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 disease ecologist Daniel Grear 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.


National Wildlife Health Center - ARMI

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.

Disease - ARMI Papers & Reports

Papers & Reports Of toads and tolerance: Quantifying intraspecific variation in host resistance and tolerance to a lethal pathogen
Authors: Bennett Hardy; Erin Muths; W C Funk; Larissa L Bailey
Date: 2024-05-30 | Outlet: Journal of Animal Ecology
Due to the ubiquity of disease in natural systems, hosts have evolved strategies of disease resistance and tolerance to defend themselves from further harm once infected. Resistance strategies directly limit pathogen growth, typically leading to lower infection burdens in the host. A tolerance approach limits the fitness consequences caused by the pathogen but does not directly inhibit pathogen growth. Testing for intraspecific variation in wild host populations is important for informing conservation decisions about captive breeding, translocation, and disease treatment. Here, we test for the relative importance of tolerance and resistance in multiple populations of boreal toads (Anaxyrus boreas boreas) against Batrachochytrium dendrobatidis (Bd), the amphibian fungal pathogen responsible for the greatest host biodiversity loss due to disease. Boreal toads have severely declined in Colorado (CO) due to Bd, but toad populations challenged with Bd in western Wyoming (WY) appear to be less affected. We used a common garden infection experiment to expose post-metamorphic toads sourced from four populations (2 in CO and 2 in WY) to Bd and monitored changes in mass, pathogen burden, and survival for eight weeks. We used a multi-state modeling approach to estimate weekly survival and transition probabilities between infected and cleared states, reflecting a dynamic infection process that traditional approaches fail to capture. We found that WY boreal toads are highly tolerant to Bd infection with higher survival probabilities than those in CO when infected with identical pathogen burdens. WY toads also had higher probabilities of clearing infections and took an average of five days longer to reach peak infection burdens. Our results demonstrate strong intraspecific differences in tolerance and resistance that explain why population declines vary regionally across the species. We used a robust, multi-state framework to gain inference on typically hidden disease processes when testing for host tolerance or resistance and demonstrated that describing an entire species as ‘tolerant’ or ‘resistant’ is unwise without testing for intraspecific variation in host defenses.
Papers & Reports Preparing for a Bsal invasion into North America has improved multi-sector readiness
Authors: Deanna H Olson; Evan HC Grant; Molly Bletz; Jonah Piovia-Scott; Jacob L Kerby; Michael J Adams; Florencia M Breitman; Michelle R Christman; María J Forzán; Matthew J Gray; Aubree J Hill; M S Koo; David Lesbarrères; Olga Milenkaya; Eria A Rebollar; Louise A Rollins-Smith; Megan Serr; Alex Shepak; Lenny Shirose; L Sprague; Jenifer Walke; Alexa R Warwick; Brittany A Mosher
Western palearctic salamander susceptibility to the skin disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) was recognized in 2014, eliciting concerns for a potential novel wave of amphibian declines following the B. dendrobatidis (Bd) chytridiomycosis global pandemic. Although Bsal had not been detected in North America, initial experimental trials supported the heightened susceptibility of caudate amphibians to Bsal chytridiomycosis.
Data Release Student Network for Amphibian Pathogen Surveillance Data: U.S. Geological Survey data release
Authors: Megan E Winzeler; Daniel A Grear
Date: 2023-05-16 | Outlet: USGS Science Base
Data in this dataset were collected as a part of the Student Network for Amphibian Pathogen Surveilance (SNAPs) program throughout the United States by undergraduate students in biology or ecology courses as a part of their curriculum throughout 2022. This data was collected in the field by students and sent to the USGS National Wildlife Health Center (NWHC) for testing of two amphibian fungal pathogens, Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bs). The dataset includes both the field records of the individual amphibians tested and the results for individuals for Bd and Bsal
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