Missouri conservation officials are hoping for a different outcome than Wisconsin had after an outbreak of chronic wasting disease in the wild population of white-tailed deer.
The outbreak in Wisconsin, which began with three deer in 2002, continues to spread despite aggressive strategies to keep it in check, said *Travis Anderson, wildlife biologist for the Wisconsin Department of Natural Resources.
Since the first three wild cases were confirmed in Wisconsin, about 1,800 wild deer have tested positive for the neurological disease out of about 177,000 samples collected, all in the southern third of the state, Anderson said. Infections in the wild increase yearly by 10 percent, he said.
“That number will go up,” Anderson said. “We’re finding more infections outside of the focus areas, and many deer that are harvested don’t appear sick.”
In Missouri, the disease first turned up in 2010 in one captive deer at a commercial hunting operation in Linn County with four more captive cases found at another commercial ranch in adjacent Macon County during October and December 2011 and March 2012.
In late January, Missouri announced it had found the disease in the wild for the first time when two bucks tested positive in Macon County — within two miles of Heartland Wildlife Ranches LLC, the commercial hunting operation where captive deer previously tested positive.
Testing in February and March around the Macon County ranch yielded three more cases in the wild — two does and one buck that brought the total number of wild deer known to be infected in Missouri to five. There's no evidence the disease has spread beyond northwest Macon County, said Jason Sumners, deer biologist for the Missouri Conservation Department.
All five cases of chronic wasting disease found to date in Missouri's wild population were within within two miles of the Macon County ranch.
"It's unlikely that chronic wasting disease will be successfully eradicated from Missouri's landscape," Sumners said.
"It's the nature of the beast we are dealing with that there is very limited opportunity to consider yourself successful," he said. "What is success when you have a disease on the landscape that nobody knows how to eradicate?"
The five cases of the disease in the wild were the first confirmed in Missouri since the Conservation Department began statewide testing in 2002 that totals more than 34,000 samples at a cost of about $12 per sample, or roughly $400,000. With no certified facilities to test for the disease in Missouri, the money was spent out of state, according to the Conservation Department.
Testing hunter-slain wild deer will continue during the fall deer season, as Missouri conservation officials look to Wisconsin and other states for help in countering the threat to a hunting industry that supports an estimated 11,000 Missouri jobs and $1 billion of business activity each year, according to the department.
Efforts in Wisconsin to contain the disease have been aggressive, but officials argue the state's deer population still needs to drop before a real impact is seen on the disease's spread, Anderson said.
Wisconsin added about three additional months of deer hunting to existing seasons that were specifically aimed at killing wild deer within the infected southern third of the state, said Timothy Marien, chronic wasting disease wildlife biologist for the state.
The extended season includes a holiday hunt starting on Christmas Eve and ending Jan. 8, and a landowner hunt beginning after the holiday hunt and lasting until March 31, he said.
Ruled by the Earn-a-Buck policy, licensed holiday hunters can kill one adult buck. If they wish to kill another adult buck, hunters must kill an antlerless deer first, Marien said. Hunters in the extra landowner shoot can kill an unlimited number of deer with free permits after buying a $2 license, he said.
In Wisconsin's traditional archery and firearms seasons, hunters must also follow the Earn-a-Buck policy when more than one adult buck is killed, Marien said.
Natural Resources Department officials had used agency sharpshooters to kill deer in overpopulated areas during 2002 and from 2003 to 2006 during winter, Marien said. The practice ended in part by landowner and hunter disapproval, he said.
Outside Illinois, very few infected states have urged hunters to kill as many deer as in southern Wisconsin, Anderson said.
Sumners said a large-scale wild-deer depopulation doesn't necessarily work for Missouri, and additional deer hunting seasons are not being considered at this point.
"I think all options have to be on the table as far as discussions are concerned," Sumners said.
Conservation Department officials are more intrigued by targeted culling, or the selective shooting of wild deer within a few square miles that's known to be infected, to reduce the population, remove potentially infected deer and reduce interactions that spread the disease, he said.
With bucks being more likely to carry the disease, the Conservation Department is considering relaxing antler-size restrictions that would allow more hunting of younger bucks, Sumners said.
Banning recreational deer feeders and salt licks — a lesson learned from Wisconsin, Illinois and other states — is another measure on the table, Sumners said. Feeders and salt licks induce a large amount of deer to gather at a specific location, giving diseased deer the chance to infect others through interaction, he said.
The transportation and disposal of infected carcasses also needs attention, as both could transport the disease to different parts of the state, Sumners said.
The Wisconsin Natural Resources Department fights the disease in two main regions where the disease in most endemic, Anderson said.
The highest rate of wild infections lies west of Madison, where he said up to one in four adult bucks and about 7 percent of adult does carry the disease. In the southeast corner of the state, he said, prevalence of the disease is lower though still a problem.
The sale of deer hunting licenses in Wisconsin declined by about 10 percent from 688,540 in 2001 to 618,945 in 2002 when the syndrome was first detected, according to a 2010 Wisconsin State Journal report. While those numbers rebounded in 2003, permit sales never returned to 2001 levels and showed declines of 2 percent in 2009 and 1.5 percent in 2010, according to the report.
Overall, $3.4 million was lost in wildlife management from the 2002 decline in deer hunting licenses, in addition to more than $11 million that was reallocated — mostly from wildlife management — to combat the disease in Wisconsin, according to a journal article from the University of Wisconsin-Madison.
Also in 2002, Wisconsin lost an estimated $55 million in resident hunters' travel, hunting equipment purchases and other general hunting expenditures such as land leases, deer licenses, permits and tags, according to a separate journal article from the University of Wisconsin-Madison.
The article noted that the estimated $55 million wasn't a total loss to the Wisconsin economy, as the resident hunters who decided not to hunt in 2002 "likely spent the money elsewhere in the state." A total loss in the market likely equaled about $6 million in 2002, resulting from a more than 19 percent decline in non-resident hunter tourism, stopping money into the state, according to the article.
The initial decline was a result of discovering the disease in wild deer, Marien said. The decline in later years is attributed to policies like the Earn-a-Buck program before it was revised in 2011, and an overall national decline in hunters and the economy, Marien said.
The disease affects elk, moose and deer. Missouri Agriculture Department and Division of Animal Health officials said there is no scientific evidence that the disease affects livestock or humans.
Ermias Belay at the Centers for Disease Control said the barrier for the disease to jump from deer to humans is substantial.
“We can never say never,” Belay said. “The barrier is substantial, not absolute.”
Missouri health officials advise against the consumption of meat from deer known to carry the disease. The disease can be present for up to three years in deer or longer before the onset of symptoms, according to the Conservation Department.
Minnesota, which found one infected wild deer in 2010, and New York, which found two infections in 2005, served as about the only glimmer of hope, Sumners said. To date, both states have yet to detect additional wild infections, he said.
"But with three additional positives in our sampling, I think that glimmer of hope faded to a single photon of light," Sumners said.