DALLAS — — State researchers tracking the herd associated with the nation’s first domestic case of mad cow disease found that most of the cattle were slaughtered before federal officials started their inquiry and that incomplete records hampered the investigation.
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One offspring of the infected cow could not be located and might have entered the food supply, the researchers said. However, transmission of the disease to a cow’s offspring or to people is unlikely, a U.S. Department of Agriculture official said Wednesday.
The federal government closed its investigation in August, saying it could not pin down how the cow became infected with the brain-wasting ailment. The Agriculture Department and the Food and Drug Administration traced 413 animals and reported that 147 herd mates and offspring were presumed to have been slaughtered for food, livestock feed or other use, and that 21 could not be traced. The USDA killed and tested 67 animals, all of which tested negative for mad cow disease.
However, reports compiled for the Texas Animal Health Commission and obtained by the Dallas Morning News show that about 350, or 85 percent, of the 413 cows were sent for slaughter.
The state investigators found that many records were no longer available, and ended up using the state’s own cattle health records from the county where the herd was located to get a picture of the herd’s animals, the Morning News said. The ranch where the infected cow was raised has not been publicly identified.
“If it were not for our brucellosis information and database, we would have had extraordinary difficulty in conducting this investigation,” said Dr. Max Coats, deputy director for animal health programs at the Texas Animal Health Commission.
Brucellosis is a bacterial disease in cattle and other animals that can be passed on to humans.
Researchers tracked 213 calves to find two that had recently been born to the diseased cow.
They were unable to specifically identify the two calves, but found that 208 went into feed and slaughter channels, entering the food supply, the newspaper reported. Four more probably did. One calf was untraceable.
“If they’re fairly confident that the group they identified as the progeny was complete and if nearly all of them were slaughtered, chances are the progeny was eaten by a human being,” said Tom McGarity, a professor of food safety law at the University of Texas School of Law and president of the Center for Progressive Regulation.
Mad cow disease is not necessarily transmitted to offspring, but it is “quite possible that a mad cow got in the food supply,” McGarity said.
However, USDA spokesman Jim Rogers said Wednesday it’s unlikely that herd mates or offspring would have been infected or that people would have eaten tissues known to carry the infection.
“Research has shown that it’s extremely unusual to find more than one infected animal in a herd, especially in a country where the disease has as low a prevalence as it does in the U.S.,” Rogers said. “Plus there are food safety measures taken at the time of slaughter that are designed to prevent potentially contaminated material from entering the food chain.”
Federal officials say the only way mad cow disease, the common name for bovine spongiform encephalopathy, or BSE, is known to spread is through eating brain and other nerve tissue from infected cows. Officials have said they believe the 12-year-old cow that had mad cow disease ate contaminated feed before the United States banned ground-up cattle remains in cattle feed in 1997.
A rare but fatal form in humans, variant Creutzfeldt-Jakob disease, is linked to eating BSE-contaminated meat products.
Coats said there should be no fear of mad cow entering the human food supply. A veterinarian inspects cattle before slaughter and the organs are inspected later to ensure sick animals are not made into food, he said.
Rogers noted the USDA is developing a national animal tracking system that that would allow livestock to be traced within 48 hours.
While the Texas cow was the United State’s first known domestic case, the nation’s first case of mad cow disease was an imported cow believed to have been infected in Canada.
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