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A cow has tested positive for mad cow disease in the United States, agriculture
officials said, opening the door to possible changes in testing procedures in
the US beef industry.
Further tests are planned to confirm the diagnosis because the animal had previously
tested disease-free, said John Clifford of the US Department of Agriculture
(USDA).
"Because of the conflicting results, ... a sample from the animal will
be sent to the ... reference laboratory for BSE in Weybridge, England,"
he said. The USDA will also be conducting further testing, which will take several
days to complete, Clifford said in a statement, acknowledging that procedural
changes were possible.
"After we receive additional test results on this animal, we will determine
what further steps need to be taken, and what changes, if any, are warranted
in our surveillance program," he said.
Beef is the number-one protein consumed in the United States, government data
show.
A confirmation would bring to two the number of known cases of bovine spongiform
encephalopathy (BSE) in the United States, where a diseased animal was discovered
in the northwestern state of Washington in 2003.
That discovery prompted Japan, previously the top market for US beef, to halt
imports of cattle products. The new case is likely to deepen woes for US cattlemen
and fan fears that the deadly human form of the brain-wasting disease could
spread in the United States.
The announcement came the same day that Portugal announced its first suspected
case of the human form of mad cow disease, while France said it had identified
its 13th case of the degenerative brain ailment.
A total of 177 people have died or been diagnosed with variant Creutzfeldt-Jakob
disease (vCJD), most of them in Britain, according to a toll compiled by AFP
from official figures.
Britain was the epicenter of the BSE outbreak that occurred in the late 1990s.
Its suspected source was cattle feed that came from cows with brain disease.
Experts believe the pathogen leapt the species barrier to humans through the
consumption of contaminated beef.
The animal that tested positive in the United States was unable to walk --
a so-called "downer" animal -- and thus was banned from human consumption,
Clifford said. There is no chance its meat entered the human food supply, he
stressed.
The bovine died in Texas in November, according to The Washington Post.
Officials did not indicate the age of the animal or whether it was imported,
the daily said.
If it was born after 1997, when the United States banned the use of cattle
feed containing animal parts, that could call the effectiveness of the ban into
question.
The animal that tested positive in 2003 was imported from Canada, and was born
prior to the feed ban. Three cases of BSE have been discovered in Canada since
2003.
The United States has applied intense pressure on Japan to resume imports of
US beef, but Japan has so far resisted the call amid further safety assessments.
Tokyo said in October it would exempt US cows aged 20 months or younger from
screening if high-risk parts such as brains and spinal cords were removed. But
the main dispute remains over how to verify the age of the cattle.
Japan is the only Asian country to have confirmed cases of BSE. Its first case
was discovered in September 2001, prompting the government to introduce measures
to screen every cow slaughtered for consumption.
The USDA, which has resisted international calls to do the same, said Friday
it had tested more than 375,000 animals for BSE since June 2004.
Three animals whose tests were inconclusive were subjected to immunohistochemistry
(IHC) testing, with negative results, the USDA said.
Earlier this week, however, the deparment's inspector general recommended further
testing of the meat samples using a different method, called the SAF immunoblot,
or Western blot, test.
"We received final results a short time ago. Of the three samples, two
were negative, but a third came back reactive," Clifford said.
So far, 150 people have died of vCJD in Britain, where another six people are
living with the disease, according to the official British vCJD website.
There have been two cases in Ireland, with single cases reported in Canada,
Italy, Japan, the Netherlands and the United States.