A fatal white-tailed deer disease has been detected near the Allegheny County border in Pa.

PITTSBURGH — First detected in Pennsylvania 13 years ago, a fatal, contagious disease affecting deer and elk has yet to be confirmed in Allegheny County. That could change, and soon, as chronic wasting disease continues to spread across the state and was recently detected in an animal in Armstrong County's Freeport — near the Allegheny County line.

A severely emaciated female was euthanized by a game warden and tested positive for the neurological condition in early June, said Andrea Korman, Chronic Wasting Disease Section supervisor for the Game Commission in Harrisburg.

The Pennsylvania Game Commission, which regulates white-tailed deer in the state, first detected the disease in 2012 in Adams County, and it has expanded to all south-central counties as well as sections of other counties.

The Freeport chronic wasting disease (CWD) case is the farthest west the disease has been documented in the state, the Game Commission said in an email. Northeast of Pittsburgh, Freeport also sits near Butler County, and is across the Allegheny River from Westmoreland County. The disease was also recently detected in Dauphin County.

"Areas with higher deer densities are a concern for increased transmission of the disease. This is the first time CWD has been detected in such a populated area," the Commission said in an email.

The appearance of CWD at the Allegheny County border is new territory for the Game Commission, because it is the first time the agency might have to try to contain or slow the disease in an urban and suburban environment.

"The combination of high human density and limited hunting access will make it difficult to harvest deer in these areas, which is one of the only tools we have for managing CWD," the Commission said.

Emaciation and erratic behavior are hallmarks of the deadly disease that attacks the brain. With neurological impairments, deer are more susceptible to car collisions and become easier targets for hunters and predation, Korman said. The Freeport doe probably suffered from the disease for one to two years.

"It's hard to say what the disease will do if it reaches Allegheny County," she said. "We are more limited when it comes to the disease in urban and suburban areas, but we will work directly with landowners and municipalities to see where we are."

The Game Commission's policy, which is similar to actions taken by game officials in other states, calls for increased hunting to cull the deer herd to slow down the contagious disease. With no cure for CWD, the approach is to remove infected animals and, Korman said, reduce the herd, "so they don't come into as much direct contact with each other."

While it's possible CWD has expanded to Allegheny and Butler counties, the disease has not been documented in either, she said.

Once CWD is detected in an area, it becomes part of a disease management area (DMA) with a 10-mile buffer zone around the sites where CWD-infected deer were found. The Commission promotes more hunting in those areas. And regulations kick in, including restrictions on where harvested deer can be transported, a ban on feeding and attracting deer, and the installation of bins for testing deer parts.

Outside of the DMAs, the Commission relies primarily on samples from roadkills and reports of sick deer, among other methods, to determine new cases of the disease.

"A lot of times, we will find CWD in roadkill first," Korman said. "The more deer we test, the better."

Catching the disease early can also help stop or slow the spread. Much depends on a deer's stage of infection. For example, a deer tested positive in York County outside of the DMA, so the Commission increased sampling — and found 10 more positives.

"The disease had been there awhile before we found it," Korman said.

In another case several years ago, the agency detected CWD in a deer in Westmoreland County and hasn't documented another case in that area. That might have been an early detection, she said.

"The more samples we have, the faster we know where the disease is and to take steps to address it."

Whether residents are in a DMA or not, the Commission recommends not feeding or attracting deer.

"Anything that brings deer to a single location can spread the disease," Korman said.

The Commission and the CDC recommend that the public not eat deer that have tested positive for CWD, though, she noted, there is no evidence that people and other wildlife can contract the disease through consumption. Deer meat donated to food banks from DMAs is tested for the disease before it is distributed.

The growth of CWD in Armstrong County has been very slow. It was first detected about a year ago near Indiana County, then turned up south of Ford City. The recent detection in Freeport is about 10 miles away from the last site where the disease was found in Armstrong County.

Bedford and Fulton counties have the highest CWD rate — over 40% — based on samples from hunters. The Commission confirms the disease by testing the lymph nodes in the necks of dead deer.

Hunters can voluntarily have their deer tested for free by depositing the animal's head in special bins installed by the Commission in DMA where chronic wasting disease has been detected. The boundaries of those DMAs are usually changed by the Commission changes once a year, at a Board of Commissioners meeting.

Residents can contact the Commission's dispatch center to report sick and dead deer along roads at 1-833-PGC-HUNT (1-833-742-4868) or 1-833-PGC-WILD (1-833-742-9453).

CWD is found in free-ranging cervids, which include deer, elk and moose, in 36 states and four Canadian provinces, according to the U.S. Geological Service.