Saturday, February 4th, 2023
Saturday, February 4th, 2023

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Putting together the pieces of CWD puzzle

Correspondent

St. Paul While the DNR investigates the condition of Minnesota’s
wild deer herds, state Board of Animal Health officials are taking
steps to isolate and eradicate chronic wasting disease in domestic
deer and elk herds. They also are attempting to figure out CWD’s
route into the state.

Paul Anderson, DVM, is in charge of CWD programs for the BAH. He
is leading the effort to contain the disease wherever it surfaces
in farmed animals and to backtrack it to its origin. Anderson leads
a team of experts that include computer specialists, records
analysts, field reps and veterinarians.

On Friday, Sept. 13, Anderson confirmed the cause of death of an
elk from the Clayton Lueck farm in Aitkin County as clinical CWD.
He cautioned that there is no information indicating any other
herds have been infected with CWD.

“This is one animal on one farm,” Anderson said. “There are
about 260 elk herds in Minnesota and most of them are a part of the
voluntary CWD monitoring program.”

The voluntary program was created as a sentry to watch for CWD
and has provided experts with valuable information to contain and
track the disease.

Since late 1997, more than 700 elk have been tested for CWD in
Minnesota. Working jointly with veterinarians, herd owners sent
samples of any elk that was killed or slaughtered for testing. None
had tested positive until last month. Other parts of the voluntary
monitoring program include fencing, animal ID tags, usually ear
tags, and record keeping. The Aitkin County farm was part of the
program.

“The voluntary program worked exactly as it was intended,”
Anderson said. “The people in the program spend a great deal of
resources to watch for CWD. That’s how this (infected) elk was
found.”

Once the animal tested positive, the Aitkin County farm was
quarantined. To date, no animals can leave or enter. The elk may
wander the fenced paddock, but no animals can be sold or
slaughtered.

By analyzing records kept by the animal’s owner and based on
information provided by import permits issued by the BAH, the BAH
is able to track the animal’s movement over the past three years,
CWD’s incubation period.

In the current case, the animal’s history was well documented.
It was born in 1997 on the Jim Moscho farm in Sauk Centre. When it
came of age, it was leased for stud to the Duane Thene farm in Sauk
Rapids. Eventually, it returned to Sauk Center before finally being
sold to the Aitkin County farm.

The Sauk Centre and Sauk Rapids farms have been quarantined.

“I want to be clear: These other two farms have been quarantined
only as a precaution,” Anderson said. “CWD has not been found on
those farms. This is like a giant jigsaw puzzle. It takes a great
deal of effort. We have much of it sorted out, but it is way too
premature to guess how (the one elk) became infected.”

Two aspects of the investigation make it difficult to make
statements of certainty. First is CWD’s long incubation period of
three years. An infected animal may move from farm to farm and
interact with other animals in a three-year period. Through the
voluntary monitoring program, the information of animal movement
may be available. Experts analyze that information, but the more
movement and the more animals involved, the more tedious and
time-consuming the analysis becomes.

Second, even with all the records of movement and exposure to
other animals, in the end, it is unknown whether the CWD-positive
animal was even infected at the time it was moved.

Cases in point are the Sauk Centre and Sauk Rapids farms. Both
farms were exposed to the elk that eventually died of CWD. But that
doesn’t mean the dead elk had the disease at the time it visited
those farms; and even if it did, none of the animals on those farms
show any symptoms of CWD to date. At this point, then, the puzzle
pieces seem to run out.

What would help is to connect Minnesota’s CWD case to an area
near one of the known infected herds in other states. This would
give experts a potential source for Minnesota’s CWD and a solid
lead from which to track the extent of exposure of the disease.
Currently, such a connection is unknown, and according to Anderson,
may never be known.

A second infected animal with a well-documented history of
movement would provide a lot of new pieces of information to the
CWD puzzle. Nobody wants a second case of CWD. Short of that, the
BAH will continue analyzing information as it becomes
available.

So where does the BAH go from here?

Investigators have enough information to make some decisions.
All indications suggest that all the animals on the Aitkin County
farm will be euthanized and tested for CWD pending discussions with
the USDA’s Animal and Plant Health Inspection Service, or APHIS.
(The USDA reimburses farmers for animals that are destroyed due to
CWD containment practices and therefore are a part of the decision
to euthanize a herd.) That decision is expected in the next
week.

The BAH is actively sharing information with the Department of
Health, the DNR and other wildlife agencies, and the Department of
Agriculture, which is educating meat processors on handling
CWD-infected animals.

Without additional information, the BAH will continue putting
together the CWD jigsaw puzzle with the current slate of
information. As more pieces of information come in, they will be
added to the puzzle.

“We are conducting an epidemiological investigation about what
happened,” Anderson said. “We learn more every day. This is not the
end of the line.”

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