![]() ![]() However, this research has been fraught with difficulty from the outset because of insufficient knowledge about the nature of many tick-pathogen associations ( Randolph, 2009 Franke et al., 2013 Medlock et al., 2013). (2002) “partially or fully-fed ticks removed from hosts that contain may or may not be vectors because nearly all hematophagous arthropods feeding on reservoir hosts are likely to ingest some microorganisms with the blood meal.” Such reporting of crude associations between pathogens and engorged ticks has only served to confuse our understanding of the relationships between ticks, tick hosts and tick-transmitted pathogens.Ī later surge in interest in ticks and tick-borne pathogens has been inspired by recent claims about the impact of forecasted climate change on the spatial distribution of ticks and associated pathogens ( Brownstein et al., 2003 Ostfeld et al., 2005 Diuk-Wasser et al., 2006 Ogden et al., 2008 Jaenson et al., 2009). Further, 109 reports in that period dealt with newly determined associations between pathogens and ticks collected while feeding on a host. Of these, 311 reported associations and relationships between tick and pathogens, at different scales (local, regional, or national). A review of digital bibliographical databases for the period 2000–2010 revealed 512 papers dealing with ticks and transmitted pathogens in Europe alone ( Estrada-Peña et al., 2013). However, this has resulted in much misinterpretation of the vectorial capacity of ticks and the reservoir competence of vertebrates. The adoption of DNA detection as a general tool during the 1990s to investigate the relationships between ticks, tick-transmitted pathogens and their vertebrate hosts further accelerated interest in the field. The discovery of formerly unknown mechanisms of pathogen transmission, such as the non-viremic transmission of TBE virus ( Labuda et al., 1993), and the re-emergence of certain tick-borne diseases, such as the ongoing epidemic of Crimean-Congo hemorrhagic fever in Turkey, likewise have created a wealth of research interest ( Gale et al., 2010). Ticks are fascinating vectors of many pathogens affecting human and animal health, and research on this topic was boosted by the emergence of the zoonotic tick-borne disease, Lyme borreliosis, three decades ago ( Ostfeld et al., 2005). This approach should provide a coherent framework for the reporting of research findings concerning ticks and tick-borne diseases. ![]() We also describe laboratory procedures and standards for evaluating the vectorial capacity of a tick or the reservoir role of a host. With the aim of standardization, we propose unambiguous definitions of the status of hosts and ticks regarding their ability to maintain and spread a given pathogen. We also provide evidence to critically reject the use of some environmental traits that are being increasingly reported as the drivers of the behavior of ticks. We detail the climatic variables that have biological importance on ticks and explain how they should be properly measured and analyzed. We review the factors affecting field collections of ticks, and we describe the biologically and ecologically appropriate procedures for describing tick host-seeking activity and its correlation with environmental traits. In this review, we focus on the ecological features driving the life cycle of ticks and the resulting effects on the eco-epidemiology of tick-transmitted pathogens. For example, unreliable identification of ticks and pathogens, erroneous interpretations of short-term field studies, and the hasty acceptance of some tick species as vectors have led to ambiguities regarding the vector role of these arthropods. However, procedural errors continue to accumulate in the scientific literature, resulting in misleading information. Routine application of tools for the detection of fragments of foreign DNA in ticks, together with a high degree of interest in the quantification of disease risk for humans, has led to a marked increase in the number of reports on the eco-epidemiology of tick-borne diseases. Interest in tick-transmitted pathogens has experienced an upsurge in the past few decades. 5Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.4Department of Environmental Science, Policy and Management, University of California, Berkeley, USA.2UCD School of Biology and Environmental Science, University College Dublin, Dublin, Ireland.1Faculty of Veterinary Medicine, Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain. ![]()
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