December 30, 2003
Mad cow disease is all over the news right now - but what is it, and how likely is it that your family will get it?
Until the end of 2003, mad cow disease (also called bovine spongiform encephalopathy, pronounced: bo-vine spun-jih-form en-seh-fah-la-puh-thee) was primarily found in the United Kingdom. Called BSE for short, the incurable, fatal brain disease that affects cattle and possibly some other animals, such as goats and sheep, has recently been found for the first time in the United States in an adult cow in Washington state. However, the Centers for Disease Control and Prevention (CDC) says the risk to human health from BSE in the United States is still extremely low.
What Is Mad Cow Disease and How Do People Get It?
BSE is called mad cow disease because it affects a cow's nervous system, causing the animal to act strangely and lose control of its ability to do normal things, such as walk.
Only certain animals can get BSE - people don't actually get mad cow disease. However, experts have found a link between BSE and a rare brain condition that affects people, called Creutzfeldt-Jakob disease (CJD). Researchers believe that people who eat beef from cows that have BSE are at risk of developing a form of CJD.
When people have CJD, which is caused by an abnormal type of protein in the brain, the brain wastes away until it eventually becomes like a sponge. During this time, people with the disease gradually lose control of their mental and physical capabilities.
To date, there have been very few people diagnosed with the form of CJD that's been linked to mad cow disease. By the end of 2003, only 153 cases of this rare condition had been reported worldwide. Of these cases, 143 were identified in Britain. However, experts believe that all 153 people got the disease in Britain after eating beef products from cows that had BSE. All 10 of the people diagnosed with the disease outside Britain, including one case in the United States, had lived in Britain during that country's mad cow outbreak in the mid-1990s.
Because the form of CJD that's been linked to mad cow disease is relatively new and extremely rare, experts are still learning about it. However, researchers believe that the disease is not contagious among people - in other words, you can't get CJD from someone else who has it. At present, it appears that the only way people get the disease is from eating contaminated meat.
Experts don't yet know exactly how long the incubation period is for CJD (in other words, how long it takes from the time a person contracts it to the time that symptoms first appear). However, they do believe that it takes years, if not decades, from the time someone gets the disease until the first signs appear. After the first signs appear, the brain can deteriorate within a year.
What's Being Done About It?
BSE doesn't spread naturally from cow to cow; it's suspected to be transmitted by feeding cows animal meal. However, the U.S. Food and Drug Administration (FDA) introduced an "animal feed" rule in 1997 prohibiting the feeding of most proteins made out of mammals to ruminant animals (i.e., cows, sheep, and goats), which was what was thought to have begun the BSE epidemic in the United Kingdom. According to the FDA, 99% of the facilities raising cattle for human consumption are currently in compliance with the feed rule.
The type of protein that causes mad cow disease can't be removed or destroyed when beef is processed or cooked. For this reason, the U.S. government has established several procedures to protect the public. One of these steps involves removing the parts of the cow that are at highest risk of containing BSE-causing proteins - the brain and spinal cord - to reduce the chances of them contaminating the meat people eat.
In addition, the FDA follows a system in which samples of meat are tested. This is one way to help prevent contaminated meat from reaching the shelves. This testing system, which has been in place since early 2003, helped officials to identify the contaminated meat in Washington state in December 2003. The government also has a recall policy in place for meat that's suspected of being contaminated.
If you're wondering if it's safe to continue drinking cow's milk, rest assured that it is - the CDC says the disease cannot be transmitted through cow's milk and milk products. It's also extremely unlikely that a person will contract CJD from eating beef. CJD itself is pretty rare - each year, only one in 1 million people in the United States die of the disease. And because only one cow in the United States has been found to be infected with mad cow disease, the chance that you or anyone in your family will eat meat infected with the disease is extremely low.
Reviewed by: Steven Dowshen, MD
Date reviewed: December 2003
