed these activities through inhibiting AChE and GST. Nevertheless, additional investigations are required to confirm the accurate mechanisms and the relevance of ECEO in practical application.
... Many tick species associated with birds that are involved in the transmission of pathogenic rickettsiae belong to the Ixodidae family (hard ticks) (Pacheco et al., 2012;Parola et al., 2013). These ticks can feed for long periods and transmit rickettsiae to their hosts (Pfäffle et al., 2013;Mukherjee et al., 2014;Luz et al., 2017). Furthermore, infected hosts can constitute a source of infection for other ticks (Hornok et al., 2014). ...
Article
Wild birds have an important role as hosts of ticks infected by rickettsiae. However, the role of birds as reservoirs of tick-borne rickettsiae is unknown and poorly understood. This is particularly relevant in several tropical and subtropical areas, where migration influences the global spread of ectoparasites and pathogens of public health importance. This research aimed to detect and evaluate the exposure to spotted fever group rickettsiae in wild birds that could represent reservoirs in the Department of Arauca in the Colombian Orinoquia region. Sampling was conducted in three municipalities of the Department of Arauca (Colombia). Blood samples were collected from 255 birds and processed to obtain serum (n = 155) and DNA (n = 255) samples. The serum samples were processed for indirect immunofluorescence assays (IFA) for the detection of antibodies to Rickettsia rickettsii, Rickettsia parkeri, Rickettsia amblyommatis, Rickettsia rhipicephali, and Rickettsia bellii. Additionally, we investigated rickettsiae DNA in blood samples by amplification of the citrate synthase gene (gltA). The IFA results revealed seropositivity in 97 samples from 54 species of resident and migratory birds. No sample was positive for rickettsial DNA. The presence of antibodies in 62.5% of the sera indicates previous exposure of these birds to rickettsiae. The null detection of rickettsiae in the blood of seropositive birds is possibly due to a short period of bacteremia. Experimental studies are required to improve our understanding of the role of wild birds as sources of rickettsial infections in ticks.
... During the last three decades, there were more than 30 new human pathogens from which 75% had originated from animals (1,2). The tick-transmitted infections of humans, currently considered zoonoses, involve ticks and wild and/or domestic animal hosts with the maintained pathogens in natural cycles (3). Tick-borne diseases are among the crucial public health issues. ...
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Background: Zoonotic diseases as health concerns worldwide account for more than half of the emerging infectious diseases. Arachnids are powerful vectors to transmit several diseases to humans. Additionally, these emerging zoonotic diseases have been a considerable health threat in the Eastern Mediterranean Region of the WHO (EMRO) due to the large population living close to farms and international trade with nearby countries. Methods: This review study is based on the reported three tick-borne diseases, Lyme disease, Tularemia, and Q fever, from Iran and other EMRO countries. To this end, we searched PubMed central, ISI web of Science, and Google with the related keywords in English at any time. The reported data are then sorted by countries for each disease. Results: According to the published data, 15 countries in the region have one/more emerging infectious diseases. Q fever has been the most frequent infection in EMRO countries, while Lyme was less recorded. Furthermore, Iran is among the countries with documented history of all three investigated diseases. Conclusion: Tick-borne disease is popular among EMRO countries, indicating that they have natural conditions for infections in animals and humans. It appears necessary to develop a disease management strategy and control programs against tick-borne diseases (TBDs). Moreover, the disease-resistant animal could be bred instead of susceptible livestock. Therefore, research studies to control TBDs should be regarded as a top priority plan.
... Host species presence and abundance may impact pathogen spread (Estrada-Peña and de la Fuente, 2014), as may host and tick vector competence, as influenced by vector density and longevity . Logically, any habitat considered fit for the tick-borne pathogen's circulation and spread must meet the prerequisite of housing ticks and their hosts for any risk to be realized (Pfäffle et al., 2013). High-throughput sequencing approaches have also emphasized the potential implications of the composition, diversity, and functional role of tick microbial fauna to public health . ...
Article
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Among blood-sucking arthropods, ticks are recognized as being of prime global importance because of their role as vectors of pathogens affecting human and animal health. Ticks carry a variety of pathogenic, commensal, and symbiotic microorganisms. For the latter, studies are available concerning the detection of endosymbionts, but their role in the physiology and ecology of ticks remains largely unexplored. This review paper focuses on tick endosymbionts of the genera Coxiella, Rickettsia, Francisella, Midichloria, and Wolbachia, and their impact on ticks and tick-pathogen interactions that drive disease risk. Tick endosymbionts can affect tick physiology by influencing nutritional adaptation, fitness, and immunity. Further, symbionts may influence disease ecology, as they interact with tick-borne pathogens and can facilitate or compete with pathogen development within the vector tissues. Rickettsial symbionts are frequently found in ticks of the genera of Ixodes, Amblyomma, and Dermacentor with relatively lower occurrence in Rhipicephalus, Haemaphysalis, and Hyalomma ticks, while Coxiella-like endosymbionts (CLEs) were reported infecting almost all tick species tested. Francisella-like endosymbionts (FLEs) have been identified in tick genera such as Dermacentor, Amblyomma, Ornithodoros, Ixodes, and Hyalomma, whereas Wolbachia sp. has been detected in Ixodes, Amblyomma, Hyalomma, and Rhipicephalus tick genera. Notably, CLEs and FLEs are obligate endosymbionts essential for tick survival and development through the life cycle. American dog ticks showed greater motility when infected with Rickettsia, indirectly influencing infection risk, providing evidence of a relationship between tick endosymbionts and tick-vectored pathogens. The widespread occurrence of endosymbionts across the tick phylogeny and evidence of their functional roles in ticks and interference with tick-borne pathogens suggests a significant contribution to tick evolution and/or vector competence. We currently understand relatively little on how these endosymbionts influence tick parasitism, vector capacity, pathogen transmission and colonization, and ultimately on how they influence tick-borne disease dynamics. Filling this knowledge gap represents a major challenge for future research.
... Blood-feeding is a prerequisite for oviposition of adult females, and thousands of eggs can be laid by a single female tick [1]. Bloodsucking of ticks not only harms hosts by causing tick paralysis, allergic reactions, damage to the skin, decreased productivity, and decreased immune function, but also transmits disease-causing pathogens, such as protozoa, viruses, and bacteria, from the infected hosts to other hosts in subsequent blood-feeding [2][3][4][5][6][7][8][9]. Ticks are currently considered to be second only to mosquitoes as vectors of infectious diseases to humans and animals [10]. ...
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Background Ticks are important vectors and transmit diverse pathogens, including protozoa, viruses, and bacteria. Tick-borne diseases can cause damage to both human health and the livestock industries. The control and prevention of ticks and tick-borne diseases has relied heavily on acaricides. Methods In the present study, using a high-throughput RNA sequencing (RNA-Seq) technique, we performed a comprehensive time-series transcriptomic analysis throughout the embryogenesis period of Rhipicephalus turanicus . Results Altogether, 127,157 unigenes were assembled and clustered. Gene expression differences among the embryonic stages demonstrated that the most differentially expressed genes (DEGs) were observed in the comparisons of early embryonic stages (RTE5 vs. RTE10, 9726 genes), and there were far fewer DEGs in later stages (RTE25 vs. RTE30, 2751 genes). Furthermore, 16 distinct gene modules were identified according to weighted gene co-expression network analysis (WGCNA), and genes in different modules displayed stage-specific characteristics. Gene Ontology (GO) annotations and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment suggested that some genes involved in organ and tissue formation were significantly upregulated in the early embryonic developmental stages, whereas metabolism-related pathways were more enriched in the later embryonic developmental stages. Conclusions These transcriptome studies revealed gene expression profiles at different stages of embryonic development, which would be useful for interrupting the embryonic development of ticks and disrupting the transmission of tick-borne diseases. Graphical Abstract
... This finding may be related to climate conditions present in this region, which favor the spread and proliferation of vector ticks. Hemoparasite transmission is usually influenced by vector abundance, which varies according to the season, period of the year, geographic location (Randolph and Rogers, 2006), climate, and microclimate (Pfäffle et al., 2013). This region presents annual maximum average temperatures above 27 • C, with humid summers and dry winters ( Table 1). ...
Article
The epidemiological aspects of Babesia caballi infection were evaluated in 516 horse samples from Rio de Janeiro, Brazil. The presence and infestation level of ticks on horses, breed conditions, and animal management were evaluated on each farm through an epidemiological questionnaire. The gene that codes for rhoptry-associated protein-1 (RAP-1) of B. caballi was amplified by nested PCR (nPCR). Among the horses sampled, 17.2% (n = 89/516) presented B. caballi DNA. The characterized samples showed 99–100% similarity with other isolates of B. caballi based on the RAP-1 gene, available in GenBank. In the final logistic regression model, the variables associated with B. caballi infection in horses were as follows: age below two years (OR = 3.33; IC = 1.7–6.5), farms located in low altitudes (OR = 3.52; IC = 1.7–7.3) and Dermacentor nitens infestation (OR = 1.91; IC = 1.1–3.4). Furthermore, a high level of D. nitens infestation in horses was also a factor associated with positivity for B. caballi (OR = 2.11; IC = 1.25–3.54). In summary, young horses bred in low altitude regions characterized with high temperatures, and infested by D. nitens, mainly with a higher level of infestation, are more likely to be infected by B. caballi. This epidemiological study provides statical evidence that the D. nitens tick play a role as the biological vector of B. caballi in the studied region.
... Among the most frequently reported hard ticks of medical and veterinary relevance, Amblyomma, Dermacentor, Ixodes, and Rhipicephalus are the four more widespread genera (Liu and Bonnet 2014). Changes in land-use patterns and environmental conditions such as climate, vegetation coverage, and closer interaction between hosts are related to the extended presence of ticks in several areas worldwide (Pfäffle et al. 2013;Wikel 2018). ...
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Tick infestation affects about 80% of livestock globally while transmitting various pathogens causing high economic losses. This study aimed to determine the degree of tick infestation in two regions, North and Middle Magdalena in Antioquia, Colombia, to identify the ixodid tick species found and the associated risk factors. A cross-sectional study was carried out in 48 farms distributed in six municipalities of Antioquia. Two paddocks and eight bovines per farm were evaluated to estimate tick infestation (adults, nymphs, and larvae). Tick species were identified through a morphological and molecular analysis based on partial sequences of data obtained from DNA molecular markers, two mitochondrial (16S rRNA and COI), and one genomic DNA gene (18S rRNA). A multivariate Poisson regression model was applied to estimate the associated risk factors with ticks in cattle. Rhipicephalus microplus, Amblyomma patinoi and Dermacentor nitens were present in the livestock agroecosystems in the Middle Magdalena region; the highest incidence of tick infestation in cows and paddocks was reported in the municipality of Puerto Triunfo. The livestock agroecosystems in Middle Magdalena were characterized by a higher presence of adult R. microplus in cattle. Larval infestation of R. microplus, followed by D. nitens, was also found in paddocks. The multivariate analysis showed that the origin of cattle was the main risk factor associated with the presence of ticks (i.e., when cattle came from outside the farm). Cattle movement between farms in Middle Magdalena can contribute to the spread of ticks in this region.
... Transmitted via the bite of infected ticks, Borrelia burgdorferi sensu lato can infect humans, resulting in over 650,000 cases in the United States and Western Europe annually (Marques et al., 2021). The distribution of Lyme borreliosis is directly linked to a range of wildlife hosts that feed, infect and transport ticks, and there is risk of transmission in areas where members of the public may encounter infected ticks (Pfäffle et al., 2013). Ixodes ricinus is the main vector of Lyme borreliosis in most of Europe, although Ixodes persulcatus also plays a key role in North-Eastern Europe (Mencke, 2013). ...
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For more than three decades, it has been recognized that Ixodes ricinus ticks occur in urban green space in Europe and that they harbour multiple pathogens linked to both human and animal diseases. Urban green space use for health and well‐being, climate mitigation or biodiversity goals is promoted, often without consideration for the potential impact on tick encounters or tick‐borne disease outcomes. This review synthesizes the results of over 100 publications on questing I. ricinus and Borrelia spp. infections in ticks in urban green space in 24 European countries. It presents data on several risk indicators for Lyme borreliosis and highlights key research gaps and recommendations for future studies. Across Europe, mean density of I. ricinus in urban green space was 6.9 (range; 0.1–28.8) per 100 m2 and mean Borrelia prevalence was 17.3% (range; 3.1%–38.1%). Similar density estimates were obtained for nymphs, which had a Borrelia prevalence of 14.2% (range; 0.5%–86.7%). Few studies provided data on both questing nymph density and Borrelia prevalence, but those that did found an average of 1.7 (range; 0–5.6) Borrelia‐infected nymphs per 100 m2 of urban green space. Although a wide range of genospecies were reported, Borrelia afzelii was the most common in most parts of Europe, except for England where B. garinii was more common. The emerging pathogen Borrelia miyamotoi was also found in several countries, but with a much lower prevalence (1.5%). Our review highlights that I. ricinus and tick‐borne Borrelia pathogens are found in a wide range of urban green space habitats and across several seasons. The impact of human exposure to I. ricinus and subsequent Lyme borreliosis incidence in urban green space has not been quantified. There is also a need to standardize sampling protocols to generate better baseline data for the density of ticks and Borrelia prevalence in urban areas.
... In many European countries, TBE is the second-most common human tick-borne disease after LB in terms of the number of diagnosed cases [39][40][41][42]. Microclimatic conditions are the main factors that support the activity of ticks and, in an indirect way, the transmission of tick-borne pathogens [43]. Nevertheless, an important role in formation and stability of TBE natural foci plays coincidence of several ecological factors such as air temperature and air relative humidity, soil humidity, vegetation, type of the biotope, population density and the dynamics of seasonal activity of ticks and their hosts. ...
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Ixodes ricinus ticks are one of the most important vectors and reservoirs of infectious diseases in Europe, and tick-borne encephalitis (TBE) is one of the most dangerous human diseases transmitted by these vectors. The aim of the present study was to investigate the TBE incidence in some European countries during the COVID-19 pandemic. To this end, we analyzed the data published by the European Center for Disease Prevention and Control (ECDC) and Eurostat on the number of reported TBE and COVID-19 cases in 2020 and TBE cases in 2015–2019 (reference period). Significant differences in the TBE incidence were found between the analyzed countries. The highest TBE incidence was found in Lithuania (25.45/100,000 inhabitants). A high TBE incidence was also observed in Central European countries. In 12 of the 23 analyzed countries, there was significant increase in TBE incidence during the COVID-19 pandemic during 2020 compared to 2015–2019. There was no correlation between the incidence of COVID-19 and TBE and between the availability of medical personnel and TBE incidence in the studied countries. In conclusion, Central Europe and the Baltic countries are areas with a high risk of TBE infection. Despite the COVID-19 pandemic and imposed restrictions, the incidence of TBE is increasing in more than half of the analyzed countries.
... Ticks (Ixodida) are obligate hematophagous arthropods that transmit a wide variety of zoonotic pathogens [9][10][11]. Among them, the castor bean tick (Ixodes ricinus) is the major vector of causative agents of viral, bacterial and protozoan zoonotic diseases in Europe [12]. ...
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Background Microsporidia is a large group of eukaryotic obligate intracellular spore-forming parasites, of which 17 species can cause microsporidiosis in humans. Most human-infecting microsporidians belong to the genera Enterocytozoon and Encephalitozoon. To date, only five microsporidian species, including Encephalitozoon-like, have been found in hard ticks (Ixodidae) using microscopic methods, but no sequence data are available for them. Furthermore, no widespread screening for microsporidian-infected ticks based on DNA analysis has been carried out to date. Thus, in this study, we applied a recently developed DNA metabarcoding method for efficient microsporidian DNA identification to assess the role of ticks as potential vectors of microsporidian species causing diseases in humans. Methods In total, 1070 (493 juvenile and 577 adult) unfed host-seeking Ixodes ricinus ticks collected at urban parks in the city of Poznan, Poland, and 94 engorged tick females fed on dogs and cats were screened for microsporidian DNA. Microsporidians were detected by PCR amplification and sequencing of the hypervariable V5 region of 18S rRNA gene (18S profiling) using the microsporidian-specific primer set. Tick species were identified morphologically and confirmed by amplification and sequencing of the shortened fragment of cytochrome c oxidase subunit I gene (mini-COI). Results All collected ticks were unambiguously assigned to I. ricinus. Potentially zoonotic Encephalitozoon intestinalis was identified in three fed ticks (3.2%) collected from three different dogs. In eight unfed host-seeking ticks (0.8%), including three males (1.1%), two females (0.7%) and three nymphs (0.7%), the new microsporidian sequence representing a species belonging to the genus Endoreticulatus was identified. Conclusions The lack of zoonotic microsporidians in host-seeking ticks suggests that I. ricinus is not involved in transmission of human-infecting microsporidians. Moreover, a very low occurrence of the other microsporidian species in both fed and host-seeking ticks implies that mechanisms exist to defend ticks against infection with these parasites. Graphical abstract
... (Schorn et al. 2011, Overzier et al. 2013, Hornok et al. 2014, Hauck et al. 2020, Mathews-Martin et al. 2020, one possible reason that urbanization was not associated with abundance of ticks infected with other microorganism species is that abundance of reservoir hosts (mainly white-tailed deer) may not vary with urbanization in Oklahoma City. Because wildlife diversity and species composition impact spatio-temporal patterns of tick-borne disease (Schmidt and Ostfeld 2001, Grund et al. 2002, Allan et al. 2010, Hamer et al. 2012, Keesing et al. 2012, Pfäffle et al. 2013) and urbanization causes changes in wildlife communities (McKinney 2008), future studies should also investigate the role of wildlife reservoir hosts in tick-borne disease transmission and how this role varies in relation to patterns of urbanization. White-tailed deer have been linked to expanding A. americanum populations and increasing Ehrlichia spp. ...
Article
Urbanization alters components of natural ecosystems which can affect tick abundance and tick-borne disease prevalence. Likely due to these changes, tick-borne pathogen prevalence has increased in many U.S. urban areas. Despite the growing public health importance of tick-borne diseases, little is known about how they are influenced by urbanization in North America, especially in the central U.S. where several pathogens occur at or near their highest levels of incidence nationally. To determine whether urban development influences tick infection with bacteria and protozoa, we collected ticks at 16 parks across a gradient of urbanization intensity in Oklahoma City, Oklahoma, USA and tested them using a variety of PCR assays. Adult ticks tested positive for Rickettsia parkeri, R. amblyommatis, R. rhiphicephali, ‘Candidatus R. andeanae’, Ehrlichia chaffeensis, E. ewingii, Panola Mountain Ehrlichia, ‘Borrelia lonestari’, Theileria cervi, Babesia spp. Coco, and Cytauxzoon felis. These results indicate the presence of a high diversity of tick-borne bacteria and protozoa across an expanding urban area in the U.S. Great Plains. Although there appeared to be some risk of encountering tick-borne microorganisms across the entire urbanization gradient, E. chaffeensis, E. ewingii, and T. cervi-infected ticks and microbe diversity decreased with increasing urbanization intensity. We identified a low rate of coinfection between different microorganisms, with coinfected ticks mainly collected from sites in the least-urbanized areas. This study suggests the need for awareness of tick-borne disease risk throughout urban areas in the central U.S., and highlights a need for studies of tick host habitat use and movement in cities.
... Eggs are sensitive to heat and risk desiccation when exposed to high temperatures and dry areas. Incubation and hatching of eggs are only possible under some particular climatic conditions (Pfäffle et al., 2013). Our results indicate that this variable is positively correlated with the presence of the tick and the models developed show that it took a large part in predicting the presence of the tick. ...
Article
Ticks have medical and economic importance due to their ability to transmit pathogens to humans and animals. In tropical and sub-tropical countries, tick-borne diseases (TBD) are among the most important diseases affecting livestock and humans. The fast spread of ticks and TBD requires a quick development and application of efficient prevention and/or control programs. Therefore, prior investigations on TBD and related vectors epidemiology, for instance, through accurate epidemiological models, are mandatory. This study aims to develop models to forecast suitable habitat for Rhipicephalus microplus distribution in West Africa. Tick occurrences were assembled from 10 different studies carried out in six West African countries in the past decade. Six statistical models (maximum entropy in a single model and generalised linear model, generalised additive model, random forest, boosted regression tree and support vector machine model in an ensemble model) were applied and compared to predict the habitat suitability of R. microplus distribution in West Africa. Each model was evaluated with the area under the receiver operating characteristic curve (AUC), the true skill statistic (TSS) and the Boyce index (BI). The selected models had good performance according to their AUC (above .8), TSS (above .7) and BI (above .8). Temperature played a key role in MaxEnt model, whereas normalised difference vegetation index (NDVI) was the most important variable in the ensemble model. The model predictions showed coastal countries of West Africa as more suitable for R. microplus. However, some Sahelian areas seems also favourable. We stress the importance of vector surveillance and control in countries that have not yet detected R. microplus but are in the areas predicted to host suitable habitat. Indeed, awareness-raising and training of different stakeholders must be reinforced for better prevention and control of this tick in these different countries according to their status.
... An adult of Ixodes hexagonus (Leach 1815) was collected on tiles from an Italian cargo in the USA. This species is commonly known as hedgehogtick due the fact that the main host is the hedgehog, but there are several records of this species parasitizing dogs and transmitting pathogens throughout Europe, including in Italy (Pfäffle et al. 2013;Maurelli et al. 2018). ...
Article
In the last century, biological invasions have increased greatly due to the intensification in international trade and world climate change, thus representing one of the most relevant issues for agricultural productivity and biodiversity. The Animal and Plant Health Inspection Service of the United States, from 2019 to 2021, intercepted different species from Italy belonging to the Orders Ixodida, Sarcoptiformes and Trombidiformes. The study reported four new records and several new host plant associations. In this framework, the inspection system not only plays a relevant role in the plant protection, human and animal health, but also contributes to the knowledge of the Acari fauna from exporting countries.
... Comparison of our prevalence to the values reported in different studies from Asian countries on bovine anaplasmosis using molecular techniques in revealed a higher prevalence in China (12.8%) (Yang et al., 2015), Japan (17.3%) (Jilintai et al., 2009), Republic of Korea (22.7%) (Miranda et al., 2021), India (7%) (Pradeep et al., 2019), and Malaysia (60.9%) (Koh et al., 2018) than in Kyrgyzstan. The prevalence of tick-borne diseases like anaplasmosis may change according to the climate conditions and habitat since changes in these factors may affect the distribution of tick species (Kocan et al., 2010;Aubry and Geale, 2011;Pfäffle et al., 2013). We speculate that the prevalence of bovine anaplasmosis in the present study could reflect the climate conditions and habitat in our sampling areas (Frenken, 2013). ...
Article
Anaplasmosis is a rickettsial infection with significant effects on human and animal health, and the discovery of new species or genotypes with zoonotic potential in recent years has increased this importance. The aim of this study was to provide the first assessment of the molecular etiology and prevalence of bovine anaplasmosis in Kyrgyzstan (specifically in the Chuy, Talas, Djalal-Abad, Naryn, and Issyk-Kul regions). The prevalence of bovine anaplasmosis was determined as 1.7% (6/358). PCR and partial DNA sequencing results of the 16S ribosomal RNA (rRNA) gene revealed that Anaplasma centrale, A. phagocytophilum like-1, and the human pathogenic novel genotype A. capra are circulating in cattle herds in Kyrgyzstan. Six DNA nucleotide sequences obtained in this study were deposited in GenBank under the following accession numbers: A. centrale (MW672117, MW672118, MW672119, MW672120), A. phagocytophilum (MW672121), and A. capra (MW672115).
Chapter
Vector-borne pathogens (VBPs) of canines are a diverse range of infectious agents, including viruses, bacteria, protozoa and multicellular parasites, that are pernicious and potentially lethal to their hosts. Dogs across the globe are afflicted by canine VBPs, but the range of different ectoparasites and the VBPs that they transmit predominate in tropical regions. Countries within the Asia-Pacific have had limited prior research dedicated to exploring the epidemiology of canine VBPs, whilst the few studies that have been conducted show VBP prevalence to be high, with significant impacts on dog health. Moreover, such impacts are not restricted to dogs, as some canine VBPs are zoonotic. We reviewed the status of canine VBPs in the Asia-Pacific, with particular focus on nations in the tropics, whilst also investigating the history of VBP diagnosis and examining recent progress in the field, including advanced molecular methods, such as next-generation sequencing (NGS). These tools are rapidly changing the way parasites are detected and discovered, demonstrating a sensitivity equal to, or exceeding that of, conventional molecular diagnostics. We also provide a background to the armoury of chemopreventive products available for protecting dogs from VBP. Here, field-based research within high VBP pressure environments has underscored the importance of ectoparasiticide mode of action on their overall efficacy. The future of canine VBP diagnosis and prevention at a global level is also explored, highlighting how evolving portable sequencing technologies may permit diagnosis at point-of-care, whilst further research into chemopreventives will be essential if VBP transmission is to be effectively controlled.
Article
The expansion of tick-borne diseases challenges ecologists, epidemiologists, and public health professionals to understand the mechanisms underlying its emergence. The vast majority of tick-borne disease research emphasizes Ixodes spp. and Borrelia burgdorferi, with less known about other Ixodidae ticks that serve as vectors for an increasing number of pathogens of public health concern. Here we review and discuss the current knowledge of tick and tick-borne pathogens in an under-surveilled region of the United States. We discuss how landscape shifts may potentially influence tick vector dynamics and expansion. We also discuss the impact of climate change on the phenology of ticks and subsequent disease transmission. Increased efforts in the Central Plains to conduct basic science will help understand the patterns of tick distribution and pathogen prevalence. It is crucial to develop intensive datasets that may be used to generate models that can aid in developing mitigation strategies.
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Background Maintaining high vertebrate diversity is promoted as a potential strategy to control Lyme disease hazard via a so-called dilution effect, which occurs when increasing diversity of an ecological community reduces the transmission of a pathogen. However, empirical evidence from Europe is limited at best, while it remains unclear whether dilution effects operate for other tick-borne diseases. Here, we evaluated how often the dilution effect occurs for a wide range of tick-borne pathogens and symbionts in forest areas in the Netherlands. Methods Data on wildlife, tick densities, and tick-borne microorganisms were collected in 19 forest sites. We calculated six different biodiversity indices based on camera trapping and live trapping data to characterize the vertebrate community of each forest site. These indices were correlated with the nymphal infection prevalence (NIP) and density of infected nymphs (DIN) of three Borrelia burgdorferi sensu lato genospecies as well as seven other tick-borne pathogens and symbionts. Results Vertebrate host species diversity, tick densities and infection prevalence varied widely among sites. However, neither the NIP nor the DIN of any of the ten tick-borne pathogens or symbionts was significantly correlated with any of the six indices of vertebrate species diversity or with total host availability. These results were consistent regardless of whether we used the relative abundance of vertebrate species or the proportion of larvae fed by each host species to calculate the diversity indices. Conclusions Our results do not support evidence for a dilution effect in Dutch forests, suggesting that facilitating high species diversity of native wildlife is unlikely to reduce tick-borne disease hazard at the scale of local forest patches. Whether (other) nature conservation strategies in other types of habitats and at other spatial scales can reduce tick-borne disease hazard warrants further investigation.
Article
Understanding the effects of local habitat and wider landscape connectivity factors on tick presence, nymph density and Borrelia species (spp.) prevalence in the tick population is important for identifying the public health risk from Lyme borreliosis. This multi-city study collected data in three southern England cities (Bath, Bristol, and Southampton) during spring, summer, and autumn in 2017. Focusing specifically on urban green space used for recreation which were clearly in urbanised areas, 72 locations were sampled. Additionally, geospatial datasets on urban green space coverage within 250 m and 1 km of sampling points, as well as distance to woodland were incorporated into statistical models. Distance to woodland was negatively associated with tick presence and nymph density, particularly during spring and summer. Furthermore, we observed an interaction effect between habitat and season for tick presence and nymph density, with woodland habitat having greater tick presence and nymph density during spring. Borrelia spp. infected Ixodes ricinus were found in woodland, woodland edge and under canopy habitats in Bath and Southampton. Overall Borrelia spp. prevalence in nymphs was 2.8%, similar to wider UK studies assessing prevalence in Ixodes ricinus in rural areas. Bird-related Borrelia genospecies dominated across sites, suggesting bird reservoir hosts may be important in urban green space settings for feeding and infecting ticks. Whilst overall density of infected nymphs across the three cities was low (0.03 per 100 m²), risk should be further investigated by incorporating data on tick bites acquired in urban settings, and subsequent Lyme borreliosis transmission.
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Urbanization is rapidly transforming much of Southeast Asia, altering the structure and function of the landscape, as well as the frequency and intensity of the interactions between people, animals, and the environment. In this study, we explored the impact of urbanization on zoonotic disease risk by simultaneously characterizing changes in the ecology of animal reservoirs (rodents), ectoparasite vectors (ticks), and pathogens across a gradient of urbanization in Kuching, a city in Malaysian Borneo. We sampled 863 rodents across rural, developing, and urban locations and found that rodent species diversity decreased with increasing urbanization—from 10 species in the rural location to 4 in the rural location. Notably, two species appeared to thrive in urban areas, as follows: the invasive urban exploiter Rattus rattus ( n = 375) and the native urban adapter Sundamys muelleri ( n = 331). R. rattus was strongly associated with built infrastructure across the gradient and carried a high diversity of pathogens, including multihost zoonoses capable of environmental transmission (e.g., Leptospira spp.). In contrast, S. muelleri was restricted to green patches where it was found at high densities and was strongly associated with the presence of ticks, including the medically important genera Amblyomma , Haemaphysalis , and Ixodes . Our analyses reveal that zoonotic disease risk is elevated and heterogeneously distributed in urban environments and highlight the potential for targeted risk reduction through pest management and public health messaging.
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Background: Lyme borreliosis is the most prevalent vector-borne disease in Europe, and numbers might increase due to climate change. However, borreliosis is not notifiable in North Rhine-Westphalia (NRW), Germany. Hence, little is known about the current human seroprevalence in NRW. However, the proportion of Borrelia burgdorferi sensu lato-infected ticks has increased in a NRW nature reserve. The literature suggests increasing age and male sex as risk factors for seropositivity, whereas the influence of socioeconomic status is controversial. Thus, we aimed to determine regional seropositivity for Borrelia burgdorferi sensu lato (B. burgdorferi s.l.) and its risk factors in the Rhineland Study population in Bonn, NRW, and to compare it with previous surveys to evaluate potential effects of climate change. Methods: We assessed seropositivity in 2865 Rhineland Study participants by determining immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies for B. burgdorferi s.l. using a two-step algorithm combining enzyme-linked immunosorbent assay tests and line immunoblots. We calculated the odds of being classified as IgG or IgM positive as a function of age, sex, and educational level using binomial logistic regression models. We applied varying seropositiv-ity classifications and weights considering age, sex and education to compensate for differences between the sample and regional population characteristics. Results: IgG antibodies for B. burgdorferi s.l. were present in 2.4% and IgM antibodies in 0.6% of the participants (weighted: 2.2% [IgG], 0.6% [IgM]). The likelihood of IgG seropositivity increased by 3.0% (95% confidence interval [CI] 1.5-5.2%) per 1 year increase in age. Men had 1.65 times the odds for IgG seropositivity as women (95% CI 1.01-2.73), and highly educated participants had 1.83 times the odds (95% CI 1.10-3.14) as participants with an intermediate level of education. We found no statistically significant link between age, sex, or education and IgM seropositivity. Our weighted and age-standardized IgG seroprevalence was comparable to the preceding serosurvey German Health Interview and Examination Survey for Adults (DEGS) for NRW.
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This study carried out to estimate prevalence of equine theileriosis (ET) caused by Thieleria equi in horses from different region of three Iraqi provinces (Baghdad, Al-Qadisiyah, and Wasit) using two diagnostic methods, competitive-ELISA (c-ELISA) and polymerase chain reaction (PCR). Therefore, a total of 130 horses of different sexes, ages and activities were selected randomly for collection of jugular blood samples during ten months (March to December/2018). Overall results were revealed on 36.92% and 5.38% positive horses with ET by c-ELISA and PCR, respectively. comparison of infection rates between the diagnostic methods were showed that 4.62% positives by both assays, 0.77% positive by PCR only, 32.31% positives by c-ELISA only, and 62.31% were negatives by both assays. An association of ET infection rates to epidemiological risk factors (age, gender, activity, location, month of season) was evaluated in the present study. Among seropositive horses, significant increases (P<0.05) in c-ELISA results were reported in groups of ≥11 years (66.67 %); females (32.14%); non-race horses (40.57%); Al-Qadisiyah (37.84%) and Wasit (37.70%) provinces; and August (61.54%), respectively. Concerning to PCR results, significant elevations were appeared in groups of 1-3 years (11.76%); females (7.14%); non-race horses (6.60%); Al-Qadisiyah (8.11%) province; and June (23.08%), respectively.
Thesis
In the last decades, the emergence of ticks and tick-borne diseases (TBD) has become a public health concern in Europe. In Piedmont region (Northwestern Italy) ticks were rare in the past, especially in mountain areas. However, in the recent years, we have been observing an increase in tick abundance in the environment but also in reported tick-bites and TBD cases in humans. Tick-borne diseases are characterized by complex transmission cycles; thus, an integrated approach is needed. The ‘One Health’ (OH) approach may effectively provide scientific evidence for TBD surveillance and prevention, and support decision makers. This PhD project investigates the presence and abundance of tick vectors and tick-borne pathogens in two natural areas of Piedmont region, recently invaded by ticks, to identify potential risk factors involved in their emergence, and to evaluate their impact on public health. Additionally, we aimed to identify ideal surveillance and control elements based on a OH approach. We recorded a further expansion of Ixodes ricinus in Europe, being maintained at altitudes up to around 1700 m a.s.l. The abundance of I. ricinus was significantly associated with altitude, habitat type and signs of roe deer presence and molecular analyses demonstrated its infection with several zoonotic agents: B. burgdorferi sensu lato, spotted fever group rickettsiae, Anaplasma phagocytophilum, Borrelia miyamotoi and Neoehrlichia mikurensis. Dermacentor spp. ticks were also collected, in particular D. marginatus and D. reticulatus. Rickettsia slovaca and Candidatus Rickettsia rioja, causative agents of SENLAT (Scalp Eschar Neck Lymphadenopathy) syndrome in humans, infected Dermacentor ticks and wild boar tissues, suggesting the greater contribution of wild boar in its eco-epidemiology and dispersion in the study area. We also confirmed that Piedmontese population is exposed to infected tick bites. However, a generalized low awareness was observed among the population; in fact, although most citizens perceive ticks as a health threat, they do not frequently adopt protective measures. This justified the longer duration of tick attachment generally observed in bitten patients (> 24 hours). A serosurvey in wild ungulates was additionally carried out in mountain areas to assess the circulation of tick-borne encephalitis virus. No serum sample yielded positive results, indicating the absence of this pathogen in our territory so far. Notwithstanding, this activity should be maintained in the long term for early pathogen detection and rapid response, since the virus is circulating in bordering areas of the Piedmont. Regarding tick ecology, this project integrated some investigations about tick symbionts, whose presence is key for tick development and survival. We detected the infection of Francisella-like endosymbionts in Dermacentor spp. which have been previously associated with positive effects in the tick fitness, by providing nutrimental support to ticks. Moreover, a large-scale study was carried out to investigate the infection of Rickettsiella symbionts in I. ricinus populations in Europe, identifying a great diversity within the Rickettsiella genus. Research on TBD requires the knowledge and skills from different disciplines. However, transdisciplinarity seems to work when structural support is provided by the system; instead, critical elements such as insufficient funding, system decentralization and monodisciplinary approaches threaten the response capacity of the systems. One Health operation and infrastructure aspects can strengthen surveillance systems and could be particularly important in areas of recent spread of ticks and TBD.
Article
The natural cycle of the TBE virus is dependent on vector ticks and reservoir hosts. There are differing transmission cycles in varying environments, from cold northern coniferous forests to temperate central European forests. Within a natural transmission cycle, there are different ways of transmission: tick-to-tick (transovarial, sexual), host-to-tick (viremic), and also tick-to-tick and host-to-host. The complexity of natural transmission cycles is inadequately explored and poorly understood.
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Climate change has influenced the transmission of a wide range of vector-borne diseases in Europe, which is a pressing public health challenge for the coming decades. Numerous theories have been developed in order to explain how tick-borne diseases are associated with climate change. These theories include higher proliferation rates, extended transmission season, changes in ecological balances, and climate-related migration of vectors, reservoir hosts, or human populations. Changes of the epidemiological pattern have potentially catastrophic consequences, resulting in increasing prevalence of tick-borne diseases. Thus, investigation of the relationship between climate change and tick-borne diseases is critical. In this regard, climate models that predict the ticks’ geographical distribution changes can be used as a predicting tool. The aim of this review is to provide the current evidence regarding the contribution of the climatic changes to Lyme borreliosis (LB) disease and tick-borne encephalitis (TBE) and to present how computational models will advance our understanding of the relationship between climate change and tick-borne diseases in Europe.
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Background: A series of abiotic and biotic modifications occur in an anthropogenic landscape which influence the ecology and physiology of wild hosts and their parasites. How these changes affect the parasitism is highly context-dependent, based on the host-parasite system and the type of perturbation. We aimed to investigate the differences in infestation with fleas and ticks of the native rodent Phyllotis darwini in three sites with different anthropogenic impacts and to evaluate environmental and host factors associated with parasite richness and load. Methods: We studied wild, rural and peri-urban sites of the semiarid region of Chile in the spring and summer seasons between 2018 and 2020. We applied a multi-level analysis to assess environmental and host variables at the individual and microhabitat level. We used Generalized Linear Mixed Models and Generalized Linear Models to test factor effects on the richness and load of ectoparasites of adult rodents. Results: Overall, out of 310 rodents trapped, 71% were flea-infested and 22% showed tick infestation. We identified six flea genera, being Hectopsylla sp. and Neotyphloceras sp. the most abundant fleas across sites. Flea richness was significantly higher in male rodents and during the spring and was positively affected by the micromammal species richness. The flea load was also higher in spring, in males, and positively associated to tick load. Hectopsylla sp., one of the most abundant fleas, showed a higher load in the peri-urban site and at grids with lower vegetation index values (NDVI), and Neotyphloceras sp. fleas were associated with tick load and lower temperatures. All ticks were larvae or nymphs of Ixodes sp. and showed a higher load in summer months and higher temperatures. Conclusions: We discuss possible environmental requirements of fleas and ticks, the association between their loads and male-biased parasitism. Further experimental investigations are needed to seasonally precise microclimate thresholds required for the survival of these ectoparasites.
Article
The public health challenge posed by tick-borne disease (TBD) has increased efforts to characterize the spatial and temporal distribution of ticks and associated pathogens to better focus tick control strategies and personal protection measures. We describe variability in nymphal Ixodes scapularis Say and Amblyomma americanum (L.) density derived from daily drag sampling at a single location in New Jersey over 4 yr and explore how observed differences in daily collections might affect the estimation of acarological risk. We found significant variability in the density of host-seeking nymphs that could suggest substantially different rates of human-tick encounters depending on sampling date, habitat, and ambient weather conditions. The spatial and temporal variability in the distribution of 2 sympatric tick species with different host preferences and questing strategies, suggests that to produce results that are comparable among sites across the area sampled, surveillance efforts may be limited to shorter collection seasons, fewer sites or less sampling effort (fewer plots or fewer visits) per site, and a geographic scope that minimizes the potential temporal and spatial biases indicated here. Our results illustrate that evaluation of models of tick distribution or relative acarological risk based on surveillance data requires a full description of the diversity of habitats sampled and the conditions under which sampling is performed. The array of factors that affect tick host-seeking and that could bias interpretation of sampling results emphasizes the need to standardize sampling protocols and for more caution when interpreting tick sampling data collected over large temporal and spatial scales.
Article
Advances in sequencing technologies have revealed the complex and diverse microbial communities present in ticks (Ixodida). As obligate blood-feeding arthropods, ticks are responsible for a number of infectious diseases that can affect humans, livestock, domestic animals and wildlife. While cases of human tick-borne diseases continue to increase in the northern hemisphere, there has been relatively little recognition of zoonotic tick-borne pathogens in Australia. Over the past 5 years, studies using high-throughput sequencing technologies have shown that Australian ticks harbour unique and diverse bacterial communities. In the present study, free-ranging wildlife ( n =203), representing ten mammal species, were sampled from urban and peri-urban areas in New South Wales (NSW), Queensland (QLD) and Western Australia (WA). Bacterial metabarcoding targeting the 16S rRNA locus was used to characterize the microbiomes of three sample types collected from wildlife: blood, ticks and tissue samples. Further sequence information was obtained for selected taxa of interest. Six tick species were identified from wildlife: Amblyomma triguttatum , Ixodes antechini , Ixodes australiensis , Ixodes holocyclus , Ixodes tasmani and Ixodes trichosuri . Bacterial 16S rRNA metabarcoding was performed on 536 samples and 65 controls, generating over 100 million sequences. Alpha diversity was significantly different between the three sample types, with tissue samples displaying the highest alpha diversity ( P <0.001). Proteobacteria was the most abundant taxon identified across all sample types (37.3 %). Beta diversity analysis and ordination revealed little overlap between the three sample types ( P <0.001). Taxa of interest included Anaplasmataceae , Bartonella , Borrelia , Coxiellaceae , Francisella , Midichloria , Mycoplasma and Rickettsia . Anaplasmataceae bacteria were detected in 17.7% (95/536) of samples and included Anaplasma , Ehrlichia and Neoehrlichia species. In samples from NSW, ‘ Ca . Neoehrlichia australis’, ‘ Ca . Neoehrlichia arcana’, Neoehrlichia sp. and Ehrlichia sp. were identified. A putative novel Ehrlichia sp. was identified from WA and Anaplasma platys was identified from QLD. Nine rodent tissue samples were positive for a novel Borrelia sp. that formed a phylogenetically distinct clade separate from the Lyme Borrelia and relapsing fever groups. This novel clade included recently identified rodent-associated Borrelia genotypes, which were described from Spain and North America. Bartonella was identified in 12.9% (69/536) of samples. Over half of these positive samples were obtained from black rats ( Rattus rattus ), and the dominant bacterial species identified were Bartonella coopersplainsensis and Bartonella queenslandensis . The results from the present study show the value of using unbiased high-throughput sequencing applied to samples collected from wildlife. In addition to understanding the sylvatic cycle of known vector-associated pathogens, surveillance work is important to ensure preparedness for potential zoonotic spillover events.
Article
PurposeHepatozoonosis and piroplasmosis are diseases caused by apicomplexan protozoa that affect different types of animals, including mammals. The present study aimed to evaluate the occurrence of Hepatozoon spp. and piroplasms in wild mammals kept in captivity in rehabilitation centers in the states of Minas Gerais and Goiás, Brazil.Methods For this, blood samples from 152 animals were collected and analyzed by conventional optical microscopy and polymerase chain reaction (PCR). In addition, positive PCR samples were submitted to sequencing for molecular characterization of the specimens found.ResultsMicroscopic analysis revealed 53 of the 152 animals (28.3%) parasitized by piroplasms. No Hepatozoon sp. was observed. On the other hand, using the primers HepF300/HepR900 and Piro1F/Piro5R, both amplifying fragments of the 18S rDNA gene, eight animals (5.2%) were positive for Hepatozoon spp. and 40 (26.3%) for piroplasms. From the sequencing of the positive samples Hepatozoon canis, Hepatozoon felis, Theileria cervi, Theileria equi and Cytauxzoon felis were identified. In addition to the aforementioned hemoparasites, some animals were found parasitized by microfilaria. Such data ratify the presence of hemoparasites in captive wild animals, and are unprecedented in the two geographical regions covered by the present study. 19.7% of mammals harbored ectoparasites of the genera Amblyomma and Rhipicephalus.Conclusion Wild mammals are infected by several pathogens that can also infect domestic animals, some of them potentially zoonotic which can directly contribute to mortality and species reduction. Therefore, a deep understanding of the parasites, the hosts and the diseases is extremely necessary so that prevention, control and treatment measures are effectively applied.
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At present, tick-borne encephalitis is registered in Siberia, Far East, Urals, Belarus and central regions of Russia. The viral infection has also been recently revealed among the population of the previously problem free regions: Penza, Yaroslavl, Magadan, Kamchatka, Moscow and Ivanovo. The disease manifests itself in various forms: febrile, meningeal, meningoencephalitic etc. The disease prognosis is favorable in case of a meningeal or febrile form, but significantly worse in case of a meningoencephalitic form – fatal outcomes take place in 25-30% of cases. Residuals in the form of convulsive hyperkinetic syndrome may remain in some patients even if the treatment started in time. Active immunization is the primary tick-borne encephalitis prevention.
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Models used to simulate plant growth and insect development on rangelands often assume that soil temperature is homogeneous over the entire area of interest. This simplifying assumption is made because few data are available on the magnitude and structure of the spatial variability of soil temperature within rangeland communities. The influence of sagebrush on the spatial variability and diurnal fluctuations of near-surface soil temperature was examined within a sagebrush-grass plant community. Hourly soil temperatures were measured at 1-, 5-, and 10-cm depths at 30-cm intervals along a 12.3-m north-south transect over a 6-day period in March, 1989. Both classical and geostatistical techniques were used to quantify and model the magnitude and structure of the spatial and temporal variability. Maximum soil temperatures at the 1-cm depth varied from 7 to 23° C under sagebrush and bare interspace, respectively. Periodic spatial patterns in soil temperature were found for all measured depths with a wavelength of periodicity approximately equal to the separation distance between sagebrush plants along the transect. Diurnal variability in near surface soil temperature was much greater in interspace areas compared to under sagebrush plants. The amplitude of diurnal variability in soil temperature at the 1-cm depth under sagebrush was similar to the amplitude of the diurnal variability at the 10-cm depth within the interspaces.
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We examined differences between populations of white-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus) in woodlot fragments and unfragmented forests and attempted to discriminate among potential causal mechanisms. White-footed mice showed increased population density and body mass in woodlots but otherwise no differences in population attributes between woodlots and forests. Eastern chipmunks showed decreased survival rates in woodlots but no other differences in population parameters between woodlots and forests. Mast production was variable among sites but showed no differences between woodlot and forest sites. Likewise, total biomass of mammalian granivores was similar between woodlot and forest sites, but woodlots contained an impoverished community of granivores. White-footed mice and eastern chipmunks may be affected differentially by forest fragmentation, presumably due to differences in their life-history stategies. Our results suggest that white-footed mice thrive in woodlot fragments due to increased mast availability resulting from decreased biomass of competing granivores. In contrast, eastern chipmunks may be influenced negatively by forest fragmentation, possibly because they are more susceptible to increased rates of predation occurring in woodlots than white-footed mice.
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Explanations for the dynamics of tick-borne disease systems usually focus on changes in the transmission potential in natural enzootic cycles. These are undoubtedly important, but recent analyses reveal that they may not be quantitatively the most significant side of the interaction between infected ticks and humans. Variation in human activities that may impact inadvertently but positively on both the enzootic cycles and the degree of human exposure to those cycles, provide more robust explanations for recent upsurges in tick-borne encephalitis in Europe. This can account for long-term increases in incidence that coincided with post-soviet political independence, for small-scales spatial variation in incidence within a country, and for short-scale fluctuations such as annual spikes in incidence. The patterns of relevant human activities, typically those related to the use of forest resources, are evidently driven and/or constrained by the cultural and socio-economic circumstances of each population, resulting in contrasting national epidemiological outcomes.
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Conceptual approaches used to understand conservation in fragmented landscapes are summarized in this chapter by Andrew F. Bennett and Denis A. Saunders. Destruction and fragmentation of habitats are major factors in the global decline of species, the modification of native plant and animal communities and the alteration of ecosystem processes. Habitat destruction, habitat fragmentation (or subdivision) and new forms of land use are closely intertwined in an overall process of landscape change. Landscape change is not random: disproportionate change typically occurs in flatter areas, at lower elevations and on more-productive soils. Altered physical processes (e.g. wind and water flows) and the impacts of human land-use have a profound influence on fragments and their biota, particularly at fragment edges. Different species have different ecological attributes (such as scale of movement, life-history stages, what constitutes habitat) which influence how a species perceives a landscape and its ability to survive in modified landscapes. Differences in the vulnerability of species to landscape change alter the structure of communities and modify interactions between species (e.g. pollination, parasitism). Changes within fragments, and between fragments and their surroundings, involve timelags before the full consequences of landscape change are experienced. Conservation in fragmented landscapes can be enhanced by: (i) protecting and increasing the amount of habitat: (ii) improving habitat quality; (iii) increasing connectivity; (iv) managing disturbance processes in the wider landscape; (v) planning for the long term; and (vi) learning from conservation actions undertaken.
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Microclimate is the suite of climatic conditions measured in localized areas near the earth's surface (Geiger 1965). These environmental variables, which include temperature, light, windspeed, and moisture, have been critical throughout human history, providing meaningful indicators for habitat selection and other activities. For example, for 2600 years the Chinese have used localized seasonal changes in temperature and precipitation to schedule their agricultural activities. In seminal studies, Shirley (1929, 1945) emphasized microclimate as a determinant of ecological patterns in both plant and animal communities and a driver of such processes as the growth and mortality of organisms. The importance of microclimate in influencing ecological processes such as plant regeneration and growth, soil resperation and growth, soil repiration, nutrient cycling, and wildlife habitat selection has became an essential component of current ecological research (Perry 1994). plant regeneration and growth, soil respiration, nutrient cycling, and
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Utilitarian arguments concerning the value of biodiversity often include the benefits of animals, plants, and microbes as sources of medicines and as laboratory models of disease. The concept that species diversity per se may influence risk of exposure to disease has not been well developed, however. We present a conceptual model of how high species richness and evenness in communities of terrestrial vertebrates may reduce risk of exposure to Lyme disease, a spirochetal ( Borrelia burgdorferi) disease transmitted by ixodid tick vectors. Many ticks never become infected because some hosts are highly inefficient at transmitting spirochete infections to feeding ticks. In North America, the most competent reservoir host for the Lyme disease agent is the white-footed mouse ( Peromyscus leucopus), a species that is widespread and locally abundant. We suggest that increases in species diversity within host communities may dilute the power of white-footed mice to infect ticks by causing more ticks to feed on inefficient disease reservoirs. High species diversity therefore is expected to result in lower prevalence of infection in ticks and consequently in lower risk of human exposure to Lyme disease. Analyses of states and multistate regions along the east coast of the United States demonstrated significant negative correlations between species richness of terrestrial small mammals (orders Rodentia, Insectivora, and Lagomorpha), a key group of hosts for ticks, and per capita numbers of reported Lyme disease cases, which supports our “dilution effect” hypothesis. We contrasted these findings to what might be expected when vectors acquire disease agents efficiently from many hosts, in which case infection prevalence of ticks may increase with increasing diversity hosts. A positive correlation between per capita Lyme disease cases and species richness of ground-dwelling birds supported this hypothesis, which we call the “rescue effect.” The reservoir competence of hosts within vertebrate communities and the degree of specialization by ticks on particular hosts will strongly influence the relationship between species diversity and the risk of exposure to the many vector-borne diseases that plague humans. Resumen: Argumentos utilitarios relacionados con el valor de la biodiversidad frecuentemente incluyen los beneficios de animales, plantas y microbios como recursos para medicinas y como modelos de enfermedades en laboratorio. Sin embargo, la idea de que la diversidad de especies por sí misma puede influenciar el riesgo de exposición a enfermedades no ha sido bien desarrollada. Presentamos un modelo conceptual de cómo la riqueza de especies y la uniformidad en comunidades de vertebrados terrestres puede reducir el riesgo de exposición a la enfermedad de Lyme, una enfermedad causada por una espiroqueta ( Borrelia burgdorferi) y transmitida por una garrapata ixódida. Muchas garrapatas nunca son infectadas debido a que los huéspedes son altamente ineficientes en la transmisión de espiroquetas a las garrapatas que se alimentan de ellos. En Norte América, el huésped reservorio más competente del agente de la enfermedad de Lyme es el ratón de patas blancas ( Peromyscus leucopus), una especie de amplia dispersión y localmente abundante. Sugerimos que los incrementos en la diversidad de especies dentro de las comunidades de huéspedes pueden diluir el potencial de infección de las garrapatas por el ratón de patas blancas al ocasionar que más garrapatas se alimenten de reservorios ineficientes en la transmisión de la enfermedad. Por lo tanto, se esperaría que una alta diversidad de especies resulte en una prevalencia de infección de garrapatas reducida y, por lo tanto, en una disminución del riesgo de exposición de humanos a la enfermedad de Lyme. Un análisis por estado y de varios estados a lo largo de la costa este de los Estados Unidos demostró correlaciones significativamente negativas entre la riqueza de especies de mamíferos terrestres pequeños (órdenes Rodentia, Insectivora, y Lagomorfa), un grupo clave de huéspedes para garrapatas, y los números per capita de casos de la enfermedad de Lyme reportados, lo cual apoya nuestra hipótesis de efecto de dilución. Contrastamos estos resultados con lo que se podría esperar cuando los vectores adquieren eficientemente agentes de la enfermedad de muchos huéspedes, caso en el cual, una alta diversidad causaría la prevalencia de infección de garrapatas permaneciendo alta aún cuando la diversidad de huéspedes disminuyera. Una correlación positiva entre los casos de la enfermedad de Lyme per capita y la riqueza de especies de aves residentes del suelo apoya esta hipótesis, que hemos llamado efecto de rescate. La capacidad de reservorio de huéspedes dentro de las comunidades de vertebrados y el grado de especialización de las garrapatas en huéspedes particulares, influenciaría fuertemente la relación entre la diversidad de especies y el riesgo de exposición a muchas de las enfermedades transmitidas por vectores que infectan a humanos.
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We used global positioning system (GPS) radiocollars on female white-tailed deer (Odocoileus virginianus )t o document details of onsets of migrations, rates of travel, patterns of travel, durations of migrations, and distances traveled by 8 deer in spring and 4 deer in autumn in northeastern Minnesota in 1998, 1999, and 2001. In spring, deer migrated 23-45 km during 31-356 h, deviating a maximum 1.6-4.0 km perpendicular from a straight line of travel between their seasonal ranges. They migrated a minimum of 2.1-18.6 km/day over 11-56 h during 2-14 periods of travel. Minimum travel during 1-h intervals averaged 1.5 km/h (SD ¼ 0.6, n ¼ 27). Deer paused 1-12 times, averaging 24 h/pause (SD ¼ 29, n ¼ 43, range 19-306 h/pause). Deer migrated similar distances in autumn with comparable rates and patterns of travel. A difference of 1.9- to 7.5-fold in duration of migrations by deer migrating the same distances suggests that much of the variation in durations may be independent of migration distance.
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Review This is a unique book dealing with tick species imported to the US through human immigration, migratory birds, exotic animal trade etc. Although the name might suggest it would focus exclusively with ticks found in the US, there are also a few chapters explaining from which continents these invasive ticks were coming and which give valuable information about their ecology, related epidemiology and animal and human health associated problems. The author also presents the different diseases transmitted by these ticks so it is not a taxonomy book per se. A special chapter is dedicated to the two most important ticks: Rhipicephalus (Boophilus) annulatus and Rhipicephalus (Boophilus) microplus. There are also two sections dealing with regulatory issues and preventive measures. Although it is rather disappointing that the Publisher decided to use only black and white figures, which does not make sense when books are competing against internet animations, colour pictures and other sources. I hope that such a poor choice will be rectified in the second edition. Nevertheless, this book seems ideal for students and scientists interested in ticks and the readership should not be restricted to the US only, The author is a well-known and respected acarologist who has taken an unusual approach to discuss these ticks. It is a book that I am sure many university libraries and acarology centers would find useful as it presents very specific, accurate and up-to-date information.
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Density and survival of a raccoon (Procyon lotor) population in Rock Creek Park, an urban national park in Washington, D.C., were estimated using mark-recapture and radio-tracking over an 8-year period following the appearance of the mid-Atlantic States (Mid-Atlantic) rabies epizootic. Raccoon density ranged from 333.3 to 66.7/km(2), with an overall park estimate of 125/km(2). This density places the Rock Creek population within the range of other urban and suburban populations and is many times greater than raccoon densities reported from other habitats. Density was particularly high in one thin spur of parkland with the smallest ratio of area to urban edge. Raccoon survival rates were high except among juveniles during the rabies epizootic. Data on rabies prevalence from Washington, D.C., indicate a cycle with peaks in 1983 during the initial epizootic and again in 1987 and 1991, a pattern similar to that seen in other carnivores and in rabies models. We found evidence of decreased raccoon density during and after the 1987 rabies resurgence relative to the years following the original epizootic, when rabies prevalence was low. While hunting and trapping represent a major mortality factor for many rural raccoon populations, urban and suburban populations and protected populations may frequently be subject to epizootics of diseases such as canine distemper and rabies, even years after initial contact with a disease.
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Many infectious diseases of humans are caused by pathogens that reside in nonhuman animal reservoirs and are transmitted to humans via the bite of an arthropod vector. Most vectors feed from a variety of host species that differ dramatically in their reservoir competence; that is, their probability of transmitting the infection from host to vector. We explore a conceptual model of what we termed the "dilution effect," whereby the presence of vertebrate hosts with a low capacity to infect feeding vectors (incompetent reservoirs) dilute the effect of highly competent reservoirs, thus reducing disease risk. Using Lyme disease as an example, we demonstrate the presence and estimate the magnitude of the dilution effect for local sites in eastern New York State. We found that the prevalence of Lyme disease spirochetes, Borrelia burgdorferi, in field-collected Ixodes ticks (37.6% and 70.5% for nymphal and adult stages, respectively) was dramatically lower than expected, (∼90% and >95% for nymphal and adult stages, respectively) if ticks fed predominantly on highly competent reservoirs, white-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus). We inferred the role of additional host species using an empirically based model that incorporated data on tick burdens per host, relative population densities of hosts, and reservoir competence of each host. Assuming an empirically realistic reservoir competence of 5% for non-mouse and non-chipmunk hosts, we determined that alternative hosts must provide 61% and 72% of larval and nymphal meals, respectively. Using computer simulations, we assembled simulated host communities that differed in species richness, evenness, and net interactions between alternative hosts and mice. We found that increasing species richness (but not evenness) reduced disease risk. Effects were most pronounced when the most competent disease reservoirs were community dominants and when alternative hosts had a net negative influence on the dominance of mice as a host for ticks. Our results highlight a critical role of biodiversity and host community ecology in the transmission of vector-borne zoonotic diseases that in turn has important consequences for human health.
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Forest destruction and fragmentation in the United States recently have been shown to reduce mammalian species diversity and to elevate population densities of white-footed mice ( Peromyscus leucopus ). One potential consequence of reduced species diversity and high mouse density in small fragments is an increase in human exposure to Lyme disease. Increased risk of exposure to this disease is expected because of the role of the white-footed mouse as the principal natural reservoir of the Lyme bacterium, Borrelia burgdorferi. Blacklegged ticks ( Ixodes scapularis ) feeding on mice have a higher probability of becoming infected with the bacterium than do ticks feeding on any other host species. We hypothesized that small forest patches ( <2 ha ) have a higher density of infected nymphal blacklegged ticks, which is the primary risk factor for Lyme disease, than larger patches ( 2–8 ha ). In the summer of 2000, we sampled tick density and B. burgdorferi infection prevalence in 14 maple-dominated forest patches, ranging in size from 0.7 to 7.6 ha, in Dutchess County of southeastern New York state. We found a significant linear decline in nymphal infection prevalence with increasing patch area and a significant exponential decline in nymphal density with increasing patch area. The consequence was a dramatic increase in the density of infected nymphs, and therefore in Lyme disease risk, with decreasing forest patch size. We did not observe a similar relationship between the density of larval ticks and patch size. These results suggest that by influencing the community composition of vertebrate hosts for disease-bearing vectors, habitat fragmentation can influence human health.
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Browsing by white-tailed deer (Odocoileus virginianus) can profoundly affect the abundance and population structure of several woody and herbaceous plant species. Enclosure studies and population surveys reveal that past and current deer densities as low as 4 deer/km² may prevent regeneration of the once common woody species, Canada yew (Taxus canadensis), eastern hemlock (Tsuja canadensis), and white cedar Puja occidentalis), as well as several herbaceous species. Prior to European settlement, forests in northern Wisconsin contained relatively sparse deer populations (<4/km²), but extensive timber cutting in the late nineteenth century boosted deer populations. Continued habitat fragmentation resulting from scattered timber harvests and the creation of “wildlife openings” to improve deer forage maintain these high densities throughout much of the Northeast.
Book
Biogeographie - Die räumliche Sicht der Biosphäre Das Buch bietet einen Überblick über die Fragestellungen und Arbeitsweisen der Biogeographie. Räumliche und zeitliche Eigenschaften des Auftretens oder Fehlens von Organismen, Lebensgemeinschaften, Ökosystemen und Großlebensräumen werden erläutert. Der Autor stellt theoretische Konzepte, Methoden und angewandte Aspekte vor. Aktuelle Entwicklungen der Biodiversität und globale Umweltfragen werden berücksichtigt.
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Under the same urbanization pressure, the local climate in large metropolitan areas is also altered. This is especially apparent when certain climatic characteristics are considered, e.g. temperature, humidity and wind. In fact, all the main meteorological parameters are severely affected, resulting in the development of a local climatic regime, which is characterized by increases in temperature (the heat-island effect) and reduction of humidity and wind. Furthermore, in central areas particularly, the continuous replacement of vegetation with buildings and roads severely affects the radiation balance and this further influences the temperature regime of the environment. Under these circumstances the comfort index for those living in big cities is quite different from that for those living in suburban and rural areas.
Article
The development, survival and oviposition of I. ovatus were observed at various temperatures (15,17,20,25,27 and 30℃) in the laboratory. Oviposition occurred at 17 to 30℃, but the mean number of deposited eggs per mg body weight of engorged female was markedly reduced at 30℃. The periods of preoviposition and oviposition were shortened as the temperature rose, except at 30℃. The egg hatchability was as high as 83-93% at 17-25℃, and was low at both higher (27-30℃) and lower (15℃) temperatures. The incubation period of eggs was shortened with increasing temperature. Engorged larvae and nymphs molted at 15 to 30℃, but the molting percentage was small at 30℃ in larvae, and at 15,20 and 30℃ in nymphs. The developmental zeroes for oviposition and eggs were 8.2 and 6.4℃, respectively. The developmental periods of engorged larvae and nymphs were generally shortened as the temperature rose, but temperature and the duration of development did not show a clear linear relationship. I. ovatus is less tolerant to low and high temperatures than the common Japanese haemaphysalids, Haemaphysalis longicornis and H. flava. This might be a factor that restricts the habitat of I. ovatus.
Chapter
This chapter discusses the humidity relationships and water balance of ticks. The life cycle of ticks is composed of relatively short parasitic phases during which engorgement takes place and of the extended nonparasitic phases without access to food and liquid. This imposes great demands on their water balance mechanisms. When a tick sucks blood from its host, it ingests large quantities of water and ions with the blood meal. To concentrate the nutrient portion of the blood, and to maintain osmotic and ionic balance, excess water and ions have to be eliminated. Various devices contribute to the maintenance of water balance in unfed ticks. The distribution of different species of ticks, with regard to environmental humidities, is primarily determined by the degree of their integumental waterproofing. Under equilibrium conditions, the amount of water in the body of a tick is related to the level of the environmental humidity; higher ambient humidities correspond with higher body water levels in the tick. The vapor uptake systems, found among arthropods, are of independent evolutionary origin. In some species, the specialized structures and essential components of the mechanism may have been evolved for the primary purpose of vapor absorption.
Article
The canopies of woody plants in semiarid ecosystems modify the microclimate beneath and around them, with canopy patches usually having lower soil temperatures than intercanopy patches. However, lacking are studies that have evaluated how heterogeneity in soil temperature, induced by woody plant canopies, influences soil evaporation rates and the consequent effects on plant-available water. Soil temperatures were measured and soil evaporation rates were estimated for canopy and intercanopy patches in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico. Soil temperature was measured at 2-cm depths in four canopy and four intercanopy locations during 1994. Maximum soil temperature in intercanopy patches was greater than in canopy patches between May and September, by as much as 10°C, while soil temperatures in intercanopy patches were lower than in canopy patches during colder parts of the day in the fall and winter months. Equations for soil drying rates for sandy loam soil samples were determined in laboratory experiments over a range of temperatures and soil water contents. Drying rates were disproportionately greater at high soil moisture and high soil temperature. Intercanopy patches were predicted to dry more than canopy patches for days in April through September by as much as 2% volumetric soil water content per day. The difference between patches was amplified at lower soil water contents when expressed as soil water potential, which more directly determines plant-available water. Our results quantify the effects of woody plants on the microclimate with respect to soil temperature and evaporation, which in turn affect herbaceous and woody plants by modifying factors such as germination, the potential for facilitation, and the amount of plant-available water.
Article
The identification of what factors determine the population dynamics of polyvoltine species has been a difficult problem in ecology because population dynamics can contain intra- and interannual variability, and because the time scale at which factors affect the population is often unknown. We created a comprehensive population model to determine how density dependence (linear, nonlinear, and time-delayed) and weather affected the rate of population growth of white-footed mice (Peromyscus leucopus) in an isolated woodlot. We studied this nonoutbreak, polyvoltine species using a 257-mo data set spanning 23 yr, which incorporated both detailed intra-annual and long-term dynamics, and we used this model to forecast future population size. We then evaluated whether 3 yr spans of monthly data or a 22-yr span of annual data were better able to identify the key determinants that drive population dynamics, and we identified which data type created more accurate forecasts. The 257-mo comprehensive model determined that the intra-annual cycle was caused by seasonally varying intrinsic growth rates and density dependence on a 1-2 mo scale and indicated that peak population size in one year did not affect the population in the subsequent year. Interannual variability in peak and trough density was caused by the effect of weather on monthly rate of growth with a 0-2 mo time delay, with the exception of two droughts. These droughts negatively affected the population for 9 mo; the effects were probably mediated through reduced seed crop. This model explained 81% of the variability in density. Because weather determined interannual variability in density, forecasts that did not use known weather data during the forecast period were poor. When weather data were used, forecasts were accurate within 1-3 animals (10%) of observed densities up to 8 mo in the future but were inaccurate beyond 8 mo. We found that short-term monthly data detected more factors affecting the population and created more accurate forecasts than long-term annual data, because all factors affecting the population (except droughts) occurred on a monthly scale. The annual model did not detect any weather effects except droughts and detected annual density dependence, which represents time-delayed density dependence in polyvoltine species. We argue that this annual relationship is spurious and caused by studying this polyvoltine species on an inappropriate time scale. Our work suggests that the time scale of the analysis may affect the conclusions drawn about which types of factors determine population size and with what time lag. It also suggests that, even when population fluctuations can be explained, accurately predicting future densities may be impossible when fluctuations are driven by weather.