- Mad cow disease remains a worrying mystery. Meat from
infected animals can infect consumers with prions, which cause variant
Creutzfeldt- Jakob disease, a progressive degeneration of the brain that
is always fatal.
- Mad cow disease (the common term for bovine spongiform
encephalopathy) is caused by prions, the infectious misshapen proteins
discovered by University of California researcher Stanley Prusiner, who
received a Nobel Prize in Medicine for his groundbreaking work. Prusiner
has referred to BSE-related diseases as "new, strange and scary."
- Unfortunately, it seems that some governmental officials
and agricultural leaders are not so worried about the threat that prion
diseases such as BSE present -- not only to animals, but to humans as well.
A human outbreak of Creutzfeldt-Jakob disease, caused by eating prion-contaminated
beef from cattle with BSE, killed approximately 150 people in England in
the 1990s. At that time, up to a third of British herds were found to be
contaminated before the infection was controlled.
- The one cow found to test positive in the United States
in December unleashed a flurry of concern here, with much confusion over
how much of a threat that case might have posed. Equally disturbing were
varying allegations that the beef industry and governmental regulators
were not being entirely forthcoming about the details of this case and
were trying to reassure the public without enough scientific evidence to
do so. There admittedly is much scientific uncertainty about how much a
threat BSE poses to humans.
- In recognition of that uncertainty, Japan has taken the
BSE threat seriously and now routinely tests all slaughtered cattle and
sheep for the presence of prion infection. The U.S. government persists
in much more limited testing -- fewer than 1 percent of all cows are so
tested -- arguing that scientific uncertainty makes universal testing too
expensive. Yet Consumers Union has testified that such testing would add,
at most, five cents a pound to the cost of beef. But Creekstone Farms in
Kansas, seeking to certify its beef BSE-free and thus be able to sell it
to Japan as well as concerned consumers here, have been threatened by the
U.S. Department of Agriculture with legal action and severe fines to stop
them from testing all their cattle for the BSE-causing prion. New tests
can detect such prions in a short enough time to allow use on all animals
at the time of slaughter.
- Why would USDA oppose such testing? If it is positive,
that would be good for human safety (one of the USDA's missions); but it
could also trigger public reaction bad for the beef industry's profits.
Wouldn't USDA be happy that any infected animal was detected before infecting
a human? What possible justification can they have for denying beef producers
who want to test every cow, at their own cost, in order to sell safety-certified
- At this time, testing all cows slaughtered for human
consumption for the presence of BSE prions rather than late-stage full-blown
neurological disease -- which is the only test now used by the USDA --
makes good sense as a public health precaution until more data are accumulated
on the new rapid tests for BSE prions. This is why the San Francisco Medical
Society supports this position -- as does Prusiner, the Nobel winner.
- While the details of the threat are being determined,
it is time to err on the side of safety, rather than on assurances from
beef industry spokesmen. If it does turn out that testing 100 percent of
animals is not warranted, good -- the standards could then be relaxed,
and we'd all be safe rather than sorry. Right now, though, despite all
assurances from those in charge, we just don't know.
- Even if we cannot test all cattle, certainly there is
no good reason to keep a ban on voluntary testing by responsible members
of the cattle industry. This would provide consumers with a real choice
regarding the safety of their beef products. It would also allow our cattle
industry to reopen the markets now closed for beef sales in Japan and other
countries that insist each slaughtered animal be certified negative for
- Congress and the public need to send our agricultural
regulators at the USDA a strong message about their obligation to public
health -- and consumer choice. Leading scientists agree that eating prions
is a bad idea. If your doctor told you an inexpensive test could reduce
your risk of contracting something that would kill you, you'd ask for that
test. Likewise, isn't it time we pay the extra nickel per pound to be sure
the beef we eat is free of a fatal disease?
- Robert Lull, M.D., is professor of medicine at the University
of California at San Francisco, chief of Nuclear Medicine at San Francisco
General Hospital and a past president of the San Francisco Medical Society.
Steve Heilig is co-editor of the Cambridge Quarterly of Healthcare Ethics,
director of Public Health and Education for the San Francisco Medical Society
and co-director of the Collaborative on Health and the Environment.
- ©2005 San Francisco Chronicle