Massive Sampling Effort Shows Management is Working
Thank you deer hunters and landowners, your help is invaluable in the Conservation Department’s efforts to limit chronic wasting disease (CWD) in Missouri’s deer herd. Tests from harvested deer guide future management, and results suggest that proactive management has limited the disease.
A half-million deer hunters harvested more than 263,000 deer during the past hunting seasons, so Missouri’s deer herd is still robust. However, CWD is a serious long-term threat — one the Missouri Department of Conservation (MDC) is proactively addressing with the help of hunters and landowners.
MDC conducted a massive, unprecedented sampling of 19,200 deer harvested during opening weekend of last fall’s firearms deer season. Those deer were from a 29-county CWD Management Zone surrounding prior cases. Testing lymph nodes from those deer revealed five new CWD cases. A sixth case was also recently found in a deer harvested by a landowner utilizing special permits issued in core zones. That’s critical because knowing the locations and prevalence of CWD helps wildlife managers battle a deadly deer disease, but one thus far mostly limited to a relatively small number of deer in northeast and eastern Missouri.
CWD is a fatal degenerative brain disease without a cure that affects deer, elk, and moose. The cause is associated with misshapen proteins in cells called prions. Test results from the deer harvested in the CWD Management Zone provide both concern and encouragement.
MDC biologists are concerned because two new cases — one in southwest Franklin County and another in southeast Jefferson County — were quite a distance from previous CWD sites. However, an upside is tests did not find substantial CWD expansion in deer harvested near core areas in Macon and Adair counties where past cases were found. Adair County had one new CWD case confirmed and Macon County had two new cases.
Since early 2012, landowners and MDC staff with permission from landowners have taken additional deer following the hunting season in small CWD core areas in Macon and Adair counties. Those efforts removeddeer with CWD and reduced the chances of disease transmission.
“It suggests the management we’ve done in these areas is working because we’re not seeing a steady increase in prevalence,” said Barbara Keller, MDC resource scientist. “The cooperation and sacrifice made by many local landowners has been critical in slowing the spread of CWD in Macon and Adair counties.”
Also in recent tests, one new case was confirmed in northern Franklin County in the vicinity of a case confirmed during the 2015–2016 hunting season. Mandatory sampling and testing found no new cases in Cole or Linn counties. Each had one case in past years.
MDC has conducted sampling for CWD since 2002. Because of this prolonged history of CWD testing, biologists did not expect to find a large number of cases from the mandatory sampling effort. The five recently confirmed cases out of more than 19,200 samples confirmed that expectation.
“This history of sampling means that when we’re finding it, it is not very well established,” Keller said. “We’re finding it early. But the recent positives may have gone undetected for some time without the huge sampling effort last fall.”
MDC’s proactive approach protects deer treasured by wildlife watchers and hunters. Deer hunting in Missouri generates $1 billion annually.
Large-scale disease testing and reducing deer numbers in specific target zones are exhaustive measures. But they draw on best-known practices to protect the entire state’s white-tailed deer heritage.
Some states that have not taken far-reaching steps to limit CWD have seen the disease spread broadly across deer habitat, said Jason Sumners, MDC Wildlife Division chief. In Wisconsin, the prevalence of CWD is steadily rising, with more than 40 percent of adult male deer in one core area infected with the disease. Illinois, however, has had success limiting CWD spread by aggressive management in the corner of the state where the disease was found.
“Our goal is to detect it as early as possible so we can implement management practices that limit the number of deer infected with the disease, and in doing so limit the geographic spread,” Sumners said. Otherwise, “at some point, if we’re not successful, it’s no longer a local issue but a regional or a statewide issue.”
The Department will adjust the CWD Management Zone and surveillance practices in target areas according to research data in specific locations, he said. Additional counties near confirmed cases may be added to the management zone.
Also, increased testing of deer began in southwest Missouri after CWD was detected in northwest Arkansas. MDC staff collected samples from road-killed deer, and hunters offered deer harvested during the recent season for testing. No deer in southwest Missouri have tested positive for CWD. But MDC will likely continue enhanced sampling efforts there as a precaution.
CWD management may temporarily drop deer numbers in small target areas.
“It is an unfortunate but necessary step to protect the state’s deer herd,” Sumners said.
But deer populations rebound quickly in good habitat. Missourians value deer and all wildlife, so MDC is sparing no effort to battle CWD.
“We’re trying to do everything we can to ensure for the long term the health of our deer herd so our children and grandchildren can continue to enjoy them,” Sumners said.
Where Has CWD Been Found in Missouri?
The first cases of CWD in Missouri were detected in 2010 and 2011 in captive deer at private big-game breeding and hunting facilities in Linn and Macon counties. A total of 11 cases were confirmed in captive deer at the facilities. The total number of Missouri free-ranging deer that have tested positive for CWD is 39, with 23 found in Macon County, 10 in Adair, three in Franklin, one in Jefferson, one in Cole, and one in Linn.
The Centers for Disease Control says there is no evidence that CWD can be transmitted to humans. But the agency recommends that humans not consume deer that look sick or have tested positive for the disease. For more information on CWD, visit short.mdc.mo.gov/Z3N.