Examination of Witnesses (Questions 1
- 19)
MONDAY 18 JUNE 2007
PROFESSOR JOHN
BOURNE CBE, PROFESSOR
CHRISTL DONNELLY,
PROFESSOR JOHN
MCINERNEY
OBE AND PROFESSOR
ROSIE WOODROFFE
Q1 Chairman: Ladies and gentlemen,
in the words of a famous and old radio programme, if everybody
is sitting comfortably, then we will begin. There is a sense of
déja" vu amongst quite a lot of us around this
table that once again we are discussing territory with which we
have become familiar over the last few years in dealing with policy
matters connected with the control and eradication of bovine TB.
Here we are once again with the final report of the Independent
Scientific Group on Cattle TB before us. Can I for the last time,
perhaps with a tinge of sadness, welcome Professor John Bourne,
the group's Chairman, supported today by Professor Christl Donnelly,
the Deputy Chairman, Professor John McInerney, who is a member
of the group, and also Professor Rosie Woodroffe. You have been
before the Committee before, for which we are grateful. We have
had a chance to look briefly at your final work of scholarship
on this particular subject and we are very grateful to you, at
relatively short notice and in fact on the very day when your
findings became public, for coming to join us. Without doubt,
you have given a real boost to Farming Today. Those of
you who were up on Saturday morning would have heard Farming
Today this week with the run-in to this, and indeed, this
morning you could not have got away from it; Professor, you were
on the radio at an early hour. So we were well armed with your
views before we even got into the House of Commons. Nonetheless,
we are genuinely grateful to you for coming and being before us
today. One of the things that we are just trying to work out in
terms of the modalities, Professor Bourne, is what Defra are actually
now going to do with this information, because we understand that,
in terms of your principal findings, they managed to get hold
of them a little ahead of the public, which is perfectly understandable
and no criticism is implied. When you presented your findings
to Defra, did they give you any indication as to how long they
were going to take to digest what you had put before them and
try and give some indication to the concerns in the farming and
wildlife areas as to what on earth they were going to do now?
Professor Bourne: These findings
are not new; they are not new to Defra. If I take you back to
September 2005, when we were asked by Mr Bradshaw to pull down
early, prematurely, trial data to inform his Autumn Statement,
we did that. We advised him that we did not wish to do that but
we did, and we presented at that time evidence of a positive proactive
culling effect and evidence of a negative edge effect. We did
extrapolate that on the basis of models because it was suggested
we did to see what would happen if one culled over a larger area.
We did state at that time that while theoretically that was possible,
pragmatically it would be extremely difficult to achieve, but
it would require far more analysis and data and a cost benefit
consideration before it could even be considered as a policy option.
We followed that with a statement in January 2006, of course,
which related to the consultation document. You will recall there
were three proposals for culling and we were surprised to see
two of them highlighted which clearly the scientific evidence
negated, and I was forced, as you know, to write to the Minister
at that time and again express our guarded views about culling
over large areas. We extended those discussions with Defra, and
I have a record of discussions on 22 March 2006 with Defra, where
we advised them very clearly that future policy should have a
cattle-based focus and that culling would make matters worse.
As we extended our analyses, I met with the Minister, Mr Bradshaw,
on 24 April, repeating those comments at a discussion with him
that localised culling was ineffective, and proactive culling
extended to 300 square kilometres was likely to make matters worse
in the way the Government perceived it would be done. I met Mr
Bradshaw again on 29 November 2006 and presented more detailed
analyses, because by this time we were able to analyse the full
50 plus triplet years of the trial where we had hardened up on
our data, closer confidence intervals, and made it clear to him
that culling would make things worse and one should focus on a
cattle control policy. I repeated that with Mr Miliband on 1 February.
In the interim, of course, we had weekly discussions—probably
more frequently than that—and certainly our monthly meeting
with Defra officials, so they clearly knew where we were coming
from. All the scientific publications that left the ISG went through
Defra's hands. Copies were rested with Ministers long before they
were in the press. Defra colleagues were asked to advise on those
publications and their advice was always taken; it was extremely
useful. Ministers received a copy of all those publications pre-publication.
So it is not only in the last few weeks that they have appreciated
what the developments have been with our work but they did see
fairly forward not a complete draft report on I think it was May
23 of this year. It has been an ongoing process of reiteration
and communication during that period.
Q2 Chairman: In terms of this piece
of work, is it, if you like, the ultimate review of all the information
that you have? The message I am getting is that really not a lot
has changed since we last discussed your findings. In other words,
you have had a chance to look back over, as you were saying, all
of the data now from the randomised trials. You have looked at
that but then you had looked at them before. The conclusion that
you have come to, which is effectively that large-scale culling
really does not have a part to play, is entirely consistent with
everything you have said, so it is almost as if you have peer-reviewed
your own research and come back to the same conclusions as before.
Is that a fair summary of where you are?
Professor Bourne: We constantly
evaluate our research but we do so in discussion with Defra. As
you know, it has been our policy to work to strict scientific
practice and good guidelines—we can talk about that later—which
involves publication of our work in peer-reviewed journals, and
we have purposely gone for high-quality journals. We have publications
in those journals, internationally peer-reviewed. In addition
to that, of course, we have had our work audited independently
by auditors appointed not by us but by Defra. The final audit
report from the statistical auditor came in today and I believe
you have copies of that. I think he makes some very pertinent
conclusions as far as the thoroughness of the work we have done
and does indeed make recommendations for how science should be
developed and translated into policy for the future.
Q3 Chairman: Do you know if Professor
Godfray, who has himself done work, I seem to recall, in 2003,
when Defra established an independent scientific review, notwithstanding
all that you have said in terms of putting this material into
high-quality scientific journals, are you aware that Defra are
planning to do that in terms of the latest publication?
Professor Bourne: I am not aware
of that. It has been mooted but I am not really aware.
Q4 Chairman: From a scientific point
of view, would you be distressed if such an exercise were required?
Professor Bourne: From a scientific
point of view, given the rigidity of the audits we have gone through
and the peer review, I would have thought it was unnecessary,
but if Defra want to do it, good luck to them.
Q5 Chairman: That answers that question.
You mentioned that Defra have had sight of this since 23 May and
were aware before that of the work that you were doing. The name
of your group is the Independent Scientific Group. Can you tell
the Committee if at any time you came under any kind of pressure
from either Defra or its Ministers and or both that might have
been deemed to be a way of influencing the direction of travel
of the work that you were undertaking?
Professor Bourne: No. If one goes
back to the outset, of course, we had great trouble in getting
much of the work in place but I think we fought our corner pretty
well and retained our independence. It is very interesting. You
mentioned the Godfray Report, and one of the recommendations of
the Godfray Report was that we should lose our independence, that
we should report not to Ministers but to the Chief Scientific
Adviser. He made other recommendations too which have subsequently
been shown to be wrong. Fortunately, the Minister did not respond
to those recommendations. I do not think in fact Defra ever responded
to his report.
Q6 Chairman: Could you just say that
again, Professor Bourne, because Mr Cox missed the point.
Professor Bourne: Professor Godfray
in his report suggested that we did lose our independence—I
am not sure he even realised what he was doing—by suggesting
that we reported not directly to Ministers but indirectly to Ministers
through the Chief Scientific Adviser. I also said that Godfray
made other recommendations—he made two, in point of fact.
One was that he suggested that 50 triplet years was inadequate
for the power of the experiment and we might have to extend that
by several more years, and that has been proven to be wrong. He
also suggested that data should be released prematurely to Defra
at that time but fortunately Ministers rejected that. I think
you know how strongly we reacted to that suggestion. It would
have completely undermined the trials.
Q7 Mr Williams: When you say that
Professor Godfray's conclusion that there were not enough triplet
years has been proved to be wrong, is that because of the statistical
analysis of the work that has been done or is that some independent
review of his conclusions?
Professor Donnelly: At the time
we did alternative calculations and we believed that we were on
track to get the level of precision that we needed in 50 triplet
years, but the real proof of the pudding is yes, once you have
the data, calculating confidence intervals, and the fact that
we have been able to estimate the impact of proactive culling
plus or minus 10%.
Professor Woodroffe: Professor
Godfray and members of his group have gone out of their way to
express their conviction that our results are correct.
Professor Bourne: We have had
pleasant exchanges with Professor Godfray.
Professor Woodroffe: One of them
last time we were here. He was with us.
Q8 Chairman: Before we get into the
detail of your work, a fact which just caught my eye re-reading
some of the material behind what you have been doing, if we go
back to 1986, there were at that time 638 cattle that were compulsorily
slaughtered because they had TB. We come to 2004 and the figure
had risen by that time to about 22,500. It just occurred to me,
I suppose, because TB has become such an accepted part of life
in certain parts of the country as to why the massive increase?
Why from 1986, at a relatively low level incidence, has TB suddenly
gone on the upward march? Can you refresh my memory as to why
that occurred?
Professor Bourne: As a result
of the work we have done, we believe there are two factors contributing
to this. One is the contribution that badgers make—there
is no dispute about the fact that badgers do contribute to the
cattle disease—and the other is the contribution the cattle
themselves make to the disease, which subsequent work has shown
to be related to the limitations of the tuberculin test, the fact
that so many infected, undetected animals remain in the national
herd and these animals are simply being moved around.
Q9 Chairman: What I was getting at
was that, at a relatively low level, there would not obviously
be the same degree of public attention as there is now because
what we have seen is suddenly from, being almost unnoticeable—600
is not unnoticeable but very low levels of disease—
Professor Bourne: There is a doubling
every four and half years.
Q10 Chairman: I was just intrigued
to know why all of a sudden, 1986-87 double, did it start to multiply
up over that period? What was the epidemiology of this sudden
explosion of this particular disease, which I presume had been
chugging along at a low level?
Professor Bourne: It had been
increasing since the late Seventies.
Q11 Chairman: But what was driving
that?
Professor Bourne: Those two aspects
that I talked about, the contribution that badgers make and the
contribution that cattle themselves make. We had no idea at that
time what the badger contribution was and we cannot be absolutely
precise about that now. Modelling suggests that it might be 30%
or no less but that modelling is imprecise and it does not take
into account perturbation, but it does indicate that the cattle
contribution is very, very large. We do know, of course, in parts
of the country the contribution from cattle is almost solely responsible
for the development of the disease and the long-distance geographical
transmission of the disease.
Q12 Mr Williams: The tuberculin test
very much in the same form as was being used at the time the Chairman
is talking about was a tool that was used to almost eliminate
TB from the national herd.
Professor Bourne: That is very
true. They were very subtle changes, of course, in the way that
test was used over the period from 1960 to 2006, certainly into
the 1990s. It was developed as a herd test. The obvious way to
use a herd test is, if you find an infected herd, to take it out.
There are, unfortunately, no historical figures about the number
of herds that were actually slaughtered in the 1960s, just the
number of cattle, and I think if you go back and see how many
cattle were slaughtered in the 1960s, it makes the 22,000 we have
now pale into insignificance. It was up around the 40,000-50,000
mark per year. Herds then were very small, very much smaller.
As the disease eradication programme progressed, cattle testing
regimes in fact were eased, and they were further eased—I
am not sure of the timing of this; it could have been the late
Eighties or into the Nineties—moving from one-year to two-year
to three-year to four-year testing. One does not know the direct
answer to your question but I suspect the rigidity of cattle testing
was relaxed. The movement control which we saw in the Sixties
with the tested herds, the TB-free herds—you were not allowed
to buy an animal from TB-infected herds and they had to be double-fenced.
All those features were relaxed when the whole country became
designated free of TB but, of course, the whole country was not
free of TB; there were patches of infection which still remained
in the West Country which were ascribed to badgers. Whether it
is true to ascribe them to badgers or not I do not know.
Professor McInerney: In the last
20 years also there have been quite significant changes in the
structure of the cattle economy and herd sizes are very much larger
now so that you get infection within a large herd and it can amplify
very much more within that herd. Secondly, the statistics show
there is a great deal more cattle movement because of the wider
trading activities of cattle farming.
Q13 David Taylor: Professor Bourne
referred to the smaller number of larger herds and Professor McInerney
just referred to the degree of transport. What was the aggregate
size in the Sixties when you were talking about 50,000 cattle
being slaughtered a year and what happens now as paling into insignificance?
What was the size of the national herd then approximately, as
opposed to where we are now? That is a factor as well, I would
have thought.
Professor Bourne: I do not know.
It surely was much greater then than now, many more million than
that. The size of herds, I do not know. I can only talk from my
experience when I was in practice in Cornwall, when the majority
of herds were 19, 20, 25 cattle, sometimes less, and a herd of
60 animals was large.
Q14 David Taylor: The aggregate size
of the national herd would also be a driver in terms of the statistics,
would it not?
Professor Bourne: Yes, surely.
Q15 Chairman: Just to conclude this
section, just to set us on our road, summarise for us, if you
would, the current state of your final conclusions.
Professor Bourne: With respect
to badger culling, our findings are that localised culling, in
whatever form that may take, will not contribute to the control
of cattle disease and is likely to make the situation worse. If
one considers proactive culling over an area the size of the trial
areas, 100 square kilometres, we have demonstrated that within
the culled area there is a beneficial effect of 23% and in the
peripheral area outside of the culled area there are an increased
number of breakdowns to the extent of a 25% increase in breakdowns
in that area. That occurs as a result of systematic culling carried
out by a professional team over a five-year period where badger
removal was about 70-73%, which suggests a trapping efficiency
of 80%, which is consistent with the design criteria of the trial,
and yet when one translates the numerical number of herds breaking
down and those not breaking down, it results in a very small number
of herds saved from breaking down over a five-year period, 14
herds over that period being saved from breaking down. That is
the difference between those that have not broken down on the
inside and the increased number breaking down on the outside.
So it is a very modest return for five years culling, sustained,
and when that culling is carried out, we have shown that it has
to be across the whole patch simultaneously. You cannot do it
piecemeal. That worsens the problem.
Q16 Chairman: Just to help me understand
the statistics of what you have said, if after five years you
have dropped 20%, roll it forward; if you carried on doing it
for another five years, what would the statistical drop be?
Professor Donnelly: What we have
shown is that we have trends in both the benefit inside the proactive
trial areas and also trends outside. So the detrimental effect
gets less bad over time and the beneficial effect gets better
over time, but we were not able, on the basis of this data, to
extrapolate beyond the fourth annual cull. All ten areas received
at least four culls, some as many as seven.
Q17 Chairman: Just stop there, because
it is quite easy for a non-expert like me to get lost. If after
five years you indicated there were two findings: minus 20% in
the area which has been culled and plus 25% increase in events
occurring outside, across the border, what I wanted to get some
feel for is, if you carried on culling in the next five years,
and then another five years, what is the trend? Do you ever get
to the Nirvana of the extinction of the disease after 20 or 30
years in the culled area and total ravaging outbreak everywhere
else? That is what I am trying to get a picture of.
Professor Donnelly: We were able
to estimate well after four culls, so the figures that John reported,
the 23% and 25%, are averaged over the whole period of the trial.
So the best picture that we are able to estimate at the end of
this period is a 33% benefit inside and an 11% detrimental effect
outside, and there is a general trend for both of the situations
to improve.
Q18 Chairman: I am trying to get
the idea. If you devote more time, is there a cumulative benefit?
Professor Woodroffe: Perhaps I
can talk to that because, of course, the root of all of this is
what is happening to the badgers. What is happening to the badgers
is that after about three culls your number of badgers caught
per cull plateaus, so you catch most on the first cull, you catch
on average fewer on the second and by about the third cull, each
time you go back and cull, you are culling a similar number from
then on, but what keeps continuing to go up is the proportion
of badgers that you catch close to the boundary. So what is happening
is that, as you cull the badgers inside the area, more are coming
in from the outside. The genetic evidence shows the same. So I
think that unless you have some barrier to prevent badgers from
re-colonising, probably what is going to happen is that, as fast
as you cull the badgers, more come in. We also know that successive
repeated culling increases mixing within the badger population,
increases TB transmission within the badger population, and so
you are going to continue to have a number of badgers present
within the area and a higher proportion of those are going to
be infected, and my suspicion, based purely on the ecology, is
that you are not going to continue down to eradication; you are
going to reach some sort of stable point where it does not get
any better, unless you had some sort of physical barrier that
prevented the badgers from re-colonising and, unfortunately, given
that badgers dig and climb, fencing them is extremely difficult.
There are very few natural boundaries that would prevent that
re-colonisation from occurring.
Q19 Chairman: What I was trying to
get some feel for was, if you carried on doing it and at the same
time adopted all the measures of bio-security cattle movement,
whether in fact you would then crack it; in other words you would
say in an area, "Right, we have bottomed this." The
message I am getting from you is no.
Professor Woodroffe: Yes, from
a badger ecology perspective, no. You cannot eradicate the TB
in the badger by culling.
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