Poll: Mad Cow Disease Have You Worried?

For the fourth time in the United States, a cow has tested positive for mad cow disease — this time in California, according to the Associated Press.

Officials at the U.S. Department of Agriculture told the AP the infected dairy cow, discovered at a Central California rendering plant, was not bound for the food supply and is not indicative of a larger problem.

"There really is no cause for alarm here with regard to this animal," John Clifford, chief veterinary officer for the department, told the AP.

But Michael Hansen, a senior scientist with Consumer Reports, said Wednesday on KQED's Forum that the discovery is alarming and underscores the gap between the U.S., where only a small percentage of cows are tested and Japan and Europe, where testing is far more comprehensive.

Mad cow disease, or bovine spongiform encephalopathy, was last seen in the U.S. in 2006 and is caused by misfolded proteins in a cow's brain. A fatal human version, Creutzfeldt-Jakob disease, can spread to people who consume diseased meat.

The United States tests about 40,000 cows per year for mad cow disease, a lower percentage of the herd than in other countries. Japan, for example, tests every cow destined for human consumption and has found more than 30 cases of the disease since 2001.

We'd like to know your reaction in our poll. And we'd welcome your comments in our comments section.