CWD culprit found in deer's leg muscles
Study says hunters may be exposed

January 27, 2006

WASHINGTON (AP) - The leg muscles of deer infected with chronic wasting disease contain the infectious proteins that cause the fatal brain disease, new research shows.

Chronic wasting disease is in the same family of brain-destroying illnesses as mad cow disease.

There is no evidence that people have caught chronic wasting disease from infected deer or elk. But University of Kentucky researchers, writing in today's edition of the journal Science, concluded that hunters may be exposed to these infectious proteins, called prions, by handling an ill deer's flesh.

Researchers have found prions in the muscle of other species with variations of these "transmissible spongiform encephalopathies," or TSEs. But the most highly infectious tissue, in deer or any other species with a TSE, is the brain and spinal cord; muscle contains far less.

The new research found the same with the deer muscle: Mice bred to be vulnerable to chronic wasting disease became infected faster when their brains were injected with brain extracts from dying deer than when they were injected with contaminated muscle.

Already, hunters in areas where chronic wasting disease has been found are urged to have the heads of their kills tested for the ailment.

The disease was first discovered in Wisconsin west of Madison in February 2002. The state Department of Natural Resources said 99,308 deer in Wisconsin have been checked for the disease since then, and 557 deer have tested positive for it.

James Kazmierczak, an epidemiologist with the Wisconsin Department of Health and Family Services, said the state has recommended that no part of an infected animal should be consumed, and all animals killed in the chronic wasting disease endemic zone should be tested for the disease. He said that will not change in the wake of the latest study.

But "whether people choose to follow that is another issue," Kazmierczak said.

Judd Aiken, a University of Wisconsin prion disease researcher, said the University of Kentucky study clearly shows for the first time that prions are present in deer muscle.

Had the study found the opposite, "We could start arguing for the potential safety of venison," the animal health and biomedical sciences professor said.

While the study does not prove that people can get brain disease from infected deer meat, he said, it suggests that caution should be practiced.

Aiken said he would not eat any venison from an area where the disease is known to exist, even if the animal tested negative for chronic wasting disease, because the available tests may not be sensitive enough to find the disease in early stages.

Alan Crossley, the Wisconsin DNR's project leader for chronic wasting disease, said some people who kill positive deer go ahead and keep the venison and presumably eat it. He estimated that 40 percent of those who had positive deer during the 2004 hunting season said they planned to keep their venison.

Some Wisconsin hunters go ahead and eat their deer before test results have been returned, and others wait to see what the test turns up, he said.

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