Until recently no one knew why the fire salamander population in the Netherlands was plummeting.

According to a new study, a deadly skin-eating fungus has proved to be the cause of why the number dropped to a staggering 10 salamanders – less than four percent of the species original population.

The study, published in the Proceedings of the National Academy of Sciences, tracked the species decline and subsequent treatment program to save the salamanders.

Researchers identified a new species of fungus that was killing the salamanders: Batrachochytrium salamandrivorans, the second word meaning “salamander-eating.” The fungus, which may live in water or soil, could also be a parasite that causes a lethal disease.

A related fungus, Batrachochytrium dendrobatidis (Bd) that invades the top layers of skin cells and causes thickening of the keratinized layer -- has already threatened over 200 species of reptiles.

Scientists discovered the skin-eating fungus after they brought 39 fire salamanders into captivity and started to breed them, but half of them died – only 10 remain.

“In several regions, including northern Europe, amphibians appeared to be able to co-exist with Bd,” study author An Martel from the University of Ghent in Belgium said in a statement. “It is therefore extremely worrying that a new fungus has emerged that causes mass mortalities in regions where amphibian populations were previously healthy.”

The fungus can be spread through direct contact and possibly indirect contact which has yet to be proven. The disease invades the salamander’s skin and destroys it completely.

“It is a complete mystery why we are seeing this outbreak now, and one explanation is that the new salamander-killing fungus has invaded the Netherlands from elsewhere in the world,” study coauthor Professor Matthew Fisher, from Imperial College London said.

The team, which created a diagnostic tool, says they tested 100 salamanders in Belgium – none of which show signs of the deadly fungus.

“Our experience with Bd has shown that fungal diseases can spread between amphibian populations across the world very quickly. We need to act urgently to determine what populations are in danger and how best to protect them,” Fisher said.