A relentless disease that has killed nearly 7 million bats is now in Alabama, a cradle for millions of endangered gray bats.

The Alabama Department of Conservation and Natural Resources announced Wednesday that lab tests confirmed the presence of white-nose syndrome, found on bats in the Russell Cave complex in Jackson County.

The news dashed the hopes of some wildlife biologists who thought the cold-craving disease would never reach so far south.

Six years have passed since the disease, linked to an aggressive fungus called Geomyces destructans, was first detected at Howes Cave near Albany, N.Y. In Northeast states, the mortality rate for some species of bats has stood at about 100 percent. Officials are worried that the common little brown bat, the northern long-eared bat and the tricolored bat will not survive.

In January, the U.S. Fish and Wildlife Service released a report saying up to 6.7 million bats had been killed by white-nose syndrome in about 12 states and four Canadian provinces.

White-nose was detected in Alabama on March 2 and confirmed days later, officials said.

Alabama, Tennessee and Georgia have a vast network of caves and a wide variety of bats. State wildlife biologist Keith Hudson called Alabama the Grand Central Station for the endangered gray bat.

“The largest winter cave is here. The largest summer cave is here,” said Hudson, who studies bats for the Division of Wildlife and Freshwater Fisheries. “If white-nose syndrome impacts gray bats as it has done other cave-dwelling bats, it will devastate the species.”

“Alabama marks the southernmost confirmation of the disease to date,” said Ann Froschauer, a national spokeswoman for Fish and Wildlife’s efforts to stop white-nose. “We had it in North Carolina and Tennessee prior to this. The response community has been sort of hoping the disease wasn’t going to progress the same way into the southeast and western direction.”

Gray bats gather in huge concentrations, up to a million in a cave, Froschauer said. Unlike most bats, they remain in caves through the year.

Building development and other human activity greatly reduced their numbers, but recently the gray bat has made a comeback, Froschauer said. There was some talk of removing the bat from the endangered species list.

“If you can imagine the disease getting into a site with a half-million or a million bats, that would really be devastating,” Froschauer said. “The impact on our agricultural area . . . may be . . . exponential . . . down the road, in terms of the economic services that these bats provide.”

Bats are a top nocturnal predator, eating night-flying insects that feed on agricultural crops. A pregnant female consumes her weight in bugs each night. A single colony of 150 brown bats can eat enough adult cucumber beetles to prevent the laying of eggs that would result in 33 million rootworm larvae, according to a study cited by Bat Conservation International.

Bats probably save the U.S. agricultural industry at least $3 billion each year, or approximately $74 per acre for the average farmer, according to studies.

No bats in Alabama have been found dead from the disease, but that outcome is feared. “We are very concerned about white-nose syndrome and its impact on Alabama bats,” Hudson said. “We will do everything practical to manage this, with the understanding that not a whole lot can be done.”

Hudson said that although other biologists are surprised to see the disease in Alabama, he’s not. “I think all of us thought it was just a matter of time before it got here,” he said.