Examination of Witnesses (Questions 220
- 223)
WEDNESDAY 7 NOVEMBER 2001
PROFESSOR DAVID
KING, PROFESSOR
MARK WOOLHOUSE
AND DR
BRYAN GRENFELL
Mr Breed
220. A 20-day movement restriction would make
no difference whatsoever in terms of the contiguous cull policy,
is that right; and, secondly, is it both technically and economically
feasible to electronically tag sheep?
(Professor Woolhouse) The first question: once the
disease was established, no, that would not affect the value of
the contiguous cull; what of course it would prevent is that early
dissemination of the disease, which gave everybody such an enormous
headache from late February. In a sense, the die was pretty much
cast by February 20, and certainly by February 23, so it would
have prevented that, definitely. The technical feasibility, I
think you would have to refer to, shall we say, a review of the
success of the cattle-tagging scheme first, and I am sure there
are lessons to be learned from that. But I appreciate the difficulties
that you have in mind.
Diana Organ
221. You just said there are lessons to be learned
from the 1967 outbreak, and you said that this virus is not so
airborne; so can I ask the question again, if it is not so airborne,
why do we need to have the contiguous cull?
(Professor King) I can only give the reply again,
I refer back to my earlier reply—
222. But would you make a refinement; different
viruses behave in different ways, this outbreak was different
from 1967, so that the old policy of just culling everything does
not necessarily fit all outbreaks?
(Professor King) Perhaps this is a point where I ought
to explain that the modellers, the teams of modellers that I brought
together, were not using data from the 1967 outbreak to model—
223. It was just a computer model, was it not?
(Professor King) It was not just a computer model,
these models were learning from the way this outbreak happened.
Please do not say it is just a computer model. It was picking
up on incubation periods, and so on, from the early stages of
this outbreak. Without that, we would have been modelling any
sort of outbreak; it was this outbreak that was being modelled.
And when we give these figures, like 17 per cent of contiguous
farms and the argument for the contiguous cull, it is all based
on this outbreak, and when it was out of control we were saying,
"This is how you will bring it under control." And what
I would like you to do is to look at the very impressive figures;
if you compare Figure 2, which is the predictions that were made,
the curves A, B, C, with Figure 3, which is how the epidemic developed,
I think you have got to agree that that was not bad agreement,
the prediction was not too bad.
Chairman: We will pursue those issues, we will
certainly come back to them; for the moment, gentlemen, thank
you very much indeed. It has been extremely helpful. And I think
there may be a little course of this to run yet, as it were, but
not, I hope, of the epidemic. Thank you very much.
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