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Compiled by Humane Society of the United
States What Is Mad Cow Disease (technically known as Bovine Spongiform Encephalopathy or SCE)? Spongiform encephalopathies are nervous system disorders in which nerve cells of the brain die, causing the brain to assume a sponge-like appearance. BSE is the term applied to this malady as it affects cows and was first recognized in November 1986. Affected cows show clinical signs such as belligerence, confusion and poor coordination. A brain biopsy is presently the only way to confirm a BSE diagnosis. What causes BSE? Scientists call the agent believed to cause BSE a "prion," an infectious protein lacking nucleic acid. Prions are thought to multiply by setting off a chain reaction that damages nearby healthy cellular proteins, converting normal proteins into abnormal ones. Traditional methods to destroy microbes do not work on prions. They show resistance to normal forms of sterilization, such as common disinfectants, ultraviolet or ionizing radiation, and autoclaving. And contaminated tissue samples fixed in formalin have been found to still be infectious. How is it Transmitted to Cows? Prions are transmissible to other species including sheep, cats and primates. For several centuries, a form of spongiform encephalopathy called scrapie has been known to afflict sheep. For the past half century, there has been a trend toward intensified production of livestock raised for consumption. To find a use for the vast tonnage of condemned and inedible remains of slaughtered animals, they are rendered down and the protein residue is fed to billions of poultry, pigs, milk cows and beef cattle. Some animals that are slaughtered are diseased. Since the agent that causes spongiform encephalopathy is not easily detected or destroyed, it can end up in animal feed. The brain, spinal cord, thymus, spleen and tonsils are the parts most suspect for contamination. There is also supporting evidence that the infectious agent of BSE can be passed form an infected cow to her unborn calf. In Britain, where mad cow disease is most prevalent, over 160,000 cattle have been stricken with it. Infected cattle also have ben found in numerous other countries including France, Italy, Germany, Switzerland, Ireland, Canada, Portugal, and Denmark. How are Humans Affected? The period between infection and clinical symptoms of BSE in cattle averages 4 ½ years. During this incubation period the agent can be transmitted. Asymptomatic animals who are infected may be slaughtered and enter the human food supply. What is the Human Form of Encephalopathy? The most common form of Human Spongiform Encephalopathy (HSE) is Creutzfeldt-Jacob Disease (CJD), 15% of which is of known origin (inherited or unintentionally transmitted surgically). The average age of onset of symptoms is sixty-five. However, 85% of HSE randomly occurs with no known cause. Clinical signs include impairment of thought, sight, and movement due to the destruction of brain cells, and a dementia resembling that of Alzheimer’s disease. Muscle spasms occur, creating rigidity and jerkiness, and there is a loss of balance. Death is inevitable and swift, usually within months. Between 1990 and 1994, the incidence of HSE in Britain has nearly doubled and continues to increase. A new form of HSE has been diagnosed in people who have had no genetic predisposition to it. Some of the afflicted people worked closely with infected cattle; some were teenagers; all ate beef. In Britain, 10 people have ben confirmed as having this new form of HSE, the average of onset being 27. The new HSE differs from CJD in that there is no genetic predisposition, it has a 10 year incubation period, the microscopic appearance of the diseased nerve cells is different, and victims die within one year of exhibiting symptoms. As with cattle, the primary symptom is dementia. HSE can very easily be confused with Alzheimer’s disease, which millions of people are diagnosed with each year. The cause of dementia is reportedly misdiagnosed 25% of the time. A postmortem microscopic examination of the brain is presently the only method available to confirm a diagnosis of HSE. What Steps Are Being Taken? No cases of BSE have been confirmed in the United States, and since 1989 the importation of live ruminants (cattle, sheep, etc.) And ruminant products from countries known to have BSE has been restricted. In other countries, cattle showing symptoms of BSE are killed. As of March 1996, the European Union banned the exportation of cattle, beef, and most beef byproducts from Britain. IN the U.S., major sheep producers claim to be voluntarily diverting sheep byproducts from cattle feed. The FDA had proposed a ban on sheep tissue in cattle feed in 1994, but took no action because of strong opposition form the livestock industry. They are now proposing a mandatory ban to prohibit the use of all ruminant byproducts in cattle feed. Is the Problem Under Control in the United States? Some cattle imported from Britain before the 1989 ban are still here. Sheep scrapie (which has been implicated as the cause of BSE) also exists here. Despite the voluntary ban on sheep byproducts in cattle feed, FDA officials admit it is very difficult to verify compliance because there is no way to test a rendered product for sheep content. Therefore, potentially infectious animal tissue is still being fed to cattle, and infected by asymptomatic animals may still enter the human food supply. Additionally, some three dozen marketed drugs are derived from cattle tissue and organs, and hundreds more contain bovine blood. Gelatin, derived from cattle hooves, hides and bones is an ingredient of many foods and drugs and is used to make capsules. The FDA is now considering formalizing a ban on the use of pharmaceutical gelatin imported from countries with BSE. What Can I Do to Reduce My Risk of Acquiring HSE? The best way to protect yourself is to eliminate from your diet any source of beef that may be contaminated. Intensive livestock production systems may promote BSE (because animals in intensive confinement are more likely to be fed animal remains). Therefor, eliminating meat from intensive confinement or factory farms is a good start. Some organic cattle farmers in Britain believe that organophosphate pesticides, widely used on other cattle, may play a role in BSE. There have been no documented cases of BSE in cows who have been born and raised on organic farms. The best way of knowing what is going into your food is to know where your food comes from. Whenever possible, buy locally grown food from organic and sustainable formers and ranchers. Let your grocers know that you want to buy local, organic produce, and animal products obtained through more humane and sustainable production methods. We can follow the 3 R’s of a more humane diet:
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