Mad cow disease a possibility in U.S. animal tested in April

Lab results inconclusive for cow that died from calving, USDA reports

July 28, 2005|By Steven Bodzin | Steven Bodzin,LOS ANGELES TIMES

WASHINGTON - A cow that died of complications from calving in April might have been infected with mad cow disease, the U.S. Department of Agriculture said yesterday.

There is no danger to the human or animal food supply, said Dr. John Clifford, the department's chief veterinarian, because the carcass was destroyed where the cow died after tissue samples were collected.

Clifford said a sample of brain tissue was submitted by a veterinarian who treats animals in "a remote area," which he did not identify. The tissue was treated with a preservative and frozen before being sent for analysis.

The presence of the preservative meant that only one type of BSE test could be done on the sample, Clifford said, and the results were inconclusive.

Additional samples from the cow are being tested at the USDA laboratory in Ames, Iowa, and at a lab in Weybridge, England, that is considered the most sophisticated in the world in identifying the illness. The results are expected next week.

USDA rules in place in April allowed the use of preservatives, but those have since been changed, Clifford said.

Mad cow disease - bovine spongiform encephalitis, or BSE - is spread when cows eat brain or nerve parts from an infected animal. Until 1997, when the United States and Canada banned the practice, the remains of ruminants, or cud-chewing animals, could be ground up and used in cattle feed.

Clifford said the animal in question was "well over 12 years old," meaning that it could have eaten contaminated feed. The farm where the cow lived has not been quarantined, he said.

So far, two cases of BSE have been identified in the United States - one in Washington state in December 2003, in a cow imported from Canada, and one last month in a cow from Texas.

In the current case, the time lag between the animal's death in April and its testing in July was "not optimal," Clifford said. "The sample was not submitted to us until last week because the veterinarian set aside the sample after preserving it and simply forgot to send it in."

He said that veterinarians who travel to remote areas frequently submit samples for testing as an extension of the department's enhanced BSE surveillance program.

Dean Cliver, a professor of food safety at the University of California, Davis, said it was surprising that a cow that died in calving would be tested at all under the current system, as that is a common way for cows to die.

The USDA tests samples from all "downer" cows, or cows unable to walk when taken to slaughter. Cows that die in other ways can be tested, but that is not always done.

"Here was a vet with no particular reason to suspect a neuropathy," Cliver said. "Even if the brain stem was submitted later, there was not a 100 percent probability of it getting tested."

BSE is associated with a brain-wasting disease in humans called variant Creutzfeldt-Jacob disease, which killed more than 100 people in the United Kingdom after an epidemic of mad cow disease in the late 1980s and early 1990s.

The inconclusive BSE test comes at a precarious moment for U.S. beef ranchers, who had hoped to restart sales to Japan, once the largest export market for U.S. beef. Sales to Japan dried up after the case in Washington state was discovered.

"I would hope it will have no impact on our negotiations," Clifford said. Japan has had 20 cases of mad cow disease and now tests every animal slaughtered. Authorities there have demanded that the United States test more animals before beef exports resume.

The Los Angeles Times is a Tribune Publishing newspaper.

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