An apocalyptic fungus that chews through the flesh of frogs and toads is the "worst disease ever recorded."

The microbe kills unsuspecting victims by eating their skin and triggering heart attacks.

For the first time, scientists have worked out the "astounding" global impact of the fungus – and it's much worse than we thought.

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The disease it causes, Chytridiomycosis, has wiped out 90 species of amphibian – including frogs, toads and salamanders – in the past 50 years.

"The results are pretty astounding," lead scientist Dr. Benjamin Scheele, from the Australian National University, told the Guardian.

"We've known that chytrid is really bad for the better part of two decades but actually researching and quantifying those declines, that’s what this study does."

The team says the disease is picking off amphibians in Europe, Australia, Central and South America and Africa.

In total, 500 species are in sharp decline or extinct as a result of the chytrid fungus.

Having condemned more creatures to extinction than any other pathogen, chytrid is the most destructive disease on record.

It has "rewritten our understanding of what disease could do to wildlife," Dr. Scheele added.

The fungus is believed to have originated in Asia.

It spread across the globe in the 1980s through human activities such as the pet trade.

Once it has infected a victim, the fungus gets into the skin, causing it to harden and slough off.

As amphibians breath and drink through their skin, the animals then die of heart disease or dehydration.

Since its discovery 20 years ago, scientists have scrambled to tally just how many species chytrid has killed off.

The new findings rely on data from conservation charities, other studies and interviews with amphibian experts.

"There was a need to objectively estimate impact, which, unfortunately, turned out to be more severe than expected," Frank Pasmans, a scientist at Ghent University, told Earther.

Scientists said the story of chytrid shows just how damaging globalization and the wildlife trade can be.

The research was published in the journal Science.

This story originally appeared in The Sun.