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


Examination of Witnesses (Questions 100 - 107)

MONDAY 18 JUNE 2007

PROFESSOR JOHN BOURNE CBE, PROFESSOR CHRISTL DONNELLY, PROFESSOR JOHN MCINERNEY OBE AND PROFESSOR ROSIE WOODROFFE

  Q100  Mr Drew: I am interested because it is my area that has a trial under way. As you will know, where we have run into arguments both with yourself and Defra is that we always call for plan B. We never specified what plan B was going to be. I am pretty sure I know what plan B is going to be. It is going to be vaccination. The problem is we are always ten years away and we are always debating: should it be cattle or badgers that are vaccinated. If I was to have more than a hunch—I have spent my life arguing this—we have to get that vaccine in place. Everybody, including the Irish, would agree that vaccination long term is the only sustainable policy. Why do we not try much harder to get a vaccine? My argument would be a vaccine to be used in badgers rather than cattle because of the problems with vaccination of cattle and TB free status and so on. Why do we not just go for that and move it forward more quickly? Forget the rest of this because to cull or not to cull is not any longer a question. Let us go for vaccination and try and persuade Defra to put some serious resources into this and hope that it does pay dividends. It did with human beings, after all.

  Professor Bourne: It has not yet. Defra are doing exactly that. We carried out a review of vaccination, as you know, which we published in 2003 with the expectancy that that work would continue over a long time frame before it led to any extension into the field. We produced a full report with the expectancy that another group other than us would pick it up and take it forward way beyond the life of the ISG. That has happened. Defra have a group in place to extend this work. We have only briefly commented on vaccination in our report to emphasise the main findings of the document that we published in 2003 and to emphasise the problems of getting a badger vaccine into the field and particularly in collating data and evidence that the vaccine was achieving what we hoped it would achieve in respect to reducing cattle breakdowns. It is a very long haul. I think it is unfair to suggest that not enough scientific effort is being directed into this area. Internationally, there is a massive global programme. The scientists at VLA of a very high calibre are closely linked into that programme as indeed are the guys who are sitting on that Vaccine Committee at the moment. Success demands a number of things. With respect to developing a badger vaccine, it does require developing a way of getting this to badgers in the field. We know there are serious limitations for BCG but no one suggests it does not have a role. Measuring the contribution it makes is difficult. With respect to getting improved vaccines, you are waiting for scientific breakthroughs and you cannot predict those. Even when one has a cattle vaccine, there has to be a clear strategy for how you are going to use that in cattle. I am not persuaded that Defra have given this any thought at all. They have not given it any thought at all yet.

  Q101  Mr Williams: The Chairman and I met with the president of the Royal College of Veterinary Surgeons the other day and we asked her about this and whether there was a technical problem in getting a breakthrough. The Chairman will correct me if I am wrong but the response was that the real problem is the cost between taking it from the laboratory to getting it to market and all the regulatory processes that have to take place then. We asked her, "What do you think the cost would be?" She said, "Perhaps £20 million." If you look at that in relation to what it is costing this country in terms of TB at the moment, it would seem to me that that would be a very little contribution to solving a big problem.

  Professor Bourne: I am sure she is right about the market. It would be extremely limited because no other European country—

  Q102  Mr Williams: The process of taking it from—

  Professor Bourne: In fairness, you really should talk to the committee that is now in place driving the vaccine programme. I would certainly give that our total support, as we have. I would also highlight that again there is no quick fix here. It is going to be a long haul.

  Q103  Chairman: One of the points that the president did make to us was that the requirements of the vaccine as defined by Defra in their judgment—I hope they do not mind us quoting around lunch table conversation, because the information may not have been given with the rigour that would have been the case had they been giving evidence to us—and the impression I gained was that what this vaccine was supposed to be doing, if you like, the performance criteria, had been set at such a high level that going back to using BCG, for example, would not score. In other words, it was not good enough to achieve the kinds of results that they would say were effective. The vets were saying, "It is better than anything and it has worked in human beings."

  Professor Bourne: I do not think that is true. That is not the approach that Defra are taking. My understanding is that they are developing the possibility of a BCG vaccine to use in badgers. The situation in cattle is very different.

  Q104  Chairman: It is currently costing Defra £90 million a year to deal with the consequences of this disease against a current background where all the ways to mitigate it do not seem to be having any serious effect. You might say, "If the Government wanted in the long term to save themselves a shed load of cash, they would bung a great deal more money at it to try and crack it now."

  Professor Bourne: I do not think that is the answer. You should speak to the group driving this programme. From my perspective, I am quite assured of the competence of the scientists and the group. Throwing more money at the problem is not going to provide the answer. They are effectively linked into an international network that is massively funded. You just have to wait for science to deliver. Defra meanwhile, from my knowledge, are pursuing the option of using a BCG vaccine in badgers and developing appropriate delivery systems. At the moment they are looking at aspects of safety control for purposes of registration. I do urge you to speak to the group that has now taken on responsibility for this work.

  Professor Woodroffe: To add a note of caution on vaccination, it would be marvellous if you could vaccinate badgers effectively. In New Zealand, they have something called a possum puffer, used for remotely delivering the vaccine to possums. One issue you have to confront is that, if you are putting vaccine out in the environment for badgers to consume, there is a strong risk of cattle encountering it and therefore becoming sensitive to the test. It is not all roses.

  Mr Williams: Professor Bourne this morning said that with improved testing there could be a reduction in TB incidence without badger culling. What is the scientific evidence for that? Is that an extrapolation or does that have real substance?

  Chairman: Mr Rogerson wanted to add to that with a point about the gamma interferon testing.

  Q105  Dan Rogerson: There is quite a lot in here about what could be done to speed things up to be far more accurate by a combination of testing.

  Professor Bourne: It is based upon cattle pathogenesis findings which are documented in the report in one of the appendices, work that is being carried out primarily in laboratories of VLA in Weybridge, Stormont and IAH. It is also extrapolation, taking information from a simple model that Sir David Cox has developed and using that model to predict how the application of these techniques would influence the curve with respect to the reproduction rate of the disease. He determined a reproduction rate of 1.1. That relates to between herd transfer, not within herd amplification of the disease. That figure has also been arrived at by an independent approach, developed by the workers at the University of Warwick, which does suggest that an effort to improve diagnosis would tip the balance and bring the reproduction rate below one and bring a downward trend to the incidence of the cattle disease. He also postulates from the model that improving diagnostic sensitivity would have a speedier effect on reducing the incidence of disease. As one is talking about herd to herd transmission, animal movement controls as well as diagnosis are important components of that.

  Professor Donnelly: In terms of the way the model works, essentially what you are looking at is trying to shorten the time between a herd becoming infected and it being cleared. Improving test sensitivity is one way of doing that so you are sure you are not missing anything. You can talk about it as a herd test but if there is only one animal in a herd that is infected it is the per animal accuracy that matters. Either improving the sensitivity—that is, the proportion of infected animals that are correctly detected—or testing more frequently, so shortening test intervals. Those two things, especially if they are combined together, reduce the time that a herd spends potentially infectious to other herds and in circulation. Obviously since that work was done pre-movement testing has been brought in and we have discussed the possibility of doing that with more sensitive tests and even the possibility of adding in post-movement testing, which would add another level of security. From that modelling work, it showed 1.1 as the figure that characterises the rate of increase of the disease. Estimating the reproduction number has been used in many other human and animal diseases but it allows you to say that one is the threshold of where you just have continuing disease at a level. If you could do things so that the model predicts it goes below one, that suggests not that you would get instant eradication but that you would start on a decline. Both faster testing and improved testing through greater sensitivity are predicted to do that.

  Q106  Mr Cox: Perhaps somebody could deal with the question of the edge effect and the 25% incidence outside the culling areas. There was a question by a number of epidemiologists that the findings of that 25% did not seem to have sufficient of a time lag in order to produce the effects that were observed. I am sure that is easily dealt with by you because you will have heard it before and therefore you will have devised some thinking.

  Professor Woodroffe: We know that to cause that effect badgers have to start ranging more widely, contacting one another more often and contacting cattle more often. That happens within the course of a few days in response to culling. What has to happen next is that cattle have to be tested. They have to become exposed and develop sensitivity to the test. That takes about three weeks. We have published the sequence of events and it has gone through peer review.

  Q107  Mr Cox: You would argue that the period is relatively short?

  Professor Woodroffe: Yes.

  Professor Bourne: Our remit throughout our study has not been badger protection. It has been control of cattle TB. That has been our driving force throughout the work we have done. How can one best control cattle TB? Our whole report is directed to cattle TB control.

  Chairman: Can I thank you very much indeed for your final appearance before us as the Independent Scientific Group? As individuals and experts it may not be your final appearance before the Committee. Thank you very much indeed, as always, for your contribution and your patience in dealing with our questions. We appreciate it very much.





 
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