Statewide Chronic Wasting Disease Sampling
Jerry Nelson, Deer and Elk Section Manager

Chronic wasting disease (CWD) was a hot topic of discussion for most western states in 2001. The disease affects the central nervous system of deer and elk and is found in wild deer and elk in north-central Colorado, southeast Wyoming, and a small portion of southwest Nebraska. In 2002, two new states were added to the list of having CWD in wild deer, Wisconsin and New Mexico.

The disease was first identified in the early 1970s but interest in CWD has increased markedly in the past few years. Once contracted, the disease is always fatal. Currently there is no test for CWD that can be performed on live animals. Brain tissue from the suspect animal has to be analyzed in a laboratory. The best source for samples are hunter-harvested deer and elk and fresh road kills. There has never been a documented case of CWD transferring from deer or elk to humans or from deer or elk to domestic livestock.

In March last year, Washington Department of Fish and Wildlife (WDFW) began planning an increased sampling effort for CWD in an attempt to get statewide coverage and much higher sample sizes. In September of 2001, the U. S. Department of Agriculture (USDA) declared an emergency as a result of CWD affecting wild game farms. Special funds were made available to states that had confirmed cases of the disease in the deer and elk farming industry. When the disease is discovered in a captive herd of elk that herd has to be destroyed and disposed of and then the site has to be monitored. Quarantine, depopulation, and disposal of animals cost millions of dollars. An indemnity program was put in place by USDA to offset some of the losses that wild game farmers were experiencing as a result of this disease. In October the news broke that an elk farm in Colorado had tested positive for CWD and had, in the previous 5 years, shipped elk to 15 different states. Washington was not one of those states.

The Department had been conducting surveillance testing for CWD, which means any animal that showed any kind of unusual symptoms was tested as a precaution. The WDFW staff veterinarian, Briggs Hall, has been testing for CWD in deer and elk since 1995 but one man can only do so much. All of those animals tested negative for CWD.

Washington is a very low risk state. Washington law does not allow farming of deer and elk, so we don’t have live animals being shipped around that could pose a risk, and we are far enough removed from Colorado and Wyoming that there is little chance of the disease spreading naturally to Washington.

To say with any kind of certainty that Washington deer and elk don’t have this disease, WDFW had to start sampling at a much higher rate. Sampling on a statewide basis is expensive and time-consuming. Washington is on the list for Federal funding to help with testing but it became clear last year that those funds would be depleted fairly rapidly by states that have the disease or are in close proximity to the disease. Because it is a low risk state, Washington is also a low priority state when it comes to outside funding sources.

To get a much broader sample and higher numbers, the Department requested special funding from the state legislature to increase the effort expended toward this investigation for the first year. As a result, WDFW has completed the first year of a three-year sampling program to test for the disease. The first year went well, and the Department was able to meet the sampling goals. Hopefully we’ll be able to meet those same goals in 2002 and 2003 if the funding is available. WDFW is trying to map the location of all samples collected to identify where effort should be directed for the 2003 hunting season.

The Department collected 785 samples in the past 4 months. When results come back from the laboratory there are three possible outcomes: (1) Positive, which Washington has not seen to date, (2) Negative, and (3) Non-diagnostic.

In order to conduct the test successfully the animal can’t have been dead too long before the brain tissue is collected. Deer or elk that have hung in hunting camp too long or road kills that are too old may be non-diagnostic. The testing laboratory cannot make a conclusive test on that sample. If a sample doesn’t have enough of the right type of brain stem tissue it may also be non-diagnostic.

Last year’s statewide effort was a learning process for all the Agency personnel involved. There were a lot of logistics that had to be worked out to sample at that scale and intensity. The Department also received a lot of support from volunteer organizations like Eyes in the Woods and Inland Northwest Wildlife Council. All of the people involved with this effort did a tremendous job. We haven’t had any positive samples so far, and we hope that trend continues.

Hunters that harvest an animal in the endemic areas of Colorado will be required by Colorado Division of Wildlife to have their animals processed in the endemic areas. Check the Colorado Division of Wildlife web site before planning your next trip http://wildlife.state.co.us/CWD/index.asp. The same precautions are probably advised for other states.