Searching for a deer killer

Scientists looking for traces of chronic wasting disease

A line of all-terrain vehicles splashed through the saturated ruts of a logging road bisecting the territory of Snake Pond Hunting Club near Burgaw.

A rainy morning had not put the damper on opening day of the state's eastern region deer season for the club members who were returning to the piney woods to run their deerhounds after breaking for lunch.

Joe Cox drove a white pickup, followed by his son, Dalton, riding an ATV. The N.C. Wildlife Resources Commission's southern coastal management biologist, Vic French, stopped them with a friendly wave. He spoke with Joe Cox through the truck window, asking if anyone had killed a deer he could sample for chronic wasting disease, often referred to as CWD.

"I've heard of the disease," said Joe Cox, 51, a computer engineer who lives in Raleigh. "I just didn't know it was going on here."

It turned out that Dalton had shot an eight-point buck that morning. After a brief discussion as to whether the buck had a rack large enough to warrant a mount, Dalton agreed to allow French to take some samples. He turned his ATV around and headed back to the skinning area.

"I'm glad to help out. I would hate for something bad to happen to our deer," said Dalton Cox, 16, a student at Garner High School.

French is hoping to help keep it from happening.

"We are taking samples on a grid," French said. "I have taken several samples in Pender County, where our goal is a total of 22. We don't want samples taken too close together or too far apart."

FIELD SURGERY

French sliced through the deer's neck, removing the brain stem or "obex" with forceps and dropping it into a bottle filled with formalin. He then removed the two retropharyngeal lymph nodes from the neck and placed them in the bottle. He filled out a form on a clipboard with the date, location and other information identifying the sample and wrote an identification number on the bottle. Then he thanked Dalton and headed off to find another hunter-killed deer.

CWD has not been found in North Carolina deer, Evin Stanford, the commission's deer biologist, says. He also said in a phone interview that the commission would appreciate any hunter who is approached by a commission biologist to allow his deer to be sampled.

"Some hunters see a guy jump out of a state vehicle wearing a uniform and think it's a wildlife enforcement officer," Stanford said. "Many hunters do not know we have a professional management staff who are also in uniform. We want hunters to cooperative with our management staff because it is in their best interests and in the best interest of deer."

Stanford said CWD is in the classification of diseases that includes mad cow disease. However, while mad cow occurs in cattle and can be transmitted to people, there is no evidence CWD can spread to people. The disease showed up in western states in 1967.

In 2002, CWD crossed the Mississippi River into Wisconsin. While deer and deer hunters have coexisted with the disease out west, its impact on eastern deer remains to be seen. While eating deer infected with CWD is not recommended, Stanford said it obviously happens.

"At the higher densities of eastern deer herds, it has been theorized that all deer in a population could be infected," Stanford said. "CWD is 100 percent fatal. It can cause death quickly or can take up to five years for an infected deer to exhibit symptoms. Symptoms include tremors, lack of coordination, walking in circles or standing in one spot for long periods, and excessive salivation"

Hunters are asked not to volunteer deer willy-nilly for sampling. The commission used N.C. Forest Service maps to set up a sampling grid that allows samples to be taken four miles apart, with a total of 1,000 samples statewide. The initial sampling five years ago tested 1,400 samples and found no CWD. The closest confirmed CWD case occurred in West Virginia.

THE CAUSE

An infected animal has prions in its brain stem tissue. Prions are proteins that have lost their typical protein configuration. They maintain the amino acid composition, but it is the protein itself that becomes the infectious agent. It's nothing living, such as a virus or bacteria.

The animal's body has no immune response because the prion is not identified as an infecting agent. Prions remain in the environment for long periods and can be destroyed quickly only by high heat or chemicals.

"If we find a positive sample, depending on time of year, we would send commission employees to remove some deer within a five-mile radius," Stanford said. "During the first hunting season, we would require testing of all animals harvested within the five-mile radius. We would ban baiting within that area to minimize deer-to-deer contact."

"If the disease were found in additional animals, we would continue drawing a five-mile circle around them and keep sampling those areas. We would continue to sample at a high enough statistical rate to discover positive samples. We would determine the number of deer in the affected area and initiate a harvest objective to lower the deer density to stop the spread of the disease. Lowering deer densities has the greatest potential of reducing the rate and slowing the spread to additional areas."