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December 20, 2002
Below is a news article that appeared in the Milwaukee Journal/Sentinel on recent CWD findings sent to me by Nancy Gilbertson via Tim Yager. As I mentioned in my last update, the Grant county findings are tentative pending IHC confirmation. All the data I've seen on the ELISA leads me to think the findings will be confirmed. USDA has already permitted the use of the test.
However, if the lab was inappropriately applying different reagents to alternative tissues (as Spraker suggests) these findings could be false positives. Despite what the news report says, the locations (Grant and Marathon) really aren't that unusual, though. Already we know of a positive game farm in Portage county. Marathon county (the next county north) also has a quarantined (trace forward from Portage), though not positive, herd. In Walworth County an escapee from the affected game farm was found positive (i.e. a game farm animal free-ranging outside the fence). Similarly, Grant county is adjacent to Iowa county. The Illinois data already suggest CWD is likely much more widely spread, and that the "CWD outbreak" is no longer confined to western Dane and eastern Iowa counties in Wisconsin.
As a "by the way" the official Wisconsin count is up to 48 animals positive, but the testing base increased dramatically so that the measured prevalence in the intensive harvest/eradication zone is now estimated at 2.33%
Thomas J. Roffe, PhD, DVM
Northern Rocky Mountain Science Center
USGS-BRD
FWP Bldg, 1400 S. 19th Ave.
Bozeman, MT
T: 406-994-5789
F: 406-994-4090
Cell: 406-539-4955
Supporting Document
By LEE BERGQUIST
lbergquist@journalsentinel.com
Last Updated: Dec. 19, 2002
A private laboratory says it has discovered chronic wasting disease in a deer shot in Marathon County - 100 miles from the closest previous known discoveries - and in two deer that were shot in Grant County during the fall gun season.
But the findings are being disputed by state officials who raised questions Thursday about the accuracy of the lab's testing procedures. And officials said they feared the results could unreasonably raise anxiety in parts of the state where the disease had not yet been found.
The new Marathon County finding would thrust the disease into central Wisconsin for the first time. Wisconsin Viral Research Group had previously announced one finding in Grant County. A second finding by the lab in Grant County is new.
Konstance Knox, a founder of Wisconsin Viral Research Lab in Wauwatosa, said she cannot say for certain whether the findings are truly accurate.
"Our job is to report what we find to hunters," said Knox, who thinks the testing technology her company is using is more sensitive than a different technology used in a state testing program for chronic wasting disease.But a DNR official said the new results are suspect.
"I think this demonstrates some of the reasons why the USDA (Department of Agriculture) has been very cautious about expanding testing to private companies," said Julie Langenberg, a veterinarian at the state Department of Natural Resources.
Wisconsin Viral Research Lab, the private lab, has now reported that three deer showed evidence of the fatal deer disease in 800 samples tested so far. It was hired by Wildlife Support Services of Hayward, which angered state authorities this fall by marketing test kits directly to hunters who wanted to know whether their deer had the disease.
Now, as the results are coming in, the private lab is reporting cases of the disease in places where Wisconsin's state-run testing program has showed up nothing. So far, Wisconsin's state-run testing program has uncovered 48 deer with chronic wasting disease out of 3,880 samples that have been analyzed to date. More results are expected today.
All the positive deer in the state's testing program have come from a 411-square-mile region of Dane, Iowa and Sauk counties, except for a separate finding of a positive deer shot outside a Walworth County game farm.
Three rounds of testing The lab's latest results come from a second and third round of testing on the same tissue samples. That follow-up testing procedure is controversial and is raising a ruckus between the lab and state authorities.
Wisconsin Viral Research Group ran the testing two ways. The first used the same antibodies employed in a testing procedure approved for a group of government labs that are testing deer. Those tests showed no evidence of the disease.
The second test uses a different antibody, which Knox, who holds a doctorate in experimental pathology from the Medical College of Wisconsin, believes is more sensitive in detecting the abnormal protein that causes chronic wasting disease. Those tests were positive.
"Our approach is that if there is any doubt, you go with the most conservative conclusion," Knox said. "Our client is the hunter. We want the most sensitive test to detect CWD in the hunters' animals. We know, frankly, they are testing it because it is a risk-management tool for them."
Chronic wasting disease provoked controversy after it was first found west of Madison in February. The disease is part of a family of fatal brain disorders than can affect animals and people. The diseases, which also include mad cow disease and Creutzfeldt-Jakob disease in people, are believed to be caused by an unusual infectious agent known as a prion.
No known cases of the disease jumping to people have been found. Laboratory research suggests such a jump is theoretically possible, but several researchers say they believe the risk to humans is low.
Government-approved test
When it has come to testing, state authorities have followed the lead of the National Veterinary Services Laboratories, or NVSL. "NVSL has designated a certain test for a reason, and you are finding out the reason for that," said Barb Powers, director of the veterinary diagnostic lab at Colorado State University.
Another expert said he does not like the test the private Wisconsin lab is using. Terry Spraker, a wildlife pathologist at Colorado State University, said the test has a tendency to report so-called false positives when the lymph - rather than brain - tissue is used.
Wisconsin Viral Research Group has been testing lymph tissue, where the disease has been found to show up faster than the brain in deer. State officials have sent two letters to Wisconsin Viral Research Group asking the company to turn over samples so results can be tested independently.
Knox said she wants to work with the state, and in fact has asked for tissue samples from positive deer the state has collected for her company's research. She has not gotten them.
"Frankly, we have done nothing wrong, and we are feeling bullied," she said.
A version of this story appeared in the Milwaukee Journal Sentinel on Dec. 20, 2002.
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