Risk to humans may be greater

Researchers have found infectious prions in muscles of infected mule deer.
MILWAUKEE JOURNAL SENTINEL
MILWAUKEE -- Ever since chronic wasting disease was detected in Wisconsin nearly four years ago, hunters were reassured that they could greatly reduce their risk of getting the deadly neurological disorder by avoiding tissue from the brain and central nervous system of the animal.
Muscle tissue never has been shown to be infective, officials said.
Not anymore.
Researchers whose work was published Thursday in the journal Science say they have found infectious prions -- the agents that are believed to cause chronic wasting disease -- in the leg muscles of infected mule deer, a finding that's likely to raise concerns among many deer hunters.
"This shows muscle contains infected material," said senior author Glenn Telling, an associate professor of microbiology at the University of Kentucky. "Anybody who may be handling or eating infected deer may be inadvertently exposed."
New report
The new report suggests that all so-called transmissible spongiform encephalopathies, ranging from chronic wasting disease to mad cow disease, should be taken more seriously, said Michael Hansen, senior scientist with the Consumers Union.
"No hunter should eat anything until after an animal has been tested," said Hansen, a biologist. "This finding along with reports last year that CWD can move into primates should raise some serious questions for hunters."
In November, researchers at Creighton University and the University of Wisconsin-Madison reported that chronic wasting disease could infect squirrel monkeys, a member of the same order as humans.
"This is the first reported transmission of CWD to primates," the authors wrote in the Journal of Virology.
The two squirrel monkeys were injected in the brain with the infectious material from mule deer. Within 34 months they developed degenerative brain disease. After the animals were euthanized, the classic sponge-like lesions common to prion diseases were found in their brains.
Potential harm
The actual experiment was conducted in the 1980s by the late University of Wisconsin researcher Richard Marsh.
The authors said they presented the findings last year, along with some additional laboratory analysis, because of the emergence of chronic wasting disease in North America and its potential to infect humans.
But whether chronic wasting disease can infect people remains an open question. Some earlier laboratory research suggests it is possible, although there is a species barrier that likely would make such a jump more difficult, researchers say.
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," said Aiken, a professor of animal health and biomedical sciences.
While the study does not prove that people can get brain disease from infected deer meat, it suggests that caution should be practiced, he said.