The worst disease ever recorded

Scheele’s team estimates that the fungus has caused the decline of 501 amphibian species—about 6.5 percent of the known total. Of these, 90 have been wiped out entirely. Another 124 have fallen by more than 90 percent, and their odds of recovery are slim. Never in recorded history has a single disease burned down so much of the tree of life. “It rewrote our understanding of what disease could do to wildlife,” Scheele says.

“It’s a terrifying summary,” says Jodi Rowley from the Australian Museum. “We knew it was bad, but this really confirms how bad. And these are just the declines we know about.”

The scale of these losses can be hard to appreciate, especially if you think that a frog is a frog is a frog. But amphibians are ancient survivors that have been diversifying for 370 million years, and in just five decades, one disease has nearly decimated their ranks. Imagine if a new disease started wiping out 6.5 percent of all mammal species—that would be roughly everything with hooves and everything with flippers. The world would freak out.