Chronic wasting disease threatens Missouri's $1 billion deer hunting culture

Based on numbers from the U.S. Fish and Wildlife Service, all those deer hunting permits, sales of archery gear, rifles and ammunition, hunting clothing, taxidermy services and other hunting-related dollars are worth about $1 billion to the Missouri economy each year.

But the presence of an insidious ailment called chronic wasting disease might threaten the future of deer hunting in Missouri.

It's 100 percent fatal in deer and elk that contract it and renders meat inedible, though there have been no confirmed cases of CWD transmission to people, according to the U.S. Centers for Disease Control and Prevention.

So far, Missouri's wild deer population remains relatively safe from CWD — only 75 confirmed cases have been found since the state conservation department recorded the first case in the wild in 2012. But it's what has happened in other states that worries Missouri wildlife biologists.

In Colorado, Wyoming, Nebraska, western Kansas and southern Wisconsin, CWD has spread widely in wild deer and elk herds. In the past two years, an outbreak of CWD in northwest Arkansas has resulted in 370 positive tests, mostly in the region's deer.

An emaciated Kansas deer suffering from CWD. (Photo: MDC)

There hasn't been an effective and proven way to stop CWD, though one controversial method shows some promise, according to Jasmine Batten, the Missouri Department of Conservation wildlife disease coordinator who is leading the state's effort to halt the disease.

When CWD is discovered in Missouri, the conservation department targets deer within one to five miles of where the positive test occurred. Landowners and MDC staff shoot a certain number deer in those areas, both to test them for CWD and to remove a greater number of deer that have been exposed to CWD.

The process is known as targeted culling.

Fewer infected deer in the population may help slow the pace of the disease's spread and limit the amount of CWD in the soil, plants and water. At least that's the theory, Batten notes, adding that not all deer are killed in a culling area.

Jasmine Batten, wildlife disease specialist with the Missouri Department of Conservation (Photo: Wes Johnson/News-Leader)

"We learned a lot from the state of Illinois, which has been culling deer for 16 years or longer," Batten said. "Culling decreases the prevalence of CWD, especially compared to its neighbor to the north (Wisconsin). Once the disease becomes too widespread, the chance to limit it really goes down."

Wisconsin tried culling but stopped the practice after deer hunters and landowners protested. The state went back to monitoring for CWD. The result: CWD began spreading again after culling was halted.

In Missouri, MDC staff and landowners who agreed to participate in targeted culling have killed approximately 4,600 deer since culling began in 2013. MDC has spent $2.15 million on culling efforts, which includes the cost of lab testing, staff time and payments to meat processors.

Meat that's free of CWD is returned to landowners or donated to MDC's Share the Harvest program.

Tainted meat is destroyed.

During hunting seasons, landowners in designated CWD Core Areas also can get up to five "CWD Management Seals" from MDC that let them take more deer than a typical deer permit allows. MDC reimburses the landowner $60 per deer for the cost of processing the meat.

The purpose of those seals is to help reduce the deer numbers where CWD has been found and to test more deer for CWD to gauge how deeply the disease has infected deer in those areas.

Culling 4,600 deer over the past five years might sound like a lot, but it's a small number compared to the 1.36 million deer that Missouri hunters killed in approximately that same time frame.

If culling works to slow the spread of CWD in Missouri, it's worth it, Batten said.

"We absolutely have those concerns, that CWD could be a threat to Missouri's long-term hunting culture," she said. "But there's no way around the fact that in these very localized areas where CWD was confirmed, landowners who participate are making a big sacrifice. Deer densities will decrease in these culling areas. But our goal is to slow or stop the spread."

How CWD works

Photos: KTHV, MDC

CWD is caused by a strange, misshapen protein called a prion that can be transmitted from deer to deer by physical contact. It also is spread by contact with soil, food, and water that have been contaminated through feces, urine, saliva — and carcasses — of infected deer.

Velvet that bucks rub off from their new antlers? CWD can be transmitted in that soft material. Batten said it's possible, though less likely, that the blood trail left behind from a wounded deer infected with CWD could transmit the disease to other deer.

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A CWD-infected deer will lose weight and stagger around, eventually dying from the disease. Perhaps more significantly, once a deer dies, those prions can persist in the ground long after the deer decomposes and can continue to infect other deer.

Even forest fires aren't hot enough to kill prions in the environment.

Another problem with CWD: It might take 18 months or more for an infected deer to look visibly sick. During that time, though, it's still spreading prions in the environment.

A growing problem in 23 states

Nationwide, CWD has been found in 23 states and continues to spread, according to Kip Adams, spokesman for the Quality Deer Management Association. QDMA, based in Georgia, works with hunters, landowners and state conservation agencies to improve the habitat and health of wild deer.

"CWD is one of the biggest threats to deer hunting and deer management programs," Adams said. "We are seeing population declines in deer herds, especially in Wyoming, and there's been no real success in states keeping it out of their borders."

Missouri hopes to stop what has happened elsewhere. In states like Colorado, Wyoming and Wisconsin, where CWD is now deeply entrenched, deer herds are diminishing. In Wyoming, 19 percent of the wild deer herd now dies annually from CWD, according to conservation figures.

While deer hunting is declining nationwide for many reasons, the prevalence of CWD in popular hunting areas is one of them. There is concern that the fear of eating deer or elk contaminated with CWD might deter others from taking up the sport.

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Adams said it's believed that CWD might have jumped from sheep to captive deer in Colorado in the 1960s, possibly through a mutated version of scrapie — a neurological disease in sheep caused by prions.

"They suspect it went from those captive deer to the wild population," Adams said. "Deer, elk and moose are the only animals that get CWD, and elk are not nearly as susceptible to it as deer."

He said MDC's intense effort to sample deer for CWD — as well as its culling efforts where CWD is found — is a good approach.

"Nobody in the country is sampling deer at as high a rate as MDC," he said.

MDC began testing deer for CWD in 2001, after seeing the disease spread in neighboring states. It now encourages voluntary testing of deer killed by hunters, as well as mandatory testing in 31 counties where CWD has been confirmed, or where it's likely to appear, such as southern counties bordering Arkansas.

While it's true that no human has contracted CWD from handling or eating an infected deer, Adams said the CDC's warning against eating CWD contaminated meat should be strictly followed.

"We don't know that barrier will always be that way," he said.

First contact in Missouri

How did CWD arrive in Missouri? That's a troubling question, according to MDC's Batten.

She said the first confirmed case was discovered in 2010 in a herd of captive deer at a big-game hunting preserve in northwest Missouri.

"That detection behind the fence triggered wider testing of our wild herd," Batten said. "In 2012 we had five positives in wild deer within one or two miles of that positive game preserve. We think it's a likely vector, but we can't say with certainty that's where it came from."

The captive deer at the preserve were destroyed, Batten said.

Once in Missouri's wild deer, CWD began showing up in pockets around the state. Batten said it is unlikely the disease is spreading in Missouri's herd of approximately 1.2 million deer through natural deer dispersal alone. It is likely that humans are helping to spread the disease, potentially through the movement of infected deer carcasses.

"It spreads slowly in the environment," Batten said. "We know it's progressing in the state, but we can't say with any certainty how it's spreading. We also can't assume the disease was introduced into the state only that first time."

The possible link between captive deer and CWD prompted the Missouri Conservation Commission in 2015 to tighten rules on businesses that hold or raise captive deer, requiring higher fences to prevent escapes, more testing for CWD and a ban on importing captive deer into Missouri.

According to MDC, as of July Missouri had 44 permitted big-game hunting preserves and 138 permitted wildlife breeders with white-tailed deer. Those operators reported about 150 captive deer escaped into the wild between 2012 and 2014.

Several Missouri deer breeders and big-game hunting preserves sued MDC, claiming captive deer were livestock, not wild animals, that were beyond MDC's authority.

They succeeded in getting an injunction to stop the implementation of the tougher regulations.

But in July, the Missouri Supreme Court ruled in favor of MDC, giving it full regulatory control over captive deer and elk and upholding the tougher rules the conservation commission approved in 2015.

Now that it understands how CWD is affecting Missouri's wild deer, MDC is proposing several new regulations to slow the disease's spread.

The department will be taking public comment on the proposals, and the earliest any of the rules could realistically go into effect would be the fall of 2019.

Ongoing efforts

MDC conducts a mandatory sampling for CWD during deer opening season at Whetstone Creek Conservation Area in Williamsburg. Tissue from the deer's neck is taken for testing in the lab. (Photo: MDC)

MDC is offering free CWD sampling and testing of deer harvested anywhere in the state throughout the entire deer hunting season, which runs through Jan. 15. The sampling is voluntary, and hunters can also get free test results for their deer.

Hunters can have their deer sampled at 11 select MDC offices around the state. Hunters can also take their deer to 64 participating taxidermists and meat processors located in the 48 counties of MDC’s CWD Management Zone.

Find locations and more information on voluntary CWD sampling at mdc.mo.gov/cwdunder “Voluntary CWD Sampling All Season.”

Hunters can get test results for their CWD-sampled deer online at mdc.mo.gov/CWDTestResults.

Mandatory CWD sampling Nov. 10 and 11

MDC will again conduct mandatory CWD sampling in 31 of the 48 counties of its CWD Management Zone during the opening weekend of the fall firearms deer season, Nov. 10 and 11.

The counties include new ones added to the CWD Management Zone, counties with previous CWD positives, and counties very near previous positives.

The 31 counties for mandatory CWD sampling are: Adair, Barry, Bollinger, Cape Girardeau, Cedar, Cole, Crawford, Franklin, Grundy, Hickory, Jefferson, Knox, Linn, Macon, Madison, McDonald, Mercer, Moniteau, Ozark, Perry, Polk, Putnam, St. Charles, St. Clair, St. Francois, Ste. Genevieve, Stone, Sullivan, Taney, Warren and Washington.

Hunters who harvest deer from these counties Nov. 10 or 11 must take their deer — or the head with at least 6 inches of the neck in place — on the day of harvest to one of MDC's 61 CWD mandatory sampling stations. Deer may be presented at any mandatory sampling station.

Find locations for mandatory CWD sampling at mdc.mo.gov/cwd under “Mandatory CWD Sampling Nov. 10-11.”

Proper deer disposal to limit CWD

MDC reminds deer hunters that properly disposing of carcasses of harvested deer is important in limiting the spread of chronic wasting disease. MDC also reminds hunters who harvest deer, elk, or moose outside of Missouri and bring the animals back to follow related regulations to help limit the spread of CWD.

To help avoid this exposure risk, MDC recommends the following carcass disposal methods:

• Place in trash or landfill: The best way to prevent the spread of CWD is to place carcass remains in trash bags and dispose of them through trash collection or a permitted landfill;
• Bury on site: If you can’t bag and place in trash or a permitted landfill, bury carcass remains at or near where the deer was harvested. Bury deep enough to prevent access by scavengers. Burial will reduce but not eliminate the risks of spreading CWD;
• Leave on site: As a last resort, leave carcass remains on site. While this will not prevent scavengers from scattering potentially infectious parts, the remains will stay in the general area where the deer was taken. If CWD is already present in that area, it will likely remain there and not be moved to another area;
• Do not place in water: It is illegal to dispose of carcasses or remains in streams, ponds, or other bodies of water;
• Do not burn: Only commercial incinerators reaching over 1,800 degrees Fahrenheit can generate enough heat for long enough to destroy the prions that cause CWD.