Perhaps it was never a matter of whether mad cow disease would reach the United States, just a question of when.
The detection last week of the nation's first case left officials defending the nation's food safety net. The U.S. Department of Agriculture maintains rigorous standards, first devised in 1990, to check cattle for bovine spongiform encephalopathy.
It has dramatically increased BSE testing programs in the past two years. The USDA far exceeds international testing standards set by the World Organization for Animal Health. The Organization's standards require just 433 U.S. head of cattle to be tested annually, but inspectors currently test almost 20,000 head of cattle each year.
That scrutiny, industry representatives say, means it was inevitable that the fatal brain disease would be found in a U.S. herd that comprises some 100 million head of cattle, of which 35 million are processed each year.
"If you look long enough and hard enough you will eventually find the needle in the haystack," said J. Patrick Boyle, president of the American Meat Institute.
But the current case has also renewed questions about potential gaps in the system.
Risks from 'downers'
USDA inspectors, who conduct inspections, focus primarily on head of cattle in at-risk groups: older cattle, often dairy cows set for slaughter; those that die on the farm or have neurological problems; and non-ambulatory cattle -- known as "downers" -- that can no longer walk on their own.
That last category again came under scrutiny this week. A downed dairy cow from Mabton, Wash., was found to have BSE, according to two tests conducted at the National Veterinary Services Laboratories in Ames, Iowa. Tissue samples were also sent to a lab in England for final testing, a standard procedure for all BSE samples.
Not all downer cattle are diseased, but they are what Daniel Puzo, spokesman for the USDA's Food Safety and Inspection Service, called "high risk vehicles." The cow in question, for example, was injured during the birth of her calves, according to federal officials. Farm veterinarians who treat the ill or injured cattle make the call as to whether the animal can be used for food. Any head of cattle with a neurological disorder will be pulled for testing, though not all downers are tested.
Assuming downers are sent for slaughter, they must first be tested by federal inspectors who watch over operations at feedlots and slaughterhouses. This so-called antemortem inspection is now required as part of the government's efforts to detect BSE specifically because of health concerns about downers.
"The antemortem inspection is extremely important because animals with chronic diseases like BSE will show signs," said Lelve Gayle, executive director of the Texas Veterinary Medical Diagnostic Laboratories.
No mandate for quarantine
But no federal regulation requires a quarantine of meat from questionable animals during testing. The meat can be released into the food supply; meat linked to the the diseased cow discovered in Washington has been traced to at least eight states. While many in the beef industry endorse a test-and-hold process, which would require a quarantine, not all processing facilities withhold the meat during testing. Neither the USDA nor Congress have proposed a requirement for test-and-hold procedures.
The Canadian cow found with mad cow disease this summer was a downer. Many big beef buyers will not accept meat from downed cattle, including McDonald's, Burger King, Wendy's and the federal school lunch program, which USDA administers. Producers often decide to reject downers, not only because it prohibits them from doing business with major customers, but also extra work is required to handle the heightened inspection process for downers.
"They're a challenge to handle at the packing plant," said John Scanga, a meat safety expert at Colorado State University's meat science program.
The Senate this year backed a move to ban downers from U.S. consumption. But the House turned down a similar measure in July, and final legislation did not include a provision to ban the meat. While the meat industry Dairy producers often rely on older cows, including downers, as an additional source of income.
"Our objective is that no downer animals come to slaughter ... but that’s not the reality," said James Hodges, president of the American Meat Institute Foundation. "We need to strike a balance."
Meat recovery concerns
Mad cow concerns have also prompted renewed focus on an industry technique known as advanced meat recovery, in which machines are used to scrape or shave muscle tissue away from cattle bones, including the head and vertebrae.
The process, which accounts for an estimated $150 million in revenue, has caused worry among regulators and safety advocates because of the recovered meat sits so close to neural tissue -- a cow's brain or spinal cord -- where the deformed proteins, or prions, that cause mad cow disease can be found.
A 2002 survey of producers using AMR techniques found that one in three meat samples was infected with neural tissue, notably bits of spinal cord. The industry disputes that figure, and the government began a more stringent inspection program this year. USDA has yet to issue new data, but the recent data actually shows an improvement from earlier in 2002, when three of every four AMR samples showed traces of contamination.
The recovered meat usually is used in processed products, such as ground beef, taco fillings and meatballs. In addition to antemortem inspections, beef carcasses and recovered meat can be tested after slaughter.
Food safety researchers maintain that the U.S. inspection process is rigorous and extremely safe, pointing to the discovery of a single mad cow case as a sign that the process is working.
"All food safety is an assessment of risk, and we do the best job we can to have a low-risk system," said Val Hillers, a food safety specialist at Washington State University.
But European beef producers face even more rigorous standards, in part because of the outbreak of BSE in Britain in 1986. The British beef industry withered through the 1990s because of fears about the disease, which is believed to cause variant Creutzfeldt-Jakob disease, a fatal brain ailment in humans. At least 129 people in Britain have died from the disease since 1995.
After years of stringent standards, Britain's beef producers have just begun to recover. The impact on the $50-to-$60 billion U.S. beef industry would be less severe, but the discovery could still cost producers a large chunk out of their income. Exports account for 10 percent of industry revenues, largely from countries, such as Japan, South Korea and Mexico, that have issued temporary bans on U.S. beef.
Agricultural economist Mark Ritchie felt the U.S. outbreak was “inevitable” because of lax U.S. regulations that allow ground-up animals to be used in animal feeds. While animal byproducts have been banned since 1997 from feed intended for ruminant animals such as cattle and sheep. Older cattle, such as the one that tested positive, are considered higher-risk because they may have had some contact with the old ruminant feed. And there are no such limits on feed for other animals, including poultry or swine.
“You can’t really control it out in the market,” said Ritchie, president of the Institute for Agriculture and Trade Policy, a research group that advocates on behalf of family farms. “Everyone … is quite aware that the current very limited regulation of the grinding and feeding of animals to ruminants hasn’t had a significant impact in the real world.”
Industry advocates believe the rendered proteins derived from the animal products pose no threat in the feeds currently being sold, and warn that farmers would take a hit from more expensive feed prices if the animal proteins were outlawed. But Ritchie believes the costs of a potentially unsafe food supply far outweigh any costs of eliminating animal byproducts.
“Using animal byproducts in this way is incredibly expensive to the whole society, and the U.S. is about to pay the bill,” he said.
Tricky tracing process
Despite the mad cow discovery, Agriculture Secretary Ann Veneman said Tuesday that she and other officials "remain confident in the safety of our food supply."
Federal officials are currently tracing the infected Holstein back to its original birth herd. While that might not be difficult, it could take a long time to trace back all the other head of cattle in that herd, and the cattle with which they might have had contact. The remaining 4,000 head of cattle at the two Washington farms where the cow came from have been quarantined.
Because meat from this cow was processed despite being flagged for testing, officials have also been trying to trace it forward to producers that handled it. They have found two in Washington and at least one in Oregon. One of them, Vern's Moses Lake Meat Co., voluntarily recalled 10,410 pounds of beef from the infected cow and 19 others processed there the same day.
But it may take a while to find all the meat that came into contact with meat from the suspect cow, in part because a single cattle carcass can turn up in dozens of secondary products, including different grades of hamburger.
"That’s not uncommon the way ground beef is formulated," Scanga said.
Despite Veneman’s confidence in the food supply, Ritchie noted she banned imports of beef from Canada after the discovery of a single case of mad cow disease in May. In October, the USDA proposed reopening the Canadian border to imports of certain meat and live ruminants intended for slaughter. “The truth is we’re talking about a very small percentage of risk, but if your kid is that one person in a million, that’s a 100 percent risk,” he said.
MSNBC's Martin Wolk and Joe Myxter contributed to this story.