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Deadly bat fungus has been found in Texas for the first time

It’s spreading westward

Most of the little brown bats in this hibernation cave in New York have the white fungus on their muzzles. 
Photo by Nancy Heaslip, NY Dept. of Environmental Conservation

For the first time, the fungus causing the deadly white-nose syndrome (WNS) in bats has been found in Texas. The fungus, called Pseudogymnoascus destructans, or PD, was also detected for the first time on two species of bats. That means PD is spreading westward and to more species, putting large populations of bats at risk in the US and possibly in Central America.

“We remain, I guess, on the edges of our seats to know exactly what’s going to happen as PD enters the ranges of those additional species,” Jeremy Coleman, national white-nose syndrome coordinator for the US Fish and Wildlife Service, said during a press call today.

The white fungus thrives in cold, humid environments, where it infects skin of the muzzle, ears, and wings of hibernating bats. A couple years after infection, bats sometimes develop what’s called white-nose syndrome. PD often causes the animals to act strange: they fly outside in the day and cluster near the entrances of caves and mines. This causes the bat to burn out precious calories and fat reserves needed to survive the long winter months without any food, contributing to their death. In some sites, 90 to 100 percent of infected bats have died.

A little brown bat found in a New York cave exhibits fungal growth on its muzzle, ears, and wings.
Photo by Al Hicks, NY Dept. of Environmental Conservation

The fungus was first discovered in New York 10 years ago, but it’s now spread to 33 states and five Canadian provinces — killing more than 6 million bats. That’s bad not only because bats are incredibly cute, but because they’re key for ecosystems. Bats eat a lot of insects, including some damaging pests like the corn earworm moth, which attacks sweet potatoes, spinach, squash, and watermelon. They also pollinate plants and disperse seeds. Their ecosystem services to US agriculture are valued between $4 billion to $50 billion a year.

Despite a national effort to contain the fungus, PD has been spreading west. In 2014, it was found in Arkansas, in 2015 in Oklahoma, and in 2016 in Washington state. Today’s announcement shows that the deadly fungus is now present in six counties in North Texas on three bat species: the tri-colored bat, cave myotis, and Townsend’s big-eared bat. None of the bats have developed WNS yet, and there’s hope some of them won’t. Twenty of the 32 species of bats in Texas do not regularly hibernate, and WNS only harms hibernating bats.

This is the first time the fungus was detected on cave myotis and Townsend’s big-eared bats — and both bats have an extensive western distribution. The cave myotis is found as far south as Honduras, Coleman said. That’s concerning because bats of different species often share caves, so they have the potential to infect one other.

“We do have concerns about the continuous bat-to-bat spread of the fungus now throughout the West, even down to Mexico and South America,” Coleman said.

A map showing the counties where PD was detected, and other surveyed counties where it was not.
Image: Texas Parks and Wildlife Department

It’s unclear exactly how the fungus arrived from either Europe or Asia; it’s found in both places, but doesn’t cause the mass death of bats there, Coleman said. It’s possible that it was brought over by foreign cave visitors: the fungus latches onto shoes, clothes, and backpacks so it’s easy to carry around. That’s why officials are encouraging private cave owners to limit the number of people who visit their caves, so that the fungus is not spread around further. There are also decontamination protocols that should be followed to limit PD’s spread, Jonah Evans, Texas Parks and Wildlife Department state mammalogist, said during the press call.

Despite today’s gloomy news, we’ve come a long way to understanding PD and the deadly white-nose syndrome. And wildlife disease experts are actively working on several treatments to help improve the bats’ survival. Swabbing bats and cave walls around the country to detect the fungus early on — before the disease occurs — like it was done in Texas, is also a way to effectively manage and control PD. Hopefully, a solution will be found before it’s too late.