Monday, February 6th, 2023
Monday, February 6th, 2023

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CWD live test scrutinized

Associate Editor

Alexandria, Minn. The February discovery of chronic wasting
disease in Wisconsin and the more recent finding of the disease in
Minnesota farmed elk has resulted in a rush to find a reliable
field, or “live test” for the brain ailment in these cervids.

While such a proven test isn’t yet on the market, a Colorado
company says its test will be soon forthcoming. Currently, a
Minnesota veterinarian is working with the company GeneThera, Inc.
to determine the accuracy of a blood test it has developed. Because
of the required accuracy or, “blind” tests, the product won’t be
available for hunter use this year.

“We’re in the approval process right now,” said Scott Wathen,
director for assay development for the Wheat Ridge, Colo.-based
company. “We’re in the process of a large-scale validation
study.”

Glen Zebarth, a practicing veterinarian in Alexandria, Minn.,
and consultant for the Elk Research Council, is studying and
coordinating the samples GeneThera now is collecting. Some of those
samples are from locations where CWD has been found, others are
coming from “isolated” locations, Wathen said. Nearly all of the
samples are from farmed elk.

Some of those samples will come from elk euthanized on an Aitkin
County farm where a CWD-positive elk was found a month ago.

“We’re collecting specimens (for blood testing) as the animals
are euthanized,” said Dr. Kristine Petrini, assistant director for
the Minnesota Board of Animal Health. “Whether or not we’ll submit
samples to GeneThera in the future, we don’t know.”

Blood test results are compared to the currently accepted means
of testing using a portion of the animal’s brain stem, referred to
as an immuno-histo-chemistry test, or IHC.

Over half of the Minnesota herd of 48 elk from the farm where
CWD was found have tested negative. The remainder of the herd has
not been tested.

“It’s good that they’ve been negative,” Petrini said, “but we’ll
need more positives to validate the test.”

Not only do officials need to know how often the blood test
identifies a negative that’s actually positive, but they need to
determine the frequency at which the test indicates a positive
that’s actually negative.

The IHC test of the brain tissue currently is considered by most
the “gold standard” in testing for CWD, a brain disease caused by
an abnormal protein called a prion.

“Basically, there are no tests that are 100 percent,” Zebarth
said. “We just don’t know about this (blood sample test) yet.”

For commercial use, Zebarth said the blood test may be six
months to over a year away, pending USDA approval. However, some
state agencies likely will test the technology on a provisional
basis, he said.

Should the blood test prove accurate, Zebarth said its most
practical application would be testing of farmed cervidae, and
removing the need for eradication of an entire deer or elk herd.
Eventually, it could be used by hunters who’d purchase a
“CWDSignal” kit, then submit the sample to GeneThera. Results in
most cases would be available within 24 hours, the company
said.

Wathen said he expects the kit and testing to cost less than
$100. And, he says, the company believes it’s ready
technology-wise.

“We need to satisfy the skeptics, and we need to ensure hunters
are getting a quality test,” he said.

Should the blood test be proved accurate, it could mean testing
on a scale much larger than officials currently are able to conduct
the brain stem testing. GeneThera officials predict the ability to
test 160,000 samples per month by next year.

“The blood test is showing some potential promise, but it has a
ways to go,” Petrini said.

Wathen says his company, WerbGen, will be marketing a “hunters’
wipe” a baby wipe-type product meant to guard against CWD by
neutralizing the prion protein, he said.

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