Athens, Ga. – While the California dairy cow that tested positive for bovine spongiform encephalopathy, or mad cow disease, made national headlines this week, University of Georgia livestock and food-safety experts say the real story is how well the nation’s food-safety system worked.

Bovine spongiform encephalopathy, or BSE for short, “was identified in a dairy cow, and the cow never entered the food supply,” said Judy Harrison, a professor and UGA Cooperative Extension food safety expert in the College of Family and Consumer Sciences. “BSE is not passed through milk, and we have many tests in place in this country to make sure problems like this are not a threat to the food supply. … This case is a good example to consumers of how the system works to keep their food safe.”

BSE first made headlines in the late 1980s with a mass outbreak in Great Britain. It’s a degenerative disease caused by small proteins called prions that attack the cow’s central nervous system. Prions are less complex than viruses but are still able to reproduce their genetic material and damage cells.

The disease caused herds of cows in Britain to act erratically and then gradually lose most of their motor function, leading to the lay term “mad cow disease.”

After eating beef that was tainted with these prions, some humans also contracted the human form of the disease.

Since the late 1980s, the USDA, the FDA and the beef industry have completely changed their practices regarding the handling of cattle and beef bound for human consumption, said Ronnie Silcox, an associate professor of animal science in the College of Agricultural and Environmental Sciences.

These changes have made it nearly impossible for a tainted cow to make it to a processing facility—much less make it onto a family’s dinner plates.

The disease spread through Great Britain’s cattle supply so quickly because of the use of animal feed made from beef byproducts. The practice of feeding mammalian byproducts to cattle has since been banned, and beef processors now remove the spine and brain from beef carcasses before they are processed.

Any cow that cannot walk into a processing facility is suspected of having BSE, excluded from the food supply and tested. Farmers and stockyards now routinely test older and sick cows for BSE, Silcox said.

Although millions of older and sick cows have been tested since these safety practices have been put in place, only four U.S. cows have tested positive for the disease—one cow imported from Canada to Washington state, one in Texas, one in Alabama and the recent dairy cow in California, Silcox said.

“When you go into the grocery store, all the steak and roasts there come from relatively young cows,” he said. “We have never seen a cow test positive for BSE who was less than 30 months old.”

The precautions taken by the USDA, FDA and the international food safety and agriculture communities have nearly eradicated BSE from cattle populations over the last 20 years, Silcox said.

With only 29 cases of BSE reported worldwide in 2011, the specter of the disease is now one of its greatest impacts.

This week’s announcement disrupted the cattle futures market, but it later rebounded. “This one wasn’t even going to end up in the food supply, and the beef futures market still dropped, but of course any news about beef can disrupt the futures market,” Silcox said.

The case will not affect beef exports to trade partners like Mexico or Japan that already require imported beef to be harvested before the cows reach 30 or 20 months of age, Silcox said.