The name "Mad Cow Disease" is unfortunate, because people sometimes think it's funny.  It's no joke.  The technical name has an almost musical sound:  Bovine Spongiform Encephalopathy (spongy-form en-sef-al-AH-puth-ee).  Names aside, this and related diseases are utter nightmares that can affect cows, humans, sheep, deer, mink, pigs, cats, and several other species.  After infection, these diseases can remain dormant and (currently) undetectable for years, but are devastating when they emerge:  people with spongiform disease suffer worsening dementia (loss of mental abilities) and progressive physical deterioration ending in death.  The only certain diagnosis is by brain biopsy:  destruction of neurons riddles the brain with tiny holes, so the tissue looks "spongy" under the microscope.  In a striking similarity with Alzheimer's Disease, brain deposits of protein "plaques" are also often found.
         Spongy brain disease is a huge challenge for medical science.  The theory was considered scientific heresy just 15 years ago, but researchers now agree that spongiform disease is caused by a "prion," an infectious protein molecule tinier than any virus.  Prions lack DNA, so scientists wondered how they could reproduce to cause a worsening infection.  It now appears that prions are nearly identical to normal proteins in the nervous system, and that disease prions somehow trigger these normal molecules to change their shape and thus themselves become infective.  Especially chilling is the fact that prions--unlike bacteria, viruses, and fungi--are not easily destroyed by heat; our usual means of sterilization won't  work.
        Prions aren't spread by casual contact and haven't been shown infective via either sex or blood, but are definitely transmitted in foods.  In the 1950s, a spongy brain disease called "kuru" nearly wiped out an indigenous people in Papua New Guinea, until heroic scientist-adventurers discovered the cause:  these folks ate their own dead--including the brains--thus enabling rapid spread of the disease.  When they learned the cause and stopped the practice, the epidemic subsided and their population recovered.
         Spongy brain disease in sheep is called "scrapie" and has been a shepherd's nightmare for 250 years.  In humans, a previously rare spongiform condition is called Creutzfeldt-Jakob Disease (CJD).  Some cases of CJD are inherited, but are nevertheless infectiously transmissible to experimental animals--current research blurs the boundary between genetic and infective disease.  Other cases of CJD have unfortunately been transmitted by doctors using brain electrodes, when disease prions from other patients weren't destroyed by sterilization.  The origin of most CJD remains uncertain, but in England 50 cases of "new variant" CJD have been definitively linked to eating meat from cattle with Bovine Spongiform Encephalopathy--Mad Cow Disease.  Many in England anxiously wonder if they're now harboring the disease, which may remain latent in humans for up to 30 years or more.
         Unlike sheep, spongiform disease had never been seen in cows before 1986, but now 180,000 cases of Mad Cow Disease have been identified in England, and the disease is also present in many countries throughout Europe.  As with kuru in New Guinea, cannibalism enabled rapid spread of the disease:  though cows are naturally vegetarian, we fed dead cows back to other cows in the form of "rendered" protein supplements added to animal feed.
         While not an ideal dinnertime topic, the practice of "rendering" must be faced.  Animals that die on farms must be removed.  With huge animal "factory farms," dead or diseased creatures are continually hauled away.  In normal slaughterhouse operations, many animal parts are unmarketable.  All this creates a huge waste problem:  incineration or landfilling are expensive and fraught with environmental problems.  "Recycling" seems like the perfect solution, creating profit while removing waste:  dead and diseased animals, slaughterhouse wastes, road-kill, large animals like horses, and even euthanized pets are all basically ground up, cooked down, and rendered into something resembling brown sugar.  Loaded with protein (the fat is usually separated for other uses), agricultural businesses can add this stuff to their feed and make cows, pigs, and chickens gain weight faster.  The use of Bovine Growth Hormone to force cows into increased milk production requires concentrated feeds and dovetails nicely with rendering practices.
         The high heat of rendering doesn't always destroy prions, and by the mid-1980s most operations had installed new equipment that saved energy by allowing rendering at lower temperatures, probably thereby helping enable the outbreak of Mad Cow Disease.  There are two main theories for how spongiform disease spread among English cattle; both implicate cow cannibalism.  First, prions from rendered scrapie-infected sheep may have passed the "species barrier" to cows (experiments have indeed shown these diseases often transmissible to other species).  The second theory is that one or more cows died with a rare form of the disease analogous to classic human CJD, and that this then spread rapidly among cattle through their feed.
         U.S. government and meat industry officials are quick to say that no cases of Mad Cow Disease have been identified here, but spongiform disease is definitely present among our wild deer, especially in Colorado and Wyoming.  Such deer could easily be killed on the highway and end up in a rendering plant.  Known as "Chronic Wasting Disease of Deer and Elk," it may be linked to some cases of CJD among U.S. deer hunters--Utah hunter Douglas McEwen died in March 1999 from CJD which he may have contracted by handling or eating infected deer.  McEwen had often donated blood in the two years before his illness emerged.  Spongiform disease hasn't been shown transmissible by blood, but the U.S. government nevertheless recalled potentially contaminated blood products such as from McEwen or from people who lived and ate meat in England during the critical period.  I ran across a website with information and support for medical patients who received such blood prior to its recall, and who may have understandable anxieties.
         Rendering practices have been increasingly scrutinized by the U.S. Food and Drug Administration; in 1997 the FDA banned "the use of most mammalian protein (with certain exceptions) in the manufacture of animal feeds given to ruminants."  Ruminant animals include cows, sheep, deer, and goats.  It's now illegal to feed cows and sheep to each other, but they can all be fed to chickens and pigs, and protein from dead chickens and pigs can still be fed back to cows.  The allowance of such feed to pigs is especially worrisome, since experiments show pigs susceptible to spongiform disease.  Remember--there are still no tests for spongiform disease in the latent stage, and diagnosis is certain only with brain biopsy of an animal either dead or dying of the disease.  Pigs are normally slaughtered young, long before the disease would show up.  Studies published in 1973 and 1985 in the American Journal of Epidemiology showed a frequent preference for pork in two clusters of patients with Creutzfeldt-Jakob Disease.  Many people in one of the clusters had been especially fond of pork brains.  Such data prove nothing, but can certainly give one pause for thought.
         Our rendering regulations remain less stringent than those now established in England, and violations probably occur because compliance is hard to verify.  Still, there's a reduced market for rendered protein.  The meat industry may now be stuck with a lot of noxious garbage--waste that had become money before may now be just an expensive problem.
         In a possibly related development, the USDA is currently establishing a new policy for meat inspection.  Since 1959, federal law has required visual inspection of all animals before their flesh was deemed safe to eat.  The new policy would require only lab tests for samples of meat.  Safeguards have already been scanty, with three overworked inspectors viewing up to 90 chickens a minute, for example.  But soon, animals with cancer, tumors, open sores, or intestinal worms may be butchered for sale if the diseased parts are cut out.  The new rule isn't final yet; the public has until August 29th to comment.  With new restrictions on rendering, could the industry be hoping to maintain profits by dumping the diseased carcasses on the public?  A frightening and cynical thought perhaps, but not impossible--"those who love sausage and the law should never watch either being made."
         Next time I'll discuss political battles surrounding Mad Cow Disease, including how Oprah Winfrey was sued by the Texas Cattlemen over her show on the issue.  I'll conclude the discussion on spongiform disease by considering that many cases of CJD in humans are misdiagnosed as Alzheimer's--the disease may be a lot more common than we think.
 
 
 

        Here's the second article:  Mad Cows, Money, Oprah, and Alzheimer's.  There are numerous internet links at the end of that article.