Eight years ago, near the height of Britain's mad cow epidemic, I took an acquaintance to an outdoor concert in California. As we sat in the lawn seating area, waiting for the band to take the stage, Julia fished a tin of mints out of her purse. She offered me a mint, and I asked to check the box to be sure it was vegan. She gave me one of her scornful looks that she reserved for when she thought my diet was losing touch with reality: "It's a breath mint," she said, "of course it's vegan."

It was one of those unpleasant social situations that vegans sometimes get into when they spend time with the wrong people. I don't even like breath mints, vegan or not. But I took Julia at her word and popped a mint in my mouth to defuse the situation.

She put the tin onto our blanket. Several minutes later, the band had still not taken the stage, so I casually looked at the mint tin. On the label, the last ingredient was gelatin. And another nearby label said "Imported from Great Britain."

I didn't realize it then, but at that moment I joined the list -- the list of people who may have been exposed to the agent that causes mad cow disease and its deadly human counterpart, new variant Creutzfeldt-Jakob Disease. Scientists don't know if gelatin made from mad cows can pass along the infection to pass along the infection, and the probability that the 1/10 of a gram of gelatin I consumed from a single mint could trigger an infection is highly remote. Nevertheless, I immediately realized that I had joined a very undesirable list and that there would be no way to remove myself.

Thirteen years have passed since the first cows in Great Britain began dying of Bovine Spongiform Encephalopathy (BSE). The disease has generated countless headlines and time and again entangled Britain in political and economic turmoil. Already one Nobel Prize has been awarded for work done on the disease. Yet for all the research and public debate undertaken so far, the central question remains unanswered: nobody has any idea how many people will die. Thanks to new advances in medical testing, however, the people of Great Britain are on the verge of learning the truth.

The truth may be much darker than feared. As far back as the 1980s, leading microbiologist Richard Lacey warned that Great Britain could lose an entire generation of people to the BSE prion. The best evidence available suggests that the average person in Great Britain has eaten over 70 meals containing meat from infected cattle. Yet the British people have been constantly encouraged by their government not to worry about beef safety. Over the years, the government has repeatedly proclaimed that human risks associated with beef eating ranged from minimal to nonexistent.

The government's lack of action to discourage beef eating has helped Britain's beef industry to recover from the mad cow crisis. Right now, British farmers' unions and butchers are lobbying hard to lift the government ban on T-Bone steaks. Recently, a representative of the National Farmers' Union said: "All the scientific evidence that has been made public so far suggests that the risks from eating beef on the bone are absolutely minuscule."

Such reassurances have won over much of the British public because nobody has any idea how widely the disease has spread. New variant Creutzfeldt-Jakob Disease (nvCJD) -- a deadly brain disorder that appears to be caused by the BSE prion -- is notoriously hard to diagnose, especially in its early stages. Until the past month or so, it was possible to diagnose nvCJD only in well-advanced cases, and even then all diagnosis were tentative because they were based on changes in behavior. Only after the victim was dead or at death's door could a brain sample can be taken to conclusively reveal the damage of advanced nvCJD. The fact that 40 people have died of nvCJD in Great Britain tells us only that the BSE prion seems capable of infecting people. The unanswered question is: will future deaths number in the dozens or in the millions? Right now, it's anybody's guess.

The guessing game is about to end, however, and in the next year or two scientists should have a clear idea of how many Britons are carrying the prion. Although the prion responsible for BSE and nvCJD causes damage exclusively to brain tissue, it is known to show up elsewhere in the body. Recently developed tests detect prions in the tonsil tissue well before the first signs of mental degradation emerge. According to the January 16 Lancet: "The find means it may be possible in the next three years to establish if a CJD time bomb is ticking within Britain's population."

Starting soon, every tonsil taken out in British hospitals will be sent to health laboratories for testing. Since British surgeons perform untold thousands of tonsillectomies each year, the prion status of a significant percentage of Britain's population is about to become known.

The new testing technology is forcing many scientists and government officials to contemplate worst-case scenarios. Already, in Britain's highest scientific circles, there is serious discussion about keeping infection rates secret. Moreover, some scientists are suggesting that test results should be withheld even from people who have tested positive for the prion.

New Scientist is one of the scientific community's most highly regarded periodicals. A January 23 editorial comes down firmly against telling people they have tested positive:

For the moment, at least, there seems to be nothing an individual will gain by knowing. There are no drugs that prevent prions making mischief in humans, nor is there any evidence that diet or exercise can improve your chances in the way it might with a predisposition to heart disease. And knowing that you carry the agent linked to nvCJD is unlikely to help you to prepare for your demise--especially if you don't know whether you have two years left or 20.

The editorial is correct that, unlike with AIDS, there may be no benefit in slowing the spread of the disease by letting people know their status. Barring cannibalism, prions appear unable to spread from one person to another, even by sexual contact. Yet it's hard to believe that the editorial writer really has the victim's best interests at heart in arguing to keep test results hidden. Nobody doubts that being told you've tested positive for nvCJD would be terrifying news. But surely it would be even worse to go through life carrying the prion, and never to learn the truth until you seek help after developing symptoms of the disease. In addition, scientists don't yet know if the disease can be spread when an infected person donates blood -- this alone would be compelling reason to track down and inform anyone who tests positive.

The more likely reason that New Scientist wants to keep all tests secret isn't out of concern for victims. It is to prevent alarm. The editorial continues: "...even a hint that tens of thousands of Britons could be incubating nvCJD could spread panic."

Here, the logic of the New Scientist editorial breaks down entirely. If the surgery tests reveals a large percentage of Britons as being infected, attempts to keep this information restricted to the hands of scientists would demand a cover-up of impossible proportions. Indeed, if the tonsil tests reveal Britain is facing catastrophe, the only way to keep hysteria from overwhelming Britain is to make the best and most accurate information public -- and to do it as quickly as possible through the most reliable sources. One way or another, if vast numbers of people are infected, word will get out. And panic would undoubtedly be less severe if the story breaks in the London Times instead of in the Drudge Report.

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While Britain's government and beef industry still say there's little or no reason to worry, some American officials are considering the possibility that Britain's absolute worst-case scenario is about to play out. Under this scenario, a single meal made from an infected animal would be enough to infect a person with nvCJD. Such a scenario would bring a death sentence for anyone in Britain who has eaten a contaminated hamburger since 1985.

In the US, policy-makers are taking this scenario seriously&emdash;so seriously that America's blood donation regulations may soon be drastically modified. By next year, any person who has set foot in England since 1985 may be forbidden from donating blood. It's by no means certain that these tough new regulations will be put into place, but they do show how seriously American scientists are regarding the BSE problem.

Even if tough new blood regulations are swiftly put in place, Americans should not yet rest easy because there are some preliminary signs that at least one new type of prion has already appeared on US shores. The US has taken some action to see that the practice that kicked off Britain's mad cow epidemic won't happen here. Since June of 1997, cattle-to-cattle feeding has been banned in the US. But it is still perfectly legal to feed one type of farm animal, say ground-up cattle by-products, to another type of animal, say pigs. And as long as farm animals are being fed back to other farm animals, there is the possibility of creating a widespread prion-related outbreak that ultimately reaches consumers.

During the past year, seven CJD cases have appeared in Utah, while statistically this rare disease should attack just two people from Utah in any given year. It's still too early to know if the Utah cases are merely a statistical aberration. Even if prions have found their way into the food supply, it's also much to early to blame commercial meat products for the outbreak.

What is known, however, is that at least one of the cases involved a man far younger than is typical among garden-variety CJD. Most cases of CJD typically involve people well past the age of fifty, whereas the new variant linked to Great Britain's mad cow epidemic commonly strikes people from their teens to early 30s.

Doug McEwen, a 30-year-old husband and father of two, is now close to death from CJD. And while the damage in his brain sample lacks the signature of Britain's New Variant CJD, the fact that CJD has appeared in someone raises troubling concerns about about America's prion status. Six months ago McEwen was big, fit, and healthy. But signs of trouble began to emerge early last summer, starting when he forgot the spelling of his wife's name. Last July, away on a business trip, he needed to call home but forgot both his phone number and the spelling of his last name.

Today, McEwen is near death and hovers in and out of consciousness. Pinning a cause on McEwen's illness, along with the six other Utah CJD cases, is all but impossible. McEwen was a hunter, so there is a possibility that he ate meat from a deer suffering from (prion-related) Chronic Wasting Disease. He also served as a Mormon missionary up in Canada, where it's possible that he was served meat or fish that was contaminated with prions. It's also still impossible to rule out that McEwen and the other Utah residents were infected through some form of contaminated beef, pork, chicken, or fish that was produced and sold in Utah.

The lessons to take from Great Britain are at once troubling and fairly obvious. The place to start is with a little humility; realizing that there is a tremendous amount about prions that we don't yet understand. We should start by banning all feeding of livestock to livestock in the United States, at least until we know more about prions.

The reason BSE was able to spread throughout Britain is that the government put the burden of proof on health advocates instead of upon the beef industry. By doing what is best for the cattle industry, the leaders of Great Britain have betrayed the public, and exposed huge numbers of people to the possibility of a wretched and undignified death. What we are about to witness in Great Britain may involve fewer than a hundred deaths or it may become the first great horror of the next century. An even greater horror would be if the rest of the world fails to learn from Britain's mistakes, and the tragedy is repeated elsewhere.

Erik Marcus is the author of Vegan: The New Ethics of Eating