WASHINGTON - A cow that was cleared of having mad cow disease last fall by the U.S. Department of Agriculture was in fact infected with the brain-wasting disease, the department announced yesterday, making it the second confirmed case of the disease in this country.
The cow was incinerated last fall and never made it into the U.S. food supply, said Agriculture Secretary Michael Johanns. He said the cow appeared to have been born in the United States, a significant fact because it suggests that the animal ate infected feed in this country that could have been eaten by other animals.
U.S. officials were able to mitigate damage from the first case of mad cow disease in the nation, discovered in Washington state in December 2003, because that cow was born in Canada and thought to have eaten infected feed there.
The infected animal, which was at least 8 years old, couldn't walk and was covered with manure, placing it in a category of "downer" cattle that are more likely to have mad cow disease and are randomly tested by the Agriculture Department. But while an initial "quick test" was inconclusive, two more sophisticated tests were negative.
Two weeks ago, the Agriculture Department's inspector general noticed inconsistencies in the testing as part of an audit of the agency's mad cow surveillance program and asked for additional tests. A renowned laboratory in England, as well as the Agriculture Department's own labs, confirmed that the cow was infected using a test known as the "Western blot."
Johanns suggested that one of the reasons the disease wasn't initially found was that the animal had a variation on the classic mad cow disease that swept through England in the early 1990s. Instead of finding the disease throughout the brain, it was isolated to certain parts of the brain, a form of the disease that has been found in some animals in France, he said.
While insisting on the safety of the U.S. beef supply, Johanns said he would initiate new protocols for testing that would include the "Western blot" test when an initial "rapid-response" test for mad cow disease was inconclusive. He also said that he was correcting a number of problems he had uncovered in how the Agriculture Department handled the diseased cow - from failing to segregate tissue samples from those of other cows to freezing the samples.
Still, Johanns tried to put a positive spin on yesterday's announcement, pointing out that the Agriculture Department had tested 388,000 cows in the past year and found only one instance of mad cow disease.
Mad cow disease is officially known as bovine spongiform encephalopathy, or BSE. The disease attacks brain cells and leaves spongy holes behind, and it can be spread to humans by eating contaminated meat. The human form, variant Creutzfeldt-Jakob disease, has killed about 150 people worldwide, mostly in England.
Critics on Capitol Hill and from consumer groups accused the government of not doing enough to detect and prevent mad cow disease.
Michael Hansen, a researcher at Consumers Union, which publishes Consumer Reports, said the fact that it took seven months to retest the animal shows "serious lapses" in the Agriculture Department's testing program. He also said it would be significant if the animal was born in the United States because it would show that the problem wasn't isolated to Canada.
John Stauber, author of Mad Cow USA and the executive director of the Center of Media and Democracy, said the Agriculture Department needed to adopt the more aggressive strategies of nations such as Japan.
Market reaction was expected to be negative, though some of the bad news has already been factored into cattle prices during the past two weeks, since the Agriculture Department announced that it was conducting further tests on the tissue.
The announcement could hurt U.S. beef exports and it might doom aggressive efforts by trade negotiators to persuade Japan to reopen its border to American beef. Once the biggest importer of U.S. beef, Japan has kept its borders closed since the first U.S. case of mad cow disease was found.
Johanns, however, said he didn't think the news would affect negotiations with Japan because the United States is proposing sending only beef that is from cows 20 months or younger. Nearly all cows infected with mad cow disease are 30 months old or more.
The Chicago Tribune is a Tribune Publishing newspaper.