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Mad cow disease

Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a fatal, neurodegenerative disease of cattle, which infects by a mechanism that shocked biologists on its discovery in late 20th century and appears transmissible to humans. While never having killed cattle on a scale comparable to other dreaded livestock diseases, such as foot and mouth and rinderpest, BSE has attracted wide attention because people assume humans can contract the disease, but it has never been proven that BSE has any link to variant Creutzfeld-Jakob disease (vCJD), sometimes called new variant Creutzfeld-Jakob disease (nvCJD), a human brain-wasting disease. more...

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Infectious agent

Unlike other kinds of infectious disease which are spread by microbes, the infectious agent in BSE is a specific type of protein. Misshapen ("misfolded") prion proteins carry the disease between individuals and cause deterioration of the brain. BSE is a type of transmissible spongiform encephalopathy (TSE). TSEs can arise in animals that carry a rare mutant prion allele, which expresses prions that contort by themselves into the disease-causing shape. Most TSEs, however, occur sporadically in animals that do not have a prion protein mutation. Transmission can occur when healthy animals consume tainted tissues from others with the disease. In the brain these proteins cause native cellular prion protein to deform into the infectious state which then goes on to deform further prion protein in an exponential cascade. These aggregate to form dense plaque fibers, which lead to the microscopic appearance of "holes" in the brain, degeneration of physical and mental abilities and ultimately death.

The BSE epidemic in British cattle

The British BSE epidemic in cattle was recognised in 1986. It was first believed to have originated in sheep, in which the related prion disease scrapie is common (such diseases collectively are called "transmissible spongiform encephalopathies" or TSEs). However, sheep and cattle TSEs are quite different and it is now thought more likely that BSE could have originated with a case of sporadic BSE in a single bovine. Prior to the BSE epidemic, cattle were fed with meat and bone meal, a high-protein substance obtained from the remnants of butchered animals, including cows and sheep. This practice allowed the accumulation of prions over many generations. As more animals became ill, more infectious tissue got into the feed, and so the number of cases reached epidemic proportions. The tissues that contain most of the pathogenic molecules are those of the brain and the nervous system, although infectious amounts have been shown experimentally to be present elsewhere, such as in blood.

The use of meat and bone meal as a protein supplement in cattle feed was widespread in Europe prior to about 1987. Soybean meal is the primary plant-based protein supplement fed to cattle. However, soybeans do not grow well in Europe, so cattle raisers throughout Europe turned to the less expensive animal byproduct feeds as an alternative. A change to the rendering process in the early 1980s may have resulted in a large increase of the infectious agents in the cattle feed. A contributing factor seems to have been lax British laws that did not require a high temperature sterilization of the protein meal. While other European countries like Germany required said animal byproducts to undergo a high temperature steam boiling process, this requirement had been eased in Britain as a measure to keep prices competitive.


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What you fear, what you should fear: obsessing about shark attacks, plane crashes and mad cow disease? Stop. Here's what you really ought to worry about
From Shape, 6/1/04 by Ron Geraci

I'm gripping the armrests while the storm bashes the plane like a pinata, when the guy next to me decides to lean over and do a good deed: "Statistically, you know, you're a thousand times safer up here than you are on any highway," he says, smiling.

Distracted by the primal urge for survival, I resist the impulse to teach him about statistics. I knew he was right, but--as I told him--I would have rather been doing a handstand in the middle of the freeway at rush hour than to stay strapped in that plane for another two minutes. And I meant it.

Illogical? Absolutely. But you probably engage in the same type of thinking about your own health every day. You worry the most about certain dangers that, in truth, are very unlikely to strike. Or at least are far less likely to happen than real threats you blissfully ignore.

Why? "We tend to fear what we can't control and those things that are most readily available in our memory," explains David G. Myers, Ph.D., a social psychologist at Hope College in Holland, Mich., and author of Intuition: Its Powers and Perils (Yale University Press, 2002). For example, most of us assume we're in control when driving a car, so we have little fear of doing things that make an accident much more likely--like tailgating, talking on a cellphone or flipping through our CD case at 65 mph.

We must thank the wonderful world of television too. "The media gives us a lot of images to remember," Myers says. When your brain sees a video of someone getting robbed at an ATM in Dallas, for example, or you witness the dramatic suffering of a shark-attack victim in Kauai, those incidents might as well have happened in your front yard; you may even recall them vividly for years. However, the much likelier risks to your life, such as diabetes, skin cancer, depression or developing a resistance to antibiotics, don't make dramatic television or memories.

Following are five common worries that you're probably stressing over too much, and a few other problems that you'd be smart to give more of your attention to, even if they're not on the evening news.

Worry less about breast cancer

Worry more about "noncelebrity" cancers

"Every woman thinks she's going to get breast cancer, and she probably won't," says Providence, R.I.-based Adelaide Nardone, M.D., medical adviser for the Vagisil Women's Health Center. The mistake is an easy one, though, given all the media attention, with celebs urging women to get mammograms and the reminders of the scary statistics: 40,000 women die a year from breast cancer, and every woman has a 1-in-8 lifetime risk of developing the disease--a stat which factors in the women who find a tiny, treatable lump at age 95.

Finally, we all know someone who, somehow, has been touched by breast cancer.

But here are some other statistics you may not know: Even if you have a family history of breast cancer, your odds of developing the disease by age 39 are only about one in 229, or approximately 0.44 percent. Your chance of developing it by age 25? Only about one in 20,000.

What should young women worry more about? "Lung cancer is the leading cause of cancer deaths among women," Nardone says. Projected female deaths from lung cancer in 2004 are 68,500 (yet 22 percent of American women still smoke), while projected female deaths from breast cancer in 2004 are 40,000. A recent study from the journal Lung Cancer found more bad news: Female smokers are twice as likely to get the disease as men are.

Women also underestimate their risk for another common cancer: "Melanoma has taken the lead as the No. 1 cancer in women between 25 and 29 years," says John J. DiGiovanna, M.D., a dermatologist at the National Cancer Institute in Bethesda, Md.

"Women are much more likely to do regular breast self-exams than they are to check their bodies for unusual moles," notes John Romano, M.D., a dermatologist at Weill Medical College of Cornell University at NewYork-Presbyterian Hospital in New York City. It's a dubious trade-off: While melanoma kills far fewer women than does breast cancer (2,900 women die of melanoma each year and another 24,000 or so are diagnosed), those deaths are much more preventable. Limiting sun exposure and detecting the cancer early would likely save many of these lives.

Worry less about taking care of others

Worry more about taking care of yourself

"From an early age, women are trained to care for others and not to focus on themselves," says Gabor Mate, M.D., author of When the Body Says No: Understanding the Stress-Disease Connection (John Wiley & Sons, 2003). Many are taught that pleasing others also means suppressing certain emotions to preserve harmony. This may be one reason why women are nearly twice as likely as men to be diagnosed with depression and anxiety disorders.

"Women who suffer from depression and anxiety are more likely to develop autoimmune illnesses, such as chronic fatigue syndrome and fibromyalgia," Mate says. This may be due to brain physiology, he adds; new research has found that areas of the brain associated with emotion also seem to be related to those affecting immune-system function. In addition, depressed women are especially vulnerable to heart disease, according to a four-year study of almost 94,000 U.S. women age 50 and above, published in the journal Archives of Internal Medicine; it found that women who were even mildly depressed had a 50 percent increased chance of dying of heart disease within four years.

The emotional stress that comes from ignoring your own needs, however, usually reveals itself in less severe ways, Mate says. "Most often the symptoms will be in the form of chronic headaches, muscle spasms, back pain, neck pain and poor sleep," he explains.

Many women simply treat these symptoms instead of trying to find their root cause. "If a woman is having chronic headaches and she is in a relationship with an extremely demanding man, she may never see the connection," Mate says. That makes acknowledging your stress and then identifying its cause a critical step toward defusing it.

Learning to say no is one of the most important ways to avoid the mental stress that can compromise your health. It's certainly difficult to tell your boss you can't take on that fourth project; saying no could lead to someone being disappointed in you. But the consequences of your giving in are immediate. "The very moment you say yes, you have avoided psychological discomfort but instead instantly feel physiological stress," Mate says.

Worry less about getting injured or humiliating yourself while working out

Worry more about staying away from exercise

Self-consciousness keeps too many women (and men, I have to admit) out of gyms--and even from beginning an exercise program. If you haven't been active in a while, you also may be concerned about getting injured.

The most common injuries women suffer while starting an exercise routine are hurting an ankle from a misstep, knee pain, shinsplints and muscle soreness, says Doug McKeag, M.D., director of the Indiana University Center for Sports Medicine in Indianapolis. "But even these risks are relatively low, and shouldn't prevent any woman from exercising." A tip to further insulate yourself from injury? "If you're starting a program to lose weight, [opt for] nonweight-bearing exercises like swimming or biking at first, to help condition your muscles without straining them," McKeag advises.

Also, remember that avoiding exercise can have far worse consequences than a pulled hamstring. In 1995 about 1.85 million women of reproductive age had diabetes, and at least 500,000 didn't know it. The risk for women is skyrocketing: From 1990-1998, the diabetes rate among females ages 30-39 increased by approximately 70 percent. The disease is a ruthless killer too. For all the harping about our treacherous highways, over the span of your life the odds of dying from diabetes are almost two-thirds higher than those of being killed in an automobile accident.

According to the Harvard School of Public Health in Boston, the most effective ways to prevent diabetes--in addition to not smoking--are to maintain a Body Mass Index (BMI) under 25 (optimal BMI is between 21 and 23, if that's possible for your body type) and to exercise at least moderately for a half-hour each day. "Even if you're perfectly thin now, you can't skimp on exercise if you want to reduce your risk of diabetes," says Frank Hu, M.D., Ph.D., a specialist in diabetes at the Harvard School of Public Health. (If you don't know your BMI, go to to find it.)

Worry less about receiving the wrong medication

Worry more about taking antibiotics you don't need

We've all been taught to worry about medication screw-ups such as your pharmacist mistakenly swapping your allergy prescription with a 78-year-old woman's heart medication. In 2003 about 3 billion prescriptions were filled in the United States. The National Association of Boards of Pharmacy has estimated that as many as 5 percent may have contained some sort of mistake (many are harmless gaffes, such as spelling "birth-control pills" as "birthcontrol pills"). Reported fatalities from medication screw-ups total about 7,000 people a year. But let's multiply that by 10, just in case a large number are unreported. Put 70,000 deaths against 3 billion transactions. Your odds of encountering a serious prescription mistake in a year may inch toward, at the closest, 1 in 44,300, making you about six times more likely to die in an auto wreck in any given year.

Two additional precautions will buy you another decimal point toward safety. "Ask the pharmacist to repeat the medication's name if it's a new prescription, and inspect refills to make sure the pills look the same," says Suraj Adiecha, R.P.H., a pharmacy manager at a Safeway in San Ramon, Calif., whose team fills as many as 55,000 prescriptions a year.

Ironically, the only dubious drug your pharmacist hands you this year might be the one your doctor did prescribe: antibiotics to heal a raw throat or unclog your sinuses. A decade from now, those very same pills could send you to the hospital with a life-threatening infection that no antibiotics can kill.

"Antibiotic resistance is becoming a dangerous problem, and most people don't understand how it affects them personally," explains Katherine Haltiwanger, M.D., a pediatrics and emergency physician at the University of Virginia Health System in Charlottesville. In her study of 129 college students ages 18-25 suffering from cold symptoms, she found that women were more likely to ask a doctor for an antibiotic prescription than men were. "Many of their upper-respiratory infections were likely viral, so antibiotics would not have helped them," she adds. These coeds aren't dumb; a survey found that 44 percent of adults mistakenly believe antibiotics can help cure a cold.

This common misconception is causing a deadly problem: Doctors have often reserved our most powerful antibiotics (such as vancomycin) as a last resort when others have failed--and now even these superantibiotics are proving ineffectual on a regular basis. Drug companies are frantically trying to develop newer, stronger antibiotics (one example is Cubicin, used for antibiotic-resistant skin infections), but bacteria begin learning how to foil each new drug almost immediately.

The Centers for Disease Control and Prevention estimate there may be 60 million unnecessary antibiotic prescriptions written each year. "Physicians feel pressured to prescribe these antibiotics, because patients ask and they don't want them to be dissatisfied," Haltiwanger says. To be sure what you're getting is what you really need, ask three questions before accepting an antibiotic prescription from your doctor, Haltiwanger advises: First, is this medication really necessary? Second, if so, can I take a less-powerful drug? And third, do I need to take it immediately, or can I wait three days and see if my symptoms go away?

If a self-diagnosed case of strep throat has you feeling like you're swallowing razor blades, have a culture done before taking antibiotics. A Canadian study found that even doctors overestimated the likelihood of a strep infection (which does require antibiotics) by 33 percent, and prescribed the drugs wrongly in two-thirds of cases. Among those who really did need antibiotics, you can bet that a good number made the big mistake we've all made: not taking the entire bottle of pills because we felt better. Don't do that; cutting the dose short can leave a few stragglers, allowing the most-die-hard bacteria to live and breed again inside you. That can make you even sicker and, as noted above, give the planet a few more bugs with even bigger muscles.

Worry less about getting mad cow disease

Worry more about undercooking a chicken fillet

It comes with dramatic video of stumbling heifers. It's 100 percent fatal, and kills horribly and slowly. No wonder bovine spongiform encephalopathy (BSE, or mad cow disease) scares the barbecue sauce out of us.

But it's really a minor worry. Consider that the average American eats about 65 pounds of beef a year and that there has been exactly one person in this country diagnosed with variant Creutzfeldt-Jakob disease (vCJD), the particular brain disorder that's strongly suspected to be caused by eating BSE-infected meat. And that case was a Florida woman who evidently got BSE while living in England.

Further, only one cow in the United States (the infamous one imported from Canada in 2001 and discovered last December) has been identified as having BSE, compared with some 184,000 cows in England in the last decade and a half. In March the U.S. Food and Drug Administration launched expanded testing to further lower the extremely small odds that tainted beef will end up on an American plate.

"It is believed that cows can only get mad cow disease by eating contaminated feed," explains Althea Zanecosky, M.S., R.D., a nutritionist in Philadelphia and a spokeswoman for the American Dietetic Association. "The United States stopped grinding animal parts into feed in 1997. Given that time frame, and the fact that most cows are slaughtered before they're 3 years old, the odds are almost minuscule that there are any infected cows [left] in the U.S. now."

Need more peace of mind? BSE contaminants naturally exist only in the brain and spinal tissues of cows, and not in the animal's muscle--which is the steak and hamburger meat we love to throw on the grill. People in England have a propensity for eating cow brains, which helps explain why they've had 143 deaths from BSE versus our zero.

"You have a much, much greater chance of getting sick or dying from undercooked or mishandled food than you ever will from mad cow disease," Zanecosky says. About 5,000 people die every year in the United States from food-borne illnesses such as E. coli, salmonella, and listeria; 76 million more become sick. "The biggest culprits are meats that are undercooked, or sit out at room temperature--or in the summer heat--for too long," she warns. To cook safely, Zanecosky recommends using separate pans, plates and cutting boards for raw meat, cooked meat, fish and vegetables (don't mix them); cooking beef and pork to 170[degrees]F and chicken to 180[degrees]F (measured at the thickest part of the meat); and washing your hands with soap and water frequently while preparing and cooking food.

Illustrations by Katherine Streeter

Ron Geraci, a freelance writer based in New York City, doesn't mind taking risks: He's currently at work on a book about his dating life.

COPYRIGHT 2004 Weider Publications
COPYRIGHT 2004 Gale Group

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