Massive amphibian die-offs have not been documented in Asia. Perhaps Asian frogs that have long co-existed with Bd have evolved resistance, or perhaps Bd only evolved its deadliness to frogs after it left Asia. (Not all Bd strains are equally deadly.) Lips also notes, however, few amphibian surveys have been done in Asia.

The fungus causes a disease called chytridiomycosis that attacks the skin. You can tell a frog is infected, says Fisher, because “the skin around the joints becomes shredded and sloughs off.” If that isn’t bad enough, frogs also use their skin to breathe and regulate their water and electrolyte balance. In a bad case of chytridiomycosis, the skin simply stops working. The frog loses so many electrolytes that it suffers a heart attack.

Frog die-offs have knock-on effects for the ecosystem. In Panama, Lips has found, streams that once ran clear will turn green without tadpoles to feed on the algae. Once the amphibians that eat mosquitoes and flies are gone, insect-borne diseases could also spread more quickly among humans.

Joyce Longcore, a mycologist at the University of Maine, first identified and named Batrachochytrium dendrobatidis in 1999, after studying blue poison-dart frogs that died at the National Zoo in Washington, D.C. Longcore is a longtime expert on chytrid fungi. “Chytrid fungi have a particular gleam that, after working with, you tend to recognize,” she says, and she saw that gleam in the frog’s skin cells.

Based on how the DNA sequences diverged, O’Hanlon and Fisher found the deadly Bd strain did not emerge 26,000 years ago, as one previous study suggested, but less than 100 years ago. Its spread coincides with the rise of global trade. It is easy for small frogs to hide out in a shipping container. “They’re sticky little characters,” says O’Hanlon. “Bunches of bananas always have frogs in them. I know herpetologists who go to the London docks when they bring in green bananas.”

Global trade has been good for Bd, maybe even good for those invading frogs. But it has been disastrous for native frogs that encountered the deadly fungus for the first time.