Increased Host Species Diversity and Decreased Prevalence of Sin Nombre Virus

Portland State University, Portland, Oregon 97207-0751, USA.
Emerging Infectious Diseases (Impact Factor: 6.75). 08/2009; 15(7):1012-8. DOI: 10.3201/eid1507.081083
Source: PubMed


Emerging outbreaks of zoonotic diseases are affecting humans at an alarming rate. Until the ecological factors associated with zoonoses are better understood, disease emergence will continue. For Lyme disease, disease suppression has been demonstrated by a dilution effect, whereby increasing species diversity decreases disease prevalence in host populations. To test the dilution effect in another disease, we examined 17 ecological variables associated with prevalence of the directly transmitted Sin Nombre virus (genus Hantavirus, etiologic agent of hantavirus pulmonary syndrome) in its wildlife host, the deer mouse (Peromyscus maniculatus). Only species diversity was statistically linked to infection prevalence: as species diversity decreased, infection prevalence increased. The increase was moderate, but prevalence increased exponentially at low levels of diversity, a phenomenon described as zoonotic release. The results suggest that species diversity affects disease emergence.

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Available from: Luis A. Ruedas, Jan 10, 2014
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    • "A concurrent extension of this research has investigated the diversity of system components beyond the host community, including predators, competitors and coinfecting symbionts. Reductions in predator diversity have been correlated with increased prevalence of Sin Nombre hantavirus in deer mice (Peromyscus maniculatus) (Dizney & Ruedas 2009; Orrock et al. 2011) and higher infectious disease levels in coral reefs (Raymundo et al. 2009; see also Rohr et al. 2015). The experimental exclusion of large herbivores in East African savanna ecosystems led to a doubling in the density of their competitors, rodents and their associated fleas (McCauley et al. 2008; Keesing & Young 2014; Young et al. 2014; but see Borer et al. 2009). "
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    ABSTRACT: Global losses of biodiversity have galvanised efforts to understand how changes to communities affect ecological processes, including transmission of infectious pathogens. Here, we review recent research on diversity-disease relationships and identify future priorities. Growing evidence from experimental, observational and modelling studies indicates that biodiversity changes alter infection for a range of pathogens and through diverse mechanisms. Drawing upon lessons from the community ecology of free-living organisms, we illustrate how recent advances from biodiversity research generally can provide necessary theoretical foundations, inform experimental designs, and guide future research at the interface between infectious disease risk and changing ecological communities. Dilution effects are expected when ecological communities are nested and interactions between the pathogen and the most competent host group(s) persist or increase as biodiversity declines. To move beyond polarising debates about the generality of diversity effects and develop a predictive framework, we emphasise the need to identify how the effects of diversity vary with temporal and spatial scale, to explore how realistic patterns of community assembly affect transmission, and to use experimental studies to consider mechanisms beyond simple changes in host richness, including shifts in trophic structure, functional diversity and symbiont composition. © 2015 John Wiley & Sons Ltd/CNRS.
    Ecology Letters 08/2015; 18(10). DOI:10.1111/ele.12479 · 10.69 Impact Factor
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    • "). For rodents, the impact of host community structure has been investigated for Lyme disease (Kilpatrick & Kramer 2006; Keesing et al. 2006, 2009), hantaviruses (Tersago et al. 2008; Clay et al. 2009a; Dizney & Ruedas 2009; Blasdell et al. 2011), anaplasmosis (a tick-borne disease for which the agent is the bacteria Anaplasma phagocytophilum) and bartonellosis (another arthropod-borne disease for which the agents are bacteria of the genus Bartonella) (Bai et al. 2009; Foley et al. 2009). For all these studies, the key concept was the " dilution effect " hypothesis (Schmidt & Ostfeld 2001). "
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    ABSTRACT: Rodents are recognized reservoir hosts for many human zoonotic pathogens. The current trends resulting from anthropocene defaunation suggest that in the future they, along with other small mammals, are likely to become the dominant mammals in almost all of human-modified environments. Recent intricate studies on bat-borne emerging diseases have highlighted that many gaps exist in our understanding of the zoonotic transmission of rodent-borne pathogens. This has emphasized the need for scientists interested in rodent-borne diseases to integrate rodent ecology into their analysis of rodent-borne pathogen transmission in order to identify in more detail, the mechanisms of spillover and chains of transmission. Further studies are required to better understand the true impact of rodent abundance and the importance of pathogen sharing and circulation in multi-host - multi-pathogen communities. We also need to explore in more depth the roles of generalist and abundant species as the potential links between pathogen-sharing, co-infections and disease transmission. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Integrative Zoology 07/2015; DOI:10.1111/1749-4877.12149 · 1.90 Impact Factor
    • "The dilution effect appears to be a common phenomenon in other hantavirus–host systems . At least 7 other studies have documented greater hantavirus prevalence in rodent communities with reduced diversity (Suzán et al. 2008; Tersago et al. 2008; Dizney and Ruedas 2009; Suzán et al. 2009; Carver et al. 2011; Voutilainen et al. 2012). Three of these studies examined SNV dynamics in the United States, 2 examined Chaclo and Calabazo hantaviruses in Panama, and 2 investigated Puumala virus in Europe. "
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    ABSTRACT: The complexity of a community can play a fundamental role in the prevalence of pathogens by altering interactions among hosts and pathogen transmission. Information on the frequency of contacts between individuals and the distribution of contact rates in a population is critical to predicting pathogen prevalence. However, contact rates are notoriously difficult to document especially in small, nocturnal species. We have been documenting the contact rates of deer mice (Peromyscus maniculatus) in nature with respect to infection with Sin Nombre virus (SNV), a zoonotic pathogen, and the biodiversity of the mammalian community. Our long-term field studies, as well as those of others, revealed that prevalence of SNV in deer mice is related to the complexity of the mammalian community such that pathogen prevalence is lower in more diverse communities. Using a combination of techniques, we found evidence that contact rates between deer mice differ with respect to biodiversity. Deer mice in more complex communities had fewer intraspecific interactions than those in less diverse communities. Contact rates of individual deer mice were highly variable with a minority of the deer mice accounting for a majority of the interactions. Infection with SNV was related to risk-taking behavior; animals categorized as “bold” were 3 times more likely to be infected than “shy” deer mice. Results of these studies have implications for pathogen management in wildlife and humans.
    Journal of Mammalogy 02/2015; 96(1):29-36. DOI:10.1093/jmammal/gyu025 · 1.84 Impact Factor
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