Select Committee on Environment, Food and Rural Affairs Minutes of Evidence


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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