How did global trade help spread amphibian chytridiomycosis among frogs?

Global trade facilitated the spread of amphibian chytridiomycosis by acting as a primary vector for the movement of the causative fungus, Batrachochytrium dendrobatidis (Bd), across international borders.1

While the fungus likely originated in the Korean peninsula between 1898 and 1962, it was transported to other parts of the world through global food and pet trading networks. These commercial activities involve the long-distance movement of live amphibians, which can carry the pathogen into new environments. Once introduced, the fungus spreads rapidly among local populations via free-swimming infectious cells known as zoospores, leading to severe population declines and, in many cases, extinction.12

The reliance on global trade for the movement of exotic species is a significant driver of such pandemic diseases, as it bypasses natural geographic barriers that would otherwise contain the pathogen.12