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Rocky Mountain News

Man vs. nature

Mad cow disease has researchers taking a close look at deer and elk

By Debra Melani, News Staff Writer
January 23, 2001

Six months before his death, Gary Hopkins was a vibrant, seemingly healthy 52-year-old man, a Colorado native and lover of the outdoors. At the end of those six months, the Aurora man was little more than a sack of bones, curled listlessly in a fetal position. He died Oct. 4, two days after his 53rd birthday.

Pat Hopkins recalls his father's rapid decline as "unreal." He says he wouldn't take photos of him in those last months, because "I just wanted to remember him the way he was before."

Today, Hopkins says, he wonders whether his father, who hunted avidly in the Fort Collins area, died because he ate the meat of deer infected with chronic wasting disease, CWD.

CWD is a relative of the "mad cow" disease that has claimed more than 80 lives in Europe. Friday, U.S. government researchers in Bethesda, Md., formally took up the question of whether CWD poses risks to human health.

So far, there is no evidence that it does.

There is no proof that humans can die from eating infected venison, as Pat Hopkins speculates, or even that the disorder can pass from one species to another.

But the U.S. government is concerned enough that within the week, it's expected to issue an opinion as to whether people are at risk if they eat venison or take nutritional supplements made from antlers of deer infected with CWD.

Gary Hopkins' official diagnosis was Creutzfeldt-Jakob (pronounced KRUTS-felt YOK-ob) disease.

The disorder has been known to science for about 80 years. It occurs in about one in 1 million people, and on average, two to three Coloradans die from it every year. Normally, onset begins after age 50.

A related disease afflicted European cattle in the mid-1980s. Because it caused them to salivate and act deranged, it was dubbed "mad cow" disease.

Scientists believe it spread to humans in Europe when they ate the meat of the infected cattle, incubating for 10 years or more. In humans, mad cow is called "variant" Cruetzfeldt-Jakob disease.

The "variant" CJD has slightly different symptoms from the classic CJD, but both disorders attack the brains of victims, filling the tissue with holes and creating a sponge-like appearance.

The result, in both humans and animals, is devastating. Human CJD patients generally lose the ability to speak, to move and to control bodily functions. They sometimes go blind and frequently slip into comas before dying.

Deer and elk afflicted with chronic wasting disease or "mad deer" disease appear confused and become agitated when touched. They often drool excessively and eventually stop eating, wasting away and ultimately dying.

All four of these related diseases - (1) chronic wasting disease in deer, (2) mad cow disease in cattle, also known as bovine spongiform encephalopathy or BSE, (3) traditional CJD in humans and (4) "variant" CJD in humans - are believed to be caused by prions, protein molecules normally found in the body that take on an aberrant shape.

Researchers are studying the differences between classic CJD and the new variant that has killed Europeans. Classic CJD generally strikes between the ages of 50 and 70. In Britain, doctors noticed that the victims of the variant were often younger people, some in their teens.

The variant CJD also tends to have a longer duration than the classic form. Europeans are living with this new form for about a year, while the older form takes its victims in an average of about five months.

Gary Hopkins' symptoms started showing up in April or May, Pat Hopkins said. "We thought he was just being forgetful, and we were kind of kidding him about it, as he was just getting ready to retire," he said.

But the kidding soon gave way to concern. Scores of medical tests followed. Spinal taps and magnetic resonance imagings were used to rule out other forms of dementia, including Alzheimer's, which is often a doctor's first suspicion.

Pat Hopkins knew his father was on a downhill path when he took him fishing and his did couldn't remember how to cast. "Stuff he'd done all his life he didn't know how to do," Hopkins said.

Then the delusions began.

"In the boat, he thought I was going to drown him. And then TV - we couldn't do that anymore," Hopkins said, explaining that his father would believe he was in the scenes and would go into a fearful rage.

"Once, he thought he was being arrested. When they were watching some other show, he thought the house was going to blow up."

For Janet McKee, the end came more quickly. McKee, who lived in Boulder with her husband, a well-known wildlife activist, died this month of Creutzfeldt-Jakob disease.

"The first sign we had was Nov. 18," said her husband, Richard McKee. "We were on a tour in Mexico, and she started having balance problems. When we came back, I noticed her handwriting was deteriorating and she was having trouble reading unless she had a straight-edge under the line."

By Dec. 18, the McKees had ruled out inner-ear problems, and a battery of tests conducted at the hospital that day revealed nothing.

Richard McKee was familiar with chronic wasting disease, which affects up to 15 percent of deer and elk herds in northern Colorado.

Not being able to talk with his wife was the hardest part, McKee said, explaining that within days of entering the hospital, she no longer seemed to recognize anyone.

She died Jan. 6 at the age of 67.

McKee is certain his wife's death is not related to Colorado's chronic wasting disease. "She hasn't eaten venison in probably 30 years," he said. But he is still concerned about the disorder.

"It's the most horrible disease that you can imagine, and we need to make the public aware. The BSE (bovine spongiform encephalopathy) variant did jump the species barrier (in Europe)," McKee said. "There is nothing that makes it impossible for it to jump the species barrier with chronic wasting disease. I certainly wouldn't eat deer or elk from northeastern Colorado.

There's no proof that chronic wasting disease can be transferred to those who hunt and eat wild game, said John Pape, epidemiologist for the Colorado Department of Public Health and Environment, who said he often gets calls from alarmed citizens. Their confusion - and the media's - is a source of frustration, he said.

"This is an extremely complicated issue. The guy who came up with the theory for prions in 1997 won the Nobel Prize," Pape said. "You don't win Nobel Prizes for coming up with ordinary ideas."

Until August, the state health department required doctors to report cases of CJD only in patients under 50 because such cases were unusual. Now, with increased concern about other forms of the disease, the state is requiring that all cases be reported.

Based on death certificates that note Creutzfeldt-Jakob as the cause of death, the disease rates are holding steady, maintaining the longtime one-case-per-million average, Pape said.

As for chronic wasting disease, the Colorado Division of Wildlife has monitored the deer and elk in certain areas northwest of Fort Collins for years and continually consults with the health department, Pape said. There's no indication the disease has jumped to domestic animals, let alone humans, he said.

Five years ago, the department recommended that hunters be advised of chronic wasting disease and of precautions they should take when handling animals. Those included wearing gloves, avoiding brain, spinal and lymph node tissues, and boning the meat.

"We also recommended that if any test is positive, the meat should be discarded," Pape said.

The division now tests hunters' animals in the highly affected areas.

Pape said the health department is taking a "cautious approach," revisiting the issue and making recommendations as science supports them.

"What we have tried not to do is go the other way and be overreactionary and yell, `The sky is falling!' We have had people approach us and say hunting should have been shut down years ago, but we are not going to cut out people's income and livelihood based on theoretical evidence," he said.

That criticism has grown louder since recent laboratory tests found that infected protein from a deer can transfer to protein from a human in a test tube. After noting that such a description is "exceedingly simplistic," Pape said that what happens in a test tube cannot be directly correlated with what can happen in a natural setting.

Gary Hopkins' Creutzfeldt-Jakob disease, like 90 percent of the cases, was categorized as "sporadic," meaning there was no known cause. The other 10 percent of classic CDJ cases are genetic.

Scientists suspect sporadic cases are a natural error. "That is the predominant theory," said Dr. Pierluigi Gambetti, professor of pathology at Case Western University and director of a government-funded study of CJD in the United States. All pathologists are asked to send suspected CJD brains to him for surveillance.

"It is believed this change occurs as an error during the wear and tear of the human body," Gambetti said.

But Gambetti acknowledged that there's still the question: How can scientists be sure some of the sporadic cases are not the result of chronic wasting disease?

"The answer is: I don't know," he said. "What can we do? It is very difficult in science to say `no' with absolute certainty. We have to go with the evidence."

http://www.rockymountainnews.com/drmn/health_and_fitness/article/0,1299,DRMN_26_1051279,00.html