One question, two answers when it comes to CWD

Published on Saturday, 7 October 2017 16:52 - Written by STEVE KNIGHT,

Chronic Wasting Disease in animals like deer and elk is a little like climate change. Everyone agrees something is happening, but no one seems to agree on what is causing it and what to do about it.

That is certainly the case when talking about state wildlife agencies and those who farm the animals. Both agree CWD can be found in rearing-pens and the wild, but those in the business of raising deer certainly don’t agree with what they feel is heavy-handed regulations by state wildlife agencies, including requiring individuals to euthanize pens of animals when the disease is detected and hamstringing deer shipments.

The American Cervid Alliance, an umbrella organization working with 51 deer and elk producer associations, recently released a paper they feel debunks some myths about CWD. Dr. Don Davis, a retired associate professor at Texas A&M University College of Veterinary Medicine, prepared the paper.

Davis writes that much of the concern surrounding the disease found in wild or pen-reared herds in 24 states and two Canadian provinces is “rooted in fear.” He said one example is that detection of the disease in an area could impact a local herd and deer hunting opportunities.

“From a scientific point of view, the evidence so far is that the effect is biologically insignificant. CWD has a long incubation period. It could be years before it has an effect on a deer. Deer will often die of something else first, such as predation, starvation or hunting. Researchers at the University of Wisconsin found ‘no evidence that CWD was substantially increasing mortality rates’ when they studied the issue,” Davis said.

The Texas Parks and Wildlife Department agrees that CWD-affected deer are more likely to die from cause other than the disease because of its effects, however, the department disagrees on its impact on infected populations.

“Peer reviewed research indicates CWD has had a significant impact on some white-tailed deer, mule deer and elk populations. In fact, CWD is a population-limiting disease in those populations,” according to a response crafted by Clayton Wolf, TPWD Wildlife Division director, Mitch Lockwood, Big Game Program director and Dr. Bob Dittmar, TPWD veterinarian.

They added that the slow-acting nature of the disease could allow it to become established within a population and area before being detected.

The former professor said another fear that has become “overblown” is that people could become scared of hunting because of CWD. Davis said a study released last summer in which researchers were able to infect monkeys with CWD has created talk.

“While the research, which has not been peer-reviewed, made for scary headlines, a look at the methodology shows a number of flaws, such as the fact that some of the transmission methods used to infect do not occur in nature. Unless something more substantive emerges, let’s stick with the (World Health Organization’s) observation,” he wrote.

TPWD again agrees, but disagrees, noting that the study was using macaques monkeys that do not have human-like traits. However they note the study has raised some red flags.

“We are quick to remind people that macaques are not little humans, but this research finding raised enough concern with the CDC that they have since changed their statement regarding testing harvested deer and consumption of venison from animals that test positive. They strongly recommend that hunters test their deer/elk, and they recommend that venison from infected animals not be consumed,” the department’s counter read.

Davis added CWD was found in the wild 30 years ago in Colorado. Still the state’s hunting heritage and wildlife populations remain strong.

In contrast, TPWD argues that not all the state’s deer populations remain strong where the disease has been found and some that have had a do-nothing approach or limited involvement are reviewing their stance.

Then comes the big debate between breeders and wildlife agencies, what can or should be done.

“Some states like Missouri and Minnesota have seen calls for state authorities to put draconian restrictions on deer farming or private hunting ranches in light of CWD being detected on a handful of these facilities. However, this isn’t logical. Farms are closely regulated by state and federal authorities to monitor for CWD. If CWD is detected on a private deer farm or hunting preserve, it’s possibly a ‘canary in the coal mine’ situation where the disease spreads to the local, free-roaming wildlife and then onto the farm or vice versa,” Davis said.

TPWD, which is joined by Texas Animal Health Commission in CWD management in the Texas, said monitoring of breeder deer is done only on mortalities within captive facilities in Texas. That, they explain, results in a low probability for early detection, and that even federal and state programs have not been foolproof. State officials say four of eight new CWD-positive deer breeding facilities in other states were enrolled in USDA’s and their local state’s certification program. A fifth had positive testing deer linked back to a facility under a monitoring program.

Davis contends that since the disease is already in the wild, even if private deer farms were banned it would continue to spread.

TPWD admits ideas for CWD management are evolving, but says those states that did nothing are now feeling the effects. That is why the department has been proactive in collecting samples, changing rules on deer movement both alive and in carcass form and setting up check stations.

“Of course, the disease can spread much faster over much larger geographic area when being transported in a trailer. TPWD cannot protect the vast majority of Texas from CWD if we allow the movement of deer from CWD infected areas or facilities. Diligent surveillance is the only way to determine where CWD exists,” the department said.

Davis said some aids in the future for deer breeders could be a vaccine against the disease and an accurate live-animal test as opposed to the current post-mortem test approved by the U.S. Department of Agriculture. Live animal testing was adopted in Texas for intrastate movement even though it is not approved under USDA plans.

“If these efforts are successful, they may help in controlled areas, such as hunting ranches or research facilities. But it’s unrealistic to expect states to try to vaccinate millions of deer in the wild,” Davis said.

And finally, because it already exists and he believes nothing can be done, Davis said, “In other words, we’d be better off worrying about deer-car collisions.”

Of course the department sees it a little differently.

“This is a relatively new disease in terms of how long we have known about it. Using caution now is prudent, and research may eventually give us more tools to manage this disease,” the department said.