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Mad cow disease

- The Washington Times - Thursday, January 1, 2004

According to the Center for Disease Control, 76 million Americans every year get food poisoning. If you do the math, that's about 1 in 4 of us every year. You know that "24-hour flu" you had this year? Well, you should know that there's no such thing as a 24-hour flu. You probably got food poisoning. From last year's Listeria and E. coli to a burgeoning antibiotic-resistant salmonella, in today's food safety lottery there's a 1 in 840 chance that we Americans will be hospitalized and a 1 in 55,000 chance that we will die from food-borne illness every year.

But E. coli? Easily destroyed by proper cooking. This new super-salmonella threat? Luckily, we still have big-gun antibiotics to kill it. Even bugs like Listeria are pretty wimpy pathogens. After millennia of humans eating the bodies and bodily fluids of other animals, you'd think Mother Nature could cook up a nastier microbe.

Well, let's use our imagination. What if there was something in our food supply that wasn't affected by cooking or antibiotics? Something new and undetectable, perhaps?Someultimate pathogen, practically indestructible, evading the immune system and maybe causing some, oh, invariably fatal neurodegenerative disease? Welcome to the world of bovine spongiform encephalopathy (BSE), or mad cow disease.

The pathogen thought responsible for this disease is not a virus, not a fungus, not a bacteria, but thought to be a prion -- an infectious protein. Because of their unique structure, prions are practically invulnerable. They can remain infectious for years in the soil. They are not adequately destroyed by cooking, canning, freezing, usable doses of radiation, digestive enzymes or stomach acid. Even heat sterilization, household bleach and formaldehyde sterilization have little or no effect. One study raised the disturbing question of whether even incineration could guarantee the inactivation of prions.

That study was performed by Paul Brown, medical director for the U.S. Public Health Service, who found prions could remain infectious even after exposure to temperatures over 1000 degrees Fahrenheit. That's hot enough to melt lead. Prions have been called the smallest, most lethal biological entities in the world.

It is perhaps not surprising that one cow in the United States has mad cow disease, given that certain cannibalistic practices of feeding slaughterhouse waste to livestock have been allowed to continue. What is surprising, given the inadequacy of our surveillance program, is that we found a case at all. Europe and Japan follow World Health Organization guidelines and test every downer cow for mad cow disease. By contrast, the United States has tested less than 2 percent of downers over the last decade. In 2003, we increased that testing, but only to about 10 percent.

Regardless of whether downer cows were tested or not, most of these animals -- cows too sick or injured to even walk -- have ended up on our dinner plates.

The Department of Agriculture (USDA) decision to finally remove downer cattle from the human food supply is a welcome departure from the past week's Pollyanna public relations, but it can only be effective in conjunction with a dramatic increase in surveillance testing. It seems the only reason we picked up the recent case was that the cow suffered a birthing injury.

Had she not, she presumably would not have been tested at all. Indeed in Europe, where they test one out of every four cows, and Japan, where they test 100 percent of all cattle bound for human consumption, they have found a number of cases of mad cow disease in animals who appeared perfectly healthy.

The discovery of a case of mad cow disease in the United States highlights how ineffective current safeguards are in North America. The United States banned the feeding of the muscles and bones of most animals to cows and sheep back in 1997, but unlike Europe left gaping loopholes in the law. For example, blood is currently exempted from the U.S. feed regulations. You can still collect cow's blood at the slaughterhouse and feed blood concentrates to calves. In modern agribusiness, calves may be removed from their mothers immediately after birth, so the calves are fed milk replacer, which is often supplemented with cow blood protein. Weaned calves and young pigs may also have cattle blood sprayed directly on their feed to save money on feed costs. The reason that the American Red Cross bars blood donations from people who spent substantial time in Western Europe is because we now know blood to be infectious.

The U.S. feed regulations also still allow the feeding of rendered cattle remains to pigs, for example, and then the pig remains can be fed back to cattle. Or rendered cattle remains can be fed to chickens, and then the chicken litter, or manure, can be legally fed back to the cows. So, the fact that the most infectious tissues of the recently reported U.S. mad cow case -- the brain, spinal cord, and intestines -- "were removed from this animal and sent to rendering" is not necessarily reassuring, given that contaminated tissues are routinely still fed to pigs, chickens and other animals who may cycle the disease back to cows, or perhaps even carry the deadly prions directly to human consumers. Where do we think all the brains, spinal cords and downer cows are going to go now?

Even with the loopholes closed, though, the feed ban will only be as effective as its enforcement. Hundreds of feed mills and rendering plants have violated the feed ban regulation. In 2002, the United States General Accounting Office (GAO) released a report on the inadequacy of our defenses against mad cow disease, and concluded that the FDA's failure to enforce the feed ban may already have "placed U.S. herds and, in turn, the human food supply at risk."

In Canada, authorities were at least able to reassure the public that the infected downer cow they discovered was excluded from the human food chain and only rendered into animal feed. U.S. officials can't offer the same reassurance, as the mad cow we discovered was likely ground into hamburger and at least some of her eaten. How then, can the USDA and the beef industry insist that the American beef supply is still safe? They argue that the infectious prions that cause the disease are only found in the brain and nervous tissue, not in the muscles, not in the meat. This can be viewed as misleading on two counts.

First, Americans do eat bovine central nervous system tissue. The GAO report noted, for example, that beef stock, beef extract and beef flavoring are frequently made by boiling the skeletal remains of the animals, including the spinal column. According to the consumer advocacy organization Center for Science in the Public Interest, spinal cord contamination may also be found in U.S. hot dogs, hamburgers, pizza toppings, and taco fillings. In fact, a 2002 USDA survey showed that approximately 35 percent of high-risk meat products tested positive for central nervous system tissues. Thankfully, the new USDA recommendations -- if enforced -- should keep these most infectious tissues off our plates.

Even if Americans just stick to steak, though, they may not be shielded from risk. There are a number of ways the muscle tissue can get contaminated by potentially highly infectious brain or spinal cord tissue. For example, the head trauma caused by attempts to stun the animals prior to slaughter (even with the non-air injection stunners) commonly blows tiny fragments of brain throughout the bodies of these animals. Even without nervous tissue contamination, though, there is now evidence that the muscle tissue itself could be infectious. Dr. Stanley Prusiner, the scientist who won the Nobel Prize in Medicine for his discovery of prions, proved in 2002 that prions can build up in muscle tissue, a finding confirmed by follow-up studies in Germany. And in November, the New England Journal of Medicine published a study in which Swiss scientists found prions in the muscles of human spongiform encephalopathy victims on autopsy.

Despite these shortcomings, Agriculture Secretary Ann Veneman and Washington's governor both assured the public that they were still having beef for Christmas, reminiscent of the 1990 fiasco in which the British agriculture minister appeared on TV urging his 4-year-old daughter to eat a hamburger. Four years later, young people in Britain were dying from an invariably fatal neurodegenerative disease called variant Creutzfeldt-Jakob Disease -- the human equivalent of mad cow disease -- which they contracted through the consumption of infected beef. With an incubation period up to decades long, no one knows how high the final human death toll will be.

One of the problems, as many English pundits saw it, is that the British Ministry of Agriculture represented the interests of both consumers and the beef industry. A similar conflict of interest exists here in the United States. USDA's mandate is to promote agricultural products, but also to protect consumer health.

Mrs.Venemanherselfappointed Dale Moore, former chief lobbyist for the National Cattlemen's Beef Association, as her chief of staff. In the end, I'm afraid this crisis may show to what length governments will go to prevent financial harm to powerful lobbies in general, and in doing so risk immeasurable harm to those they claim to represent.

Michael Greger, M.D., is the chief BSE investigator for Farm Sanctuary and Mad Cow Coordinator for the Organic Consumers Association.