The first US case of the deadly mad cow disease, which devastated parts of the European agriculture industry in the 1990s, was found in a dairy cow, and overseas buyers immediately shut their doors on Wednesday to American hamburgers and steaks.
Discovery of the brain-wasting disease in Washington state threatened the US$27 billion US cattle industry, pressured share prices of fast-food companies and raised consumer concerns about food safety -- especially as an official said meat from the cow may have been eaten as hamburgers.
"A single Holstein cow from Washington state was tested as presumptive positive for BSE or what is widely known as mad cow disease," Agriculture Secretary Ann Veneman said.
Taiwan, Japan, the largest importer of US beef, the UK, Spain, Germany, Canada, South Korea, Singapore and Malaysia immediately halted imports of American beef, a move likely to be followed by other major US customers. Shares of fast-food companies like McDonald's Corp. dropped, and analysts in Chicago predicted beef and grain prices would fall sharply when trading began yesterday.
Mad cow disease, also known as bovine spongiform encephalopathy, has never been found in the US before.
Scientists believe humans can be infected by eating meat contaminated with diseased brain or spinal column material. BSE is not found in meat like steaks and roasts.
Veneman urged American consumers not to panic.
"I plan to serve beef for my Christmas dinner," she said. "The risk to human health from BSE is extremely low."
The animal's brain and nervous system tissue -- material considered at high risk for conveying BSE -- did not enter the human food chain, Veneman said. That material was sent to a rendering plant to be made into pet food or for other uses.
Still, a Washington State official said other meat from the diseased cow may have already been consumed, possibly in the form of hamburger.
An outbreak of BSE in Europe more than a decade ago resulted in 137 human deaths, mostly in Britain. British farmers destroyed some 3.7 million cattle because of the outbreak.
A sample from the US diseased "downer" cow -- one that is too sick to walk -- was obtained on Dec. 9 and tested positive, Veneman said. A tissue sample was flown by US military jet to an animal laboratory in England for additional confirmation. Those results will not be ready for three to five days.
The farm where the dairy cow was found near Mabton, Washington, was quarantined and officials were checking with other processing plants where parts of the animal were sent.
Investigators scrambled to detect how the cow was infected and were expected to focus on the animal's food supply. Mad cow disease has been spread to other cattle when an infected animal was ground up for livestock feed.
"I think it's very important to recognize that this disease does not spread easily," Veneman said.
In 1997, the US Food and Drug Administration, which regulates livestock feed, banned feeding cattle remains to other livestock. The FDA said in July its test results showed 13 US animal feed plants out of a total 1,555 had feed that contained some of the banned material. One of the plants that sold adulterated feed was based in Tacoma, Washington.
Jan Busboom, a professor of meat science at Washington State University, said dairy cows typically have detailed records of what they were fed.
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