Disease can be detected in five hours instead of five days
A new, rapid test for chronic wasting disease will allow Montana to broaden its efforts to detect an infection in wild deer and elk, according to a state wildlife agency official.
And if Montana ever does find CWD in its wild deer or elk, the new test could possibly be used upon the request of hunters to determine if animals they killed were infected, said Keith Aune, supervisor of the Montana Fish, Wildlife and Parks Wildlife Research Laboratory in Bozeman.
However, Aune added that several recent studies found no link between CWD and human health.
Bio-Rad Laboratories of Hercules, Calif., announced last week that its rapid test for CWD has been approved by the U.S. Department of Agriculture for use on white-tailed deer, elk and mule deer. The test is currently used in Colorado.
The company says its new test generates results in just five hours, compared to the traditional IHC (immunohistochemistry) method, which can take up to five days. Bio-Rad’s tests will be used only by USDA-authorized labs.
CWD is a one of a family of brain diseases, including mad cow disease, called transmissible spongiform encephalopathies that are always fatal to the infected animal. Scientists believe the malady is caused by mutated proteins called prions.
Bio-Rad’s new tests will allow Montana wildlife managers to do more chronic wasting disease testing and get results faster, Aune said.
There are only 10 USDA-approved labs in the country doing CWD testing, he said. Since the recent discovery of CWD in wild deer in Wisconsin, Illinois and Minnesota, those labs have been overloaded.
In Wisconsin this fall, tens of thousands of hunters complied with requests from state wildlife officials that they provide heads of their harvested deer for CWD testing.
Because chronic wasting disease has not been found in the wild in Montana, Aune said, the state’s requests for CWD tests from USDA labs have been given lower priority than states that have the disease.
This year, he said, FWP collected tissue from more than 1,000 deer and elk killed by hunters to have tested for CWD. Getting results will take about six weeks, because of the backlog at the labs.
Since 1996, Montana has tested more than 1,700 deer and elk from its wild herds, but has never discovered one case of the disease. In addition, more than 1,700 elk from game farms have been tested. The only incidence of CWD in the state was found in elk at a game farm near Philipsburg in 1999. The entire herd was destroyed.
“We probably just dodged a bullet in our Philipsburg situation,” Aune said. “There weren’t a lot of wild animals around the infected game farm. And it was detected early and aggressively tended to.”
Montana’s CWD surveillance efforts have been concentrated in three geographic areas, including the Philipsburg vicinity, where FWP has tested about 500 wild deer and elk since 1999. All tests were negative.
“So we’re feeling pretty confident now about Philipsburg,” Aune said. “But we’ll maintain surveillance in the area.”
The other two areas of the state where FWP is focusing attention are along the Alberta-Saskatchewan border, from Havre eastward; and along the Wyoming border, from Big Timber eastward. CWD has been found in the wild in Saskatchewan and Wyoming. Alberta and Saskatchewan also have “had a nightmare” with CWD outbreaks in game farm elk herds, Aune said.
“And of course, any time there’s a sick animal anywhere, we try to take a look at it,” said Aune. “We will continue that, probably, forever.”
In the future, he said, Bio-Rad’s new CWD test may allow FWP to do its own testing on the spot in its targeted high-risk surveillance areas.
Eventually, Aune added, FWP may consider using the test, upon request of hunters, to determine if animals they kill are infected. But that probably would only happen if CWD were found in the wild in Montana, he said.
Recent discoveries of the disease in other states have prompted considerable debate about human health risks associated with CWD.
“Because there has been a degree of uncertainty about the transmission between species,” Aune said, “it’s led people to speculate that it could happen. But in the real world, there is a pretty significant species barrier for transmission of CWD to humans. In addition, there’s a huge cultural barrier. In Montana, hunters don’t eat brains or spinal cords, which is where the prions are concentrated.”
No link between CWD and the human form of the disease, Creutzfeldt-Jakob disease, has ever been demonstrated, according to Aune. He cited reports by the U.S. Centers for Disease Control, the World Health Organization, and most recently by the Mayo Clinic, that concluded there is no evidence that CWD can be passed to humans.
“It’s incredibly unlikely,” Aune said.
Nevertheless, the World Health Organization advises people not to eat any part of an animal that shows signs of the disease.
FWP already has received some requests from hunters to have their animals checked, according to Aune. The department refers them to laboratories in Colorado and Wyoming that do tests for individuals.
Bio-Rad’s test “will open that possibility for us,” he said.
“But we’re in a state with no known CWD in wildlife,” he added. “And even if it were, there’s no link between CWD and humans, so I question if it would be worth the money. But that’s an individual choice.”