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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

A DNR wildlife technician collects blood and tissue samples at a deer registration station. Monitoring at 72 of DNR's
130 deer management units between 1999-2001 gave us our first clues that chronic wasting disease had spread into Wisconsin. © Robert Queen
A DNR wildlife technician collects blood and tissue samples at a deer registration station. Monitoring at 72 of DNR's 130 deer management units between 1999-2001 gave us our first clues that chronic wasting disease had spread into Wisconsin.

© Robert Queen

August 2002

CWD update

Practical tips for dealing with chronic wasting disease in Wisconsin whitetails.

Robert Manwell

Efforts to eradicate a chronic wasting disease (CWD) outbreak in white-tailed deer continue. Though new information streams in every day, we wanted to give readers as up-to-date a summary as we can to answer common questions.

Why will Chronic Wasting Disease continue to be a concern for years or decades?

Chronic wasting disease is the most significant health issue to affect Wisconsin wildlife in anyone's memory. There is no vaccine or treatment to cure the disease, and it is invariably fatal to an infected animal. To complicate matters, a deer can carry the disease for 15 months or more before showing outward symptoms.

The only way to treat the disease is to destroy its host – the white-tailed deer that is carrying it. It is a communicable disease among some cervids – whitetails, black-tail deer, mule deer and elk – meaning an infected deer can pass it to a healthy one, but researchers don't know exactly how this happens. Veterinarians and wildlife biologists agree that drastically lowering the deer population in the infection area for up to five years is Wisconsin's best chance to eradicate the disease.

How long has CWD been present in Wisconsin?

No one knows for certain how long CWD has been in Wisconsin. Scientists at the Department of Natural Resources and the University of Wisconsin using a mathematical model developed by western states estimate CWD has likely been here for three to five years. Like most mathematical models, certain assumptions must be used to calculate an answer. This incorporates what we know about deer population density in the infected area, transmission rates of the disease and the results of testing more than 500 deer for CWD earlier this year.

How is CWD spread and what kinds of animals are infected by it?

Scientists don't know just how CWD is passed from one animal to another – whether it's passed in mucus, urine, feces or some other pathway. Chronic wasting disease is only shared among deer and elk. Other species have their own form of this disease, which scientists call a TSE or transmissible spongiform encephalopathy. Other forms of the disease are scrapie in sheep and bovine spongiform encephalopathy or "mad cow disease" in cattle.

Humans also have their own form of a TSE disease; it's called Cruetzfeldt-Jakob disease or CJD and it infects about one in one million people. Wisconsin could be expected to record about five human cases of CJD each year based on our population. There is some evidence that CWD can exist in the environment – outside of its deer host - for some time and still retain the ability to infect a healthy animal. There is no evidence that CWD can be passed to cattle or to humans.

What is Wisconsin doing to try and prevent the spread of CWD?

Wisconsin's Department of Natural Resources has been monitoring the state's wild white-tailed deer herd for tuberculosis and cranial abscessation syndrome since 1996 and for CWD since 1999. This effort has tested approximately 1,000 deer for CWD from all Wisconsin counties. Until the three positive cases were found this spring, all CWD and tuberculosis tests have been negative. Early detection of CWD gives Wisconsin a fighting chance at eradicating it as it appears to be localized in an area in western Dane and eastern Iowa counties.

Review the article, Keeping an eye on the border and the future, (October 2001) for a more complete report on deer health monitoring. More recently, expanded fall shoots were authorized by the Natural Resources Board and temporary deer feeding and baiting bans were instituted to stem the spread of this disease.

What causes CWD and what is the timetable to try and eradicate the disease?

There is no vaccine or cure for CWD. It is caused by an abnormal protein called a prion (PREE-on). In some way not yet understood, the abnormal prion is passed from an infected animal to a healthy one. Over time, the abnormal prion causes normal prions to change to abnormal. This change eats away at the brain tissue of the animal causing it to look like a piece of Swiss cheese under the microscope. The only way to remove the prion from the deer population is to remove the deer-host, thereby capturing the abnormal prion material present in the brain, spinal, lymph, eye and tonsil tissue of the infected animal and limiting new infections. Year-old deer tend to disperse in the fall at the approach of the mating season, so by acting now wildlife managers hope to limit additional spread of the disease.

What have legislators in Madison and Washington, D.C. done to get Wisconsin the legal authority and money to control CWD?

Wisconsin has appealed to the federal government for assistance in dealing with this wildlife crisis. Governor McCallum has asked for $18.5 million in aid over a period of three to five years to finance CWD management, research and build capacity to test for CWD at Wisconsin laboratories.

In an unusual special session called by the Governor, the Wisconsin Legislature passed a CWD bill that authorized the Department of Natural Resources to spend up to $4 million from its existing budget to manage CWD. Most of the money would come from the Wildlife Damage Account that is normally used to reimburse farmers for crop losses caused by wildlife. The account is funded with hunter dollars collected through a $1 surcharge on hunting licenses and through sales of bonus antlerless deer harvest permits.

The CWD bill also gave the DNR authority to use hunting methods normally not allowed, such as herding/shooting from aircraft, shooting from vehicles and shooting from tractors.

Game farms may be one source of CWD infection because deer and elk are transported from areas out west where CWD has been present for years. Who is testing these captive herds?

Wisconsin has 575 farms with captive white-tailed deer, and 272 with captive elk. CWD has not been diagnosed on any Wisconsin deer or elk farm. We also have about 100 farms raising red deer, reindeer, fallow deer and sika deer. We don't know if these species are susceptible to CWD.

The Wisconsin Dept. of Agriculture, Trade and Consumer Protection licenses and inspects game farms and shooting preserves. Emergency rules passed by that agency to combat CWD spread in Wisconsin have effectively shut down new imports of deer and elk into the state. The rules also require strict monitoring of all captive deer and elk herds if the owner wants to move live animals in the state. Manditory CWD testing is also required if any captive deer or elk 16 months or older is slaughtered, dies on the farm or if any portion of its carcass leaves the property.

All deer killed on hunting preserves or game farms must be tested if the shooter wants to keep the meat or a trophy for mounting.

Under emergency rules, all deer and elk farm operations must be annually inspected by certified veterinarians and found to be CWD-free before animals can be imported, transported or sent to slaughter. Test results indicating positive CWD tests must be immediately reported.

A big deer baiting pile. Many hunting groups had started the practice of placing huge piles of feed corn and other foods to attract deer. Deer congregate around such stations and may exchange CWD through face-to-face contact, in mucus, urine or some other manner. Deer feeding and baiting has been temporarily banned statewide until further notice.© DNR Photo
A big deer baiting pile. Many hunting groups place huge piles of feed corn and other foods to attract deer. Deer congregate around such stations and may exchange CWD through face-to-face contact, in mucus, urine or some other manner. Deer feeding and baiting has been temporarily banned statewide until further notice.

© DNR Photo

How will the special CWD shoots be managed this summer?

During the summer months, DNR issued "scientific collector's permits" to landowners in the CWD Eradication Zone. The permits allow landowners or their designees to shoot deer of either sex and any age during the four one-week periods in June, July, August, and September.

Special season regulations for the fall hunting period were approved as emergency rules by the Natural Resources Board in June. The rules set an extended gun hunting season and almost limitless harvest tags but with an "earn-a-buck" provision. The emergency rules would open the fall gun-hunting season on Oct. 24 in the CWD Management Zone and Intensive Harvest Zones. Shooting hours would continue to be one-half hour before sunrise to 20 minutes after sunset.

Will shooting and deer removal in the Eradication Zone be limited to private property?

Yes. Shooting this summer will be confined to privately owned lands within the Eradication Zone through September. If an obviously sick looking deer is reported on state-owned land or elsewhere, a DNR employee will act on all such reports to observe the animal. If deemed safe and appropriate to do so, such deer would be shot and tested for CWD.

Who will shoot deer on public lands in the Eradication Zone? How and when will property users be notified?

During the fall CWD special season, public lands will be open to all licensed hunters. With the exception of shooting already done in Blue Mound State Park in early May, no special hunts are scheduled for parks, until fall.

As a camper, hiker or bicyclist do I have to take safety precautions using public lands during CWD hunts this fall?

Safety precautions recommended during hunting seasons will be repeated for these special deer removal shoots. There will be ample public notice in advance of these special shoots.

Practical tips for those involved in the CWD shoots.

Landowners participating in summer deer collection within the Eradication Zone will be issued special collector permits and logs, and will be supplied with as many carcass tags as they can use. All shooters must carry and keep the collector permits with them while shooting, or transporting deer to the registration stations.

Additionally, landowners will have a log sheet to record names and contact information for any shooters they authorize to shoot for them on their property. Tagging shot animals – Each deer must be tagged with a carcass tag. Shooters will be asked to indicate the animal's sex, approximate age, date, time and location of the shoot.

Registration – All deer shot during summer collection must be promptly registered at one of the two registration sites: Trout Creek Fishery Area, two miles north of Barneveld on County Highway T; or Mazomanie Wildlife Area, three miles north of Mazomanie on County Highway Y. DNR personnel will staff these sites from 6 a.m. until 10 p.m. every day during the special summer shoots.

Shooters are requested to shoot the animal in the chest thereby avoiding damage to the brain stem and lymph tissues needed for testing. It is important to transport the kill to one of the collection sites as soon as possible especially in warm weather in order to prevent spoilage of the important brain stem and lymph tissues used for testing.

If you are merely disposing of a shot animal, it is not necessary to field dress it. The state will assume disposal costs.

If you want to save the meat for potential consumption, take these precautions during field dressing. Work quickly to prevent spoilage during hot weather. Wear rubber or latex gloves when field dressing. Register deer promptly. When butchering deer, minimize contact with brain, spinal cord, eyes or other nervous system tissue. Do not use household knives or utensils to field-dress the deer. Seal the remainder of the carcass in plastic garbage bags or containers along with gloves, and dispose of them in a landfill or bring inedible portions of these animals to a DNR disposal site. All bones, offal and scraps from processing should be carefully bagged and sealed in plastic. The DNR has not been advised that any private or municipal garbage collectors have refused to collect such wastes if properly packaged.

Clean knives and equipment, then soak them in household bleach diluted 50 percent with water.

Butcher and package the meat and place in your freezer clearly marking the packages.

All deer from these summer shoots that are kept for potential consumption will be tested for CWD. You will be notified by phone if the test is positive. You will be notified by letter if the test is negative. Hold onto this letter. If you intend to have your meat processed, some processors will want to see proof of test results before they will accept meat for processing.

There are no bag limits on numbers of deer you can keep from summer shoots within the Eradication Zone as the goal is to bring the deer population there as close to zero as possible. Pending Natural Resources Board approval, fall hunters in the larger CWD Management Zone will receive an additional buck and antlerless tag for each antlerless deer they register.

A sharpshooter removes a deer for sampling in Spring 2002. This early harvest collected 500 animals in the Eradication Zone. © Bob Manwell
A sharpshooter removes a deer for sampling in Spring 2002. This early harvest collected 500 animals in the Eradication Zone.

© Bob Manwell

Are there any tests to determine the safety of venison I already have in the freezer?

The short answer is, "No." Scientists have never found prion material (the infectious agent) in muscle tissue even in CWD-positive animals. Though we have no research to question the safety of venison, some people may choose to wait and see before eating venison based on widespread testing in the area where they hunted.

What's next?

CWD descended on Wisconsin very quickly. Deer testing over the previous two years had all been negative, providing a false sense of security. Deer watching and deer hunting are inextricably linked with Wisconsin culture and tradition. These activities are also the basis of an important economy in Wisconsin.

Knowing what to do next is a complex question. DNR Secretary Bazzell, has set the department's sights on eradicating the disease outbreak in Wisconsin – a tall order, but possible. A great deal depends on the cooperation of landowners in the affected area and the results of additional testing of deer from the CWD area.

As we learn more, it's possible our management plan will change or be modified. The initial plan – to reduce deer populations to as near zero as possible in a small area with significant population reductions in a buffer area – has been acknowledged by wildlife experts across the country as a sound strategy.

One of our biggest challenges is to provide a scientifically sound base of knowledge about CWD to all citizens and to keep the public up-to-date on this rapidly evolving wildlife issue.

The legislature has given the department and its partners strong tools to address this problem including authority to ban baiting and feeding of deer, shooting from vehicles and to use aircraft in herding or shooting deer. It remains to be seen which of these tools will be used and to what extent.

Robert Manwell is a senior public affairs manager for the Wisconsin Department of Natural Resources and the chief communications officer helping manage CWD disease containment.

CWD Chronology
1999, 2000 and 2001 – DNR wildlife disease specialists begin surveillance for chronic wasting disease in 1999 by collecting tissue samples from deer at fall hunting registration stations. Sites include deer units where deer populations congregate and near concentrations of captive herds. Approximately 1,000 deer from 72 of the 130 deer management units in Wisconsin have been tested for CWD in that time.

Feb. 28, 2002 – Testing laboratories notify DNR staff that three deer tissue samples collected during the 2001 gun deer hunt in Mt. Horeb area tested positive for CWD. Conservation officers are immediately dispatched to inform the hunters who submitted these deer and to establish exact locations of the kills.

March 1, 2002 – DNR establishes a CWD Incident Command System to investigate CWD in Mt. Horeb area. Conservation law enforcement officers start an inquiry into possible sources of CWD infection.

March 4-6, 2002 – DNR establishes CWD Field Operations Command Post at the DNR Service Center in Dodgeville.

March 6, 2002 – Landowners in a 415-square mile area surrounding the sites of confirmed infection are asked to bring in additional deer for testing and special collector's permits are issued to cooperating landowners. The same day, DNR launches a CWD website Click on "chronic wasting disease" to provide immediate updates as CWD investigations expand and evolve.

March 7, 2002 – An Interagency CWD Task Force forms to begin weekly meetings among state natural resource (DNR), agricultural (DATCP), and public health (DHFS) staffs.

March 6 – April 9, 2002 – 516 deer are collected for CWD testing from the sample area. The majority of test animals were provided by area landowners, some were collected as roadkills and some were shot by DNR-authorized sharpshooters.

March 14, 2002 – Investigators began series of briefings for legislators on CWD issues, potential financial needs and consequences.

March 20, 2002 – DNR, DATCP and DHFS hold a public informational meeting on CWD at Mt. Horeb High School. Attendance is estimated at 1,100.

April 23, 2002 – Final results of additional CWD testing are reported. Eleven additional positive deer are found among 516 submitted. Including original samples, DNR reports 14 deer show positive signs of CWD infection from a total sample of 598 deer.

May 1, 2002 – DNR, DATCP and DHFS host a second public CWD-information meeting at Mt. Horeb. Attendance estimated at 1,600.

May 1, 2002 – As a strategy to contain the disease, the public is informed that investigators will establish a CWD Management Zone consisting of 13 deer management units in all or part of 14 counties in south central Wisconsin including a 287-square mile CWD Eradication Zone where as many as 15,000 deer may need to be shot in an attempt to eradicate CWD.

May 1, 2002 – Additional statewide CWD informational meetings are announced for Eau Claire, Rhinelander, Waukesha and Green Bay to update the public and answer questions.

May 22, 2002 – A new experimental CWD testing procedure using lymph nodes discovers four cases of CWD in deer. A total of 18 whitetails have now tested positive for CWD. The Eradication Zone is expanded to 361 square miles as one positive test came from just outside the previously indicated zone. To start reducing deer populations in areas where infected deer have been detected, four one-week shoots are planned for summer months. Most carcasses not claimed by landowners from the Eradication Zone will be incinerated.

May 28, 2002 – The first batch of shooting permits is issued to landowners in CWD Eradication Zone. The first shooting period is set for June 8-14. Other periods are July 13-19, August 10-16 and September 7-13.

June 26, 2002 – DNR staff ask the Natural Resources Board for emergency rules to establish a special hunt in CWD management area. The rules were approved as well as a temporary statewide ban on feeding and baiting deer.