April 25, 2012 at 10:06 AM ET
By msnbc.com news services
Although the U.S. reported the fourth confirmed case of mad cow in six years this week, the government is stressing there is no threat to human health and no danger of the meat entering the food chain. Officials are still investigating how the dairy cow contracted the disease.
The cow had been picked up by a facility near Fresno, Calif., that takes dead livestock. The non-descript building in the heart of California's dairy country has become the focus of intense scrutiny as 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), a disease that is fatal to cows and can cause a deadly human brain disease in people who eat tainted meat. It has been sent to the USDA 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."
In humans, experts say it can occur in one in 1 million people, causing sponge-like holes in the brain. But they say not enough is known about how and how often the disease strikes cattle.
Experts said the case was "atypical," meaning it was a rare occurrence in which a cow contracts the disease spontaneously, rather than through the feed supply.
The risk of transmission generally comes when the brain or spinal tissue of an animal with BSE, or mad cow disease, is consumed by humans or another animal, which did not occur in this case.
The disease cannot be transmitted by contact among cows, and experts say it's unclear whether this rare type of BSE ever has been transmitted from a cow to a human by eating meat.
The California Department of Public Health and the state Department of Food and Agriculture quickly worked to assure consumers that the food supply is safe — and that the cow hadn't been destined for human consumption. The building where the cow was selected to be tested sends animals to 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 are 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.
"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 Cullor, director of the UC Davis dairy food safety laboratory and an authority on BSE.
Cullor 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.
"Are you worried about all of the meteors that passed the earthlast night while you were sleeping? Of course not," Cullor said. "Would you pay 90 percent of your salaries to set up all of the observatories on earth to watch for them? Of course not. It's the same thing."
The National Cattlemen's Beef Association said in a statement that "U.S. regulatory controls are effective, and that U.S fresh beef and beef products from cattle of all ages are safe and can be safely traded due to our interlocking safeguards."
The infected cow was identified through an Agriculture Department surveillance program that tests about 40,000 cows a year for the fatal brain disease.
First discovered in Britain in 1986, the disease has killed more than 150 people and 184,000 cows globally, mainly in Britain and Europe, but strict controls have tempered its spread.
In the UK, 175 people, including Jonathan Sims, got a human form of the disease from eating meat from the infected animals. He was left blind, deaf and immobile from 2001 until his death last year. Health officials say milk does not transmit the disease, so an infected dairy cow does not pose a hazard.
There have been three confirmed cases of BSE in cows in the United States — in a Canadian-born cow in 2003 in Washington state, in 2005 in Texas and in 2006 in Alabama.
Both the 2005 and 2006 cases were also atypical varieties of the disease, USDA officials said.
"I would say this is an extremely isolated, atypical event," said Dr. Bruce Akey, professor of veterinary medicine and director of the Animal Health Diagnostic Center at Cornell University, which tests for Mad Cow and Chronic Wasting diseases for New York state and several Northeastern states.
"There is still no evidence at all that BSE is anything but an extremely rare event in the United States and nothing that poses a threat to the human or animal food chain."
Import restrictions from major customers could deal a fresh blow to companies such as Tyson Foods Inc and Brazil-based JBS.
Korean retailer Lotte Mart, a unit of Lotte Shopping Co. , said it had suspended sales due to what it said was "customer concerns," as did Home Plus, a unit of Britain's Tesco PLC.
Not in the feed
The USDA has begun notifying authorities at the World Organization for Animal Health as well as U.S. trading partners, said John Clifford, its chief veterinary officer.
"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," Tom Vilsack, U.S. Secretary of Agriculture, said in a statement.
The USDA is still tracing the life of the infected animal, and the carcass of the cow is under quarantine and will be destroyed.
The Agriculture Department is sharing its lab results with international animal health officials in Canada and England who will review the test results, Clifford said. Federal and California officials will further investigate the case. He said he did not expect the latest discovery to affect beef exports.
State and federal agriculture officials plan to test other cows that lived in the same feeding herd as the infected bovine, said Michael Marsh, chief executive of Western United Dairymen, who was briefed on the plan. They also plan to test cows born at around the same time the diseased cow was.
"Our members have meticulous records on their animals, so they can tell when the animal was born, the parents, and they can trace other animals to the same facility," Marsh said.
For now, all of the other dead cows that arrived on the truck with the diseased one are still in cold storage at Baker's transfer station, which sits in the middle of a wheat field.
The Associated Press, Reuters and NBC's Robert Bazell contributed to this report
Copyright 2013 Thomson Reuters.