Host Range and Emerging and Reemerging Pathogens

Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom.
Emerging infectious diseases (Impact Factor: 6.75). 01/2006; 11(12):1842-7. DOI: 10.3201/eid1112.050997
Source: PubMed


An updated literature survey identified 1,407 recognized species of human pathogen, 58% of which are zoonotic. Of the total, 177 are regarded as emerging or reemerging. Zoonotic pathogens are twice as likely to be in this category as are nonzoonotic pathogens. Emerging and reemerging pathogens are not strongly associated with particular types of nonhuman hosts, but they are most likely to have the broadest host ranges. Emerging and reemerging zoonoses are associated with a wide range of drivers, but changes in land use and agriculture and demographic and societal changes are most commonly cited. However, although zoonotic pathogens do represent the most likely source of emerging and reemerging infectious disease, only a small minority have proved capable of causing major epidemics in the human population.

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    • "Collectively, these pathways capture nearly all the ways in which pathogens and the diseases they cause can change in the human population. These seven pathways have been used predominantly to identify emergence, but have been overlooked in macroscale analyses of EIDs [18] [19] [21]. Neglect of the pathways used to designate diseases as emerging has left some important questions unanswered . "
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    ABSTRACT: Microbial infections are as old as the hosts they sicken, but interest in the emergence of pathogens and the diseases they cause has been accelerating rapidly. The term 'emerging infectious disease' was coined in the mid-1900s to describe changes in disease dynamics in the modern era. Both the term and the phenomena it is meant to characterize have evolved and diversified over time, leading to inconsistencies and confusion. Here, we review the evolution of the term 'emerging infectious disease' (EID) in the literature as applied to human hosts. We examine the pathways (e.g., speciation or strain differentiation in the causative agent vs. rapid geographic expansion of an existing pathogen) by which diseases emerge. We propose a new framework for disease and pathogen emergence to improve prioritization. And we illustrate how the operational definition of an EID affects conclusions concerning the pathways by which diseases emerge and the ecological and socioeconomic drivers that elicit emergence. As EIDs appear to be increasing globally, and resources for science level off or decline , the research community is pushed to prioritize its focus on the most threatening diseases, riskiest potential pathogens, and the places they occur. The working definition of emerging infectious diseases and pathogens plays a crucial role in prioritization, but we argue that the current definitions may be impeding these efforts. We propose a new framework for classifying pathogens and diseases as " emerging " that distinguishes EIDs from emerging pathogens and novel potential pathogens. We suggest prioritization of: 1) EIDs for adaptation and mitigation, 2) emerging pathogens for preventive measures, and 3) novel potential pathogens for intensive surveillance.
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    • "Zoonotic infectious diseases represent a current threat for public health and biodiversity (Daszak et al., 2000; Jones et al., 2008), especially in the current context of agriculture intensification and biodiversity erosion (Jones et al., 2013). Despite representing 62% of emerging infections (Jones et al., 2008), understanding epidemiological patterns of these mostly multi-host diseases (Woolhouse and Gowtage-Sequeria, 2005) remains a great challenge for ecologist and public health authorities. One reason of our inability to improve our understanding is the quantification of the respective contribution of the two scales involved in pathogen transmission, namely exposure and receptivity (Combes, 2002). "
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    ABSTRACT: Infection is a complex biological process involving reciprocally both the intensity of host exposure to a pathogen as well as the host intrinsic "receptivity", or permissiveness to infection. Disentangling their respective contributions is currently seen as a fundamental gap in our knowledge. Here, we take the advantage of a rare semi-natural experiment context provided by the emergence of the West Nile virus (WNV) in North America.Focusing on the pathogen emergence period, we combine datasets from i) wild birds exposed to WNV in an urban zoo to evaluate the species intrinsic receptivity to WNV infection in an environment where exposure to WNV vectors can be assumed to be relatively homogenous for all captive species, and ii) from free-ranging birds in their natural habitat where species ecological traits is expected to influence their exposure to WNV vectors. We show that ecological trait and intrinsic receptivity to infection both contribute similarly to the species variation in WNV seroprevalence, but considering only one of them can lead to erroneous conclusions. We then argue that degree of pathogen host specialization could be a fundamental factor for the respective contribution of species exposure and receptivity for numerous pathogens. Copyright © 2015 Elsevier B.V. All rights reserved.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 04/2015; 33. DOI:10.1016/j.meegid.2015.04.011 · 3.02 Impact Factor
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    • "As climate and forest conditions grow more favorable to I. scapularis populations in MN, we can expect that risk of HA and babesiosis will rise in a fashion similar to that modeled for LD, and continuing the trend observed since 1996. In fact, other research has suggested more generally that warming climate may favor emergence of several TBD (Kurtenbach et al. 2006; Ogden et al. 2008; Woolhouse and Gowtage-Sequeria 2005). Predictive models come with important caveats. "
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    ABSTRACT: As humans and climate change alter the landscape, novel disease risk scenarios emerge. Understanding the complexities of pathogen emergence and subsequent spread as shaped by landscape heterogeneity is crucial to understanding disease emergence, pinpointing high-risk areas, and mitigating emerging disease threats in a dynamic environment. Tick-borne diseases present an important public health concern and incidence of many of these diseases are increasing in the United States. The complex epidemiology of tick-borne diseases includes strong ties with environmental factors that influence host availability, vector abundance, and pathogen transmission. Here, we used 16 years of case data from the Minnesota Department of Health to report spatial and temporal trends in Lyme disease (LD), human anaplasmosis, and babesiosis. We then used a spatial regression framework to evaluate the impact of landscape and climate factors on the spread of LD. Finally, we use the fitted model, and landscape and climate datasets projected under varying climate change scenarios, to predict future changes in tick-borne pathogen risk. Both forested habitat and temperature were important drivers of LD spread in Minnesota. Dramatic changes in future temperature regimes and forest communities predict rising risk of tick-borne disease.
    EcoHealth 10/2014; 12(1). DOI:10.1007/s10393-014-0979-y · 2.45 Impact Factor
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