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Mad cow disease: Only fear spreads to U.S. so far.
|[Times file photo]
Mad cow fears caused beef consumption to slump 27 percent in the European Union states at the end of last year.
By DAVID BALLINGRUD
© St. Petersburg Times, published March 12, 2001
In Italy, villagers toss dead cows down an abandoned mine shaft, fearful of a terrible disease that might be incubating in the animals' brains.
|Agents block disease at airport gate|
In Rome, a couple transform the family business -- a butcher shop for generations -- into a fish store.
Throughout Europe, mad cow disease has become a lollapalooza of a health scare and an economic horror story. Almost a hundred people are dead, and an industry is on the ropes. Beef consumption slumped 27 percent in the 15 member states of the European Union in the final quarter of last year.
On the other side of the Atlantic, however, there is relative calm.
Not a single case of mad cow disease, or the related deadly, brain-wasting disease it causes in humans, have been found in this country.
But the calm -- perhaps even the freedom from the disease -- may be temporary.
As mad cow worries spread in the world, many Americans are wondering if it can happen here.
And if consumers are worried, the nation's $52-billion beef industry is worried, too.
Steve Meyer, an economist with the U.S. Livestock Marketing Information Center in Colorado, warns that the appearance of a single case of the disease in this country could send demand for beef down "from 40 to 60 percent" in a matter of days.
The plummet would begin immediately as the news spread, he said, and recovery would be slow. "It's continuing to linger in the European mind-set," he said. "We would not see a quick turnaround here either."
The Harvard Center for Risk Analysis is evaluating the measures in place to prevent a mad cow outbreak in this country and is expected to report its findings in the next month or so.
Meanwhile, representatives of the nation's beef industry and government regulators say there will not -- cannot -- be an outbreak of the disease like that experienced in Europe. Import bans and processing safeguards will see to that, they say.
U.S. consumers should remember these facts, they say:
About 12,000 U.S. cattle have been tested for the disease over the past 10 years, including about 2,300 in the past year. None has tested positive.
The human form of the mad cow disease that has killed about 90 people in Europe thus far -- variant Creutzfeldt-Jakob disease, or vCJD -- also has not been found in this country.
The government and the beef industry have taken steps to keep mad cow beyond U.S. borders, and to quickly isolate and remove it should it make an appearance here. The importation of European beef has been banned, as has the use of cow or sheep remains as a protein supplement in cattle feed.
The infectious agent thought to cause mad cow is found in the animal's brain and spinal cord tissue -- not the muscle, which makes up most of the beef we eat. Nor is there evidence that milk or blood pass on the disease.
So don't toss out the beef in the fridge, they say; it is safe and will remain that way.
"We feel confident that we have kept the agent out of the United States," said Dr. Gary Weber, executive director of regulatory affairs for the National Cattlemen's Beef Association. "We are confident we will never have a situation here like they had in the United Kingdom."
But not everyone is so certain.
Mad cow disease is poorly understood, and closely related illnesses are already found in this country -- without knowledge of their cause.
The uncertainties add to a longstanding mystery surrounding a baffling disease -- a medical detective story that began half a world and half a century ago with a tribe of cannibals in the highlands of Papua-New Guinea.
For hundreds of years, the stone-age Fore tribe in Papua-New Guinea attracted little attention from the outside world. Then, in the 1950s, tribal members began dying in an unusual, disturbing way.
The victim first showed loss of coordination. Then came staggering, jerking body movements, increasing lethargy, helplessness and finally, within a year, death.
Fore tribe members called the disease "kuru" -- roughly translated "laughing death," or "trembling with fear."
Within years, thousands of the Fore died of this mysterious malady, and rumors of "plague" spread to nearby Australia.
In 1957, when scientists arrived to investigate, they found an isolated group of people with an extraordinary social practice: the Fore were cannibals; they ate the brains of their honored dead.
But when scientists searched for known agents of infection -- a bacterium, a slow-acting virus -- they found neither. An unknown killer was at work, one that would not be acknowledged in the medical community for 40 years.
When finally identified, the killer turned out to be a piece of misshapen protein that concentrates in the tissues of the central nervous system, including the brain and spinal cord. Somehow this misshapen protein molecule persuades other proteins to copy it and become misshapen, too. The brain develops a spongy consistency and eventually holes. Dementia follows, then death.
This newly discovered "brain assassin," as one researcher called it, was called a prion (pree-on). The disease it caused in the Fore people is Creutzfeldt-Jakob Disease, or CJD. It killed more than 2,000 tribe members before a ban on cannibalism halted it.
But the story doesn't end in New Guinea. CJD is just one in a family of killers called transmissible spongiform encephalopathies -- TSEs for short.
Identifying the deadly work of prions in the Fore tribe began the medical detective work that continues today in the search for other dangerous members of the TSE family -- notably bovine spongiform encephalopathy, or mad cow disease.
Last October, Tulane University Hospital officials made a startling announcement. A patient who died after brain surgery had an incurable disease that might have been spread to eight other patients through tainted instruments.
The hospital stopped using the surgical instruments as soon as officials realized the first patient had died from Creutzfeldt-Jakob Disease, said a Tulane vice president. The instruments, he said, went through normal washing and sterilization procedures before the eight other brain surgeries.
Given the disease, however, conventional sterilization may not have been enough. A prion is a tough molecule. It can't be "killed," since it is not really alive. So it is difficult to defend against or disable.
How it works is also complex and, at this point, poorly understood.
It was only four years ago that Dr. Stanley B. Prusiner was awarded a Nobel Prize in medicine for his "pioneering discovery of an entirely new genre of disease-causing agents.
"Prusiner has added prions to the list of well known infectious agents including bacteria, viruses, fungi and parasites," wrote the Nobel committee. Prusiner began his work in 1972, after one of his patients died of CJD.
Given the newness of the discovery, then, it's not surprising that some important questions lack answers.
While it is true that mad cow disease has not been found in this country, closely related diseases have been found, among them Chronic Wasting Disease in deer and elk.
At least two hunters in this country who ate deer and elk, and one non-hunter who ate venison, have died from CJD, according to the U.S. Department of Agriculture.
A direct, scientific link between the hunters' disease and those animals has not been established, however, because it is not known whether the victims ate animals infected with a transmissible spongiform encephalopathy.
So far, cases of so-called mad deer disease have been identified in wild animals in Colorado, Wyoming and Nebraska, and on 13 elk farms in those states plus Montana, South Dakota, Oklahoma and Saskatchewan, Canada.
"Variant CJD," the human form of mad cow disease, has not been found in this country. But the closely related "classic" or "sporadic" form of CJD shows up with some regularity in U.S. citizens, its cause unknown.
Death records show that 15 people in Florida died of the classic form of the disease in 1999. In 1997 there were 22 Florida deaths blamed on classic CJD. And the actual numbers may be higher. A common symptom of classic CJD is dementia, and some fear the illness is routinely misdiagnosed as Alzheimer's disease.
Since science has linked mad cow in England and the variant CJD cases that have claimed some 90 lives there, might there be a link between the classic form of CJD in this country and the consumption of animals such as cow, elk or deer?
On this point, government, industry spokesmen and many experts are insistent: There is no evidence of such a link, they say.
"Eighty-five percent of the CJD in this country is from an unknown cause," said Dr. Ermias Belay, a mad cow expert at the U.S. Centers for Disease Control. "It occurs at a rate of about one case per million population, and it seems to occur randomly throughout the population.
"But there is no evidence that links these cases to the consumption of the flesh of ruminant animals (grazing animals such as cow, sheep, deer)."
There is concern, however. Several western states warn hunters not to consume the flesh of animals that act in an unusual manner.
A small number of the classic CJD cases in this country have been linked to a specific genetic mutation. Weber of the National Cattlemen's Association says new research suggests genes may play a large role in the spread of the disease -- in both animals and humans.
There is some evidence that between 28 and 31 percent of the human population carry the gene that allows the malformation of the prion protein, he said.
"It's likely there is a very large genetic component to this disease," he said.
The public "should not be too reassured by the reassurances," said Michael Hansen, research associate at the Consumer Policy Institute of the U.S. Consumers Union in New York, which publishes Consumer Reports.
"We have been pointing out for years that there are a number of peer-reviewed studies that associate the classic form of CJD with meat products."
Hansen, the Consumers Union's expert on food safety, acknowledged that a link has not been proven, but argues that more study should be done.
Furthermore, he said, "you can't assume that all the cases of classic CJD are being reported. The families of the victims will tell you that it's a struggle to diagnose CJD, that it is often mistaken for other forms of dementia such as Alzheimer's disease. They will tell you that the autopsies (needed to confirm CJD) are seldom done."
In fact, said Hansen, a small number of isolated cases of mad cow disease may already be in this country. Finding it may simply be a matter of looking for it, he said, and therefore larger-scale testing of cattle is needed.
"I would predict that if they tested enough animals here, they'll find a positive," he said.
That was the case in Germany, which once confidently declared itself mad cow free. Only when private meat-producers began their own testing were the German cases discovered.
Some researchers believe the disease already made an appearance in this country, in a herd of Wisconsin cows in the mid-1980s.
Commercially raised mink in Steadsonville, Wis., mysteriously came down with a spongiform encephalopathy in 1985, and when investigators checked they discovered that the animals had been eating feed made from "downer cattle" -- cattle that cannot stand or otherwise show symptoms similar to those of mad cow disease.
A Wisconsin researcher named Richard Marsh, now deceased, then took brain material from the infected mink and placed it inside the brains of a group of test cows. They developed a bovine TSE, or transmissible spongiform encephalopathy, he reported, suggesting the disease had gone from cow to mink and back to cow again.
Weber of the National Cattlemen's Beef Association said he was familiar with the research, but did not think the cows had a form of mad cow disease. "The person managing the mink operation said the only feed purchased was from downer cows. But Dr. Marsh spent the rest of his career looking for TSE in cattle (without finding it). In the mink industry it's not an uncommon practice for mink to eat mink. It's most likely that this operation fed mink to mink, and that's what caused the disease."
Whether or not the Steadsonville cattle had the same kind of BSE that British cattle later developed may not be important now, since there is no evidence the disease is still present in this country.
But it does spotlight the elusive nature of prion-caused disease.
"Of course we hope it doesn't happen (in this country)," said Dr. Steve DeArmond, a pathologist and collaborator with the Nobel-winner Prusiner at the University of California, San Francisco. "But there are so many ways it could cross borders, you wonder why we haven't seen it yet."
Nevertheless, he said, "I would be surprised to find a case of BSE (mad cow) or a case of variant-CJD in this country."
"There is a lot of caution, and there is a lot of worry," said pathologist DeArmond. "But will the barriers do the job? I think so."
It's not enough just to keep sick cows out of the country.
Tons of meat-and-bone meal containing rendered cow parts were shipped from the UK around the world, helping spread the disease to other animals.
To protect the public -- and their industry -- the many businesses involved in meat processing and sale in this country are pushing the U.S. government hard to keep the disease out.
Dr. Peter Lurie, is a physician who works for the consumer advocacy organization Public Citizen. He is also one of the FDA's independent scientific advisers on BSE.
The government has not done enough, he said.
"We should be expanding our surveillance of the downer cow population, for one thing. The French are now checking (brain tissue from) 20,000 cows per week. Since 1990, we have examined only 12,000 cows in this country."
Public Citizen is concerned that feed containing animal protein might elude some customs inspectors, or be mislabeled.
"Is the ban being enforced? The FDA reported in January that enforcement was poor."
He's right. A recent FDA survey found that only about 2,700 of the nation's estimated 9,500 feed manufacturers had been inspected for compliance.
Among smaller companies that handle cattle byproducts, nearly half did not have a system for putting labels on their products, labels that would warn that they should not be fed to cattle or sheep.
Dale Dubberly, chief of compliance monitoring for the Florida Department of Agriculture, said the state is preparing an inspection plan with the FDA.
Lurie would not speculate on the possibility of the disease appearing in the country.
"It would not take long for a human case of mad cow (the variant CJD) to come to the attention of authorities," he said. "The incentives to find a human case are very strong. The incentives to find a case of BSE in cows is quite different.
"I'm more worried on the cow side than on the human side."
Should a case turn up in this country, "the beef industry has a strong commitment to inform the public as quickly as possible," said Alisa Harrison of the National Cattlemen's Beef Association.
"We have a reaction plan. If a case is confirmed, the animal and its offspring would be isolated and destroyed."
Meanwhile, she said, "polls show that public awareness of this issue is extremely high. We would want to get accurate information out.
"An informed public is a calm public."
- David Ballingrud can be reached at (727) 893-8245 or via e-mail at
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