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Deadly Venison?

 
February, 2001 
Field and Stream 
by Brian McCombie

Suspicion that a fatal, incurable illness can spread from infected deer to humans is increasing. Here, a special report on chronic wasting disease and how one hunter may have lost his life from it.

Jay Dee Whitlock was a husband and father, a sportsman from Oklahoma with a passion for deer hunting. But in January 1999, his wife, Julie, noticed he was forgetting phone numbers and seemed confused while driving. When Julie voiced her concerns, Jay Dee said it was nothing, and Julie told herself she was overreacting. Everyone forgets something, right?

But a few weeks later, two of Jay Dee's coworkers called on her. "They said he was more and more withdrawn at work," Julie Whitlock remembers, "that he wouldn't eat lunch with people." A truck driver for six years, Jay Dee was also having problems delivering his loads. Before, "You'd give him an address and directions, and he'd find it 400 miles away," Whitlock says. But now, said his coworkers, Jay Dee couldn't locate places he'd delivered to in the past. "It just made me sick when they told me that," Whitlock says.

Over the next 15 terrible months, in and out of various hospitals and, at the last, a nursing home, Julie watched helplessly as Jay Dee deteriorated physically, mentally, and emotionally from Creutzfeldt-Jakob (pronounced CROYTS-felt YAH-kob) disease, or CJD. It is untreatable, incurable, and always fatal. While Whitlock says doctors have no idea how her husband contracted this dreadful disease, no one can rule out the venison Jay Dee regularly ate.

"I'll never touch another deer," says Whitlock, "or eat deer meat ever again."

Mad Cows and Englishmen
 

CJD is a form of transmissible spongiform encephalopathy (TSE). According to research, TSE appears to alter proteins in the brain called prions (PREE-ons). The transformation leads to a series of microscopic holes in and around brain cells. Prior to this damage, behavioral changes become apparent, as with Jay Dee.

A second form of TSE is mad cow disease, which affects cattle. It is so named because the animals become agitated, shake with tremors, and kick violently when touched.

In Great Britain, a rash of human deaths from CJD occurred in the early 1990s. Some suspected that cattle feed containing protein and bone meal processed from diseased or injured cattle was to blame; the practice had been halted in 1988, but by then mad cow disease was apparently distributed throughout Great Britain. Initially, the British government insisted there was no connection between cattle with mad cow disease and humans with CJD. But after much research and political wrangling, officials announced it was indeed possible to contract CJD by eating infected beef. A spokesperson for a British government advisory committee recently confirmed a total of 76 cases of CJD in Great Britain attributable to mad cow disease.

A third version of TSE is chronic wasting disease (CWD), which is currently afflicting Western deer and elk. So, the obvious question for hunters is, Can humans contract CJD from eating CWD-infected venison?

The answer: It's possible. Research has shown that CWD-infected materials can transfer to human matter in test tubes. "CWD may not transmit that easily," says Dr. Thomas Pringle, a molecular biologist who tracks CWD-type diseases for the Sperling Biomedical Foundation in Eugene, Oregon, "but the rate isn't zero." Pringle points out that it was tests like this that helped convince the British that CJD could result from people eating infected cattle.

When the Deer Began Dying


The Foothills Wildlife Research Facility in Fort Collins, Colorado, is believed by many to be where CWD first appeared and then spread into the wild. It's also a good example of how tough CWD is to eradicate. According to Michael Miller of Colorado's Division of Wildlife, mule deer at Foothills began dying in 1967 of a strange disease. In 1980, CWD was determined as the cause.

Attempts to rid the facility of the disease by culling out sick deer failed, so all animals were killed in 1985. Then, everything the animals had contacted (water troughs, feed bins, etc.) was cleaned with a powerful disinfectant. The ground was sprayed with the same disinfectant, plowed to a depth of about a foot, and resprayed. Paddocks went unused for up to a year, and double fencing was installed to eliminate any nose-to-nose contact with possibly infected wildlife. Eventually, new deer and elk were introduced, but within the year they began contracting CWD.

No one is completely sure how it spreads. Blood transmission seems likely, as from doe to fawn. But CWD has transferred between adult animals at game farms, leading Miller and other wildlife professionals to believe simple contact can pass it. This could include nose-to-nose touching, shared saliva (as at a feed trough), or brushing against urine or feces from an infected animal.

In 1981, CWD was discovered in a wild elk in southwest Larimer County, Colorado. Today 15 percent of mule deer in this area test positive. "Overall, the endemic area has a 3.5 to 4 percent rate of infection," says Miller, though pockets exist where CWD is twice as prevalent. Wyoming's southeastern corner sees similar rates for mule deer, and in both states elk contract CWD at about 1 percent. Deer or elk with CWD may slobber uncontrollably, appear listless, and will lose a great deal of weight before eventually dying.

Miller says CWD "probably should be considered an epidemic," given that it has spread through some 14,600 square miles of north-central and northeastern Colorado, plus parts of Wyoming, in two decades. The fact that mule deer and elk in both states are relatively dispersed seems to have slowed transmission. But he also notes that CWD has been found in whitetail deer along the Platte River. Whitetail densities are quite high there, and Miller warns, "As it moves east, CWD could pick up momentum."

There are no tests to detect CWD in living animals. The disease can only be confirmed by examination of a dead animal. Pringle argues that this makes the interstate transportation of animals onto game farms a big problem.

The Game Farm Connection


CWD has been documented at deer or elk farms in Colorado, Montana, Nebraska, Oklahoma, South Dakota, Alberta, and Saskatchewan. Between 1997 and 1998, South Dakota officials discovered animals at three game farms with CWD and acted quickly to halt other infected animals from entering. State veterinarian Dr. Sam Holland says a risk assessment is now done before a game farm can import an animal. "If the [originating] state is not actively doing CWD surveillance for captive animals-and that means CWD testing for all deaths of animals over 18 months of age-then we won't let their animals in," he says.

To test for CWD, South Dakota requires a brain necropsy for all dead animals. Game farm herds must also be monitored and inventoried; Nebraska and Montana have similar requirements.

But regulations vary by state. Wisconsin game farms, for instance, can import any animal as long as it possesses an interstate health certificate, according to state veterinarian Clarence Siroky. It's a good preventive to keep out a detectable disease like bovine tuberculosis but does little for an untestable one like CWD. Since 1992, at least 370 elk have been imported there from farms having direct or indirect contact with the disease, and two animals came from herds later found to have CWD. These imported elk caused Wisconsin's Department of Natural Resources to test the brains of 250 wild deer last year, and all came back negative.

Other states apparently think there's a risk, too. As of 1999, 14 had either tested or were actively testing free-ranging deer, antelope, and/or elk for CWD. Alberta and Saskatchewan are also looking for it. Game farms are prime test sites.

Though they're fenced, game farms provide many opportunities for contact between captive and wild animals. Nose-to-nose touching occurs at fence lines, and fences are breached by storms and accidents. Gates are left open. Even when captive animals don't escape, such openings allow wild deer to come in, mix, and leave. After CWD was detected at a South Dakota game farm in 1998, for example, one of the 30 free-ranging whitetails harvested outside the fence tested positive.

Steve Wolcott, past president of the North American Elk Breeders Association, thinks this focus on game farms ignores a key avenue for spreading CWD around the country. "People who hunt in the Colorado and Wyoming endemic areas are free to take those carcasses anywhere in the country," he points out. Once home, hunters with an elk or muley carrying a nice rack are going to saw it off themselves or have it professionally mounted. Either way, the brain and spinal cord-the most infected parts of a CWD animal-will end up in a landfill or pitched into the woods, he says, perhaps introducing CWD-infected materials.

What's Next?


Two officials from the Centers for Disease Control (CDC) visited Julie Whitlock while Jay Dee was struggling to stay alive. They asked her hundreds of questions about Jay Dee: his diet, his work, his habits. But one of their questions sticks in her mind. "They wanted to know where he hunted." She told them: the area around Miami, Welch, and Wyandotte in the very northeastern corner of Oklahoma. She also offered them the two deer in her freezer, animals Jay Dee harvested in 1998, thinking the CDC might be able to test the meat. "They said maybe they'd be interested," Whitlock remembers. "But they never got back to me."

That lack of interest bothered her, especially when she discovered that two other deer hunters had recently died from CJD: Jim Koepke, 39, of Nevada in February 1999; and Doug McEwen, 30, of Utah in March of the same year. In a January 1999 article in USA Today, Whitlock read that Lawrence Schonberger of the CDC said only five cases of CJD per billion people are reported annually worldwide for people aged 30 and under. Given this rarity, she couldn't help but wonder how three young deer hunters would contract CJD so closely together in time.

Currently, the Colorado Division of Wildlife recommends that hunters wear rubber gloves while cleaning and butchering deer and elk, and that brains, spinal cords, and lymph nodes be handled as little as possible. If a hunter's harvest tests CWD positive, the Colorado Department of Public Health advises hunters to not consume the meat, as does the World Health Organization.

In May 2000, Dr. Byron Caughey of the National Institutes of Health announced that he had converted human prion materials using CWD prion matter at rates roughly equal to the transfer between cattle and humans. Commenting on Caughey's research, Dr. Elizabeth Williams, of the University of Wyoming's veterinary science department and a member of the state's CWD task force, says, "We were very pleased with his work. It showed a substantial barrier" to CWD transmission between animals and people.

Pringle has reviewed the test data and agrees transmission rates are very low. Yet low is not absolute. Caughey's work provides "concrete evidence that there is a definite risk here," Pringle contends. However, Pringle also admits there are significant chemical differences between materials transferring in a test tube and a person eating meat.

Jay Dee Whitlock died on April 7, 2000, six months shy of his 31st birthday. "I guess I thank God Jay Dee never knew he was dying," says Julie.