The worst disease ever recorded!

Ed Yong writes in the Atlantic about

the worst disease ever recorded. A doomsday fungus known as Bd has condemned more species to extinction than any other pathogen.

A century ago, a strain of pandemic flu killed up to 100 million people—5 percent of the world’s population. In 2013, a new mystery illness swept the western coast of North America, causing starfish to disintegrate. In 2015, a big-nosed Asian antelope known as the saiga lost two-thirds of its population—some 200,000 individuals—to what now looks to be a bacterial infection. But none of these devastating infections comes close to the destructive power of Bd—a singularly apocalyptic fungus that’s unrivaled in its ability not only to kill animals, but to delete entire species from existence.

Bd—Batrachochytrium dendrobatidis in full—kills frogs and other amphibians by eating away at their skin and triggering fatal heart attacks. It’s often said that the fungus has caused the decline or extinction of 200 amphibian species, but that figure is almost two decades out-of-date. New figures, compiled by a team led by Ben Scheele from the Australian National University, are much worse.

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.

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