Examination of witnesses (Questions 460-463)
WEDNESDAY 25 APRIL 2001
PROFESSOR DAVID
KING, DR
NEIL FERGUSON,
DR ALEX
DONALDSON AND
PROFESSOR MARK
WOOLHOUSE
Mr Drew
460. Clearly, where we are at now, if the figures
are to be believed, is, the issue is becoming concentrated around
disposal, and safe ways of disposal of the animals. As you said
earlier, you have to face the media and hope that they get it
right; how do you convince constituents that I have who have burning,
we have not had burial, although that is always a possibility,
how do you convince them that they have not been affected, healthwise?
I know it is an open-ended question, but that is the sort of question
that people want to have answered. What level of risk are we really
dealing with?
(Professor King) If we take the question of pyres
then the Environment Agency and the Department of Health standards
have been operated very consistently, which is, for example, that
pyres should be set on the top of hills, that pyres should be
lit only when we know what the wind conditions are going to be
and that the wind is going to carry the smoke from the pyres away
from a neighbouring village, and this has been carried through
in practice. In addition, monitoring is being done of the output
from those fires. But I would not want to understate the potential
hazards from these fires. Chairman, the fires are not only producing
dioxins, the fires produce PM10 particles, and, of course, these
do pose a risk to people who are asthmatic or have a potential
for asthma. And advice is also clearly going out to people, if
they are in the neighbourhood of a fire, to stay indoors, where
possible, and so on. But we have also to keep it in perspective.
It is not the same as having a fire burning continuously in your
neighbourhood, over a long period of time; if these fires are
burnt out over a few days then, again, the risk to human health
is relatively small. But I am not trying to say that this is not
a problem, it is a problem.
Chairman
461. Gentlemen, a final point. We now appear
to have got the first case of a man contracting the disease; does
that make any difference at all to your calculations? For example,
you said that there were issues about the acceptability of products
from vaccinated animals, one thinks immediately that this might
have some impact upon human perception of the acceptability of
product. I realise that you are not responsible for human health,
but, insofar as your responsibilities do embrace this, what conclusions
have you drawn and what impact might it make?
(Professor King) Can I try to clarify the position
with vaccinated animals first, in response to your question. A
vaccinated animal has antibodies produced which will kill off
the virus, and a vaccinated cow, for example, will not pass the
virus through into the milk, and the virus is not sustained in
the beef, in the meat, in the blood system. The only place where
the virus can exist as a carrier state is in the mucus in the
throat and in the mouth region, so that there is no possibility,
with a vaccinated animal, of posing any kind of health risk from
foot and mouth disease. In the case of the 1967 outbreak, there
was one reported case, which was fully established, of a person
contracting foot and mouth disease as a virus. As you know, we
are now examining whether or not the case currently reported very
widely in the newspapers is a case of foot and mouth or not, we
do not know. But, in that instance, there is a very vivid description
of how this individual was splashed by the outpourings of an animal
that was infected; this is not quite the same as drinking milk
or eating meat. But what I would say is that, in terms of human
contact with animals, for example, it is known that somebody who
works with animals that are infectious will get the virus into
their own mucus system, and for four or five hours the breath
will contain the virus which will operate as a challenge to other
animals. So a person coming into contact with an infectious animal
will take on the virus, the virus can replicate for a while, and
that person then poses a threat; which is precisely why the advice
to our vets is that if you have been on an infectious premise
you cannot go to another farm premise until an overnight stay
at least.
462. I was reflecting merely on the perceptions
of safety, because you will recall the wholly different debate
on GM food, in which, of course, public perception has played
an enormous role, quite separate from any scientific evidence
about threats to safety of that product. But that is a comment
not requiring an answer.
(Professor King) Can I make just one comment, as a
different kind of health warning, and that is, over reading the
output from our modellers, I heard somebody mention June 7, other
dates have been looked at very carefully. The model, and I am
sure that Dr Ferguson will not mind me saying this, the mean-field
model becomes a little problematic when the number of cases gets
small, and in that case the farm-scale models, of the kind that
John Wilesmith is using, do rather better; and John Wilesmith's
models are currently indicating that the outbreak will continue
to bump along until about mid July to early August.
(Dr Ferguson) It is notoriously difficult to predict
the end of an epidemic, because of these random outbreaks.
(Professor Woolhouse) I did want to say one thing,
Mr Chairman, which brings me right back to your opening comments
about the contiguous cull, and just one observation for you, because
you were obviously concerned about this. The estimations we have
done at the moment is the contiguous culling would have removed
hundreds, almost certainly, of incubating foot and mouth disease
outbreaks, and if those had been allowed to come through to normal
reporting, diagnosis and slaughter they would have infected hundreds
more, by our estimation. So that must be included, of course,
in your evaluation of the effectiveness of contiguous culling.
Mr Paterson
463. How many of the contiguous cull farms have
you tested?
(Professor Woolhouse) That information is still being
analysed, is it not?
(Professor King) Can I suggest, Chairman, that the
question may be a little misleading, for the following reasons.
We have put forward a policy, a cull policy, that is based on
the models but based not on bringing the epidemic under control
most quickly but bringing the epidemic under control in such a
way that we minimise the number of animals that would be culled
at the end of the epidemic. So this cull policy, with the contiguous
farm removal, may remove healthy animals that are not incubating
the disease, but it is absolutely clear to us that this is the
policy for reducing the overall number of healthy animals that
would be culled, or healthy animals that would become infected
and then have to be culled.
Chairman: We must get on. Gentlemen, thank you.
Our preoccupation with June 7 was due entirely to the anniversaries
of the battles on the Normandy beaches, as you can imagine. Thank
you very much indeed for coming here today, it has been very illuminating,
on the whole, I think; and we wish you well of the worm, as Enobarbus
said to Cleopatra.
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