Extra! Mad Cow Disease
CNN STUDENT NEWS
(CNN Student News) -- Use this explainer to help students understand mad cow disease, a topic relevant to today's news.
What is it? "Mad cow" is the common name of a disease that affects cattle. It is known to the scientific community as bovine spongiform encephalopathy (BSE). The disease attacks the cow's nervous system. The animal's resulting behavior gives the disease its common name: mad cow.
When were the first cases of BSE reported? A veterinarian visiting a farm in England first noticed cattle with symptoms of the disease in 1985. By 1986, authorities there had identified two cases of BSE. The BSE epidemic in the United Kingdom peaked around 1993, when about 1,000 new cases were reported per week. Thousands of cattle were slaughtered in order to stop the spread of the disease. Cases in the United States have been far less common. The cow that tested positive for BSE in Alabama in March 2006 was only the third confirmed U.S. case.
How is BSE contracted? It is believed that cows encounter BSE from eating contaminated feed composed of organs from other cattle. BSE is not a contagious disease in that it cannot be passed from one live cow to another. What about humans? Since 1996, evidence has demonstrated a connection between BSE and variant Creutzfeldt-Jakob disease (vCJD) in humans. Few people had heard of this disease until about 10 years ago, when several cases were seen in Great Britain. Through testing and research, scientists concluded that vCJD was linked with eating beef contaminated with BSE. The Centers for Disease Control describes both BSE and vCJD as "invariably fatal brain diseases" that may exist for years before any symptoms appear. Variant Creutzfeldt-Jakob disease may include symptoms such as personality changes; problems with balance, coordination, vision and speaking; and eventually coma and death. (Important note: There is another type of Creutzfeldt-Jakob disease known as Classic Creutzfeldt-Jakob. This disease has some different characteristics from the variant type and has not been connected with BSE.)
What steps are being taken to prevent BSE? Most countries have adopted measures to prevent BSE from entering their food supplies. For example, Great Britain and the European Union have strict guidelines preventing the feeding of meat and bone meal to cattle. Japan tests nearly all cattle for BSE. The U.S. Department of Agriculture limits what can be fed to cattle. In 1997, the U.S. banned ground-up cattle remains from being added to feed.
What can you do if you're still concerned about BSE and vCJD? Health experts advise you to be careful when traveling to countries that have not imposed strict measures to control BSE. If you're not traveling and want to eat beef, experts say it's a good idea to avoid the high-risk parts of cattle, such as the eyes, brain, spinal cord and intestine. Still concerned? Consider organic beef, since certified organic beef comes from cattle that feed only on grass and grains.
(Sources: CNN.com, Centers for Disease Control and Prevention, World Health Organization, USDA Food Safety and Inspection Service)
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