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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. Effect of amphibian chytrid fungus (Batrachochytrium dendrobatidis) on apparent survival of frogs and toads in the western USA
Authors: Russell RE, Halstead BJ, Mosher BA, Muths E, Adams MJ, Grant EHC, Fisher RN, Kleeman PM, Backlin AR, Pearl CA, Honeycut RK, Hossack BR | Outlet: Biological Conservation
Despite increasing interest in determining the population-level effects of emerging infectious diseases on wildlife, estimating effects of disease on survival rates remains difficult. Even for a well-studied disease such as amphibian chytridiomycosis (caused by the fungus Batrachochytrium dendrobatidis [Bd]), there are few estimates of how survival of wild hosts is affected. We applied hierarchical models to long-term capture-mark-recapture data (mean = 10.6 yrs, range = 6?15 yrs) from >5500 uniquely-marked individuals to estimate the effect of Bd on apparent survival of four threatened or endangered ranid frog species (Rana draytonii, R. muscosa, R. pretiosa, R. sierrae) at 14 study sites in California and Oregon (USA) and one bufonid toad (Anaxyrus boreas) at two study sites in Wyoming and Montana. Our models indicated that the presence of Bd on an individual reduced apparent survival of ranid frogs by ~6?15% depending on species and sex. The estimated difference between toads with and without Bd was 19% for the Montana population and 55% for the Wyoming population; however, the 95% Credible Interval of these estimates included zero. These results provide evidence for negative effects of Bd on survival in wild populations even in the absence of obvious die-offs. Determining what factors influence the magnitude of the effects of Bd on wildlife populations is an important next step toward identifying management actions. These estimates of Bd effects are important for understanding the extent and severity of disease, whether disease effects have changed over time, and for informing management actions.

This is an ARMI Product. Identifying common decision problem elements for the management of emerging fungal diseases of wildlife
Authors: Bernard RF, Grant EHC | Outlet: Society and Natural Resources
Emerging infectious diseases (EIDs) of wildlife have characteristics that make them difficult to manage, leading to reactive and often ineffective management strategies. Currently, two fungal pathogens, Pseudogymnoascus destructans (Pd) and Batrachochytrium salamandrivorans (Bsal), are causing declines in novel host species. To improve the application of management strategies to address the risk of these pathogens to North American wildlife, we queried wildlife managers about their concerns regarding managing populations of bats and amphibians potentially impacted by Pd and Bsal. Using these responses, we identified aspects of each decision problem that were shared across pathogens, regions and agencies ? and found similarities in decision problem elements for disease management. Reframing management problems as decisions can enable managers to identify similarities across EIDs, i.e. uncertainties within management actions, and improve reactive responses if proactive management is not possible. Such an approach recognizes context-specific constraints and identifies relevant uncertainties that must be reduced in developing a response.

This is an ARMI Product. Salamander chytrid fungus risk assessment on Department of Defense Installations.
Authors: Petersen C, Richgels KLD, Lockhart G, Lovich R | Date: 2018-12-01 | Outlet: Department of Defense Legacy Resource Management Program | Format: .PDF
The United States Department of Defense Partners in Amphibian and Reptile Conservation (DoD PARC) network and the U.S. Geological Survey (USGS) National Wildlife Health Center developed this report to serve as an informational tool to assess which U.S. military installations may be at risk to Bsal introduction, improve the potential response to an outbreak, and help prioritize relevant actions on their respective installations if this fungal pathogen were to be introduced into the U.S. Since 2015, DoD PARC has been directly involved in identifying research, monitoring, and management strategies for Bsal (Grant et al. 2015). The military installations included in this assessment were those documented to have confirmed presence of salamander species as determined by a 2017 inventory of herpetofauna of military lands