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Texas Agriculture Archive

September 20, 2002

Hunters: Be aware
of chronic wasting disease

Besides finding a good hunting lease, one of the main topics of conversation among deer hunters is Chronic Wasting Disease (CWD), a fatal brain and nervous system disease found in deer and elk in certain regions of the country. To date, CWD has been detected in 10 states and two Canadian provinces.

"At this time," said Texas Cooperative Extension wildlife specialist Byron D. Wright, "there is no proof that CWD occurs in Texas, but the potential for introduction exists because of past movement of elk and deer for husbandry purposes."

Interstate movement of deer and elk led the Texas Parks and Wildlife Department and the Texas Animal Health Commission to issue separate orders suspending the importation of these animals into Texas from other states.

As of Sept. 1, the animal health commission rescinded its order prohibiting elk and black-tailed deer from entering the state. However, importation of these animals must meet the commission's more stringent entry requirements, which includes requiring that the animals come from herds that have been monitored for CWD for three to five years.

The Texas Parks and Wildlife Department's moratorium on importing mule deer and white-tailed deer into Texas is still in place, but will likely be repealed in the near future, Wright said. The agency's entry requirements for mule and white-tailed deer are expected to be consistent with the animal health commission's rules governing elk and black-tailed deer.

CWD belongs to a family of diseases known as transmissible spongiform encephalopathies (TSE) or prion diseases. The disease attacks the brain of infected white-tailed deer, black-tailed deer, mule deer and elk. During the past year, cases of the disease have been found for the first time in Wisconsin, New Mexico and Minnesota.

Texas hunters should be watchful for deer and elk exhibiting symptoms of illness. Symptoms of CWD include emaciation, excessive drooling, staggering, and an overly wide posture with head and ears carried low. Infected animals may exhibit a combination of the symptoms.

Hunters who see deer with these symptoms are urged to mark the area and notify Texas Parks and Wildlife officials at (800) 892-1112 (enter 5 for wildlife and 1 for general information).

"While this disease fits in the group of TSEs," Wright said, "it is not the same as mad cow disease." As far as contracting the disease, "no scientific evidence currently exists proving CWD is transmissible to humans. However, for general health purposes, persons harvesting deer and elk in Texas should avoid consuming any animal that appears ill," he said.

CWD was first recognized in the late 1960s as a syndrome among captive mule deer at research facilities in Colorado. The disease is terminal, with no vaccine or treatment for infected animals. The suspected mode of transmission among deer and elk is through the animal's saliva, feces and urine.

"There is still a lot to learn about the disease," Wright said. "We are not positive of the agent that causes it, but scientists suspect a type of protein (prions) that has an alteration of amino acids resulting in an abnormally folded shape. This protein recruits other normal prions to take on the abnormal shape."

The diseased prions are believed to accumulate only in particular portions of the body, specifically lymphatic tissue, brain matter, the spinal cord, and the spleen. The length of time from exposure to the onset of clinical symptoms for animals in the wild is yet to be clearly defined.

Texans hunting in areas where the disease is found in free-ranging deer and elk, such as northeast Colorado, southeast Wyoming and the extreme southwestern corner of Nebraska, can follow some common-sense precautions, which include:

1. Not eating any portion of deer or elk that show symptoms of CWD.

2. Not eating the brain, spinal cord, eyes, tonsils, lymph nodes or spleen of any deer or elk.

3. Wearing rubber or latex gloves when field dressing.

4. Minimizing exposure to brain or spinal tissues, particularly when removing the head and antlers from the body and use tools designated only for this purpose.

5. Cleaning dressing equipment and work area with a 50/50 solution of chlorine bleach and water, soaking knives for one hour.

6. De-boning all meat.

7. Removing all lymphatic nodes from the portions of the carcass that will be consumed.

8. Processing animals separately to avoid mixing meat and trimmings.

9. Sanitizing work area and equipment with bleach solution after processing.

Texans hunting in states where CWD occurs should check with the state game agency in that area for any restrictions on transporting harvested game.

Deer imports must
meet new entry requirements

Texas' borders were reopened September 1 for the importation of live black-tailed deer and elk, but the animals now must meet new, stringent entry requirements.

For nearly six months, the Texas Animal Health Commission (TAHC) and Texas Parks and Wildlife Department (TPWD) prohibited the entry of these species, along with white-tailed deer and mule deer, while new health standards were developed to help prevent the introduction of Chronic Wasting Disease (CWD).

Following the TAHC actions that established the new entry requirements, TPWD commissioners have begun the process that will allow white-tailed deer and mule deer to be imported as well. Adoption of the TPWD changes are expected during their November meeting.

The fatal, brain-wasting ailment, CWD, has been diagnosed in deer and elk in 10 states (most recently in Minnesota), and in two Canadian provinces.

"Although only a low percentage of animals have been diagnosed with CWD in the U.S., this is a high-profile disease. Hunting, wildlife management, and deer and elk farming and ranching have an enormous impact on the agricultural community," commented Dr. Gary Svetlik, a U.S. Department of Agriculture (USDA) veterinarian in Texas who works with transmissible spongiform encephalopathies (TSEs).