White-Nose Bat Deaths: Fungus Behind Mysterious Deaths In U.

LOS ANGELES, Calif. - The mysterious deaths of millions of bats in Canada and the United States over the past several years were caused by a fungus that hitchhiked from Europe, scientists reported Monday.

Experts had suspected that an invasive species was to blame for the die-off from "white nose syndrome." Now there's direct evidence the culprit was not native to North America.

The fungal illness has not caused widespread deaths among European bats unlike in the U.S. and Canada. In North America more than 5.7 million bats have died since 2006 when white nose syndrome was first detected in a cave in upstate New York. The disease does not pose a threat to humans, but people can carry fungal spores.

It's unclear exactly how the fungus crossed the Atlantic, but one possibility is that it was accidentally introduced by tourists. Spores are known to stick to people's clothes, boots and caving gear. Read More