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Disease


Cave Bd sampling
Left to Right: Tabby Cavendish (Great Smoky Mountains NP), Brian Gregory (USGS), and Jamie Barichivich (ARMI) swabbing salamanders for Batrachochytrium dendrobatidis (Bd) in Rockhouse Cave, Wheeler NWR, Alabama. Photo by: Alan Cressler.

ARMI conducts original research on various amphibian diseases in the lab and field. Our research has included estimating the impacts of diseases on the growth of populations, developing and testing potential treatments, affects of stressors on susceptibility to disease, how diseases are transmitted in the wild, and how to model disease distributions and spread.

ARMI disease research is conducted throughout the country, but ARMI pathologist Dr. David Green is based at the National Wildlife Health Center in Madison, Wisconsin, and coordinates the health screenings and investigations of amphibian mortalities (e.g., identification, pathology) in addition to collaborating on many disease research projects.

Amphibians at our long-term monitoring sites are periodically screened for diseases and we investigate mass mortality events.

Resources

National Wildlife Health Center - ARMI

ARMI Products on Disease

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This is an ARMI Product. Pre-publication communication of research results
Authors: Adams MJ, Harris RN, Grant EHC, Gray MJ, Hopkins MC, Iverson SA, Likens R, Mandica M, Olson DH, Shepack A, Waddle H | Date: 2018-08-11 | Outlet: EcoHealth | Format: .PDF
Until publication, communication of provisional scientific findings beyond participants in the study is typically limited. This practice helps assure scientific integrity. However, a dilemma arises when a provisional finding has urgent societal consequences that may be exacerbated by delay. This dilemma may be particularly pronounced when a discovery concerns wildlife health, which could have implications for conservation, public health, or domestic animal health. Eleven researchers suggest that common concerns about directed prepublication communication largely stem from misperceptions and that none should cause a delay in the communication of time-sensitive provisional findings to appropriate authorities. Instead, they suggest that rapid communication of a provisional discovery could be beneficial, such as in the example they use involving the potential discovery of the amphibian fungal pathogen Bsal that is currently causing salamander die-offs in Europe.

B. Hossack  
This is an ARMI Product. Beyond the swab: ecosystem sampling to understand the persistence of an amphibian pathogen
Authors: Mosher BA, Huyvaert KP, Bailey LL | Date: 2018 | Outlet: Oecologia, | Format: .PDF
Understanding the ecosystem-level persistence of pathogens is essential for predicting
and measuring host-pathogen dynamics. However, this process is often masked, in
part due to a reliance on host-based pathogen detection methods. The amphibian
pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are
pathogens of global conservation concern. Despite having free-living life stages, little is
known about the distribution and persistence of these pathogens outside of their
amphibian hosts. We combine historic amphibian monitoring data with contemporary
host- and environment-based pathogen detection data to obtain estimates of Bd
occurrence independent of amphibian host distributions. We also evaluate differences
in filter- and swab-based detection probability and assess inferential differences arising
from using different decision criteria used to classify samples as positive or negative.
Water filtration-based detection probabilities were lower than those from swabs but
were >10%, and swab-based detection probabilities varied seasonally, declining in the
early fall. The decision criterion used to classify samples as positive or negative was
important; using a more liberal criterion yielded higher estimates of Bd occurrence than
when a conservative criterion was used. Different covariates were important when
using the liberal or conservative criterion in modeling Bd detection. We found evidence
of long-term Bd persistence for several years after an amphibian host species of
conservation concern, the boreal toad (Anaxyrus boreas boreas), was last detected.
Our work provides evidence of long-term Bd persistence in the ecosystem and
underscores the importance of environmental samples for understanding and
mitigating disease-related threats to amphibian biodiversity.

 
This is an ARMI Product. Host pathogen metapopulation dynamics suggest high elevation refugia for boreal toads
Authors: Mosher BA, Bailey LL, Muths E, Huyvaert KP | Date: 2018 | Outlet: Ecological Applications | Format: .PDF
Emerging infectious diseases are an increasingly common threat to wildlife. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease that has been linked to amphibian declines around the world. Few studies exist that explore amphibian-Bd dynamics at the landscape scale, limiting our ability to identify which factors are associated with variation in population susceptibility and to develop effective in situ disease management. Declines of boreal toads (Anaxyrus boreas boreas) in the Southern Rocky Mountains are largely attributed to chytridiomycosis but variation exists in local extinction of boreal toads across this metapopulation. Using a large-scale historic dataset, we explored several potential factors influencing disease dynamics in the boreal toad-Bd system: geographic isolation of populations, amphibian community richness, elevational differences, and habitat permanence. We found evidence that boreal toad extinction risk was lowest at high elevations where temperatures may be sub-optimal for Bd growth and where small boreal toad populations may be below the threshold needed for efficient pathogen transmission. In addition, boreal toads were more likely to recolonize high elevation sites after local extinction, again suggesting that high elevations may provide refuge from disease for boreal toads. We illustrate a modeling framework that will be useful to natural resource managers striving to make decisions in amphibian-Bd systems.


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