DNA tests confirm 'mad' cow from Canada
A woman with the human form of mad cow disease has outlived predictions.
|THE HUMAN LINK|
Mad cow disease was first reported in the United Kingdom in 1986, peaking in 1993 with almost 1,000 new cases per week.
In 1996, variant Creutzfeldt-Jakob Disease (vCJD) was detected in humans and linked to the mad cow epidemic. Eating contaminated meat and cattle products is presumed to be the cause.
Both are fatal brain diseases with unusually long incubation periods, often lasting years.
Source: Centers for Disease Control and Prevention
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WASHINGTON (CNN) -- DNA tests verify "with a high degree of certainty" that the cow in Washington state found to have mad cow disease originated from a dairy farm in Alberta, Canada, USDA chief veterinarian Ron DeHaven said Tuesday.
DNA from the cow's brain was compared with DNA from the semen of her sire as determined by records from the Alberta farm, DeHaven said.
The infected animal was a Holstein that was slaughtered in early December after giving birth left it paralyzed. U.S. investigators say they believe the cow was among a herd of 81 or 82 animals that entered the United States from Canada in 2001.
Investigators have tracked down 11 of the other animals in that herd, DeHaven said.
Officials are trying to locate all the animals in the infected cow's original herd not because there is concern that they could have contracted BSE from the infected cow, but because it is possible they shared the same food source, DeHaven has said previously. Feed containing parts from infected cows is blamed for its spread.
Rogue proteins called prions that cause the disease bovine spongiform encephalopathy, or BSE, collect in the brain, central nervous tissue and small intestines of cattle.
BSE can make it impossible for infected cows to stand. The disease is of concern to public health officials because it can cause variant Creutzfeld-Jakob disease, a fatal brain disorder in humans.
Officials say the infected animal was born more than six years ago, before Canada and the United States banned such feed, though officials have acknowledged that the ban was not uniformly followed.
Since the first U.S. case was disclosed December 23, federal authorities have quarantined three Washington cattle herds, including the one the infected cow was in before its slaughter.
U.S. officials this week will kill about 450 bull calves, including the offspring of a dairy cow that tested positive for mad cow disease last month, the Agriculture Department said Monday.
"None of those animals will enter the human food chain, nor will any of the product from those animals go into a rendered product," said DeHaven about the animals, which are on a farm in Washington state.
The Agriculture Department will compensate the herd's owner, DeHaven said.
DeHaven would not disclose where the animals would be killed. USDA officials are still trying to determine what to do with the remains, department spokeswoman Julie Quick said.
Because the offspring of the infected cow was not tagged at birth, the USDA can no longer single out the animal, requiring the entire herd's destruction, Quick said.
The decision about quarantining is not wholly based on science, DeHaven said, acknowledging the tremendous impact that public perception has had on the industry.
Several countries have blocked imports of U.S. beef since the discovery, but U.S. officials say American beef is safe.
Agriculture Secretary Ann Veneman announced last week that the United States no longer will allow meat from "downer" animals -- cattle unable to walk without assistance -- to enter the food supply.