| AMES,
Iowa –– All 260 Vermont sheep suspected of having
been exposed to a form of mad cow disease have been killed,
and tissue samples were being tested Tuesday at a U.S. Department
of Agriculture veterinary laboratory.
Before
the flocks were sent to Iowa, four sheep tested positive
in Vermont for transmissible spongiform encephalopathy,
or TSE, a family of diseases that includes bovine spongiform
encephalopathy (BSE), or mad cow disease, and scrapie, a
common sheep disease that doesn't affect humans.
Scientists
at the National Veterinary Services Laboratory here said
they were running a series of blood and tissue tests on
the carcasses. They said they would know within two or three
months how many of the sheep were carrying TSE.
The
East Friesian milking sheep, seized from two farms in Vermont,
were imported before an epidemic of mad cow disease prompted
a ban on European livestock in 1997. The animals were thought
to have been exposed to contaminated feed.
An epidemic
of mad cow disease devastated the British beef industry
in the 1990s. Nearly 100 people in Europe have died of a
human form of BSE since 1995, but no cases have been confirmed
in the United States.
The
USDA also said Tuesday it was tracking a handful of cattle
imported from Britain before the 1997 ban. None of the animals
had shown any illness, said USDA spokesman Jim Rogers.
"It's
my understanding they are going to be bought and destroyed,
but none of them have ever entered the human or animal food
chain," said Ed Curlett, a USDA spokesman.
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