This week, the United States' elaborate wall of rules and regulations designed to keep mad-cow disease out of the country showed its first cracks.
For more than a decade, the American system of detection has helped prevent the illness from spreading to the country's farms and ranch lands. The announcement Tuesday of the first detection of mad-cow disease in US history, however, has raised questions and concerns about how effective the American regimen really is.
To critics, the discovery is a confirmation of the need to adopt the more rigorous standards of Europe and Japan. To proponents, it is evidence that the system is working precisely as it should.
Still, even supporters acknowledge that, in a world skittish about mad-cow disease, the discovery of a single case could prompt major reforms, as the American beef industry seeks to avoid an economic disaster by assuring customers both at home and abroad that US beef is safe.
"The international stakes in this are very high," says Dean Cliver, a professor at the University of California's School of Veterinary Medicine in Davis. "[More] testing will [probably] be implemented because we won't be able to export without it."
A single case of mad-cow disease in Canada this spring devastated its beef industry. Canada's beef was subject to worldwide embargoes - many of which have yet to be lifted.
The US exports a comparatively smaller percentage of its beef - about 10 percent. But because the cattle industry represents the largest segment of American agriculture, generating $50 billion in sales among US consumers alone, the fallout to US agriculture will undoubtedly be significant. Several nations, including South Korea, Taiwan, and Japan - the largest overseas market for US beef - have halted US beef imports.
Among some scientists, it seems a reaction wildly out of step with the dangers of the disease. Since bovine spongiform encephalopathy (BSE) - the scientific name for mad-cow disease - was first diagnosed in Britain in 1986, some 130 people have died from eating tainted beef products.
"It's a little hard to comprehend" all the fear surrounding BSE, says Clive Gay, a professor of veterinary medicine at Washington State University in Pullman. "If you look at the number of deaths relative to the exposure, the risk of it is very low."
Part of the reason for that is because of the way mad-cow disease is transmitted - solely by eating specific parts of cows that are infected. Scientific studies suggest that muscle tissue, from which supermarket meat cuts come, does not transmit BSE. The disease is usually transmitted through parts of the brain or nervous system. Scientists posit that human deaths, all in Europe, have come from eating tainted sausages.
Likewise, cows became infected by eating feed made from the leftover portions of slaughtered cows. To ensure this would not happen in the United States, the federal government banned the use of cow parts in cow feed in 1997. In recent years, it has also bolstered its detection program, testing nearly 20,000 cattle in 2002 - roughly four times more than it tested in 2001.
A 2001 study by Harvard University's School of Public Health found that such regulations would prevent a public-health crisis from breaking out in the US even if 500 cows were infected.
Generally, the government now tests cows that have symptoms that could be related to BSE. The cow from a farm near Yakima, Wash., that tested positive for BSE fitted that description. It was a "downer" - the term for a cow that cannot stand on its own due to poor health.
To critics, though, the detection is not a sign that the system is working, but rather that it is woefully inadequate. For comparisons, they need only look to Europe, which tests one-quarter of its beef cattle each year. Japan tests all meat for human consumption. The US, meanwhile, tests only about one in every 1,800 cows.
Just a week before the Agriculture Department announced the detection of mad-cow, the Federal Court of Appeals for the Second Circuit overturned a decision to throw out a suit against the government's prevention policies. The suit, filed by an animal rights group, says that the government's policy of allowing the slaughter of "downer" cows poses a serious risk to public health.
"USDA needs to take swift action to ensure that the meat that is found in hot dogs, hamburgers and those others doesn't pose a risk," says Caroline Smith DeWaal, food safety director of the Center for Science in the Public Interest.
The government acknowledges that its cattle-testing regimen is lighter than some other countries. But it also notes that America has never had a case of BSE before, so comprehensive testing was unnecessary. Officials note that, according to the guidelines laid out by the Office International des Epizooties, which sets international testing standards, the United States only is required to test 433 cows a year.
Considering that BSE isn't even among the deadliest food-borne illnesses, setting up a comprehensive testing system like the one in Japan would create an enormous cost for a questionable benefit, some say.
"We might find it expedient to do that," says Dr. Cliver. "But I don't think this is about saving lives."
The investigation into how the Washington cow got BSE will play an important role. But even the Agriculture Department's detective work could take several months, partly because the US does not have a national identification system that tracks each head of cattle through its lifetime.
Such a system was vital in Canada's effort to follow the path of the cow that tested positively earlier this year. Even ranchers admit that concern over the nation's systems of mad-cow prevention and detection could lead to significant changes in how the industry does business. "This potentially could have a huge impact on the industry, and the economies of several states," says Jim Petersen, a rancher in Buffalo, Mont.
• Correspondent Todd Wilkinson in Bozeman, Mont., contributed to this report.