WASHINGTON – Ending seven months of uncertainty, the U.S. Agriculture Department confirmed Friday that a cow first suspected of having mad cow disease in November has tested positive – the second such case identified in the United States.

Agriculture Secretary Mike Johanns, calling U.S. beef “the safest in the world,” said the case posed no threat to public health because the animal was not sent to a food processing plant.

“The BSE threat to humans in this country is so remote that there is a better chance you’ll get hurt crossing the street to get to the grocery store than by the beef you buy in the grocery store,” he said.

Johanns also praised the USDA’s testing regimen for bovine spongiform encephalopathy, or BSE, saying positive tests are so rare it’s like “finding a needle in a haystack.”

He also announced that department scientists had been ordered to develop a new protocol for dealing with cases in which initial tests for mad cow disease are inconclusive. And he said the USDA would re-examine the system for storing the remains of suspect animals.

The latest case of mad cow disease, however, raised concerns in the cattle industry that consumers would turn to poultry and pork and that trading partners would continue to ban U.S. beef from their markets.

Consumers largely shrugged off the previous incident, the discovery in December 2003 of a Washington state dairy cow infected with BSE. That cow was imported from Canada, which earlier had its own BSE discovery, and was born before a 1997 Food and Drug Administration rule prohibiting the feeding of ruminant meat and bone meal to cattle. The use of remains from cows, sheep and other ruminants as feed is one of the key suspects in spreading the disease.

USDA officials refused to identify where the second infected animal was located when it was slaughtered in November. They said they were investigating the cow’s herd mates to determine how the sick cow got the disease. The animal reportedly was a Texas beef cow, born before the ban, and was slaughtered for pet food.

Food safety experts said that there still was little chance of consumers eating contaminated meat, which causes a human form of BSE known as variant Creutzfeldt-Jakob disease. The disease in humans has no treatment and is always fatal. It has affected 153 people worldwide, most of them in Britain, which has found more than 180,000 animals infected with BSE.

By comparison, this was only the second American case found among an estimated 100 million head of cattle in this country.

“Happily, the risk of contracting the human form of mad cow disease is minuscule,” said Caroline Smith DeWaal, food safety director for the Center for Science in the Public Interest in Washington.

But DeWaal criticized the nation’s lack of a mandatory animal tracking system.

“This cow was exposed at a time early in its life,” DeWaal said. “Because we don’t have a tracking program, we don’t know where it was born, where it grew up and what other animals might have been exposed.”

DeWaal said the USDA has delayed implementation of such a system until 2009, even though Canada was able to move from a voluntary to a mandatory animal tracking system in one year.

And critics noted that, in the case of the second infected animal, it was only after prodding by the department’s inspector general that officials took the action that led to Friday’s announcement.

On Nov. 18, 2004, the USDA announced that two preliminary tests on an animal were “inconclusive” for mad cow disease. More sophisticated tests were ordered and, on Nov. 23, officials announced that the new tests were negative. Officials said they were confident the animal was free of mad cow disease.

But in February, the Consumers Union advocacy group urged the USDA to use another, more sophisticated test called the “Western blot” test.

In early June, the USDA’s inspector general also recommended using the Western blot test, which resulted in the announcement that the animal had mad cow disease.