Mixed Signals
Wisconsin might be able to wipe
out Chronic Wasting Disease, but it could take a decade of getting
everything right.
It’s not exactly news that
deer hunting is big in Wisconsin. To grasp just how big, consider
the 2000 season. Sales of licenses to hunt deer with guns that
year fell just a few dozen shy of 695,000, the vast majority
of which would have been used during the traditional nine-day
season in late November, bracketing the Thanksgiving holiday.
So for that one extended week, the number of people bearing
arms in the woods and fields of Wisconsin could have exceeded—by
as many as 20,000—the numerical strength of the entire
United States Marine Corps during all of World War II.
But a year ago last February,
those who are devoted to the sport and its traditions had to
face questions about whether the Wisconsin deer hunt was on
the brink of permanent change and perhaps even headed for unstoppable
decline.
February 2002 was when Chronic
Wasting Disease (CWD), a brain-destroying and uniformly fatal
affliction of deer and elk, first turned up in Wisconsin. It
was found in tissue samples from three deer taken the previous
fall by hunters in a single township of western Dane County.
For some time, state wildlife and animal health officials had
watched apprehensively for the disease to appear, and the discovery
triggered a crash program to determine the extent of the problem
and figure out how to deal with it.
Dealing with it successfully,
everyone understood, could matter in a big way to more than
just Wisconsin’s million-plus whitetail deer. If the rogue
protein, or prion, blamed for causing CWD could manage to jump
the species barrier, a lot of hunters and their families and
friends might have a horrible surprise waiting for them months
or years down the road. Some researchers in Great Britain thought
the prion related to the not- dissimilar Mad Cow Disease had
jumped from one species to another at least twice and reached
about a hundred unfortunate humans. So the threat of human CWD
infection, unproven even today, appeared at least conceivable.
The early stages of this state’s
anti-CWD activities were reported in the January 2003 Wisconsin
Energy Cooperative News. Now, with this year’s major deer
season upon us, we look back at what’s been learned in
the meantime.
The Zero Option
If concerns about eating venison
have suppressed participation in the Wisconsin hunt, it certainly
hasn’t been by the huge percentages spoken of in some
quarters during the run-up to last year’s nine-day gun
season.
About one-third of the licenses
used during that season are typically purchased in the five
days immediately preceding the hunt, so press-time predictions
of a trend for 2003 would be highly speculative. But Department
of Natural Resources (DNR) spokesman Bob Manwell indicated that
as of mid-October, both archery and gun license sales were up,
compared with the same period in 2002. In fact, Manwell said,
gun-license sales were running 12 percent ahead of the previous
year.
That may bode well for what his
department is hoping to accomplish, because if one thing is
clear, it’s that a lot of hunters are going to be needed.
Testing of tissue samples from
the 2002 deer harvest—a project DNR Secretary Scott Hassett
has called “the most intensive testing effort in the history
of North American wildlife management,”—identified
207 animals with the disease.
That figure represents slightly
more than 1-1/2 percent of the 41,245 deer sampled statewide.
Probably more important, every one of the infected animals was
taken in the southern Wisconsin zone where officials seek to
wipe out the deer herd so as to arrest the disease or in a narrower
intensive herd-management zone immediately adjacent to it (201
and 6 animals, respectively).
It’s prudent to say “probably
more important,” because the 2002 sampling was most extensive
in the area where CWD’s presence had already been confirmed.
Among DNR priorities this year is to test more deer from outlying
counties where last year’s sample size was smaller than
desired. But the overall testing effort will aim for 15,000
to 20,000 animals from selected counties, with the majority
from within the designated Herd Reduction, Intensive Harvest,
and Disease Eradication Zones.
The Disease Eradication Zone is,
of course, exactly what it sounds like: a 411-square-mile area
mainly in Dane and Iowa Counties but including small parts of
Columbia, Grant, Green, Richland, and Sauk Counties as well.
A separate Disease Eradication Zone exists in part of two Rock
County townships bordering Illinois.
In those zones, the objective
is to go as far as possible beyond simply thinning the herd.
According to Secretary Hassett, “We believe the best approach
currently available to eradicate CWD from an affected area is
to reduce the wild deer herd to near zero.”
Hassett says a somewhat rueful
attitude has evolved among officials in Colorado and Wyoming.
CWD was detected there decades ago and the response has been
to individually eliminate infected animals rather than seek
to exterminate infected herds.
Selective eliminations haven’t
gotten the job done in those Western states, Hassett says, and
even assuming success in Wisconsin’s all-out effort to
thin an exploding deer population, making the state once again
disease-free looks to be a long-term project.
“Depending on hunter and
landowner cooperation it may take as long as a decade to reduce
the deer population low enough to stop CWD transmission and
allow the disease to ‘die-out,’” Hassett wrote
in October.
The Prospects
Whether CWD can be wiped out is,
of course, an open question, and to call the effort unprecedented
may not be stretching things too far. Some diseases have been
effectively eradicated in domestic animals, but it’s different
in the wild.
Manwell points to an early 20th
century outbreak of hoof and mouth disease in a wild deer herd
in California, addressed by severe reduction of the population
through hunting. “That’s the only analogy [to Wisconsin’s
current situation], and there was a successful outcome at that
time, but here we have a much more difficult disease,”
Manwell says.
More difficult, he explains, because
“animals may carry it around for a year and a half without
symptoms and we don’t know during what part of that time
they can infect others.”
Neither, logically, can we know
where they might carry the disease.
Almond, in Portage County, is
more than 60 miles from the major Disease Eradication Zone.
In September, a whitetail shot at a hunting preserve there tested
positive for CWD. State officials said early inquiries suggested
the deer was purchased from a game farm at Beloit, and that
facility has been placed under quarantine by the Department
of Agriculture, Trade and Consumer Protection (DATCP).
Asked about game farm animals
spreading CWD, DATCP spokesperson Donna Gilson told Wisconsin
Energy Cooperative News such facilities have come under stringent
regulation since the disease became an immediate concern.
“There are strict record-keeping
requirements for breeding farms; they have to account for every
animal entering or leaving,” she said.
Gilson added that hunting preserves
are required to be a minimum of 80 contiguous acres, enclosed
by fencing, and every animal shot in such a facility must be
tested for CWD. That adds up to closer monitoring than for deer
taken in the wild, she pointed out.
Manwell says it’s impossible
to tell if Wisconsin can ever again be completely free of CWD,
but cites “the considered opinions of the best minds working
on this: veterinarians, epidemiologists, wildlife biologists,”
who seem to agree, “If we are going to clear it out we
have to act quickly and decisively. We have our best chance
right now.”
Never Say Never
In a video produced for the DNR
Bureau of Communications and Education earlier this year, James
Kazmierczak, an epidemiologist with the state’s Division
of Health, remained reasonably confident that the combination
of careful testing and species barriers should leave hunters
without too much to fear from eating venison.
“If there is any risk—and
I said if—it’s likely to be quite low, based on
the fact that CWD has never been known to affect humans,”
he said.
He repeated warnings heard before,
about eating no part of an infected animal and in healthy ones
avoiding things that would probably be unlikely choices in any
case, such as the spinal cord, spleen, lymph nodes, tonsils,
brain, or eyes.
As for comparisons with more familiar
lifestyle choices that can threaten health and well-being—like
smoking, or drinking and driving—Kazmierczak said he’d
like to be able to offer that kind of perspective on the risk
of contracting CWD, “But it’s impossible to quantify
an event that’s never occurred.”—Dave Hoopman
Many can hunt free!
The key ingredient in the DNR’s
recipe for a healthy deer herd is lots of hunters, and CWD control
efforts give many the opportunity to have license fees waived.
People who own and hunt on land in the Disease Eradication Zone
can hunt for free, and so can anyone to whom they extend permission
to hunt there. For information on applying for the needed permit,
call 608-935-3368.
