For decades, a silent killer has slaughtered frogs and salamanders around the world by eating their skins alive. Now, a global team of 41 scientists has announced that the pathogen—which humans unwittingly spread around the world—has damaged global biodiversity more than any other disease ever recorded.

The new study, published in Science on Thursday, is the first comprehensive tally of the damage done by the chytrid fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). In all, the fungi have driven the declines of at least 501 amphibian species, or about one out of every 16 known to science.

Of the chytrid-stricken species, 90 have gone extinct or are presumed extinct in the wild. Another 124 species have declined in number