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How Now, Mad Cow? 

Grazing bovines have been a symbol off bucolic calm for so long that the expression “contented cow” has become part off the vernacular. It’s ironic, then, that more recent association gives quite the opposite impression. By the time British authorities finally admitted last year that “mad cow” disease was a problem, more than a million off he unfortunate animals had to be slaughtered, and 40 people had contracted the human form of the fatal disease, in all likelihood from eating infected beef.

But that was in England, or the other side of the Atlantic. American farmers may have felt a false sense of security that such a thing could not happen here. On a national level, regulations — designed to protect the human food supply from the kind of disaster that hit Britain — do not provide enough protection. Vermont officials are being called on to fill in the gaps. With dairy still the state’s number one agricultural industry, there could be a lot to lose.

But cows are not the only vulnerable mammals. So-called mad cow is one of a family of diseases known generally as transmissible spongiform encephalopathies, or TSEs, that have various names in different species: Creutzfeldt-Jakob disease in humans; scrapie in sheep; chronic wasting disease in elk and deer; as well as bovine, feline and mink spongiform encephalopathies.

TSEs cause severe neurological deterioration, such as loss of motor control, erratic behavior, a downhill slide into dementia and inevitably death. In the end, the brain of the victim is usually riddled with myriad tiny holes, hence the name “spongiform.” The diseases can jump species, as was demonstrated when the strain of TSE affecting some people in Britain was traced back to mad cow disease.

But it is chronic wasting disease — the TSE that affects deer and elk — that is worrying Vermont officials. CWD is endemic in some states in the western United States, regions from which Vermont elk farmers have imported stock. There are currently four farms in Vermont raising elk, in Isle La Motte, Tunbridge, Hinesburg and Derby. The commercial value of the stock lies in the velvet on their antlers, which is harvested annually and sold to Asia for its medicinal qualities. In Vermont, only a small amount of the meat is served up for dinner. As the price for animals drops, predicts Isle La Motte elk farmer Larry Larrabie, “the low-cholesterol meat is likely to be in demand.”

Concern about CWD has prompted Vermont state officials to tighten controls on the importation of elk into the state and to mandate better fencing for those already here. According to state Veterinarian Dr. Samuel Hutchins, as far as can be determined, none of Vermont’s imported elk came from herds of farm-raised elk found to contain animals with CWD. But Vermont relies on other states — and the federal government — to notify it which-elk farms were contaminated and whether they shipped animals to Vermont. The problem is that there is no national tracking or notification program.

“Vermont would have to call each state and ask for more information,” says Lisa Ferguson, senior staff veterinarian at the National Center for Import Export and part of the government’s TSE Working Group. “That is up to the state if they want to do that.”

John Buck, wildlife biologist with the Vermont Department of Fish and Wildlife, also believes that there have been no known cases of chronic wasting disease in Vermont in either deer or elk. But without a formal testing program, he conceded, “there is no way to know for sure.” Indeed, there is no way to test live animals, and no animals in Vermont have been autopsied looking for TSEs.

That uncertainty had led some officials to recommend a quarantine period for imported animals. But for how long? “Admittedly,” said Buck, “the incubation period is unknown and the symptoms can be vague. Unfortunately, we don’t know how effective a quarantine is that is shorter than the incubation period.” Furthermore, it appears that apparendy healthy animals can be carriers.

“Vermont could be lucky,” said Dr. Thomas Pringle, scientific consultant for the California-based Sperling Biomedical Foundation, “or it could already have disease. Without monitoring, there is no way to know, and state officials who insist that there is no danger are in denial.”

Last year, Vermont instituted a ban on importation from farms with CWD-infected deer and elk. It still accepts animals from high-risk regions so long as the animal does not present obvious symptoms. There are several potential problems with this policy: The first case of CWD was found in Colorado in 1968, 30 years before Vermont’s ban. Given the incubation period — typically three to fours years, but possibly much longer — some imported elk may be quietly incubating the disease.

Furthermore, since elk in Vermont have escaped their pens for a while to wander in the wild, a sick animal could conceivably infect the native deer population. While most scientists believe that eating infected animals is the most common means of transmission, there is some evidence, at least in laboratory tests, of infection passed through wounds and contaminated pastures.

“We are concerned,” said Buck, “about all kinds of exotic diseases that could enter the population and could do irreparable harm to our wildlife.” Scrapie, the TSE found in sheep, is already found in most states. While no cases have been reported recently in Vermont, veterinarian Lisa Ferguson warned against complacency. “There is no state where we can guarantee that there is no scrapie,” she said. “The reporting program is voluntary, but there is no eradication program. To make a statement that the state is free of disease implies that there is a level of surveillance in place.”

The same might be said for chronic wasting disease in deer and elk.

Derby elk farmer Doug Nelson is concerned, but believes his herd is healthy. He has 130 head, and had bought 25 animals from Idaho, Saskatchewan — both regions that have reported isolated cases — and possibly other western areas. He has begun reading up on CWD. “I know what disease can do to a herd. I lost 1,000 head of cows to brucellosis in 1978,” Nelson said.

Paul Casey of Hinesburg, who recently bought 25 elk from Nelson, doesn’t know where the animals originated, but doesn’t see any need for Vermont to investigate further or impose more regulations. “I think it’s being worked on by a lot of different people from a lot of different angles, and I think it would be very premature for Vermont to get involved at this stage,” he said.

Despite their reassurances that everything in Vermont is under control, state officials really have no idea where the animals imported into the state originated. According to Pringle, “no elk farm can be certified CWD-free. Elk are traded around like baseball cards. Everyone assumes they have the best quality elk from the best herd, but so far five farms have been seriously contaminated.”

The paperwork that accompanies each shipment of elk to Vermont certifies only that each animal tested negative for tuberculosis and brucellosis. It states the place where the animals were bought, not where they were a year or even a month before that. “You can’t say the farm or herd of origin,” says Hutchins. “Doug [Nelson]’s herd was an 'assembled herd.’ He bought animals from one individual who assembled them from various herds.”

Asked for an example, Hutchins explained, “Somebody buys five animals from one person, five from another, and five from another.” When the animals are sold, the place where they were “assembled” is listed on the health chart as the place of origin. Because of the requirements for testing, “they’ve probably been there for at least two weeks. The ear tag would give us a clue [further back] if we wanted to pursue it.”

At this point, they don’t. But on January 1 the state sent notices to vets about CWD and reminded them to report any suspicious symptoms or deaths. “There is also in draft form a requirement to test any animal over 16 months of age for TSE that is killed, died or has clinical symptoms,” said Hutchins. The cost per animal is $100.

In the West, where chronic wasting disease is already a serious problem, some state officials are calling for a complete halt on the interstate trafficking of elk. Pat Graham of the Montana Fish, Wildlife and Parks Department reported to Gov. Marc Racicot last September that CWD had infected some of the state's elk. “The disease cannot be detected in live animals. It is fatal. The mode of transmission is unclear,” he wrote. “Under current standards, direct contact between game farm and wild animals is possible ... I recommend a moratorium be imposed on importation of all game farm animals until a test for CWD is developed or other measures are identified to prevent the potential transition of the disease.”

In a briefing paper, the Montana department warned that “Contaminated pastures may be difficult to disinfect, and may have to remain free of game animals for years to prevent the transmission of the disease to wild animals. It is unclear if contaminated pastures could ever be used for other agricultural purposes.”

According to the Montana officials, the disease has also been diagnosed in Wyoming, Colorado and Saskatchewan, and detected in six game farms in South Dakota, Nebraska and Oklahoma.

In parts of Colorado, the state requires hunters to submit the heads of deer to the Department of Wildlife within five days after harvesting their animal for testing.

Although scientific research into TSEs has garnered Nobel Prizes for two separate researchers, it remains one of the most mysterious and intriguing phenomena. TSEs are like no other disease in that they are thought to be caused by prions, a mutated form of protein. Because the body recognizes prions as native, they induce no fever, inflammation or other immune-system reaction. Once inside the body, they quietly erode the nervous system, especially the brain.

Unlike viruses and bacteria, prions are not alive in the usual sense, so they cannot be killed through the usual means. They can remain on surgical instruments correctly sterilized by the most sophisticated procedures, in blood products from seemingly healthy animals and humans, in corneal transplants, and in growth hormones, cadaver-source tissue, and in meat that has been thoroughly cooked. Until recently, no test could detect TSE without dissecting brain matter.

In the case of mad cow disease, large numbers of cattle probably acquired the mutated prions when they were fed commercial animal feed containing the brain, spinal cord and possibly other internal organs, or the meat or blood of infected cows. The practice of increasing production by giving herbivorous cows animal protein made them unwitting cannibals and began a deadly cycle. When those infected cows died, they, in turn, were fed back to their species and also ended up in the human food chain.

A human strain of TSE, called Creutzfeldt-Jakob Disease, or CJD, can incubate invisibly for decades and, by the time it can be detected, victims are often only months from death. It occurs “sporadically” in about one in a million people worldwide — almost all of them over the age of 50. About 10 percent of cases appear to have a genetic component, and another small number is iatrogenic — caused by medical procedures such as transplants.

And then there is the unknown number of sporadic cases that — like mad cow disease — comes from the food we eat. This strain is called new variant-CJD. While there has been no mad cow disease reported in the U.S., the level of concern over diet was recently raised in this country by the illness of a Utah man. After extensive tests, his doctors finally performed a brain biopsy and determined that 30-year-old Doug McEwan had Creutzfeldt-Jakob Disease. There are only five reported CJD cases per billion people worldwide who are McEwan’s age or younger, says Lawrence Schonberger of the Centers for Disease Control and Prevention.

Because CJD in someone as young as McEwan is so rare, some health authorities took a special interest. When they learned that he was an avid hunter and had, since childhood, been regularly eating elk and deer, their concern grew. McEwan had hunted near areas of the western United States and Canada, where up to 6 percent of tested wild deer and elk have chronic wasting disease.

Although the Center for Disease Control has already decided that McEwan’s consumption of elk or deer is unrelated to his illness, many researchers say that conclusion is based on politics, not science. Until McEwan dies and scientists can strain-type the CJD attacking his brain, the source of his infection cannot be proven. Even then, scientists may not be able to determine the source.

Soon after McEwan was diagnosed, the FDA quarantined all the blood products containing plasma he donated since last January. Plasma given before January is thought to have already been used.

The ban, health officials assure, is just precautionary. Although CJD has been transmitted in the laboratory through blood, there is no evidence that it can be acquired through blood transfusion. But with research limited and no screening test for TSEs, fear remains. Last December, in the wake of the British mad-cow outbreak, a U.S. FDA panel recommended consideration of a ban on blood donations from people who lived in or visited Britain from 1980 to the present.

The British themselves have gone one step further. Government science advisers told the London Sunday Times that they were considering a recommendation to destroy almost all operating equipment used in National Health Service operating theaters to insure that CJD was not passed from one patient to another. Although this is only one of several options, the scientists said, it is the only way to be 100 percent safe.

Recently, the Center for Food Safety, the Humane Farming Association and families of CJD victims, among others, called for stricter regulation in the U.S. They filed two legal petitions this month calling on Washington to immediately monitor, regulate and take steps to prevent the always-fatal neurological disease. They demanded that the Food and Drug Administration eliminate loopholes in regulations and ban feeding any mammalian protein to any food animal. Current regulations permit the use of blood, blood products, gelatin and pig byproducts, and scrapie-infected sheep in animal feed.

Blood and blood products are used as animal feed in two ways that could affect Vermont dairy farmers. In accordance with modern farming practices, newborn calves are often removed from their mothers immediately after birth. They are then given a formula which may contain bovine blood serum to replace or supplement antibody-rich colostrum, the first milk a newborn calf would normally receive from its mother. In the second use, a calf milk replacer containing spray-dried bovine blood plasma is given to weaning calves. Calling the use of blood “a high-risk practice,” the petition calls for it to be banned.

The petition also asks the Centers for Disease Control to track TSEs more rigorously in humans and animals, and urges state health officers in all 50 states to make CJD a reportable disease. Washington will have 180 days to reply; meanwhile, the states are under no legal obligation to institute reforms. Vermont State Health Commissioner Jan Carney said she will review the petition and pass it on to staff and the Department of Agriculture. She will also ask a task force to review it. Currently in Vermont, chronic wasting disease is a reportable disease for animals, but CJD, which affects humans, is not.

While an outbreak of TSE in the Vermont elk population may be unlikely, if it did occur, and if it spread to the native deer population, the consequences could be serious. The Vermont Department of Agriculture is in a difficult position. It combines two functions: promoting agriculture and protecting the public interest. Although these functions are performed by separate subdivisions, Pringle sees a fundamental conflict of interest in those roles. “You are asking an agency to do the impossible if it is supposed to be promoting agriculture at the same time as being asked to blow it out of the water,” he said.

Another potential problem for Vermont is that it is generally up to farmers and herders to report sick livestock, whether elk and deer or cows. And when destruction of the whole herd is possible, no compensation is guaranteed and the facilities might be unsafe for livestock of any kind, farmers could be sorely tempted to keep quiet about potentially infectious diseases. “We would hope someone would say something about it,” said Hutchins. “With past outbreaks of TB and brucellosis, there was no automatic compensation, but the legislature did approve some. But with those diseases there were tests.”

Until test are cheap and available, the danger remains. And until a treatment is found, the prognosis for those infected — animal or human — is grim.

Thomas Pringle believes that Vermont could be doing more to keep CWD out of the state. He recommends precautions for maximum risk reduction, including:

• Establish a database for all elk in the state going back 10 years to record where each animal comes from and where it goes.
• Require autopsies in all deaths from illness.
• Track ear tags back in order to identify the farms of origin of imported elk.
• Do not allow domestic livestock, especially sheep and dairy cows, to come into contact with elk or pastures where elk have been kept.
• Cut down on imports and ban all wild deer and elk from infected areas in the western U.S. and Canada.
• Identify sick animals.
• Establish an indemnification program that mitigates the financial risk for farmers reporting infected animals.

For farmers, it’s one more thing to worry about — ironically resulting from technological advances intended to make them more competitive. In an effort to increase production by giving their cows bovine growth hormone, farmers have to supplement the stressed animals’ diet with protein, sometimes of animal origin. When they try to raise profits by separating newborn calves from their mothers, the newborns require special diets that may include bovine blood products. And when farmers turn to diversification — perhaps raising elk for an exotic Asian market — they discover the threat of a bizarre disease.

Most farmers are simply trying to survive on a harsh landscape dominated by developers and agribusiness. For them — and for the Agriculture Department officials whose job it is to promote and protect the state’s farms and farmers — the risk of importing some unknown illness must seem impossibly remote. Especially as compared to the risk of going under and losing the life and the land they care most about.


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