Second U.S. Case of Mad Cow Disease Confirmed
Infected Cow Was Pulled From Food Supply Last Year
WebMD News Archive
June 24, 2005 -- A U.S. cow -- pulled from the food supply last November --
really did have
Agriculture Secretary Mike Johanns today announced that tests confirm the
animal had bovine spongiform encephalopathy -- BSE, commonly known as mad cow
Humans who eat infected nerve tissue from beef infected with BSE can
contract a human version of the mad cow disease called variant
Creutzfeldt-Jakob disease (vCJD). However, the U.S. cow was never used as meat.
The animal was a "downer" cow --- that is, it was unable to stand when
it arrived at the processor. An "interim" USDA rule in effect since
January 2004 prohibits the use of downer cows for meat.
Conflicting Results in Early Tests
An initial quick test showed that the animal had mad cow disease. But a more
sophisticated test came up negative. When yet another quick test was positive,
tissues from the cow were sent to the U.K. for further tests. These tests
finally confirmed that the cow had BSE.
"This animal was blocked from entering the food supply because of the
firewalls we have in place," Johanns says, in a news release.
"Americans have every reason to continue to be confident in the safety of
Currently, the USDA tests some 1,000 animals a day for mad cow disease.
That, of course, is a small fraction of the animals slaughtered each day.
In 1989 the federal government prohibited the importation of certain types
of live animals from countries where mad cow disease is known to exist. This
ban also includes meat products used in human, animal, and pet foods.
The cow is the second U.S. animal to have tested positive for BSE. The USDA
is investigating the animal's herd of origin.
Cows get the disease after eating feed made from an infected cow. Cattle
feed made from processed cattle has been banned in the U.S. since 1997. Both
U.S. cows with BSE were born before the ban was in place.
Critics of the U.S. ban have said that it is not uniformly enforced.
Editor's note: On June 29, the USDA reported that the herd that the
infected cow was part of had been identified. The herd is now under a hold
order while officials identify any other animals of interest, such as those
born around the same time as the infected cow.