BSE retest 'can of worms'
John A. Harrington, DTN
06/13/2005
First impressions can be dangerous things, long on instinct and bias, short
on new information and thoughtful reflection. Words and analysis offered in
haste should be well seasoned given the distinct possibility that they will
eventually have to be eaten. Having said all that, we can't resist reacting to
the USDA's decision to retest cow tissue that was originally judged to be BSE
free in the late fall of 2004 (i.e., nearly seven months ago).
The Decision: What was the Department thinking? We see no justifiable
reason to open an old can of worms, especially one that was responsibly vetted
when it was first discovered last year. The USDA has indicated that it was
prompted to revisit the results of last November by a recommendation early last
week from the Department's Office of the Inspector General (OIG). Apparently
the OIG did not see the gold in the so-called gold standard (i.e., the IHC
test), suggesting that the credibility of the entire monitoring system might be
enhanced if the Western blot test--considered to be the gold standard by many
European countries--was also used. This may seem reasonable looking forward,
but why go back and dig up dead bodies? Yet that's exactly what the gov did,
retesting three samples with Western blot. Unfortunately, the test results were
mixed with two samples showing no BSE and the third called a "weak" positive.
So with two gold standards contradicting each other (wasn't this
possibility anticipated?), Secretary Johanns has been forced to call the World
Reference Laboratory in Weybridge, England, to act as a tie-breaker. At this
point it is unclear as to exactly how UK scientists will proceed. Will they
rerun the Western blot, the IHC, or both? The fact is that no samples have yet
been UPSed to England. The rapidly disappearing cow brain (we understand that
there are only 12 ounces left) will stay in the U.S. until scientists in both
countries agree regarding a course of action.
Here's where the whole situation really looks dumb. There are no
internationally accepted rules regarding how to separate an accurate IHC test
from a faulty Western blot test. To be sure, scientists can review test
procedures and make sure there was no human/mechanical errors that skewed final
results. We assume this will be among the first steps that the UK scientists
will take. Yet is it quite possible (some would say quite likely) that when the
last Bunsen burner and centrifuge is turned off, we could still be left with two
test results that point in opposite directions. And guess what, such a
situation would not be unheard of. In fact, enough European countries have
reported conflicting BSE test results (i.e., IHC versus the Western blot) that
the OIE have invented a special category of classification. Specifically, these
hard to define cases are called "atypical BSE".
Please understand, none of this argues that these tests are unreliable.
They are the best science now have available, and reliably indicate an extremely
low incidence of BSE on the North American continent. But they are certainly not
perfect with one absolutely trumping the authority of the other. The USDA
should know this and it strike us as foolish for the government to back into
what could be a no-win situation. Hopefully--now that we're down this road--the
UK lab will discover that the IHC and Western blot agree after all in terms of
negative results. But if it simply confirms that they disagree, we will have to
haul all of our former beef customers back to the classroom, drilling foreign
buyers with the critical lesson that meaningful safeguards and firewalls (e.g.,
the tanking of downers, the removal of specified risk materials) matter more
than all the tests one can imagine.
agdayta.com