CLARKSVILLE, Tenn. -- Three states are reporting an outbreak of a deadly virus among native deer.

Video: Drought-Aided Disease Killing Deer

"There is a widespread outbreak of epizootic hemorrhagic disease this year that is affecting white-tailed deer in Kentucky, Tennessee and Indiana," said Lucky Pittman, head of pathology at the Murray State University Breathitt Veterinary Center in Hopkinsville, Ky. "Outbreaks of the disease occur every two to three years, but this year is especially severe because of the heat and drought conditions."

With water harder to find, more deer are congregating at the same watering spots and contributing to the spread of the disease, experts said.

In Montgomery County, about 50 miles northwest of Nashville, the deaths of more than 30 deer have been reported to wildlife agents.

"There are probably many more that have not been reported," said Montgomery County Wildlife Officer Jereme Odom.

Hemorrhagic disease is a viral ailment spread by biting flies, according to the Southeast Cooperative Wildlife Disease Study at the University of Georgia.

Mitch Bailey with Tennessee Wildlife Resources Agency said tens of thousands of white tail deer will likely die due to the virus.

“This fly bites one deer that's infected, (goes) to another deer and infects it,” he said.

The flies, also known as sand gnats, sand flies or no-see-ums, can spread the disease to livestock, but there is no risk to humans, experts said.

The disease can kill up to a quarter of the deer in an outbreak area, which could affect the deer hunting season that opens Sept. 22 in Tennessee. Hunters are cautioned not to eat venison from visibly sick deer.

“If we don't kill enough deer every year, Mother Nature has a way of taking care of it this is one of those ways,” Bailey said.