How do You Get Mad Cow Disease?

Mad cow disease seems to pop up in the news now and then. But what is it, and how likely are people to get it? What Is Mad Cow Disease?

Mad cow disease is an incurable, fatal brain disease that affects cattle and possibly some other animals, such as goats and sheep. The medical name for mad cow disease is bovine spongiform encephalopathy (pronounced: bo-vine spun-jih-form en-seh-fah-la-puh-thee), or BSE for short. It's called mad cow disease because it affects a cow's nervous system, causing a cow to act strangely and lose control of its ability to do normal things, such as walk.

How Do People Get It? 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 variant Creutzfeldt-Jakob disease (vCJD).

Researchers believe that people who eat beef from cows that have BSE are at risk of developing a form of vCJD. VCJD is caused by an abnormal type of protein in the brain called a prion. When people have vCJD, cells in the brain die until the brain eventually has a "sponge-like" appearance.

During this time, people with the disease gradually lose control of their mental and physical capabilities. To date, very few people have been diagnosed with vCJD. By October 2009, only 217 cases of this rare condition had been reported worldwide.