Biologists need hunter cooperation for study

By Mike Marsh
Published in Sports on October 31, 2008 1:46 PM

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Bobby Futrell was hunting in Pender County on opening day of the eastern deer season. Vic French, a biologist with the N.C. Wildlife Resources Commission found out Futrell had taken a deer and drove to his house after calling the hunter on his cell phone.

"We are sampling for Chronic Wasting Disease," said French. "I have taken some of my samples, but I need several more."

Chronic Wasting Disease is a disease of animals called cervids. The disease originated in the western states then spread to a few eastern states in the early 2000s. The disease infects black-tailed deer, mule deer, elk and moose.

No one is certain where the disease originated. But it is thought to have infected captive deer after they were fed animal parts from cows or sheep.

According to Evin Stanford, the state's deer biologist, CWD is similar to mad cow disease in the way it infects brain tissues. Once it is established, it is difficult -- if not impossible -- to eradicate.

"This is our second round of sampling," said Stanford. "The first was conducted five years ago. We have never found CWD in any deer in North Carolina. The closest occurrence was in West Virginia."

Stanford said CWD is not caused by a virus or bacteria. It is caused by a protein called a prion. Prions multiply in the nervous system until they interfere with motor functions. Deer with the disease may exhibit many different symptoms and may take five years after becoming infected to show signs of infection. Others die quickly.

Anyone seeing a deer with tremors, lack of coordination, walking in circles or standing in one spot for long periods of time, or showing excessive salivation and urination should notify the Commission. But many deer may show these outward signs of CWD when in reality they are suffering from another disease or injury.

"That's why it's important that we sample deer taken by hunters, to give us a statistical look at what may be occurring," said Stanford. "We are also sampling road-killed deer. If we find a deer with CWD, we have a plan in place to deal with it.

"We would attempt to reduce deer densities within a 3-square mile area around the site where the infected deer occurred to slow or prevent the spread of the disease."

Stopping the spread of CWD would be difficult or impossible. Buried remains of deer with the disease still showed the presence of prions after two months. Since they are not living, prions cannot be killed. Only strong chemicals or high heat would likely destroy them. Stanford said CWD appears to be spread directly and indirectly.

"CWD appears to be associated with the alimentary route," he said. "Saliva, urine or feces seem to play a role, with the strongest evidence pointing toward feces. Studies show live infected animals can be put in a facility and removed and non-infected animals will still get the disease.

"You can put animals in a facility with a decaying animal and they will also get the disease.

In western deer herds, CWD does not appear to have much of an impact. In the wide-open spaces, deer occur sparsely and therefore may have low transmission rates. However, in deer-dense states east of the Mississippi, CWD could have a severe impact, perhaps even eliminating deer from the landscape if it should gain a foothold. In areas of northern states where CWD is present, reducing the deer population to control the spread has not been effective.

People have obviously been eating CWD-infected deer in western states since the 1960s, so apparently the disease does not create problems with humans like mad cow disease, which comes from cattle. But hunters are advised not to eat infected deer nonetheless.

The Commission has an active program for preventing CWD from entering North Carolina. All deer hunters should visit the commission's website at www.ncwildlife.org to familiarize themselves with the plan. Prohibitions on importing deer or deer parts from areas where CWD is present are in place.

Hunters should not call the Commission to offer deer for sampling. Biologists will contact hunters in the field or obtain their contact information through the harvest-reporting network. The deer's head is removed and the obex (brain stem) and the retropharyngeal lymph nodes excised.

"We want hunters to know how important it is to help us obtain at least 1,000 samples," said Stanford. "If they are approached by a biologist, we would appreciate their cooperation."