Amphibians are the most threatened vertebrates on Earth, with 41% of species facing extinction. In the highlands of Central and South America, a killer fungus has wiped out much of the once abundant amphibian diversity. Yet in the Sierra Nevada de Santa Marta, an isolated mountain range in northern Colombia, amphibians still thrive. The mountain range is home to a remarkable amphibian community of at least 48 species, including 25 found nowhere else on the planet. New research led by Ghent University and Trier University shows that the threat is dangerously close.

After screening more than 2,000 frogs, toads and salamanders, researchers found no evidence of the deadly fungus in the region. Yet only around 20 kilometres away, they detected a highly virulent variant of the disease.

Warm and dry lowlands probably act as a natural barrier that has kept the fungus out so far. But the study shows that some of the region's unique amphibian species are highly vulnerable to infection. Arrival of the fungus is thus expected to lead to massive loss of amphibian communities as witnessed elsewhere.

The findings offer a rare opportunity to protect an intact amphibian community before a devastating disease outbreak occurs. Researchers warn that contaminated equipment, materials or transported amphibians could carry the fungus past the natural barrier.

Preventing introduction must therefore be a conservation priority. The authors call for strict biosecurity, continued disease surveillance and urgent protection of particularly vulnerable species.