Mad-cow tainted livestock found in California rare in U.S.WASHINGTON — Mad cow disease, identified in four cases involving U.S. cattle starting in 2003, is related to an incurable condition in humans called variant Creutzfeldt-Jakob that leads to a rapid decline of mental function and movement.
By: Stephanie Armour and Angela Zimm, Bloomberg News
WASHINGTON — Mad cow disease, identified in four cases involving U.S. cattle starting in 2003, is related to an incurable condition in humans called variant Creutzfeldt-Jakob that leads to a rapid decline of mental function and movement.
The latest mad cow case, found at a California rendering plant this month, didn't enter the food chain for humans, according to the U.S. Agriculture Department.
Here's a rundown on the two conditions, based on information from the U.S. Centers for Disease Control and Prevention in Atlanta and the National Institutes of Health in Bethesda, Md.:
Q: What is mad cow disease?
A: Known formally as bovine spongiform encephalopathy, it is a neurological disorder in cattle that leads to degeneration in the brain and spinal cord, and eventually death. The infection, first diagnosed in Britain in the 1980s, probably originated from cattle feed that contained ground-up infected animal parts. BSE is considered to be caused by an abnormal protein known as a prion that lodges in brain and spinal tissue. Animals become disoriented, stumble and eventually die.
"It's been rare here," Michele Jay-Russell, a researcher at the Western Institute for Food Safety and Security at the University of California in Davis, said by telephone. "Canada has had more cases than we have. We have a fairly robust surveillance system."
Q: How many cases have been identified in North America?
A: Twenty-two were identified in North America through the end of 2011, including three in the United States. One of the U.S. cases involved an animal born in Canada, where 19 cases have been recorded. An outbreak in Britain peaked in January 1993 at almost 1,000 new cases in cattle a week.
The latest case is atypical, said Guy Loneragan, an epidemiologist and professor of food safety and public health at Texas Tech University in Lubbock. That means it "may be a spontaneous, extraordinary event in older animals" and not likely due to animal feed, he said.
Q: Can people get mad cow disease?
A: The human form is called variant Creutzfeldt-Jakob disease, or vCJD, and studies have shown a link between the human prion disease which was first reported in Britain in 1996, and the animal form. The disease in humans is probably spread through consumption of processed food containing infected beef, scientists said.
Symptoms can include blurred vision, disorientation, hallucinations, lack of coordination and speech impairment. The condition is progressive, and can be fatal within months. There is no treatment. In the 1990s, an outbreak of the disease in Britain led to the wholesale destruction of English cattle to prevent further cases.
Q: Are there treatments for animals?
Q: Should I be concerned about eating meat?
A: The USDA said it "remains confident in the health of the national herd and the safety of beef and dairy products."
Q: What protective restrictions or preventive measures are in place in the U.S.?
A: Concern about tainted beef resurfaced in 2003 when the first infected cow was found, and the government expanded its screening program at the time. State veterinary laboratories do surveillance to identify cattle showing neurological symptoms that suggest mad cow. The U.S. bans the use of cow brains and spinal tissue in cattle feed.
There is also evidence from a small number of case reports that vCJD can be transmitted through transfusion. Since there is no test that can be used to screen human blood, the American Red Cross doesn't accept blood from people who lived or visited Britain for more than three months from January 1980 through December 1996; or spent five years or more from January 1980 to the present in any European country.
U.S. and international surveillance systems are working, according to John Clifford, the USDA's chief veterinarian. Last year, there were 29 worldwide case of mad cow, a 99 percent reduction since the peak in 1992 of 37,311 cases, he said.