CWD FAQs

CWD is a fatal, contagious brain disease caused by a misfolded protein that affects deer and other members of the deer family (called cervids). It was first discovered in Colorado during the 1960s and has since been detected in most states and several other countries. CWD poses a significant threat to Missouri’s deer population, hunting culture, and economy.

CWD spreads through direct deer-to-deer contact or when an infected deer’s saliva, feces, or urine enters the environment and is contacted by another deer. CWD can also spread when deer encounter the carcass of a CWD-positive deer.

No. Hemorrhagic disease (commonly called blue tongue or EHD) is a viral disease spread by biting midge flies during summer. It typically kills deer within a week, and dead deer are typically found near water.

CWD is a 100% fatal disease caused by a misfolded protein. It is spread directly from deer to deer or when deer encounter the misfolded proteins in the environment after they have been shed by an infected deer. Deer live for 18 to 24 months before beginning to appear sick. CWD is a significant long-term threat to the health of the deer population and has the potential to cause significant, long-term declines in deer populations and to reduce the age structure of the herd. HD is caused by a virus and spreads during summer through a biting midge fly. HD typically kills deer within a week, but some deer can survive after becoming infected. Although HD can cause significant declines in deer numbers during a severe outbreak, deer numbers recover within a few years. HD is not a significant long-term threat to the health of Missouri’s deer population.

Yes. CWD kills deer and is 100% fatal. Studies have placed radio collars on deer to determine how survival rates and causes of death differ between CWD-positive deer and deer that do not have CWD. Preliminary results indicate that CWD is a common cause of death. In addition to killing deer, CWD increases the chances that deer will die from other causes, such as hunter harvest and predation. Deer with CWD have significantly lower survival rates than those without the disease.

Yes. Research projects (see Additional Resources below) indicate that if CWD infection rates increase significantly in Missouri, the state’s deer population will decline. CWD could also affect the age structure of the deer population, resulting in fewer mature deer.

No. After infection, deer appear healthy for 18 to 24 months. After that time, they begin showing outward signs of sickness.

CWD was first found in Missouri in confined deer facilities in Linn and Macon counties in 2010 and 2011. The disease was first detected in Missouri’s wild deer population in Macon County in 2012.

No. MDC began CWD testing about a decade before detecting the disease. More than 30,000 deer were tested for CWD throughout Missouri prior to the detection of the first case. This indicates that CWD has not always existed in the state and that the disease had been relatively recently introduced before being first detected.

See up-to-date CWD surveillance information.

No. Although CWD has been detected in numerous areas throughout the state, the percentage of deer in Missouri that have CWD remains very low. MDC’s efforts to detect the disease early and to conduct targeted removal have slowed the spread of CWD and kept infection rates low.

Yes. If CWD continues to spread and begins to infect a higher percentage of the deer population, the disease could have significant effects on Missouri’s deer population, hunting culture, and economy. 

MDC is:

• Conducting extensive CWD testing to find new areas of disease as quickly as possible and monitoring distribution of the disease.
• Implementing regulations in the CWD Management Zone such as the feeding and mineral ban, removal of the antler-point restriction (APR), and carcass disposal restrictions to minimize the risk of CWD spreading within the state.
• Using targeted removal in areas where CWD has been found. Targeted removal efforts remove additional CWD-positive deer and lower deer density within these localized areas to slow the spread of CWD.

Aggressive action when infection rates are low helps slow the spread of CWD. Currently, less than 1% of Missouri deer have CWD. However, by the time just 5% of a deer population has CWD, the percentage that becomes infected begins to rise significantly. At that point, little can be done to slow the spread of the disease.

Not necessarily. Where CWD exists at low levels, like it does in Missouri, you should not expect to see sick deer. Because CWD is relatively rare in Missouri and typically causes deer to die of other causes prior to looking sick, it is rare to see a deer in Missouri showing clinical symptoms of CWD. By the time people regularly see clinically sick deer with CWD, infection rates are high, and there is little that can be done to slow its spread.

MDC received funds through the Wildlife Restoration Program (formerly known as the Pittman-Robertson (P-R) program). Annual appropriations are allocated to all 50 states based on the size of the state and the number of paid licensed hunters. The funds are eligible to state and territorial fish and wildlife agencies for public hunting access, hunter education, wildlife management and research, R3-related activities, and the development, operation, and maintenance of target ranges.

These funds are provided to MDC through grants from the U.S. Fish and Wildlife Service, which administers the Wildlife Restoration Program. The grant that MDC has through this program for CWD surveillance and management allows the department to be reimbursed for a portion (75%) of qualifying expenses associated with CWD surveillance and management efforts. Wildlife Restoration Program funding is essential to Missouri for the conservation, management, and enhancement of wildlife and their habitats, including addressing wildlife health concerns such as CWD. These funds do not generate profit for MDC.

The CWD Management Zone includes counties with a CWD-positive detection and those within 10 miles of a CWD-positive detection.

CWD can spread through direct contact between deer and when deer contact infectious prions (that cause CWD) that have been deposited in the environment by infected deer. Providing feed and minerals for deer increases contact between deer, which can increase the spread of CWD. Bait and feed sites also accumulate infectious prions in the soil. Deer in Missouri do not need supplemental feed and minerals to be healthy.

The rule that prohibited transporting high-risk deer parts (such as the brain and spinal cord) out of the county of harvest has been rescinded. Hunters are now required to dispose of deer carcasses and unused parts either 1) in trash that is dumped in a sanitary landfill or 2) on the property where the deer was harvested. Hunters are also required to Telecheck their deer before the deer (or any parts) are transported outside the county of harvest or prior to 10 p.m. on the day of harvest (whichever occurs first). The interstate Carcass Movement Restrictions (for those bringing harvested cervids into Missouri) have not changed.

Because CWD can be spread if deer contact an infected carcass, the new carcass disposal restrictions will help to slow the spread of CWD. The new restrictions will also allow hunters greater flexibility in how they can transport deer within the state.

Testing all hunter-harvested deer is not necessary to understand the distribution of CWD or CWD infection rates. By sampling a percentage of the deer hunters harvest, MDC can detect CWD early and monitor its spread. During most years, MDC tests more deer for CWD than any other state.  

Estimated times are:

• Sept. 15 until November Portion: 1 to 2 weeks
• November Portion through mid-December: 4 to 6 weeks
• Mid-December through Jan. 15: 2 to 3 weeks

Although there have been no known cases of CWD affecting humans, the Centers for Disease Control and Prevention (CDC) recommends that people do not consume deer that test positive for CWD.

There are no known cases of humans contracting CWD. However, the CDC advises against people consuming deer that test positive for CWD.

MDC has tested deer for CWD since 2002. Testing was ongoing for about a decade before the first CWD detection in Missouri.

Mandatory sampling allows MDC to obtain a large number of CWD samples within a short time frame. This helps MDC detect new CWD areas and monitor disease spread, directing management efforts to slow the spread of CWD.

There are many opportunities for hunters to have their deer sampled for CWD. These include MDC offices, cooperating meat processors and taxidermists, and self-serve freezer head-drop locations. There is no cost for hunters to have their deer sampled for CWD. Find information for voluntary CWD sampling.

MDC staff remove a pair of lymph nodes from the deer’s neck and submit them to an independent lab for testing.

Targeted removal is the removal of deer within localized areas where CWD has been detected to slow the disease’s spread. In Missouri, targeted removal is used to remove additional CWD-positive deer and lower deer numbers in localized areas near where CWD has been found.

Targeted removal is only conducted in CWD Core Areas, which are located within about two miles of where CWD has been detected. Find information about where targeted removal is being conducted.

No. Participation in targeted removal is voluntary.

Targeted removal occurs from Jan. 16  to March 15.

Landowners with property in a CWD Core Area where targeted removal is being conducted may allow trained MDC staff to conduct targeted removal or receive authorization from MDC to conduct targeted removal. 

Yes. Although these practices are not permitted during the deer hunting season, they can be used during targeted removal because targeted removal is a disease-management tool, not hunting. To maximize the effectiveness of targeted removal in slowing the spread of CWD, it must be conducted as efficiently as possible. Using bait and allowing deer to be shot at night increases the number of deer that can be removed, thus maximizing the effectiveness of targeted removal to slow the spread of CWD.

Baiting has the potential to spread CWD, but the degree to which this happens is likely to depend on the length of time bait is available to deer. The length of time an area is baited can affect the number of deer-to-deer contacts that occur and the number of infectious prions deposited in the soil should a CWD-positive deer visit the site. During targeted removal, bait is used at a site for as little time as possible. An area is baited, and when the removal goal for that site is reached, baiting stops. This minimizes the risk of CWD spread. The use of bait is also critical to reaching targeted removal goals. If baiting were not used during targeted removal, the number of deer removed would be much lower, thus reducing the effectiveness of targeted removal to slow the spread of CWD.

In contrast to the limited amount of time that bait is used during targeted removal, where feeding deer is permitted by the public, there is the potential for feed to be available to deer for prolonged periods of time. This could increase the number of visits by deer, the amount of direct deer-to-deer contact at these sites, and the number of infectious prions that get deposited in the soil should a CWD-positive deer visit the site.

The landowner decides how many deer can be removed from their property during targeted removal.

In nearly all CWD Core Areas, the number of deer removed during targeted removal is less than the number of deer removed during the regular deer hunting season, based on the county-level average. From 2012-2024, approximately 22,000 deer were removed during targeted removal; during that same period, hunters harvested about 3.4 million deer in Missouri.