More research needed in CWD disease
Wednesday, February 15, 2017 10:51 AM
By Gretchen Mensink Lovejoy
Bluff Country Newspaper Group
Cars lined Main Street and the side streets surrounding the Chatfield Center for the Arts (CCA) last Wednesday evening as hunters, deer farmers and landowners from Chatfield, the surrounding area, and as far away as Hayfield, Byron and upper Iowa towns gathered at Potter Auditorium for a presentation on chronic wasting disease (CWD). CWD now affects wild deer populations in southeastern Minnesota, parts of Iowa and Wisconsin.
Guest speakers at the event included Dr. James C. Kroll, professor emeritus of forest wildlife management; Patrick Hogan, associate publisher of North American Whitetail; and Clifford F. Shipley, attending veterinarian at the University of Illinois College of Veterinary Medicine.
What is CWD, where is it?
Shipley explained the first recorded incident of CWD was noted in Fort Collins, Colo., in 1967, but the disease might have existed before that.
He related wild deer were put in captivity, and by the time the researchers approached completion of their experiments, the deer had all died.
In 1978, it was discovered that the disease is transmissible, and it was discovered in wild elk in 1981. By 2000, it had been found in mule deer in Saskatchewan.
Shipley noted CWD is not the only prion disease found in mammals.
“There are other prion diseases in other species – scrapie is CWD for sheep, and it’s a very common disease in sheep and goats. Then there’s bovine spongiform encephalopathy, or ‘mad cow disease,’ and there’s CWD in humans – Creuzfeld-Jakob disease,” Shipley explained.
“A prion is not a bacteria or a fungus, but there are theories that it may bind with the soil, or particles may bind with plants. It’s resistant to sterilization – that’s darn near impossible.”
How does it spread?
The most popular theory as to how CWD ended up in the deer populations is that it is transmissible by oral, fecal or saliva contact – with saliva being the most implicated – or through contact with infected muscle or nervous tissue.
Shipley pointed out, “Deer are social animals, and they groom each other. They could be getting it from mineral licks – salt or natural – or it’s because they share habitat and food.”
He stated that other theories of transmission include deer scavenging deer bone and gut piles after the death of other deer, transportation by coyotes and other predators, through taxidermy and improper disposal of infected deer carcasses.
Shipley assured the audience that CWD is not zoonotic, meaning it doesn’t have a link between deer and humans, though it is advised that deer that test positive for CWD are not processed into meat.
“It doesn’t affect other domestic livestock like cattle, sheep and goats,” he added.
Shipley remarked it is often perceived that farmed deer are to blame for being a cause of CWD’s spread, but so far, that has yet to be proven.
Culling won’t eradicate it
Kroll then spoke, opening with the question, “Does anybody in this room like to see the whitetail deer extinct and deer hunting gone forever?”
Silence followed, and Kroll outlined his experience as the man appointed to be in charge of the management of deer in Wisconsin at the outset of the discovery of CWD among wild whitetail populations.
He stated he witnessed the increase in deer hunting limits and the use of sharpshooters to take out deer that were obviously suffering from CWD resulted in Wisconsin only having fewer deer – the disease had not been vanquished or even slowed.
“What we found were two interesting data sets. It became obvious that it was more prevalent among older deer, and especially among older male deer, the trophy bucks,” Kroll said.
He highlighted that the efforts to eradicate CWD illustrated that it is not a “density-based disease, but a frequency-based disease.”
“You can try to eradicate all day – culling won’t work – but you’ll still have CWD,” he said.
Kroll maintains that whitetail deer are among the most poorly-managed species in the country, but he advocates for the targeted removal of the animals’ social groups, those in which there are animals wasting away.
“The deer population is not declining because of CWD, but because of poor management,” he reiterated.
“We’ve spent millions on research and testing stuff, but we still don’t know the questions to ask – like how long it’s been around, where it’s originated, and can we artificially change its resistance.”
Working together is important
Kroll encouraged attendees – hunters, landowners and deer farmers alike – to become involved with the process of managing deer and following the evolution of CWD.
The panel took questions. A person wanted to know what the likelihood is that CWD could mutate over time?
Shipley answered that professionals “still don’t know a lot about CWD.”
While there have been research facilities that have harbored animals for study, he said when those animals died and the facilities were cleaned and allowed to stand without infected animals on them, the replacement herd that was brought in for further study died of CWD.
Kroll countered, “The science is not complete on the plant thing, but we know that a deer has to be exposed to the prion many, many times before a deer gets CWD.”
Shipley reiterated, “Everybody needs to work together – the DNR, the landowners, the farmers. I wish there were a live test to help everybody if the DNR wants to move live deer, but there isn’t.”