Madagascar is home to a mind-boggling array of frogs, 99 percent of which are found nowhere else in the world. But a study released Thursday finds the island nation now also hosts the greatest threat to amphibian biodiversity in modern times—the chytrid fungus.

As many as 7 percent of the world's amphibian species live only in Madagascar, says Molly Bletz, a researcher at the Braunschweig University of Technology in Germany. Chytrid is responsible for the decline or extinction of hundreds of amphibian species around the world. One forest in Panama lost 30 amphibian species to the fungus in about a year, according to a 2010 study.

Why It Matters

Researchers had thought Madagascar was chytrid-free. A 2014 study found chytrid on Madagascar frogs shipped to the U.S. for the pet trade, but researchers weren't sure whether the animals were contaminated en route or infected in Madagascar. (See "African Clawed Frog Spreads Deadly Amphibian Fungus.")

But a new study in the journal Scientific Reports finds that chytrid is present in multiple Madagascar frog species. Bletz and colleagues examined skin swabs and tissue samples from 4,155 amphibians tested for chytrid from 2005 to 2014. They found, to their surprise, that the fungus began to appear on frogs starting in 2010.

View Images Mantidactylus pauliani is another Malagasy frog found near the Ankaratra Massif, an area with evidence of the chytrid fungus. Photograph by Franco Andreone

What they haven't found yet is sick frogs. "It could mean we just caught it very early," Bletz says, or it's possible the chytrid strain in Madagascar isn't very lethal.

The Big Picture

"It's the best worst-case scenario," says Jonathan Kolby, a researcher at Queensland's James Cook University, who was not involved in the study. "[Chytrid] is there, but the frogs aren't dying right now."

Scientists need to figure out where the chytrid came from, though, he says. If it was introduced, scientists need to know how it got into the country and how they can prevent another introduction. "Because next time, it could be a strain that's supervirulent," says Kolby, a National Geographic grantee. (See "Killer Fungus Threatens Salamanders.")

What's Next

Meanwhile, experts are working on a multipronged response to the threat. Bletz is working on a possible preventive treatment using frog skin bacteria that may fight off the fungal invader. Other groups around the world—such as in Panama—are setting up breeding facilities for especially vulnerable amphibians just in case, while others in places including Madagascar and Panama are working on long-term amphibian monitoring efforts.