This is getting ridiculous, so I shall not continue after this.

In article ,
Jeff Layman wrote:

1) There was a scrapie-like disease that was MUCH more aggressive,
was widespread in cattle and had been seen in humans.

I assume you are referring to nvCJD. Yes, BSE was much more aggressive in
cattle, but by putting that phrase "and had been seen in humans" in the same
sentence you are drawing an unsubstantiated conclusion that the disease is
much more aggressive in humans. Even if the BSE prion and nvCJD prion are
the same (I have not checked this) can the conclusion be drawn that they
behave identically in cattle and humans?

That is close to trolling. No, I didn't draw that conclusion, and I
didn't even imply it. I said that it was much more aggressive than
scrapie, which it was. If I recall, the VERY few human cases were a
lot more aggressive than the few cases where 'normal' scrapie had
been observed in cattle.

Obviously, no conclusion could be drawn, most especially not the one
you seem so keen on (i.e. that it was not going to be aggressive in
humans). The real experts said that they didn't have a clue.

5) We didn't have a clue what proportion of the UK cattle herd
was infected, and educated guesses ranged from 0.1% to 99%.

How can you use the term "educated guess" and "ranged from 0.1% to 99%"?
Why is a smiley missing from the end of that sentence?

Because I said what I meant and I meant what I said. I am not going to
give a seminar on parameter estimation, but educated guesses are what
experts use when they have to make an estimate based on very incomplete
data. It's a perfectly valid statistical technique, though a bit beyond
most scientists.

8) We had no test except an autopsy, and even that was very
unreliable except in advanced cases.

So why draw only the worst conclusions? It's like multiplying all degrees
of error together to come up with the worst possible outcome.

I didn't, nor did any expert I read. I could respond to you by:

So why draw only the best conclusions? It's like multiplying all
degrees of error together to come up with the best possible outcome.

But a more informed answer is that people who have to take serious
decisions use the appropriate analysis (based on game theory), where
the risk is the probability of an outcome multiplied by its cost.
Only politicians and other ignoramuses rely solely on the probability.

In particular, the cost of the worst plausible scenario combined with
a laisser faire attitude (as you are saying should have been adopted)
was horrific. The probability of the worst case was low, but the risk
of the combination was huge.

The optimal scenario was that it wasn't very infectious at all, and a
large proportion of infected subjects showed symptoms within a couple
of years. There was ABSOLUTELY NOTHING to distinguish this one in
plausibility from the nightmare scenario.

Sorry, I don't understand what you are saying here. If a large proportion
of infected subjects showed symptoms within a couple of years, isn't that a
nightmare scenario - early onset disease and no cure? Delay for 30+ years
might mean a cure being found in the interim.

No. Because it would mean that only a small proportion of people were
infected. Even in the early days, we knew that it was a few years
(about 5?) from first symptoms to death. If the first symptoms didn't
show for 30+ years in most people, it could mean that the majority of
the UK was infected.

Yes, a cure MIGHT be found. But relying on fairy godmothers isn't
something that any competent person does.

What evidence do YOU have that the optimal scenario (which seems to
be the case) could have been determined to be more plausible than
the nightmare one USING ONLY INFORMATION AVAILABLE AT THE TIME.

I no longer have access to the original papers, but this is from a review
paper by Peter Campbell on BSE/MCD (Med Principles Pract 1998;7:172-186).
It is thus only a couple of years on from the original papers on the
subject.

"In view of the long incubation period of 5-10 years for nvCJD, based
largely on the assumption that the greatest chance of people eating infected
beef was between 1980 and 1988 when the ban on MBM was instituted, no sound
estimate could be given of the likely scale of the epidemic of nvCJD, but
the possibility was mentioned that it could run into thousands of cases.
Fortunately, so far the worst predictions have not been fulfilled since the
number of new cases is about 1 per month with a total to date of 23."

Aargh! That paper was TEN BLOODY YEARS after the action was taken!
Yes, BY THEN, we knew that the nightmare scenario was implausible.
But why do you claim that was obvious in 1986-1988?

Given what we know now, if the government had not been pressured into
acting until 1998, the problem would be something like ten times worse
(not a major issue). But, BASED ON THE INFORMATION AVAILABLE IN 1987,
we had NO reason to believe the best plausible scenario over the worst
plausible one (or conversely). And, if the latter had been the case,
a ten year delay would have been CATASTROPHIC.


Regards,
Nick Maclaren.