So not surprisingly, the fallout from America's first case of mad cow disease is as large as a herd of Wild West steers. Government investigators conceded on Friday that it could take days, if not weeks or months, to retrace the path of the deadly infection and determine if other cows are sick.

Cattle in other states, or possibly in Canada, may have eaten the same infected feed, said Ron DeHaven, chief veterinarian at the US department of agriculture. This last week, federal officials announced that British tests had shown a Holstein dairy cow slaughtered in Washington state almost three weeks ago was infected with BSE.

A total of 4500 cattle, including the cow's own herd at Sunny Dene Ranch near the town of Mabton, are quarantined as America scrambles to cope with the scare and the possibility of more cases. A second herd has been quarantined after officials discovered it contained a calf of the infected cow, which born in Canada. The US has 100 million head of cattle.

A single case might mean there are more as yet undetected. William Hueston, a former official with the US department of agriculture who now directs the Centre for Animal Health and Food Safety at the University of Minnesota, says he wouldn't be surprised if up to another two dozen infected cows are found in the US.

Scientists believe that BSE, or bovine spongiform encephalopathy, is spread when cattle eat contaminated feed made of other animal parts.

The stricken cow was tested only because it was a "downer", a cow that could no longer walk. The results were not made public for a fortnight, in part because of a backlog of test samples.

Vern's Moses Lake Meats had agreed just three months ago to participate in the government testing programme - and only because it specialises in dairy cows that are past their prime, according to the Washington Post.

President Bush was en route to his holiday home in Texas cattle country. "He continues to eat beef," said spokesman Scott McClellan on Friday. He also assured reporters that the country's beef is safe, as had agriculture secretary Ann Veneman on Tuesday.

The US beef industry is worth £20 billion a year. The Bush administration's initial tack may seem all too familiar, especially in Britain.

According to news reports, some of the beef from the abattoir - from 20 carcasses produced on December 9 - was shipped to supermarkets in Washington state and Oregon. And although most of the 10,000lbs of meat was successfully recalled, some of it, in the form of mince or ready-made patties, appears to have been sold and consumed.

Mike Read, of WinCo Foods supermarkets, told the Washington Post that the company has fielded phone calls from customers saying, "I have purchased it, I have already eaten it, and what should I do?"

Trading of beef futures on the Chicago Mercantile Exchange had to be halted on Friday, for the second business day in a row, when prices plummeted too fast.

Within three days of the first news of the case, almost two dozen countries which consume 90% of America's beef exports had banned US beef and cattle products. They include the largest three, Japan, Mexico and South Korea, as well as China, Hong Kong, Australia, Russia, Egypt and many South American countries.

Canada was more forgiving, saying its ban would remain partial and only for older cattle. That's more than ironic, given that the US stopped all Canadian imports earlier this year after North America's first case of the brain-wasting disease was found in a dairy cow in Alberta.

No more Canadian cases have been detected since, a situation the US is keen to replicate. Some leading scientists now say BSE may occur spontaneously in about one cow in a million.

Britain, which imports only around 50 tonnes of US beef annually, has not imposed a ban. A spokesman for the National Farmers' Union said: "This is only one case of disease in a country that has been on the alert for a number of years. They have learned lessons from experiences in Europe and we are sure this will not turn into an epidemic."

A US delegation is to arrive tomorrow in Japan, which buys about one-third of US beef exports. The issue is especially sensitive in Japan, which has been struggling with its own cases of BSE this year.

Producers in other beef-exporting countries are eyeing US export and import markets. The US is on a beef-eating binge, based in part on faddish high-protein weight-loss diets. Brazil, with the world's largest beef herd, is well positioned for 2004. Most of its farmers do not feed cattle ground-up animal parts, thought to be how BSE is transmitted.

The US banned feeding most animals to cattle in 1997, because of the BSE outbreak in Britain. But cow blood and fat can still be fed to America's calves; and it often is, especially on dairy farms because it will boost milk yield.

Cattle parts can also legally be fed to other animals, such as chickens or pigs, which in turn are sometimes used in cattle food. The government disputes that BSE can spread in either of these ways.

In addition existing regulations are not properly enforced, In 2001, the US Food and Drug Administration, which oversees feed factories, was so short of inspectors it did not inspect more than 3000 of them even once.

And a federal survey last year found 35% of meat, mechanically scraped from a cow's carcass, is infected with spinal and nervous system tissue, which is most likely to carry the infection. Vern's Lake Moses Meats, where the sick cow was slaughtered, does not use mechanical scraping.

The financial fallout from this first case is far from clear. The Bush administration told Congress in 2001 the beef industry could lose almost £10bn from a BSE outbreak. But that was based on the disease spreading as widely as in the UK, where domestic beef sales dropped by a quarter and exports decreased by 80%.

The likelihood of an individual contracting the always-fatal human form of BSE, variant Creuztfeldt-Jakob disease, is slim even after eating infected meat. Yet some of the most risky parts of the animal, such as brain, are a delicacy in, for example, Mexican culture.

Ground beef is also, strictly speaking, more likely than steak to include infected meat. One who changed plans on Christmas Day was ex-patriate British author Jonathan Raban, who lives in Seattle, where several supermarkets have pulled beef from their shelves.

He tossed out three pounds of top-quality mince, even refusing to feed it to his dog. It was, he said, more aesthetic than logical, given the actual probability of contracting BSE.

"Had I gone ahead and made shepherd's pie, everyone would have thought of downer cows with each forkful," he said. "Not pretty. I preferred to risk salmonella with chicken instead."

  28 December 2003

Sheep producers also affected by BSE crisis

UK Government to change
BSE controls