Download Public Health Magazine: Spring 1996, Vol.4, No.1 EndGram-

Public Health Magazine: Spring 1996, Vol.4, No.1
EndGram-- Mad Cow Disease: An Ostrich
Phenomenon
An invited editorial by Michael Katz, M.D.
Bovine spongiform encephalopathy (BSE)-commonly, but inelegantly called "Mad Cow Disease"-has
been known to exist for at least 10 years. Official assurances from the British health establishment that
consumption of British beef was not dangerous were suddenly reversed in the wake of a report of 10 cases in
young people of Creutzfeldt-Jakob disease (CJD), a fatal human encephalopathy. The consequence of this
about-face is panic. What are the facts?
BSE is a relative newcomer among the spongiform encephalopathies. Other diseases with this pathologic
hallmark of spongy lesions in the brain include scrapie in sheep, transmissible mink encephalopathy, and two
human diseases, kuru among the Fore people of New Guinea, and CJD, a rare condition reported world wide, but
usually among the elderly. All of these conditions are caused by an unconventional agent, a protein named prion,
and are transmissible within and across species. They may indeed all be the same condition, the differences
being attributed to a differential clinical expression in the various species.
Scrapie has been transmitted by a deliberate experimental injection of the affected material to sheep, mice and
hamsters, kuru to chimpanzees; and CJD from man to man accidentally by reuse of electroencephalographic
scalp electrodes, by transplantation of cadaver corneas, and by administration of human growth hormone derived
from pooled cadaver pituitary glands. Moreover, the epidemiology of BSE has been traced to feeds into which
sheep offal was admixed as an added source of protein.
Whether this encephalopathy can actually be transmitted by ingestion is moot. Yet, in the process of oral
administration there can be exposure of abraded gums or lips to the infectious agent and thus transmission can
occur as if by an inoculation. Kuru, in fact, had been transmitted as part of ritual cannibalism, but the transmission
probably happened at the time of the removal of the affected brains by hands that may have had abrasions,
rather than by the ingestion itself. By analogy it is reasonable to assume that BSE can also be transmitted in like
manner.
It is pertinent to note that the agent of spongiform encephalopathy cannot be readily inactivated. Because it lacks
DNA, it remains infectious even after radiation or heating. Beef originating in animals with BSE, regardless of how
it is cooked, can well continue to harbor the agent in a transmissible form.
What then is the risk of human disease resulting from eating British beef? It must be very low in spite of the
current hoopla. Considering how much of this meat has been eaten by a population of 56 million during the past
10 years, the finding of only 10 cases of CJD putatively attributed to BSE is minuscule. Not so, however, when
one takes into account its portent. Ten cases of a potentially preventable fatal disease among young people may
not be readily dismissed, let alone ignored.
Beef is not the only product derived from cows, of course. Milk is a staple, yogurt a common snack. Other parts of
the cow are used in nutritional supplements, in cosmetics, even in mucilage. Although there is no evidence that
spongiform encephalopathy can be transmitted by any of these products, absence of evidence may simply reflect
an absence of relevant studies. I expect such studies will soon be carried out.
What course of action should now be taken? Beef is not an essential ingredient of human diet so that the decision
to avoid is of no adverse personal consequence. A boycott of British beef has major economic implications,
clearly. Steps are apparently now being taken by the European Common Market to help Great Britain in this
financial crisis. Plans to destroy the potentially contaminated cattle are underway. This approach has an historic
precedent, because destruction of sheep in Iceland eliminated scrapie from that country.
There have now been reports of BSE from Switzerland, but they remain unconfirmed. There is no evidence that
the disease has crossed the Atlantic. Most of these facts were known when BSE was first reported and they could
well have been the basis of a plan of action, once the epidemiology of BSE was worked out.
Instead the authorities chose to ignore the problem in the futile, but not uncommon, attitude that if you cover it, it
may go away. Obviously, just because the problem was of a zoonotic origin, people in charge should not have
adapted a posture from ostriches.