On Thursday, 41 scientists published the first worldwide analysis of a fungal outbreak that’s been wiping out frogs for decades. …The researchers conclude that populations of more than 500 species of amphibians have declined significantly because of the outbreak — including at least 90 species presumed to have gone extinct. …The losses were puzzling, because the frogs were living in pristine habitats, unharmed by pollution or deforestation. In the late 1990s, researchers discovered Batrachochytrium dendrobatidis — Bd. …The fungus turned up in other countries — probably via the international trade in pet amphibians. …Certain factors once thought to account for the decimation of frog populations — like climate change and deforestation — are not the greatest threats, the scientists found.  …Today, 39 percent of the species that suffered population declines are still declining. Twelve percent are showing signs of recovery.