The US government was yesterday scrambling to calm public fears over its food supply after America's first recorded case of mad cow disease was found in a sick animal in Washington state.

I suggest this cow is the tip of an invisible iceberg. My presumption is mad cow disease is spread throughout North America at some level, but because our testing program is so inadequate we have not identified it.

John Stauber, co-author of "Mad Cow U.S.A."

Ann Veneman, agriculture secretary, said the positive test for BSE (bovine spongiform encephalopathy) was "presumptive" and would be confirmed in a British laboratory. But she said the administration was confident that the finding was accurate and had already implemented measures to curb its spreading.

A sample was believed to be on its way to the World Reference Laboratory in Pirbright, Surrey, where a sample was sent from Canada in May after a BSE alert there.

The US was last night notifying the country's trading partners and Ms Veneman was not sure how they would react.

However, she assured Americans: "The risk of spreading is low based on the safeguards and controls we have put in place." She said the risk of the disease entering the human food chain was minimal. "I plan to serve beef for my Christmas dinner and we remain confident in our food supply," Ms Veneman said, in an echo of the then British agriculture minister John Selwyn Gummer's ill-fated ploy to have his young daughter eat a hamburger on behalf of British beef in 1990.

The infected cow identified yesterday was a Holstein which was tested because it was a "downer", unable to walk, when it arrived at a Washington state slaughterhouse. The meat from the cow was nevertheless sent to a processing plant.

Agriculture department investigators were yesterday urgently trying to track it down.

Ms Veneman said that only the "muscle cuts" had been sent for processing for human consumption and there was no record of the disease being transmitted through the meat. The brain and spinal column had been sent to a "rendering facility" elsewhere, but she did not specify how it had been used.

The news hit an already nervous American public, entering the Christmas holiday under a high state of alert because of the risk of a new terrorist attack. Ms Veneman felt it necessary to stress there was no evidence of terrorism in the BSE incident.

However, her assurances that the outbreak would be contained were questioned by public health activist, John Stauber. He called them "extremely disingenuous", and pointed out Ms Veneman was a former lobbyist for the cattle industry. "I suggest this cow is the tip of an invisible iceberg," Mr Stauber, co-author of a book ( Mad Cow U.S.A.: Could the Nightmare Happen Here? ) about the threat of the disease, told CNN last night. "My presumption is mad cow disease is spread throughout North America at some level, but because our testing program is so inadequate we have not identified it."

He said the US livestock industry, unlike its European counterparts, continued to practice "animal cannibalism".

An isolated case of BSE was identified in Canada in May, but Ms Veneman said there was no immediate evidence of a link with the cow identified yesterday.

© Guardian Newspapers Limited 2003

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