By Stephanie Schupska
University of
Georgia
From Washington to Texas and now in Alabama — it may seem as if
mad cow disease is making a migration to Georgia. But that’s
not how it works, says a University of Georgia expert.
“We’re not dealing with something like your normal virus or
bacteria that would be spread from animal to animal,” said
Ronnie Silcox, an animal and dairy science professor in the UGA
College of Agricultural and Environmental Sciences. “We’re
dealing with something that’s spread through feed.”
On March 13, the U.S. Department of Agriculture announced a
positive bovine spongiform encephalopathy test result from a
cow sampled on an Alabama farm.
BSE, also known as mad cow disease, is a degenerative brain
disease. “Cows will lose coordination,” Silcox said. “They act
crazy. That’s where the term ‘mad cow’ came from.”
The human variant, called Creutzfeldt-Jakob disease, has been
diagnosed in only 150 humans worldwide, none of whom were from
the United States.
The attending veterinarian said the Alabama cow may have been
more than 10 years old. If so, it was old enough to be eating
before a 1997 U.S. Food and Drug Administration ban on ruminant-
to-ruminant feeding practices took effect.
“We have such an incredibly low incidence of BSE in the United
States,” Silcox said. “In Great Britain, where they’ve had the
disease since the 1980s, their very rapid spread of the disease
came from feeding meat and bone meal from infected cows to
healthy cows.”
On Wednesday, March 15, Japan reported its 23rd case of mad cow
disease with a positive test on a 5-year-old Holstein bull. The
country’s first case was discovered in 2001, and since then,
Japan has tested every domestically slaughtered cow entering
the market, according to the Associated Press.
In 1997, the U.S. banned the practice of feeding meat and bone
meal back to cattle. The feed ban, according to the USDA, has
broken the cycle of BSE.
The average age of a beef cow is 5 to 6, Silcox said. “Over 10
years is fairly old,” he said. After a cow consumes a BSE
agent, it takes four to five years for the disease to
develop.
When the USDA suspected the Alabama cow could have BSE, they
sent samples to the University of Georgia for a rapid test run.
The test provided inconclusive results.
“Under USDA testing protocols, surveillance samples are sent to
contract laboratories for screening tests,” said USDA Chief
Veterinary Officer John Clifford. “If the sample is found to be
inconclusive on the screening test, it is then shipped to our
National Veterinary Services Laboratories in Ames, Iowa, for an
additional rapid test and two confirmatory tests. … USDA
considers an animal positive for BSE if either of the two
confirmatory tests returns a positive result.”
Silcox and other cattle experts have been dealing with BSE in
the U.S. since December 2003.
“There’s been a lot of testing going on, and this is the third
case that’s come up,” he said. “So it’s not a new issue. In all
the testing USDA has done, we’ve only detected three cases.
It’s more of an indication that we don’t have a high level of
the disease.”
The first infected animal was a Washington state dairy cow that
was born in Canada. The second was found in June 2005 in a cow
born and raised in Texas. The USDA is still trying to determine
where the Alabama cow originated. It had been on its most
recent farm for less than a year, Clifford said.
(Stephanie Schupska is a news editor with the University of
Georgia College of Agricultural and Environmental Sciences.)
