Bovine spongiform encephalopathy, or mad cow disease, was first
found in British cattle in 1986. Now, almost 20 years later, BSE
has been found in U.S. cattle.
On Dec. 23, 2003, the U.S. Department of Agriculture announced
that an infected cow had been identified in the state of
Washington.
By that date, meat from the contaminated cow had already been
distributed throughout the nation.
The discovery prompted the USDA to recall beef from the infected
cow in eight states and in the U.S. territory of Guam.
Human consumption of the brain or spinal tissue of beef infected
with mad cow disease can lead to the development of variant
Creutzfeldt-Jakob disease.
A 24-year-old British woman living in Florida is the only case
of vCJD in the United States, but it is believed that she
contracted the disease while living in Britain.
Muscle meats have not been found to be infectious, said John
Maas, Cooperative Extension veterinarian at the University of
California, Davis.
“If you don’t eat brain or spinal cord tissue, the
chances of getting infected are very slim,” said Dean Cliver,
professor of food safety at UC Davis.
Following the news of this infected cow from the United States,
over 30 countries banned the import of U.S. beef, including Japan
and Mexico. This may be a response to U.S. trade policies in the
past banning the import of beef from other countries affected by
the disease.
“Everyone else is treating us how we treated other
countries with BSE,” Cliver said. “We are on the
receiving end of what we were dishing out before.”
The U.S. cattle industry is the world’s leading exporter
of beef and could face losing billions of dollars.
When mad cow disease first affected Europe in 1986, there were
approximately 1,300 cattle infected with BSE for every human
infected with vCJD, so BSE would have to be more widespread in U.S.
cattle to affect humans, Cliver said.
“I wouldn’t expect to see a human contracting vCJD
unless there have been a thousand cases of BSE quoted in
America,” Cliver said.
“I don’t think we’re looking at an incipient
epidemic,” Cliver said.
From past international examples of mad cow disease, the United
States has learned about the disease and the precautionary measures
that should be taken. In 1997, a feed ban was implemented
throughout North America to prevent cow tissue from being recycled
and fed to other cattle.
The feed ban, however, does not extend to chickens and pigs.
“The best thing to do is convert (uneaten cow tissue) to
something nutritive and if we don’t do that, we’re
wasting potential food,” Cliver said.
“Pigs and chickens don’t get BSE, so that’s
been a safe way to recycle that material as long as we know,”
Maas said.
Though the infected cow was born before the 1997 feed ban, it is
still possible that the cow came down with BSE spontaneously,
Cliver said.
For cows and humans, the disease can take years or even decades
to fully develop.
Many cattle are slaughtered before the disease develops, Cliver
added.
Scientists have not found infective traces of the agent in
cattle before symptoms are exhibited, Maas said.
However, biological chemistry professor David Eisenberg feels
government agencies should avoid inflating public confidence in
their food supply.
“I was surprised to see the Department of Agriculture
spokesperson say that there is essentially no risk.”
“In fact, there is a risk, but it is very, very
small,” he said.