The discovery of mad cow disease in a dead dairy cow came soon after it arrived at a nondescript building in the heart of California's dairy country.
The finding, announced Tuesday, is the first new case of the disease in the U.S. since 2006 and the fourth ever discovered in the country. The test was performed when the animal was brought to the building, a transfer facility for a processing plant near Hanford.
In a teleconference with reporters, U.S. Agriculture Secretary Tom Vilsack quickly assured them that the food supply, and the system used to test it, are both safe.
"We’re very confident that we’ve got the right inspection regime and process in place," said Vilsack. "As this particular circumstance pointed out, the system worked."
He added that the 40,000 number for testing is based on an international standard, and didn’t think a larger sampling was needed to detect sick cows.
The cow had died at one of the region's hundreds of dairies. A plant official said the cow hadn't exhibited outward symptoms of the disease: unsteadiness, incoordination, a drastic change in behavior or low milk production. When the animal arrived at the facility with a truckload of other dead cows on April 18, it met criteria for government testing: older than 30 months and a fresh corpse.
"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. "It showed no signs" of disease.
The samples went to the food safety lab at the University of California, Davis. By April 19, markers indicated the cow could have bovine spongiform encephalopathy (BSE), a disease that is fatal to cows and can cause a deadly human brain disease in people who eat tainted meat. It was sent to an Agriculture Department lab in Iowa for further testing.
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.
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. "Random mutations go on in nature all the time."
The cow hadn't been destined for human consumption and people cannot become ill from drinking milk, experts say. The building where the cow was selected to be tested sends animals to a rendering plants, which process animal parts for products not going into the human food chain, such as animal food, soap, chemicals or other household products.
Among the unknowns about the current case is whether 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.