The fungus causing white-nose syndrome (WNS), which is devastating bat populations across northeastern Canada and the United States, continues to spread, according to a study from the Illinois Natural History Survey at the University of Illinois.

“After taking an in-depth look at the basic biology of a fungus that is decimating bat colonies as it spreads across the U.S., researchers report that they can find little that might stop the organism from spreading further and persisting indefinitely in bat caves,” a press release from the university stated.

According to the U.S. Fish and Wildlife Service, the fungus wiped out at least 5.7 million to 6.7 million bats in America and Canada from 2006 to 2013. The U.S. Geological Survey’s Wildlife Health Center estimates that the bat population in the Northeast has declined by 80 percent since the emergence of WNS.

The Fish and Wildlife Service explained the effects of the syndrome: “First documented in New York in 2006, the disease has spread quickly into 16 states and four Canadian provinces. Bats with WNS exhibit unusual behavior during cold winter months, including flying outside during the day and clustering near the entrances of caves and mines where they hibernate. Bats have been found sick and dying in unprecedented numbers near [hibernation areas].”

In addition, the service reported that mortality rates “reach up to 100 percent at many sites.”

Farmers rely on the flying mammals to pollinate crops and keep insect populations in check. According to a 2011 study by the Department of Ecology and Evolutionary Biology at the University of Tennessee, Knoxville, the value of bats on the North American agriculture industry is estimated to be $22.9 billion.

“All in all the news for hibernating bats in the U.S. is pretty grim,” Andrew Miller, who directed work on the Illinois Natural History Survey study, said in the University of Illinois press release.

The National Wildlife Health Center stated that even if WNS were eradicated—which is highly improbable—the bat population would take many years to normalize: “It is unlikely that species of bats affected by WNS will recover quickly because most are long-lived and have only a single pup per year.”

In contrast, Mr. Miller stated that the fungus “can live perfectly happily off the remains of most organisms that co-inhabit the caves with the bats,” which “means that whether the bats are there or not, it’s going to be in the caves for a very long time.”