An American bullfrog

American bullfrogs (Rana catesbeiana) and other amphibians are prone to infection with a fungus that arose in the early twentieth century. Credit: Dirk Schmeller

Genetics

DNA points to a frog-killer’s birthplace

Pathogen first appeared when the amphibian trade began to boom.

A lethal fungus that is wiping out amphibians around the world hails from the southernmost tip of Korea.

First identified in the 1990s, the chytrid fungus (Batrachochytrium dendrobatidis) has spread rapidly to nearly every continent as a result of the global trade in frogs and other amphibians. But the fungus’s geographic origin and the timing of its spread have remained unclear.

To address these questions, Simon O’Hanlon and Matthew Fisher of Imperial College London and their colleagues analysed DNA sequences in 234 fungal samples from around the world to build the most complete evolutionary tree of B. dendrobatidis yet. This allowed the researchers to trace the fungus’s origin to the Korean peninsula in the early twentieth century — a period when global trade of amphibians for exotic pets or food also took off.

Knowledge of the pathogen’s origins could help to prevent future outbreaks, the scientists say.