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Mad Cow U.S.A.: Could the Nightmare Happen Here?
by Sheldon Rampton and John Stauber
The bizarre infectious agent that causes mad cow disease has now produced two U.S. Nobel prizewinners, 22 confirmed deaths in Europe, and fears that thousands more may follow, along with an economic catastrophe for the European meat industry. In the United States, however, it has barely made a dent in the deadly complacency of industry and government regulators.
Mad cow disease, technically called bovine spongiform encephalopathy or BSE, belongs to a class of fatal brain dementias known as "transmissible spongiform encephalopathies" or TSEs. They have raised enormous concern in Europe because of their unique nature. They are remarkably resistant to disinfection, almost impossible to detect in live animals, 100% fatal, and can take years or even decades to incubate before symptoms emerge, giving the disease ample time to spread to others before it is detected.
"If an evil force could devise an agent capable of damaging the human race, he would make it indestructible, distribute it as widely as possible in animal feed so that it would pass to man, and program it to cause disease slowly so that everyone would have been exposed to it before there was any awareness of its presence," observes British microbiologist Richard Lacey, a leading critic of his country's policies for dealing with BSE. These characteristics of the TSEs were what enabled mad cow disease to infect large numbers of British cattle.
A disease this insidious is capable of slipping below the radar of even the most extensive surveillance, yet in the United States complacency has been ensured by government and industry spin control which endlessly harps on the point that mad cow disease has not yet been detected here--even though the U.S. has seen outbreaks of a variety of other TSEs, some of which are in fact unique here or more comman than anywhere else in the world.
Everything's Fine So Far
"BSE is NOT in the United States," insists an internet web page maintained by the Animal and Plant Health Inspection Service of the U.S. Department of Agriculture (emphasis in the original). It bases this claim on its postmortem surveillance program, which has examined the brains of more than 5,000 U.S. cattle.
Unfortunately, the TSEs have one more unique characteristic which undermines this argument. Unlike any other known transmissible diseases, they seem to emerge "spontaneously," even in uninfected populations--a characteristic which can be explained, perhaps, by California biochemist Stanley Prusiner, whose "prion theory" recently won him a Nobel prize.
The prion, Prusiner says, is a new type of infectious agent which, unlike all others, can reproduce without DNA or RNA--the genetic coding materials needed for reproduction by all known life forms, from microbes to plants to human beings.
Prions, by contrast, are sticky, infectious proteins which reproduce through another means entirely. They are made of healthy proteins which have gotten bent out of shape--"flipped or folded from their usual conformation" in Prusiner's words--into a new, deadly shape which enables them to rub up against other healthy proteins and recruit them into also becoming strangely folded.
The prion theory helps explain many of the unusual characteristics of the TSEs. To begin with, it explains how the disease can "spontaneously" emerge through occasional rare mutations that cause the prion protein to change its conformation. In humans, one known mutation of the prion gene causes a rare TSE that runs in families called Fatal Familial Insomnia. Another TSE, called sporadic Creutzfeldt-Jakob Disease (CJD), occurs throughout the world at an observed rate of one case per million people per year, and leading TSE researchers believe that similar diseases occur at similar low rates of incidence in all mammalian species.
"Is BSE endemic? My answer to that is yes," says Clarence Gibbs, who heads TSE research at the U.S. National Institutes of Health. "All mammalian species thus far tested have the prion protein. . . . Hypothetically, every mammalian species in the world should have its own spongiform encephalopathy, which means that the disease is endemic in all species. You cannot escape it. That's what we're discussing here, not whether or not we have recognized the disease in this country yet. . . . If the incidence rate is one to two in a million, how many cattle brains do you have to look at before you're going to find something?" Gibbs asks.
"There's no way that we can test for the one-in-a-million scenario," admits Linda Detwiler, the official in charge of USDA's surveillance program. "To rule it out, every year we'd have to look at 2.3 million brains in the United States. Unless some miracle happens and Congress gives us all its money, that's not going to happen."
Of course, a one-in-a-million disease isn't exactly the plague of the century either--unless something happens that causes it multiply, which is what happened with England's outbreak of mad cow disease.
Prusiner's prion theory also may explain why the disease agent is so hard to kill. If he is correct, TSEs can't be killed at all because they aren't living organisms to begin with--just proteins. It follows that the only way to disinfect meat contaminated with the infectious agent would be to use something which destroys proteins--which would pretty much negate the whole point to having meat in the first place.
In addition to radiation, TSEs can withstand antibiotics, boiling water, bleach, formaldehyde, and a variety of solvents, detergents and enzymes known to destroy most known bacteria and viruses. In one experiment, the infectious agent remained infective even after exposure for an hour to a temperature of 360 degrees centigrade (680 degrees fahrenheit)--enough heat to melt lead and to reduce a good-sized slab of meat to fine ash. This in turn forced researchers to raise "the disturbing question of whether even incineration can be guaranteed to inactivate the agent."
Worse yet, testing for the presence of a TSE is much harder than testing for a bacteria, virus or other foreign invader. TSEs produce no signs of inflammation or fever, and no detectable antibody response.
Fortunately for us all, the transmissible spongiform encephalopathies have an Achilles heel. Although they are transmissible, they are usually difficult to transmit, especially from one species to another. With the exception of a disease in sheep called "scrapie," TSEs have therefore only spread widely in populations engaged in unnatural feeding practices.
In humans, the most notable example of this occurred among the Fore society of Papua New Guinea, which experienced a devastating epidemic of a TSE called kuru that spread through the practice of ritual cannibalism during Fore funeral ceremonies. By the time the practice was stopped, kuru had become the leading killer of the Fore people, accounting for more than half of all deaths and threatening extinction of the tribe.
These days, however, unnatural feeding practices are not only practiced but preached as the latest miracles of modern efficiency, progress and cost-containment in the high-tech world of today's factory farms. These practices are in fact more widespread in the United States than in any other country in the world--including the practice of feeding animal protein byproducts back to other members of their own species, which is what caused the epidemic of mad cow disease in England.
To this day, no one knows what caused the first case of mad cow disease. What we do know is that the spread of BSE was caused by feeding cows with meat and bone meal--feed supplements derived by grinding and cooking waste animal parts in a process called rendering.
"That is one of the best documented pieces of evidence that we have. I really can't emphasize it too strongly," says British TSE researcher Richard Kimberlin. The use of rendered proteins amounted to cow cannibalism, which became the decisive factor enabling the disease to multiply.
"Once infection had become established in cattle, and once they were rendered or their waste tissues were rendered and entered the feed chain, then of course you had the potential for exponentially building up an increasing reservoir of BSE infection," Kimberlin explains.
Moreover, the slow incubation period of the disease meant that by the time the British even realized they had a problem, the disease had already multiplied out of control. The first study which linked BSE to rendering was carried out at a time when the country had only seen 200 cases. In the subsequent eight years, another 160,000 cases surfaced, and studies estimate that up to 1.5 million undiagnosed cases may have occurred in cattle that were slaughtered for human consumption before symptoms started showing.
That is why Europe is so alarmed by the 22 human deaths that have been observed so far. If those 22 became infected in the early years when only a few cows were sick, how many thousands more were exposed later and may be silently incubating the disease?
"It is impossible to predict the size of the epidemic--it may only involve hundreds, but it could be Europe-wide and become a disaster of biblical proportions," says leading prion researcher John Collinge. "We have to face the possibility of a disaster with tens of thousands of cases. We just don't know if this will happen, but what is certain is that we cannot afford to wait and see. We have to do something, right now. We have to find the answers, not only to the questions of the nature of the disease, but to find a way to develop an effective treatment."
Outbreak in America's Dairyland
In the United States, some of the most disturbing questions about the disease have come from University of Wisconsin Professor Richard Marsh, whose research strongly suggests that a strain of transmissible spongiform encephalopathy may already be present in U.S. cattle. In 1985, Marsh investigated an outbreak of "transmissible mink encephalopathy" which occurred in Stetsonville, Wisconsin. The affected mink had all been fed a diet of meat from downer dairy cows, and Marsh's laboratory tests provided strong evidence that downer cows were the source of the disease.
In the late 1980s and early 1990s, Marsh faced harassment and threats of lawsuits from the meat industry in response to his warnings about the need to end the practice of feeding rendered cows back to cows. Today, those warnings have been vindicated, but neither the USDA nor the meat industry has shown any willingness to accept his conclusions that a TSE is already present in the U.S. cattle population.
And cows are not the only species about which we have to worry. In early 1997, a federal veterinarian named Masuo Doi talked with the Government Accountability Project (GAP), a Washington, DC-based nonprofit organization which exists to protect government whistleblowers from harassment, intimidation and firing. In 1979, Doi was among a group of USDA inspectors in upstate New York who investigated an outbreak of a mysterious disease in pigs with symptoms and pathology that closely resembled a TSE.
When the British BSE announcement hit the headlines in 1996, Doi was stunned to see video footage on the evening news that showed cows staggering just the way his pigs had. Fearful that U.S. pigs might already be carrying a spongiform disease, he and other government colleagues spent the subsequent year pleading with USDA officials to conduct an investigation.
"Although USDA has been aware of the dormant study and its role for nearly a year, it has not acted on it," said GAP Food Safety Director Felicia Nestor, who charged that USDA officials were not only dragging their feet but actively misinforming public interest groups, the media, and even the national association of federal veterinarians.
On repeated occasions, officials had said that they were not concerned because BSE experts had looked at slides of pig brains from the 1979 study and said there was "no problem." In reality, the USDA never sent any slides to England.
"Agency officials repeatedly misrepresented scientists' investigations and conclusions to consumer groups and government employees and neglected to keep other agencies also working on TSE issues informed," Nestor said.
Michael Hansen, a scientist who works for Consumers Union, points also to two separate epidemiological studies that link consumption of pork to Creutzfeldt-Jakob Disease. One study, published in 1973, surveyed past eating habits of CJD patients and found that over a third were reported to have eaten brains.
"Clearly, far fewer than one-third of the general population consumes brains, so there is an overabundance of brain eaters among the CJD patients," Hansen said. "Sources at USDA tell us that approximately one million animal brains are removed for human consumption every year. If each brain eater consumed only one brain a year, this would mean that less than 1% of the population consumes brains."
Even more disturbing was the fact that some 71% of the CJD patients who ate brains were reported to have a "preference for hog brains."
The second study, published in 1985, looked for correlations between CJD and consumption of 45 different food items which ranged from raw oysters to hot dogs. Nine items showed a statistical correlation, six of which came from pigs: roast pork, ham, hot dogs, pork chops, smoked pork, and scrapple.
"The present study indicated that consumption of pork as well as its processed products (e.g., ham, scrapple) may be considered as risk factors in the development of Creutzfeldt-Jakob Disease," the authors concluded. "While [a TSE] has not been reported in pigs, a subclinical form of the disease or a pig reservoir for the [TSE] agent might conceivably be present."
"The fact that evidence from a pig study and human studies both point to an unrecognized TSE in pigs is very disturbing," Hansen said. "That's why the FDA's rule prohibiting feeding of meat and bone meal is inadequate. The language of the rule states that you can't use protein from any mammalian tissue in ruminant feeds, but they've created a taxonomic loophole for pigs by excluding them from the category of 'mammals.' Not only is this arbitrary and contrary to fact, it sends a dangerous message by suggesting that pigs are safer than other mammals--even though the 1979 Doi study tells us that pigs may already be infected with a TSE-like disease."
"The feeding of swine protein to swine should be prohibited, at least until there is scientific evidence available on the possibility that swine are or not able to transmit a TSE agent," commented Dr. Karl Lonberg-Holm in written comments to the FDA. "Consider the following scenario: A pig spontaneously develops a TSE agent. This animal is within one of the large factory-like businesses that have more than 100,000 animals and which is vertically integrated so that the same corporation handles all operations from feed production to marketing pork. The offal of the pig, when rendered to protein meal, might infect many other animals within a month or so. Within a year there may be 100,000 infected animals that have already been sent to the market and consumed by the public. . . . If the latent period for the disease is long enough in swine, no overt symptoms would have been detected among pigs at the same time that much of the human population of North America had already become infected."
Deer and Elk
The United States, moreover, is the world headquarters for yet another TSE--chronic wasting disease (CWD) in free-ranging deer and elk. With the exception of a single case reported in Canada, CWD has only been observed in northwestern Colorado and Wyoming.
Until 1996, CWD was believed to be extremely rare, but when the Colorado Division of Wildlife actually conducted a study, they found that about 6.5 percent of deer and 1.5 percent of elk shot by hunters in the area tested positive for the disease. In September 1997, the Division began further study by requiring big game hunters to submit the heads of deer and elk harvested during the coming season.
When asked whether the disease posed a risk to humans, Division veterinarian Mike Miller admitted in 1996 that "we can't make any absolute guarantees about this or any other disease." Subsequently, he seems to have become more adept at expressing his uncertainty in language that minimizes the sound of risk.
"If there were a concern that this poses a serious threat to human health, the hunting season would be closed," Miller said in announcing the new upcoming study, adding that no evidence has been found linking human TSEs with the consumption of venison.
Of course, until a year ago no evidence had been found suggesting that many deer even had the disease. Researchers have no idea how long the disease might have been this widespread, so the absence of evidence for human risk is not entirely reassuring.
As a safety precaution, Miller urged hunters to take basic precautions when field dressing game, including wearing rubber gloves, minimizing handling of brain and spinal tissues and washing hands afterward. He also advised hunters against consuming brain, spinal cord, eyes, spleen and lymph nodes of animals harvested in northwestern Colorado.