VIENNA — Scores of landowners from Maries and Osage counties filled the bleachers at the Knights of Columbus Hall in Vienna on Jan. 25 for an informational meeting about chronic wasting disease …
VIENNA — Scores of landowners from Maries and Osage counties filled the bleachers at the Knights of Columbus Hall in Vienna on Jan. 25 for an informational meeting about chronic wasting disease (CWD).
The Missouri Department of Conservation (MDC) hosted the meeting to provide landowners with an update about recent CWD detection in the area. In the last couple of months, MDC has found the disease in samples taken from two white-tail deer in Osage County and one in Maries County.
According to the agency’s website, Chronic Wasting Disease is a deadly illness affecting white-tailed deer and other cervids. Misshapen proteins cause the disease by concentrating in the brain and lymph nodes of infected animals. The disease is more likely to occur in adult male deer. Symptoms of the disease include excessive salivation, drooping head and/or ears, tremors, emaciation, lack of coordination and change in behavior. CWD is always fatal to infected deer.
CWD has no known treatment or cure. As a way of limiting the spread of the disease, MDC focuses on closely monitoring and testing the deer population.
Aaron Hildreth, a cervid programs specialist with MDC, gave a presentation about CWD, the agency’s efforts to stop its spread and how the public could assist. He began by sharing the frustration employees of the agency feel because of the disease.
“Every single person wearing a triangle would rather do pretty much anything else than deal with CWD,” he said. “It’s a disease that is miserable to deal with.”
The first part of Hildreth’s presentation discussed CWD itself. He said part of what makes the disease frustrating when compared to other kinds of illnesses is the fact that the disease is not a living organism. Bacteria or viruses do not cause it. Proteins called prions create the problem, which makes it difficult to treat.
“The only thing we can do is try to find a way to denature it,” Hildreth said. In biochemistry, the term refers to the destruction of the characteristics of proteins or other macromolecules through heat, acidity or other effects to disrupt the molecular structure.
Although MDC is unaware of any natural prevention of CWD, the disease spreads slowly. Hildreth said that if conservationists took no action over the next few decades, the public might not notice a significant change in the deer population. However, once the population noticed an increase in sick deer and a decrease in the deer population, it would be too late to apply aggressive management to curb the disease.
As an illustration of CWD’s slow spread, Hildreth shared several maps of the disease’s progression. Researchers first found it in Colorado in 1967. Within a few years, it had made its way to Wyoming. Most other states did not begin detecting the disease until the 2000s.
CWD spreads through both direct contact with an infected deer and environmental contamination. Animals may pass along infected prions through saliva, urine or feces. Researchers suspect that direct transmission is the likely cause of an area’s early contamination before becoming a more prevalent part of the environment over time.
Hildreth reminded attendees that MDC is not a health organization and does not make recommendations on matters of public health. However, at this time, there is no documented case of CWD spreading to humans. The Centers for Disease Control and Prevention recommends that anyone harvesting a deer in an area where CWD has been detected get the deer tested before consumption.
In addition to spreading slowly, CWD also takes time to present as symptoms in infected animals. Hildreth said the average minimum time span between infection and the start of symptoms is about 18 months. Although deer may not be displaying signs, they could be infected and spread the disease. At the end of last year, MDC had found 511 infected deer throughout the history of testing. Only a handful of those deer appeared outwardly sick.
Deer infected with CWD are more likely to die from any cause. Most testing for CWD occurs after a deer dies, but a study in Wisconsin tested and tracked live deer using tonsil biopsies. One year after the tested deer were released, the researchers checked how many of the deer had survived. Factoring in all causes of death, 70 percent of the deer without CWD had survived while only 30 percent of the deer with the disease survived.
In 2001, Wisconsin detected CWD in some of its deer population. The federal government provided funding to states to sample deer populations for a decade, so Missouri began testing deer in 2002. The first detection in Missouri was in 2010 with a captive deer. The first free-range detection occurred the following year. In more than 20 years, MDC has tested more than 265,000 deer.
When MDC takes a sample from a deer, it sends the sample to the University of Missouri for testing. The first test examines a small piece of a deer’s lymph node. If researchers suspect the test shows infected prions, then they conduct a confirmation test. After two more tests, if all three tests conclude infected prions, then the tests confirm an infection. In cases where a sampled deer came from a location more than 10 miles away from another confirmed positive, then researchers use two additional tests to confirm an infection.
Hildreth said MDC gets many questions about why the agency spends time combating CWD.
“It’s because a heck of a lot of people care about white-tail deer,” he said.
Hildreth shared some data to support his statement. About 500,000 people in Missouri hunt white-tail deer each year. The practice of hunting white-tail deer contributes about $1 billion annually to the state economy. The free-range hunting of white-tail deer supports about 12,000 jobs in the state.
“Unfortunately, we know that CWD can have long-term population impacts if we do nothing,” Hildreth said. “That’s one of the reasons we have to focus the time and effort on it.”
Hildreth addressed a misconception that MDC works to manage the disease because it makes money in the process. Although efforts to conserve the deer population can bring the state some federal money from the Pittman-Robertson Act, the management of CWD comes at a net cost to the agency.
“Every hour that staff spends managing this disease is time that they can’t spend working with private landowners to help manage their property,” Hildreth said. “It’s time that we can’t be working on public lands. Time we can’t be doing prescribed burns.”
MDC takes a couple of approaches to managing CWD. The first is through broad-scale surveillance. An example of this would be testing that occurs when deer are sent to taxidermists or meat processors. More than 100 of those businesses across the state work with MDC to sample deer for disease. The agency also uses regulations such as bans on feed and mineral supplementation for the deer population. MDC is also working to make freezers for sample drop-offs available in counties with CWD management zones.
Another approach by the agency is active management.
“Active and aggressive management is buying us time,” Hildreth said. “We are not going to eliminate CWD from Missouri. I wish we would, but we’re not going to be able to. It’s not possible at this point in time with the science and technology we have.”
MDC breaks areas into sections called cores when looking at managing the deer populations. Cores encompass an area of about two miles around the site of a confirmed infection. Maries County has one core. Osage County breaks into two separate cores labeled Osage 1 and Osage 2 because MDC has confirmed two infections there.
Permitted ‘targeted removal’ through March 15
Landowners within the core areas may apply for permits to help increase sampling within the core through a process called targeted removal. From Jan. 16 to March 15, permit holders may kill deer in the core area for the purpose of having them tested for CWD. MDC sets harvesting goals that serve as hard caps for permit holders. The Maries core may harvest up to 70 deer as part of active management. Each of the Osage County cores may harvest up to 80 deer. Eligible landowners will receive letters that they may apply for a no-cost permit. Targeted removal only occurs with landowner permission.
“By doing this only in the cores, it allows us to greatly limit the scale on the Missouri landscape where we’re doing this,” Hildreth said. “We’re trying to work as close to positives as we can.”
Landowners may also authorize MDC to send its own team to harvest deer on their property. The landowners set the rules for the team and how many deer it can kill on their property.
“We want to work with you however you’re willing to want to participate with us,” Hildreth said.
Deer killed during the targeted removal period do not go to waste. If a deer does not test positive for CWD, then the landowner may choose to take the meat. MDC covers the cost of having the deer processed into ground meat though a landowner can choose to have the meat processed another way at their own cost. If the landowner declines the meat, then MDC supplies it to people in need through its Share the Harvest program.
Hildreth shared data on Missouri’s deer population to put the impact of targeted removal into perspective. On average, Missouri hunters harvest more than 300,000 deer annually. Since 2012, MDC has killed 17,000 deer through targeted removal. Targeted removals accounted for about 40 percent of positive CWD cases in Missouri.
“Targeted removal works,” Hildreth said. “Seven percent of the samples we’ve taken today are from targeted removals, but they still account for 40 percent of the positives we’ve had through the end of the last fiscal year.”
If a core reaches its targeted removal goal and does not return any more positive CWD results, then a targeted removal season will not be necessary next year. However, if targeted removal returns another positive test, then the season will resume next year. If several more positive tests occur, then targeted removal will likely become a long-term fixture in the core area.
“There’s nothing about managing this disease that is fun or enjoyable for anyone in the process,” Hildreth said. “We would not be here asking if it wasn’t important.”
At the end of the presentation, Hildreth spent about 30 minutes answering questions from those in attendance. Several MDC agents and staff were at the meeting to help sign eligible people up for targeted removal permits.
More information about CWD and conservation programs related to it are available online at mdc.mo.gov/hunting-trapping/species/deer/chronic-wasting-disease.