Instances of “mad cow” disease are few and far between. Although medical authorities attributed about 175 deaths in Europe in the 1980s and ’90s to the human form of the disease, no human cases have been reported in the United States.
It’s important to know that, say government authorities and beef industry officials, in assessing the instance of the disease discovered this week in central California.
"USDA remains confident in the health of the national herd and the safety of beef and dairy products,” John Clifford, the US Department of Agriculture’s chief veterinary officer, said in a statement. The dairy cow in question, Dr. Clifford pointed out, was not intended for human consumption (it was to be rendered for other products), and he also noted that the disease is not transmitted through milk.
Mad cow, known scientifically as bovine spongiform encephalopathy (BSE), is believed to be carried by animal feed made from cattle brains or spinal cord. Such feed is now banned in the US and other countries, but cases of BSE have continued to appear around the world.
Prior to this week, there were three confirmed cases of BSE in cows in the US – in a Canadian-born cow in 2003 in Washington State, in 2005 in Texas, and in 2006 in Alabama.
According to the USDA, the infected animal discovered this week had “atypical BSE,” which means it most likely did not get the disease from eating infected cattle feed.
It was "just a random mutation that can happen every once in a great while in an animal," Bruce Akey, director of the New York State Veterinary Diagnostic Laboratory at Cornell University, told the Associated Press. "Random mutations go on in nature all the time."
"The United States has had longstanding interlocking safeguards to protect human and animal health against BSE,” USDA veterinary officer Clifford said in a statement. This includes a ban on “specified risk materials” in the food fed to cattle as well as a ban on all nonambulatory "downer" cattle (whose behavior might indicate presence of the disease) entering the human food chain.
“The bottom line remains the same – all US beef is safe,” said Tom Talbot of the National Cattlemen’s Beef Association in a statement.
But not all food-safety experts are reassured by the statements of government and industry officials.
Consumers Union, a nonprofit independent testing and information organization, says it is “seriously concerned” by the most recent case of mad cow disease and the questions it raises about beef industry practices and current government regulation.
“First, the USDA testing program for mad cow disease is way too small,” said Naomi Starkman of Consumers Union in a statement. “USDA only tests some 40,000 cows a year of the millions slaughtered annually. So we really don't know if this is an isolated unusual event or whether there are more cases in US beef.”
“Second, detection of BSE is needlessly hindered by the fact that USDA prohibits private companies from testing their own beef,” said Ms. Starkman. “Private testing could augment USDA testing and provide an extra measure of monitoring and assurance of safety to consumers. USDA only tests cattle that are sent to the renderer and doesn’t test at slaughterhouses.”
(In 2006, Creekstone Farms, a beef processing company in Arkansas City, Kan., sought to privately test all its cattle – not just the small sampling conducted by USDA testers – so it could market its beef in countries that refused to accept untested US beef. Creekstone sued the USDA, which has the sole authority to issue the test kits for mad cow disease, but lost that suit in federal court.)
Food-safety attorney Sarah Klein of the Center for Science in the Public Interest said the case of a single cow with BSE “is not a reason for significant concern on the part of consumers, and there is no reason to believe the beef or milk supply is unsafe.”
But, she added, while the US has first-world resources and technology, it has “a third-world animal identification system.”
“In fact, some third-world countries do a better job of tracking livestock than America does,” Ms. Klein said. “Botswana, for one, uses [radio frequency identification] microchips to track its animals up and down the supply chain.”
Another criticism of current regulation and practice involves the ruminant-to-ruminant feed ban in the US to prevent spread of mad cow disease, which critics say is inadequate.
“Cows can't be fed to other cows, which is a good thing,” said Starkman of Consumers Union. “But remains of cows can be fed to pigs and chickens, and pig and chicken remains can be fed back to cows. We believe this could allow for the spread of mad cow disease.”
On Wednesday, two major South Korean retailers pulled US beef from their stores.
South Korea's agriculture ministry decided to step up inspections of US beef and request detailed information on the case from the US – initial measures to appease public concern while avoiding possible trade conflicts, the AP reported.
South Korea is the world's fourth-largest importer of US beef, buying 107,000 tons of the meat worth $563 million in 2011.