Bovine Spongiform Encephalopathy: Is It A Threat?

Bovine Spongiform Encephalopathy: Is It A Threat?

June 12, 2001, by Tosha 

Mad Cow Disease; it's a British problem. It will never show up in the United States. Or will it? This paper will explain what Bovine Spongiform Encephalopathy is and how it is spread, then illustrate why it is a threat to human lives in the United States. It will also explore other Transmissible Spongiform Encephalopathies, including Creutzfeldt-Jakob disease, Chronic Wasting Disease, and scrapie.

"Beef is one of the great unifying symbols of our culture. The Roast Beef of Old England is a fetish, a household god, which has suddenly been revealed as a Trojan horse for our destruction." --THE GUARDIAN

An Overview of Transmissible Spongiform Encephalopathies

Tracie McEwen reaches over to the dying man... As he moans softly, she strokes his arm and kisses his forehead. "It's OK. Doug, it's OK."

Tracie married Doug exactly four years ago. She marked their anniversary by pouring sparkling cider into cups, making a toast, and lovingly dropping some into Doug's mouth....

It started slowly. First, there was the memory loss and the inability to do simple math, then the light tremors. Eventually came violent seizures as well as unexplainable outbursts of emotion--hysterical laughter, sometimes followed by uncontrollable crying. By late January, he could no longer speak in sentences....

"This is the worst thing I have seen," [Tracie McEwen] says. "I wouldn't wish it on my worst enemy."

The above, reported by Mark Kennedy in the Ottawa Citizen, accurately describes death from Creutzfeldt-Jakob disease. At first, victims like Doug McEwen just seem to have memory problems. They often forget phone numbers or seem confused. Nobody thinks it's a big deal. Then their personalities suddenly change, they lose their balance, and their vision blurs. Finally they stop walking and swallowing and lose all bowel and bladder control. Most victims spend their last months on a feeding tube in a vegetative state.

Doug McEwen was a sportsman with a passion for deer hunting. He regularly ate deer meat. Two other deer hunters recently died from CJD: Jim Koepke, 39, of Nevada in February 1999, and Jay Dee Whitlock, from Oklahoma in April 2000. Despite the fact that doctors cannot confirm how these deer hunters developed CJD, no one can rule out the venison they regularly ate. In a January 1999 article in USA Today, Lawrence Schonberger of the Center for Disease Control said only five cases of classic CJD per billion people are reported annually worldwide for people aged 30 and under. These young hunters may have contracted CJD from eating the meat of deer infected with chronic wasting disease.

Chronic wasting disease, or CWD, is a neurological disorder found in elk and deer that causes brain damage, results in severe weight loss and is eventually fatal. It has been found in 5-15% of wild deer and elk in areas of Colorado and Wyoming. It has also been identified in animals in Nebraska, and in elk farms in the above-mentioned states, as well as Montana, Oklahoma, South Dakota, and Saskatchewan, Canada. Like Creutzfeldt-Jakob disease, chronic wasting disease is a form of Transmissible Spongiform Encephalopathy.

Transmissible Spongiform Encephalopathies, or TSEs, are neurological disorders that are caused not by viruses or bacteria, but by abnormally folded proteins called prions. Because prions are proteins, not foreign bodies, they are invisible to the immune system. They are also virtually indestructible; they can survive conditions that kill any known pathogen. Boiling, freezing, and soaking in harsh solvents like formaldehyde, carbolic acid, or chloroform have no effect on prions. They have survived temperatures of over 700F, and easily jump the species barrier.

Infectious prions are chemically identical to normal proteins; they have the same amino acids, they just have a different 3D structure. Enzymes can break down normal proteins, but they cannot break down prions, because of their unusual shape. Once a tiny amount of abnormal prions appears, they can convert normal proteins into prions. This leads to "clumping" of proteins, which causes tiny holes, called "vacuoles", in nervous tissue. The holes make it hard for electrical impulses to be transmitted between neurons.

Creutzfeldt-Jakob disease is a TSE that infects humans. German researchers discovered classic CJD, or sCJD, in the 1920's. sCJD is considered a biochemical fluke, a disease that strikes randomly and infrequently all over the world. It has a long incubation period, and strikes mainly older people. Most of the time it appears sporadically, striking one person in a million, typically around age 60.

Alison Williams, a twenty year old woman from North Wales, developed CJD in 1986. Her case led to the description of new variant Creutzfeldt-Jakob disease, or vCJD, a more virulent strain that can be spread through the consumption of infected animal protein.

The most well known form of TSE is Bovine Spongiform Encephalopathy, otherwise known as Mad Cow Disease. It is so named because the animals become agitated, shake with tremors, and kick violently when touched. BSE has spread across Europe like a plague, and has many concerned that it will spread even farther. But how did it all start?

History of Transmissible Spongiform Encephalopathies Scrapie, which infects sheep, was the first TSE discovered. Shepherds in Britain and Europe first described it in the 1730's. Like BSE, scrapie causes infected animals to grow ill tempered and wobbly. Then they experience seizures, paralysis, and blindness for the next three to six months until their deaths. So far, no one has contracted CJD from consuming tainted mutton, although scrapie is still common in sheep.

Dr Carleton Gajdusek, a virologist employed by the National Institutes of Health in Maryland, found a similar disorder in the Fore people of Papua New Guinea in the 1950s. The condition was called Kuru, and was thought to be a curse cast by sorcerers. The symptoms of Kuru were eerily similar to those of CJD. Gajdusek believed it to be an epidemic disease, because the appearance of this disease coincided with a change in eating habits of the women and children of the Fore people. They had been eating the prion-infected brains of dead relatives in a religious ritual.

Gajdusek examined living patients, and found no outward signs of infection, and nothing suspicious in their spinal fluid. His colleagues in Maryland found that their brains resembled those of CJD patients. Dr. William Hadlow, a scrapie expert, read one of the many reports that Gajdusek wrote about Kuru. Hadlow recognized many of the symptoms of Kuru victims, and noticed that the vacuoles in their brains were similar to those of sheep with scrapie. Hadlow wondered what would happen if he injected a healthy animal with brain tissue of a Kuru victim. Studies had shown that healthy animals developed scrapie when injected with a sheep's diseased brain tissue. So, Gajdusek injected chimps and monkeys with the ground brains of Fore tribeswomen, then repeated the experiment with brain tissue from an American CJD victim. He won a Nobel Prize when the results of his experiments proved that both Kuru and CJD were transmissible.

Just before Christmas in 1984, a vet inspected a cow at Pitsham Farm in South Downs, England. The cow was drooling, arching its back, waving its head, and threatening its peers. The vet named this unfamiliar disease Pitsham Farm syndrome. In 1986, pathologists discovered that Pitsham Farm syndrome was yet another variation on scrapie, Kuru and CJD--a Bovine Spongiform Encephalopathy, or BSE.

The Epidemic

BSE has spread at an alarming rate. Since its discovery in Britain, it has been found in Belgium, Ireland, Italy, France, Spain, Switzerland, Portugal, Holland, Denmark, Luxembourg, Liechtenstein, Germany, and Canada. In February of this year, Italy confirmed its fourth case of BSE in domestic cows. Denmark confirmed its forth domestic case of BSE recently, and officials from the Danish Veterinary and Food Administration said that they expect the figure of confirmed cases to reach 10 by the end of the year. BSE has killed nearly 200,000 cattle, and claimed 94 human lives so far.

How did BSE spread to epidemic proportions? [...]

One influence that caused BSE to spread to such a great magnitude was tainted feed. Infected cows were ground up and shipped around the world as animal feed. For several years after the disease first appeared at Pitsham Farm, the British government allowed cattle to be fed a gruel derived from meat by-products, which includes "downer" cows, considered unsafe for human consumption, and meat stripped from the spinal area of carcasses, as well as bones and inedible organs. This infected feed was fed to British cows until the government banned the use of beef by-products in any feed meant for ruminant animals.

Yet they continued to allow feed to be exported, and Asian nations alone bought nearly a million tons from 1988 to 1996. Fortunately, many countries have banned beef products imported from the United Kingdom. But it may be too late. Sumolya Kachanapangka, of Bangkok's Chulalongkorn University said, "It is probable that some of our cattle were fed with tainted feed that was imported into the country before the ban was imposed."

The government also allowed feed containing beef by-products to be fed to non-ruminant animals. They soon found it impossible to keep the possibly infected pig and chicken feed separate from cattle feed in factories and on farms. In a recent inspection, nine percent of feed mills were found to lack a system to prevent the mixing of cattle feed with feed made for other animals. The continued sale of feed made from the meat and bone meal of contaminated animals was the factor that is most responsible for BSE's rapid spread across Europe. [...]

Other ways that BSE spread was through Growth Hormone, organ transplants, and vaccines. "The thing that worries me is the immunization of the children," says Dr. Tom Pringle, a molecular biologist and the administrator of the Official Mad Cow Disease Home Page. "Every kid in the United States can't go to school without their shots... They're growing vaccines out of fetal-calf serum. Then you're injecting four-year-old children--which is much worse than eating, 100,000 times more effective... Every schoolchild in the UK has already been immunized with vaccine made from serum from infected bovines."

There have been several documented cases of people getting CJD from corneas, brain matter grafts, and other organs transplanted from infected donors. Blood, blood products, bovine extracts and transplant organs are not screened for CJD in the United States, although around the world infected organ recipients, who developed symptoms sometimes decades after treatment, have been traced to infected donors. Blood meal and horticultural bone meal can be easily inhaled or enter the body through the eyes, a direct route to the brain. [...] Surgical instruments are at a high risk of transmitting the infection, because standard sterilization does not neutralize infectious prions.

In the early 1960's, endocrinologists discovered that human Growth Hormone may possibly help dwarves attain normal heights. Human cadavers were the only known source of hGH, which is produced in the pituitary gland. The National Pituitary Agency, started by the federal government in 1963 to gather pituitaries, distributed hGH to roughly 8,200 kids within the next two decades.

This continued until a frightening pattern emerged in 1984. Normally, sCJD is rare in people under 50. But patients who had received hGH injections were getting CJD in their 20s. By spring 1985 there were four such cases on record, and 27,000 of the world's children had received injections when the practice was stopped on April 20. No one knew how many pituitary donors had been silently incubating CJD, or how many recipients were now set to die from it. [...]

Growth Hormone recipients weren't the only people unknowingly exposed to CJD. In November 1999, scientists produced experimental evidence that blood can contain infectious prions. In April of the next year, the U.S. FDA and American Red Cross established a ban on blood donations from people who have spent six months or more in Britain between Jan. 1, 1980, and Dec. 31, 1996.

"We have to be very responsible and be extremely safety conscious and keep [blood] donations as safe as possible even at the risk of depleting the blood supply," said Rebecca Haley, a chief medical officer at the American Red Cross. She warns that mad cow disease could pose as great a threat to the blood supply as AIDS if precautions aren't taken.

The American Red Cross will soon broaden its ban to include blood from all Western Europe countries, and blood donations from anyone who has lived or traveled in Western Europe for at least three months.

The Reaction

The Mad Cow Disease craze has caused myriad extreme reactions among consumers, government officials, and expert scientists.

Unfortunately, many government officials are spreading the deception that the United States is completely free of Mad Cow disease. Susan Combs, Texas Commissioner of Agriculture and a rancher, assured investors of U.S. beef safeguards. "We've not fed ruminant feed to cattle in years...I don't think we're going to see BSE in this country. We have a firewall," said Combs. Apparently, she was not aware that until the end of January, Purina had fed ruminant feed to cattle in Texas.

"Banning imported meat from the countries would minimize the risk of contaminated meat that will enter the human food chain," said Dr. Eric Tayag. He insists that stringent measures put up by the Department of Agriculture have prevented the spread of the disease by prohibiting the entry of contaminated meat or livestock from countries reported to be having problems with BSE.

Many consumers don't buy into the government's misinformation, and are avoiding beef. A study by Gardenburger Inc. concluded that nearly 20 percent of Americans have already reduced their beef consumption or have stopped eating beef entirely. Six out of ten Americans polled say they are concerned that the disease may affect beef in the United States. Three-quarters of Americans say they would be likely to avoid or reduce their consumption of beef if the disease was even suspected in American cattle. Forty-two percent of Americans polled said they would be likely to try meat alternatives, such as soy or veggie burgers.

And experts agree with these consumers. House Speaker Feliciano Belmonte Jr. urged the public to temporarily refrain from eating beef until the government has a way to detect if meat products are contaminated with BSE. Belmonte said, "It would be better for our people to eat fish, vegetable, chicken or pork in the meantime."

"I don't think that any country can say they are 100% sure that they are free of BSE," says Ralph Blanchfield of the independent Institute of Food Science and Technology based in Britain.

The Future

Mounting evidence indicates that U.S. ranches already contain Mad Cows, and that the occurrence of vCJD in the U.S. is exponentially higher than the Centers for Disease Control has revealed.

CJD's tremendous complexity, long incubation period and similarity to Alzheimer's have probably obscured the leading edge of a deadly epidemic in the United States. CJD is so rare that few doctors even recognize the symptoms, so it's frequently misdiagnosed as Alzheimer's disease. Dr. Michael Hanson, chief scientist of Consumers Union, reviewed the situation, "A study at the University of Pittsburgh, in which autopsies were done on 54 demented patients diagnosed as having probable or possible Alzheimer's or some other dementia (but not CJD), found three cases (or 5.5%) of CJD among the 54 studied (Boller et al., 1989). A Yale study found that of 46 patients diagnosed with Alzheimer's, six (or 13%) were CJD at autopsy [...]. Since there are over two million cases of Alzheimer's disease currently in the United States, if even a small percentage of them turned out to be CJD, there could be a hidden CJD epidemic."

TSEs have been found in populations of American mink, deer, elk, sheep, goats, and squirrels. These TSEs were acquired through contaminated feed and maternal transmission, and probably from contaminated areas and through close proximity of animals to one another. Wild animals might also contract the disease by raiding contaminated feed meant for livestock. That means that these animals catch TSEs from eating feed meant for cattle and other livestock. Feed that contains prions. Since the cattle are eating the same food, it's only logical to conclude that they have also consumed prions.

How did infected feed end up in the United States? For three years after BSE was diagnosed in Britain, feed made of rendered animals was imported from Britain. In addition, over the past decade, 32 cows were shipped in from Britain that USDA officials can't account for.

"The sheep thing in the US is demonstrably worse," says Pringle. "They know they've got scrapie in thirty-nine states, that there are a lot of really infected flocks, and they know those flocks are being eaten by people, and there's no effort to keep scrapie out of the human food chain. They've gotten away with murder."

America's safeguards and surveillance efforts are far weaker than most people realize. Sure, officials have examined brain tissue from 12,000 "downer" cattle without finding any BSE. But they are ignoring the fact that not only "downer" cattle can have BSE; in reality infected cows may look healthy for five years.

Leading food-safety advocates question the USDA's small test sample, methodology and motives. Dr. Pierluigi Gambetti says, "thirty-seven million animals are slaughtered a year for consumption and less than 1,000 are tested a year - it's too low," he said. "If you don't look, you don't find it. Our testing is not on the cutting edge,"

Dr. Pringle agrees. "The FDA is taking half-measured steps. It's a surveillance problem, it's weak. It's more than a matter of time before we get our first case." Germany seemed BSE-free when only downers were tested, says Marcus Doherr, an epidemiologist. "Now, with very intensive screening, they have found over 30 cases within two months."

Not only is the testing weak, but regulations are as well. Dr. Stephen Sundlop of the FDA said that at least 700 of 5,000 feed handlers inspected were not in compliance with regulations aimed at keeping U.S. cattle feed free of bone and meat meal from dead cattle, and inspections of about 5,000 more have yet to be completed. The General Accounting Office found that 20 percent of the 1,700 U.S. companies handling both restricted and unrestricted feed "did not have a system... to prevent commingling and cross contamination."

Says Dr. Hanson on the regulations concerning the feeding of beef by-products back to cattle, "All they said is that you've got to label it 'Do not feed to cattle and other ruminants.' Farmers can walk in a feed store and still buy it. Nobody asks 'Are you feeding it to cattle or pigs?'.... The way the rule is written, you can take scrapie-infested sheep, CWD-infested deer and BSE-infested animals and legally put that in animal feed and give it to pigs, chickens--anything but ruminants, as long as it's labeled. That's outrageous."

Britain utilized the existing U.S. standard from 1988 until 1996. There was so much cross-contamination that an estimated 60,000 cattle were contaminated as a consequence. Why do Americans believe that this technique will be any more successful here? If more stringent measures are not taken, Americans will soon find out exactly why neurogeneticist John Collinge, a member of the British government's Spongiform Encephalopathy Advisory Committee has warned of "a disaster of Biblical proportions."

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