HANFORD, Calif.—The first new case of Mad Cow disease in the U.S. since 2006 has been found in a dead dairy cow in California.
Two South Korean retailers suspended sales of U.S. beef in response. Reaction elsewhere in Asia was muted. South Korea is the world’s fourth-largest importer of U.S. beef, buying 107,000 tons of the meat worth $563 million in 2011.
The fact that the discovery was made at all was a stroke of luck. Tests are performed on only a small portion of dead animals brought to the transfer facility in central California.
The cow hadn’t exhibited outward symptoms of the disease: unsteadiness, lack of coordination, a drastic change in behaviour or low milk production.
But when the animal arrived at the facility with a truckload of other dead cows on April 18, its age and recent demise made it eligible for USDA testing.
“We randomly pick a number of samples throughout the year, and this just happened to be one that we randomly sampled,” Baker Commodities executive vice-president Dennis Luckey said.
Samples went to the food safety lab at the University of California, Davis on April 18. By April 19, markers indicated the cow could have bovine spongiform encephalopathy (BSE).
Federal agriculture officials on Tuesday 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.
It was “just a random mutation that can happen every once in a great while in an animal,” said Bruce Akey, director of the New York State Veterinary Diagnostic Laboratory at Cornell University.
It is unknown if the animal died of the disease and whether other cattle in its herd are similarly infected. The name of the dairy where the cow died hasn’t been released, and officials haven’t said where the cow was born.
The infected cow was identified through an Agriculture Department surveillance program that tests about 40,000 cows a year for the fatal brain disease.
The mad cow cases that plagued England in the early 1990s were caused when livestock routinely were fed protein supplements that included ground cow spinal columns and brain tissue, which can harbour the disease.