A deadly and infectious fungal disease first struck Mexican salamanders in the 1970s, found a new study. From there, it spread through Guatemala and Costa Rica over the next two decades.

As the first study among salamanders to document the history of an epidemic of the sickness, the research helps verify the fungus (known as Bd, for Batrachyochytrium dendrobatidis) as a major cause of widespread amphibian collapse in current decades. Some 40 percent of frogs, toads and other amphibian species are presently in decline.

The findings could also lead to enhanced ways of slowing or preventing the spread of Bd and similar outbreaks in the years to come.

"This really shows how devastating this disease can be," said lead author Tina Cheng, a graduating master’s student in ecology at San Francisco State University. "Up until now, it was not known that this pathogen had any bang on salamanders, and many are highly threatened right now."

Animals that become tainted with the fungus develop chytridiomycosis. They shed their skin and become lethargic. Sickened salamanders lose their tails. Frogs lose weight and become so insensitive that they fail to turn themselves over when put on their backs. Death comes in a matter of weeks.

Since the discovery of Bd, researchers have associated the fungus to the collapse of frog and toad populations in California, Australia, Panama and Peru. Some species have already gone extinct because of it.