Article

Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome

Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada R3B 2E9.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 04/2012; 109(18):6999-7003. DOI: 10.1073/pnas.1200374109
Source: PubMed

ABSTRACT

White-nose syndrome (WNS) is an emerging disease of hibernating bats associated with cutaneous infection by the fungus Geomyces destructans (Gd), and responsible for devastating declines of bat populations in eastern North America. Affected bats appear emaciated and one hypothesis is that they spend too much time out of torpor during hibernation, depleting vital fat reserves required to survive the winter. The fungus has also been found at low levels on bats throughout Europe but without mass mortality. This finding suggests that Gd is either native to both continents but has been rendered more pathogenic in North America by mutation or environmental change, or that it recently arrived in North America as an invader from Europe. Thus, a causal link between Gd and mortality has not been established and the reason for its high pathogenicity in North America is unknown. Here we show that experimental inoculation with either North American or European isolates of Gd causes WNS and mortality in the North American bat, Myotis lucifugus. In contrast to control bats, individuals inoculated with either isolate of Gd developed cutaneous infections diagnostic of WNS, exhibited a progressive increase in the frequency of arousals from torpor during hibernation, and were emaciated after 3-4 mo. Our results demonstrate that altered torpor-arousal cycles underlie mortality from WNS and provide direct evidence that Gd is a novel pathogen to North America from Europe.

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    • "This ongoing epizootic has killed millions of bats and is affecting six or more species (Turner et al. 2011;Appendix S8); important populations are in serious decline due to WNS (Frick et al. 2010a, Thogmartin et al. 2013). WNS is caused by the cold-growing fungus Pseudogymnoascus destructans, which severely infects the skin tissues of hibernating bats and catastrophically disrupts hibernation and physiology during winter (e.g.Lorch et al. 2011, Warnecke et al. 2012). The fungus also infects bats in Europe, where it is not known to cause MMEs (Puechmaille et al. 2011). "
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    ABSTRACT: Despite conservation concerns for many species of bats, factors causing mortality in bats have not been reviewed since 1970. Here, we review and qualitatively describe trends in the occurrence and apparent causes of multiple mortality events (MMEs) in bats around the world. We compiled a database of MMEs, defined as cases in which ≥ 10 dead bats were counted or estimated at a specific location within a maximum timescale of a year, and more typically within a few days or a season. We tabulated 1180 MMEs within nine categories. Prior to 2000, intentional killing by humans caused the greatest proportion of MMEs in bats. In North America and Europe, people typically killed bats because they were perceived as nuisances. Intentional killing occurred in South America for vampire bat control, in Asia and Australia for fruit depredation control, and in Africa and Asia for human food. Biotic factors, accidents, and natural abiotic factors were also important historically. Chemical contaminants were confirmed causes of MMEs in North America, Europe, and in islands. Viral and bacterial diseases ranked low as causes of MMEs in bats. Two factors led to a major shift in causes of MMEs in bats at around 2000: the global increase of industrial wind-power facilities and the outbreak of white-nose syndrome in North America. Collisions with wind turbines and white-nose syndrome are now the leading causes of reported MMEs in bats. Collectively, over half of all reported MMEs were of anthropogenic origin. The documented occurrence of MMEs in bats due to abiotic factors such as intense storms, flooding, heat waves, and drought is likely to increase in the future with climate change. Coupled with the chronic threats of roosting and foraging habitat loss, increasing mortality through MMEs is unlikely to be compensated for, given the need for high survival in the dynamics of bat populations.
    Full-text · Article · Feb 2016 · Mammal Review
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    • "Further studies of the role of IRIS in the ecology of WNS are essential for understanding the potential for populations to recover from WNS. A down-regulated immune response in hibernating bats generally, combined with increased arousal frequency (Boyles and Willis 2010; Reeder et al. 2012; Warnecke et al. 2012) and possibly increased metabolic rate and body temperature during torpor following infection (Storm and Boyles 2011; Verant et al. 2014), appears to result in premature fat depletion and starvation. However, why fungal infection would increase arousal frequency is still not fully understood. "
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    ABSTRACT: White-nose syndrome (WNS) is an infectious disease of hibernating bats that has killed millions of bats since it first emerged in eastern North America in 2006. The disease is caused by a pathogenic fungus, Pseudogymnoascus (formerly Geomyces) destructans that was likely introduced to North America by human trade or travel, demonstrating the serious problem of global movement of pathogens by humans in the Anthropocene. Here, we present a synthesis of the current state of knowledge on WNS, including disease mechanisms, disease ecology, global distribution and conservation and management efforts. There has been rapid research response to WNS and much about the disease is now well understood. However, critical gaps in our knowledge remain, including ways to limit spread, or effective treatment options to reduce disease mortality. There are several hibernating bat species in North America that are threatened with extinction from WNS. Protecting those species has become a race against time to find and implement creative solutions to combat the devastating impacts of this disease.
    Full-text · Chapter · Jan 2016
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    • "Hypotheses for this include behavioral or physiological adaptations in European bats, or environmental differences between Europe and North America (Wibbelt et al., 2010). European strains of Pd are lethal to North American bats, demonstrating that the presence of different strains of Pd does not explain the lack of bat mortality in Europe (Warnecke et al., 2012). Whether Pd interacts with fungi and bacteria naturally occurring on bats, or whether the microbiome on bats or in hibernacula differs between North America and Europe, is unknown. "
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    ABSTRACT: http://scholarcommons.usf.edu/ijs/vol45/iss1/5/
    Full-text · Article · Jan 2016 · International Journal of Speleology
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