But last year, wildlife officials found it in lowland leopard frogs (Rana yavapaiensis) outside the city of Phoenix, Arizona, and in boreal toads (Bufo boreas boreas) near Denver, Colorado.
Boreal toads in Colorado have been attacked not just by the chytrid, but also by a bacterium, Aeromonas hydrophila.
Erin Muths, began monitoring boreal toad populations within Rocky Mountain National Park.
In an effort to keep the boreal toad from going the way of so many others, the USGS has been working to understand all aspects of the fungus and its impact on the toads.
Once widespread and abundant throughout Rocky Mountain National Park, the boreal toad is now a rare sight.
With a tight grip around the female's chest, a male boreal toad fertilizes the thousands of eggs she produces.
Dedicated to understanding the factors associated with amphibian decline, the agency's scientists come to this site again and again to monitor one of the last remaining populations of boreal toads in Rocky Mountain National Park.
Data collected from park populations and other populations of boreal toads allow researchers to examine demographic characteristics such as survival and recruitment (the addition of new breeding adults into a population), and to look at patterns in movements and breeding events.
Even with the species on the verge of extirpation, there are still signs of hope for the boreal toads of Rocky Mountain National Park.
Braving the frigid temperatures, USGS researchers Erin Kenison and Leah Swartz spend many long nights looking for boreal toads in Rocky Mountain National Park.
Two pairs of boreal toads breed in the shallows of a high mountain lake in Rocky Mountain National Park.
Nearly camouflaged in the spruce, fir and pine understory, boreal toads are well adapted to live in the harsh elevations of Rocky Mountain National Park.
The chytrid skin fungus, which made headlines last year after killing off amphibians around the world, has now turned up in boreal toads from Clear Creek County, west of Denver.
At the Colorado study site, a monitoring team found dead and dying boreal toads in May, and Green's microscopic exam revealed chytrid infection.