A rapidly spreading fungus is threatening frogs everywhere, causing mass amphibian die-offs, according to a new study.

The study published online Friday in the peer-reviewed journal Science calls the loss from chytridiomycosis "catastrophic," saying the disease has "caused death and species extinction at a global scale." At least 501 amphibian species have died over the past 50 years, including 90 that are presumed extinct, the study says.

Chytridiomycosis is caused by two fungal species that likely originated in Asia, Batrachochytrium dendrobatidis (discovered in 1998) and B. salamandrivorans (discovered in 2013). When contracted, the disease can eat away at skin. It's been known to kill frogs for decades now, but recently its spread has caused global alarm.

Study authors say the outbreak is contributing to "the Earth's sixth mass extinction." Deaths have been most extreme in wet climates of the Americas and Australia, peaking in the 1980s. Just 12 percent of the declined species are showing signs of recovery, the study notes, as 39 percent continue to decline.

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Wendy Palen, a biologist at Simon Fraser University who is a co-author of a commentary accompanying the study, called the fungus associated with the disease "the most deadly pathogen known to science," The New York Times reports.

Researchers are calling for new research and monitoring to stop the spread of the pathogen, and save at-risk species.

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