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Mad cow danger may even be bigger
SCRIPPS HOWARD NEWS SERVICE / Seattle Post-Intelligencer ^ | January 13, 2004 | TODD HARTMAN

Posted on 01/13/2004 5:14:09 AM PST by Freebird Forever

Research suggests sick animals may not show symptoms

Below the drumbeat of reassurances from government and the cattle industry that the meat supply remains safe despite this one case of mad cow disease, a small universe of scientists working on a family of related illnesses is finding disturbing evidence to the contrary.

Several studies, including research at a government laboratory in Montana, continue to spark questions about human susceptibility not only to mad cow, but also to sister diseases such as chronic wasting disease, which mainly affects deer and elk, and scrapie, which infects sheep.

Mice research and clusters of cases in which humans contracted a disease similar to mad cow also has a few scientists wondering whether consuming infected meat might have killed far more people than medical experts have long assumed, not only in Great Britain, but in the United States as well.

Most scientists believe the relatively small number of known human cases, called Creutzfeldt-Jacob disease, strongly indicates this disease -- whatever its cause or origin -- is rare and difficult to transmit. There is also no evidence yet that scrapie in sheep or chronic wasting disease in deer has ever been passed to humans.

But some scientists say it's possible that chronic wasting, endemic in Colorado's wild deer and elk, has sickened and proved fatal to humans. These experts challenging the standard view note that doctors haven't -- or can't -- recognize signs of these other forms of the disease during an autopsy.

Little of this research reaches the broad public audience, leaving most people to hear only the oft-repeated promises of well-funded interest groups or high-profile public officials.

Just last week, for example, the National Cattlemen's Beef Association described mad cow disease solely as an animal and economic problem -- not a human health problem. The U.S. Department of Agriculture has said repeatedly that the nation's beef supply is safe.

Such statements, offered frequently since the December discovery of a Holstein with mad cow disease in Washington state, spark criticism from some scientists and consumer advocates who say that the government and industry are injecting certainty into a field where uncertainty remains the dominant theme.

Much remains unknown about so-called transmissible spongiform encephalopathies, or TSEs, the family of diseases to which mad cow, scrapie, chronic wasting disease and two human versions -- known as Creutzfeldt-Jakob, or CJD, and "new variant" CJD -- belong.

This rogues' gallery of deadly illnesses features an array of frightening symptoms. In humans they can include depression, inability to conduct simple tasks such as operating a telephone and loss of balance and speech. In every case, the victim's brain becomes riddled with holes; thoughts, emotions and memories disappear on the way to death, often in just a matter of months.

But much about the diseases remains a mystery.

Clusters of a rare disease

It's long been believed, for example, that only one of the two versions of human CJD can be linked to eating meat contaminated with mad cow disease. The other version, known as sporadic or classical CJD, has long been thought to occur randomly in about one in every million people, a distinctive illness with no link to meat from an infected animal.

But a few studies in the past three years have challenged that view, suggesting that classical CJD, might, in some cases, also result from eating contaminated meat.

Scientists in Great Britain injected tissue from a cow with mad cow disease, also known as bovine spongiform encephalapothy, into mice whose brains were genetically engineered with human genes. One set of mice fell sick with the human form of mad cow, or new variant CJD.

But, in a finding that stunned researchers worldwide, another set of the genetically altered mice developed what looked like the sporadic form of CJD, the one scientists have long believed has no relationship to mad cow disease or meat-eating.

"This finding has important potential implications as it raises the possibility that some humans infected with (mad cow disease) may develop a clinical disease indistinguishable from classical CJD," the researchers wrote in November 2002.

French scientists a year earlier found a strain of scrapie, the version of the disease that infects sheep, also caused brain damage in mice similar to classical CJD.

Though these findings run counter to most studies, the two studies suggest that some of the hundreds of Americans who contract classical CJD each year could have been infected by mad cow-contaminated meat, and not simply by biological bad luck.

Then there are the mysterious clusters of human cases. Because classical CJD is so rare, scientists don't usually expect it to occur in clusters. But such clusters have occurred, including among hunters eating venison.

The most recent example involves seven people who apparently died of classical CJD in New Jersey. All of them had a link with a racetrack in Cherry Hill where they ate, according to reporting this month in The Philadelphia Inquirer.

Most surprising: The deaths included a 29-year-old. It's extraordinarily rare for someone so young to die of classical CJD. Victims are typically older than 55. In contrast, victims of new variant CJD in the 1990s mad cow panic in England were often young people.

The U.S. Centers for Disease Control and Prevention wasn't initially interested in the cluster, but since the discovery of the case of mad cow in Washington state the agency is taking another look at the case, according to The Inquirer.

CJD may be underreported

Even so, experts caution that clusters can also be coincidences. Rare diseases don't always end up geographically spread out.

"The cluster is curious, but these sorts of things can happen by random chance," said Patrick Bosque, a neurologist at Denver Health and an expert on TSE.

Bosque is open-minded about the possibility of humans contracting such diseases at a higher rate than is currently believed, but is also cautious about jumping to conclusions.

"With almost 300 cases of CJD expected in the U.S. each year, it isn't too surprising that over a few years one might occasionally find a cluster associated with some ill-defined event or place," he said.

But some scientists believe the true number of U.S. CJD cases is underreported, and the disease is not as rare as once believed. Some experts believe that it is possible that some cases diagnosed as Alzheimer's could actually be CJD. Some other dementia-like diseases could also be misdiagnosed, experts say.

"Given the new research showing that infected beef may be responsible for some (classical) CJD, thousands of Americans may already be dying because of mad cow disease every year," wrote Dr. Michael Greger, a physician and vegan advocate.

Many scientists, however, caution that if mad cow disease were really fueling an increase of classical CJD in the United States, then we should also be seeing many more cases of new variant CJD, the form of mad cow disease that struck people in Great Britain.

Even in Britain, where millions of people were estimated to have eaten mad cow-contaminated meat, fewer than 150 people came down with new variant CJD.

"Could BSE have been transmitted to people in the U.S. but gone unrecognized because it looked like (classical) CJD?" Bosque said. "I suppose it is possible, but there would be no obvious explanation for the fact that (new variant) CJD has not been seen in the U.S."

But the critics answer that the United States has no formal monitoring system in place to track CJD cases and autopsy the victims. That would enable scientists to more accurately detect trends in occurrences and study the pattern of destruction in the brain that reveals whether a victim died of classical or new variant CJD.

TSEs borne by silent carriers

At a National Institutes of Health laboratory in western Montana, researchers are focused on the question of what happens when TSEs move back and forth between different animals. What they've found is unsettling.

Their latest research is an extension of work they've been conducting for several years. It shows that TSEs can be passed to some animals without causing disease, but then passed onto another species where they cause illness.

The implications are significant.

Researchers began by taking brains of hamsters infected with scrapie and injecting that tissue into mice. Then, they killed the mice at various points and tested for presence of the infectious agents -- called prions -- in the brains of mice. They didn't find any.

But researchers took the next step, injecting tissues from these apparently prion-free mice into another set of healthy mice and hamsters. That's when the outcome turned frightening: the newly infected creatures developed TSEs and died.

What does it mean? The mice from the earlier part of the experiment were not free of the disease after all. They were silent carriers of a sort, not showing any signs of the illness but able to infect others.

This could have dramatic implications for the real world. What if, for example, some humans carry mad cow disease or another TSE, but aren't affected by it? Perhaps they could still pass it on through blood transfusions or transplants. In the words of researchers: "Subclinical human carriers might pose a serious risk for contamination of surgical instruments, tissue transplants and blood products," according to a 2002 report on the mice-hamster experiments in Montana.

Then there are the ramifications for animals.

Michael Hansen, a scientist for Consumers Union, points out that cattle tissues that are mostly removed from the human food chain are still converted to feed for chickens and pigs, among others.

Remains of those animals, in turn, are still rendered into cattle feed -- a practice derided by critics and banned in Europe, but still legal and common in the United States.

"Those animals could become silent carriers and infect cattle," Hansen said.

The Montana researchers have continued their work, injecting tissues from the mice and hamsters that became sick into yet another set. The next generation of mice and hamsters got sick as well.

The experiments have also revealed another disturbing fact.

The infectious prions appear to persist and adapt, evolving to infect a new species and even becoming more virulent as they move between species. In some cases, incubation periods change, growing longer or shorter depending on the experiment.

In short, behavior of the diseases has been unpredictable, making statements of certainty about them untenable.

Bosque, the Denver neurologist, said the ability for TSEs to hide inside some animals and increase their infectivity is worrisome.

"It raises an additional level of concern, that these prions can persist in animals, and increase, even though (the animals) don't appear sick," Bosque said. "For one thing, it shows you that screening for just obviously sick animals may not be sufficient."

But currently, the United States focuses its testing almost solely on sick or "downer" animals. Industry officials have said testing every cow for mad cow disease as Japan does would be a waste of time and money.

DEFINING DISEASE

Several similar brain-wasting diseases affect livestock and wild animals:

* Mad cow disease: Also known as bovine spongiform encephalopathy, this disease infects cattle. Infectious proteins called prions kill brain cells, causing spongelike holes to develop. First identified in Europe in the 1980s.

* Chronic wasting disease: This illness infects deer and elk. No cases of transmission to hunters eating the meat have been confirmed.

* Scrapie: This spongiform disease is found in domesticated sheep.


TOPICS: Business/Economy; Culture/Society; News/Current Events
KEYWORDS: bse; cjd; health; madcow; prion
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For your thoughts & opinions.
1 posted on 01/13/2004 5:14:09 AM PST by Freebird Forever
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To: Freebird Forever
My thoughts? Time to become a vegetarian..
2 posted on 01/13/2004 5:17:32 AM PST by Zipporah (Write inTancredo in 2004)
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To: farmfriend; civil discourse; Battle Axe; meatloaf; vetvetdoug; Phaedrus
Thoughts, opinions & high volume pings appreciated.
3 posted on 01/13/2004 5:20:20 AM PST by Freebird Forever
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To: Zipporah
Time to become a vegetarian.

I do think it's prudent to be as informed on this topic as possible. But giving up all meat is something I'd like to avoid. Steak is one of life's little pleasures.

4 posted on 01/13/2004 5:27:43 AM PST by Freebird Forever
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To: Freebird Forever
I have studied the odds and decided to continue eating beef as usual.
5 posted on 01/13/2004 5:29:13 AM PST by MEG33 (We Got Him!)
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To: Freebird Forever
Scientists in Great Britain injected tissue from a cow with mad cow disease, also known as bovine spongiform encephalapothy, into mice whose brains were genetically engineered with human genes.

For more valid results I would have cooked and digested the tissue first. But you can be damned sure I'm going to cut down on injecting infected tissue into my brain.

6 posted on 01/13/2004 5:29:45 AM PST by Agnes Heep
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To: Agnes Heep
But you can be damned sure I'm going to cut down on injecting infected tissue into my brain.

Man, that's gotta hurt! Blackbird.

7 posted on 01/13/2004 5:32:18 AM PST by BlackbirdSST
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To: Agnes Heep; Freebird Forever
Injecting infected tissue into my brain is one of life's little pleasures.
8 posted on 01/13/2004 5:32:21 AM PST by ClearCase_guy (France delenda est)
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To: Freebird Forever
there goes my stock in Weber grills......
9 posted on 01/13/2004 5:33:25 AM PST by joesnuffy (Moderate Islam Is For Dilettantes)
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To: Freebird Forever
I keep remembering all the things that "research" has shown to cause DANGER TO HUMANS!!!. Things like peanut butter causes cancer, any non-sugar sweetener causes cancer(if you drink 40 gallons of the stuff everyday for 50 years) and all the rest. But, I guess an outbreak of a brain-wasting disease would explain the democRAT party
10 posted on 01/13/2004 5:34:24 AM PST by sticker
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To: Freebird Forever
If I eat carbs, I'll become fat and die.

If I eat meat, I'll get chronic wasting disease, become thin, and die.

I'll take thin, please.

11 posted on 01/13/2004 5:35:02 AM PST by Lazamataz (I slam, you slam, we all slam, for Islam !)
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To: Agnes Heep
I'm going to cut down on injecting infected tissue into my brain.

That's sound reasoning.

I fully concur.

12 posted on 01/13/2004 5:35:18 AM PST by Freebird Forever
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To: sticker
I guess an outbreak of a brain-wasting disease would explain the democRAT party

Truer words are rarely spoken.

13 posted on 01/13/2004 5:37:24 AM PST by Freebird Forever
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To: sticker
"But, I guess an outbreak of a brain-wasting disease would explain the democRAT party"

Of course, you know there have been observations of Mad Cow in New York State, everywhere Broomstick One has landed.
14 posted on 01/13/2004 5:37:59 AM PST by punster
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To: Zipporah
Time to become a vegetarian.

Several years ago while discussing BSE I made the same quip to a Dept. of Agriculture official sitting next to me on a plane.

The response was "you can't escape it by becoming a vegetarian". Do you know why?

15 posted on 01/13/2004 5:39:23 AM PST by Hostage
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To: Freebird Forever
Wonder if the writer is a vegan trying to get the rests of us to swear off beef.

Nah, couldn't be.

16 posted on 01/13/2004 5:40:47 AM PST by MEGoody
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To: ClearCase_guy
Injecting infected tissue into my brain is one of life's little pleasures.

Did you used to party with Keith Richards?

; )

17 posted on 01/13/2004 5:41:49 AM PST by Freebird Forever
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To: Freebird Forever
You are safe eating steak. Just don't eat the chicken feed.
18 posted on 01/13/2004 5:44:00 AM PST by hotpotato
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To: Freebird Forever
I used to party with Keith all the time! Then I got me knighthood and he stopped returning my calls. What a wanker!
19 posted on 01/13/2004 5:47:58 AM PST by ClearCase_guy (France delenda est)
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To: MEGoody
Wonder if the writer is a vegan trying to get the rests of us to swear off beef.

My current understanding is that beef raised here in Texas is still safe. I would encourage y'all to forgo vegenism and support our ranchers.

20 posted on 01/13/2004 5:48:14 AM PST by Freebird Forever
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