The U.S. government has confirmed the first case of “mad cow disease” in six years, but is stressing that there is no threat to human health and no danger of the meat entering the food chain.

The cow had been picked up by a facility near Fresno, Calif., that takes dead livestock, reports MSNBC. Results of a random test on April 18 at the lab of the University of California, Davis showed positive results for bovine spongiform encephalopathy (BSE). On Tuesday, federal agriculture officials announced the findings: the animal had atypical BSE. That means it didn't get the disease from eating infected cattle feed, said John Clifford, the Agriculture Department's chief veterinary officer.

"We are sharing our laboratory results with international animal health reference laboratories in Canada and England, which have official World Animal Health (OIE) reference labs,” Clifford said in a statement. “These labs have extensive experience diagnosing atypical BSE and will review our confirmation of this form of the disease. In addition, we will be conducting a comprehensive epidemiological investigation in conjunction with California animal and public health officials and the FDA.

USDA Secretary Tom Vilsack added in a statement: "The beef and dairy in the American food supply is safe and USDA remains confident in the health of U.S. cattle. The systems and safeguards in place to protect animal and human health worked as planned to identify this case quickly, and will ensure that it presents no risk to the food supply or to human health. USDA has no reason to believe that any other U.S. animals are currently affected, but we will remain vigilant and committed to the safeguards in place."

"It's appropriate to be cautious, it's appropriate to pay attention and it's appropriate to ask questions, but now let's watch and see what the researchers find out in the next couple of days," said James Culler, director of the UC Davis dairy food safety laboratory and an authority on BSE.

Culler said that in this case the food safety testing program worked and that this form of BSE so rarely occurs that consumers shouldn't be alarmed.

Internationally, three large South Korean retailers halted sales of U.S. beef, although one retailer resumed sales within hours.

“We stopped sales from today,” said Chung Won-hun, a Lotte Mart spokesman. “Not that there were any quality issues in the meat but because consumers were worried.”

Canada, Japan and Mexico have announced that regular U.S. beef exports will continue, reports Reuters.

"Cases of atypical bovine spongiform encephalopathy (BSE) occur occasionally," Mexico's agriculture ministry said in a statement. "These cases have appeared in different places around the world and don't affect trade between countries."

The meat industry has been quick to dispel any concerns about the U.S. food supply as a result of the BSE discovery.

“U.S. beef products are among the safest in the world and USDA’s announcement today confirms that the U.S. animal disease surveillance system works to protect our herds and the public,” said American Meat Institute Executive Vice President James Hodges. “The U.S. cattle herd is more than 90 million head, and more than 30 million head are processed annually. Since 2003, the U.S. has diagnosed four total cases of BSE. The last case was diagnosed in 2006. That translates into one of the lowest rates of BSE in any nation that has ever diagnosed a case.

“Also reassuring is the fact that no case of the human version (called Variant Creutzfeld-Jakob Disease or vCJD) has ever been associated with U.S. beef consumption. In the United Kingdom, where nearly all of the human cases have occurred, it was common to consume parts of the animal that can transmit the disease, like the brain of older animals. That was not a practice that was ever common in the U.S., and since 2003, it has been illegal.

“The disease emerged in the United Kingdom in the late 1980s and peaked in 1992 at over 37,000 cases in a single year. The U.S. learned from the British experience with the disease, and we were able to translate our learnings into strong, proactive interlocking safeguards that have served us well.”

Sources: MSNBC, FSIS, Associated Press, Reuters, AMI