TUESDAY 9 FEBRUARY 1999

PROFESSOR SIR JOHN R KREBS

  40. When you were drawing up the basis of the triplet sites, how much did you have meetings with people that actually live and work in the countryside and listen to their views about how they felt they could take this trial on in their area over five years?
  (Professor Sir John Krebs) During the process of drawing our conclusions, we took evidence from and spoke with all the interest groups. I had meetings with the conservation groups, with the farming industry and with other countryside interest groups, CLA etc. During the course of forming our view, we certainly listened very carefully and took note of what people felt.

  41. Was the view that you had from these groups that, yes, this trial was practical, was deliverable, would be able to be carried out in the living landscape?
  (Professor Sir John Krebs) There is a great diversity of views ranging from those who said the trial was a complete waste of time because we already know that badgers give TB to cattle, to those who said the trial is a complete waste of time because we already know that the badger is completely innocent -- the two ends of the spectrum could not be further apart -- to those who said, "We can see why you are recommending it. It will be difficult but we are willing to support it". Particularly the farming industry recognises that policy in the future should be based on sound evidence, sound science, and therefore they were willing to give some significant support and put their weight behind the idea of a trial. The answer to your question is that I got a very great range of responses from those who felt that it would be feasible and desirable to those who felt it was a complete waste of time.

  42. Do you have any fears that the trial will in the end be totally unscientific because there will be interference with the trial, either because of illegal killing of badgers in non-trial areas and in the control area or even that there will be non-compliance in the areas that are the proactive or reactive culling areas?
  (Professor Sir John Krebs) I think that is a risk, certainly. It would be naive not to admit that risk. So far, with the first part of the trial that has been implemented, I am told it has proceeded with a reasonable degree of orderliness without huge disruption. There is still a long way to go of course. What I have always said is that it is not really in the interests of those who want to find a sustainable policy for the future to disrupt the trial. If, for example, farmers are tempted to cull out badgers in the control areas and take things into their own hands, the implication of that would be that, after a period of years, the trial would show no difference between the removal areas and the control areas. MAFF would conclude that removing badgers was not an effective way of controlling the disease, so farmers would be stuck then with a conclusion that may be inappropriate but was nevertheless shown by the experiment. Equally, if the wildlife and conservation groups believe that the badger is completely innocent, as some of them do, then this is a way for them to gain incontrovertible evidence that the badger is completely innocent and the debate will then close. Attention will be focused on rats or deer or something else.

  43. What about the activity in the non-trial areas? The experiment is only going to cover about 60 per cent of the area of the country where TB in badgers and cattle is a problem. If we do not take any action in those areas over a five years period -- maybe even longer, because we are already slipping a little on the timetable -- and TB continues to spread outside the traditional areas, are we not just allowing this disease to spread into the non-trial areas so there is mayhem going on in the other areas and we have this scientific experiment going on for five years and everybody is holding the line on that?
  (Professor Sir John Krebs) I agree that that is a problem and I suggested that MAFF, perhaps through the Bourne Group, should keep a close eye on what happens in those other areas. If you ask what should be done -- I am not sure whether that is what you were leading to -- I think it is important first to distinguish between two kinds of areas outside the trial. There are areas where there are one off occurrences. They may be new areas or they may be old areas. If there is a one off occurrence, culling badgers a priori makes no sense because the whole point of culling them is to prevent a recurrence. There are many areas of the country where you get an isolated event and then nothing for 10 or 15 years without culling, so culling makes no sense there. If you look at the other places, the ones that we analyse -- and as you say 40 per cent of them were not included in the trial -- these are places where there are repeat or contiguous breakdowns, so those are real high risk areas. In my view, there are several obvious options that could be sought for those. Either MAFF sits tight and just says, "Well, we have to hang on there for another few years" or they say, "We will expand the trial to encompass more of these areas so we get the results more quickly and remove more badgers maybe", or they could say, "The recommendation that I proposed that nothing should be done outside the trial area is unsustainable and something else has got to be done". I personally think that the idea of culling badgers outside the trial area whilst you are carrying out a trial to find out whether culling badgers is a good idea is a kind of non sequitur. If you have signed up to a scientific investigation, you cannot at the same time say, "Even though we do not know, we will do it out here because we think it will keep people happy". I do not think that third option is the way to go.

  44. For the scientific basis of the proposal of a control and a reactive and a proactive cull, you took the work done at the other four culls in Thornbury, Hartland, Steeple Leaze and East Offaly. The feeling from the report was we had badger clearances there and that seemed to provide the strongest evidence to suggest that badgers represent a significant source of M bovis, but none of these clearances had a control.
  (Professor Sir John Krebs) That is right, yes.

  45. How can they provide a credible scientific basis for the experimental cull that you have proposed?
  (Professor Sir John Krebs) It is like a very strong observation, is it not? It is like saying okay, I did not have a proper control but it is true, when I remove badgers from this area, in the case of Thornbury, the incidence dropped from 5.6 per cent to 0.45 per cent over 15 years; in Steeple Leaze, there were 626 cases in the few years before and none in the following seven years so it is pretty strong circumstantial evidence. As I said in the beginning, there are still those people up and down the country who quite rightly say, "This is not good enough; we do not believe it". Hence, what do you do? You try to address it more rigorously.

  46. Can I ask about the proactive cull trial site? Why are we having a total clearance of badgers as part of the triplet sites when government policy leads us to believe that this would never be an end policy in itself? If, at the end of five years, we have irrefutably proven that there is a link between bovine TB in cattle and badgers and the transmission is done through badgers, that is not going to be an end policy because the badger is a protected species. We are not going to be wiping out badgers in all the hot spots throughout the UK.
  (Professor Sir John Krebs) So why have the proactive treatment in the scientific trial?

  47. Yes.
  (Professor Sir John Krebs) One could look at it in a number of ways. First, if you are trying to test whether there is any effect of removing badgers on the disease, it is helpful to have the two extremes: leave well alone and remove as many badgers as possible. That is from the scientific point of view. If you looked at it from the policy point of view, whilst I agree with you that it seems unlikely that in the long term the government would move to a policy of mass removal of badgers from huge swathes of the countryside, I could imagine that if this trial shows that localised removal is incontrovertibly a very effective and cost effective way of dealing with the problem on a local basis, that might become part of a longer term policy, although it is not for me to judge.

  48. In the report you state that a clearance experiment with a control treatment would be compelling evidence that badgers have been responsible for tuberculosis in cattle if alternative explanations could be eliminated. I wonder if you would like to clarify what alternative explanations might be? Might not these explanations be more convincing than a transmission hypothesis based solely on badger activity?
  (Professor Sir John Krebs) Can you remind me which paragraph of my report that came from?

  49. Page 30, paragraph 2.5.5.
  (Professor Sir John Krebs) What we are saying there is really restating what we have already discussed. Unless you carry out a proper scientific analysis, there will always be the alternative that there is a confounding variable, some other factor that came in that influenced the results. That is why it is so important that in the trial the treatments are assigned at random. The purpose of assigning treatments at random is to wipe out the possibility that there are these other confounding factors. When you have simply observation, as we do at the moment, there are always these potential confounding factors and that links back to the question I discussed with Mr Marsden about the multi-variate analysis of risk, trying to calculate through statistical analysis what proportion of risk is attributable to different factors.

  50. If at the end of five years we discover that there is not a direct link between badgers and TB in the trial, are we saying then that we are going to start the whole thing all over again looking at other factors?
  (Professor Sir John Krebs) No, because we are moving forward on a number of different fronts. The trial, as I have said right from the beginning, is about looking at the effect and the cost effectiveness of culling. At the same time, MAFF are looking at this multifactor analysis of risk and that in itself may reveal important things that will guide future policy. MAFF is also in the longer run trying to work towards the development of a vaccine. Also, through the development of these molecular techniques that we discussed earlier, they are opening new avenues to look at other wildlife sources of infection for the cattle. If at the end of five years the conclusion was that killing badgers has no effect or it has an effect but the effect is not worth it, that will be ruled out of the options for the future, I would guess, but significant progress will have been made in other areas of research and understanding so that the whole policy framework will have moved forward.

  51. Professor Stephen Harris disagrees pretty fundamentally with the recommendations you have made and says that the experiment designed by Krebs serves no useful purpose. The logic behind the five year experiment is flawed. It is not practical. The results are predictable. Illegal killing of badgers in the no control squares will nullify the results of others, as Diana has suggested in some of her questioning. He goes on to say that we know too little about the epidemiology of TB -- and I think you conceded that -- to gain a great deal from this experiment. What is your opinion on his view of this? Presumably you weighed those opinions in the preparation of the report?
  (Professor Sir John Krebs) Yes. Stephen Harris came and gave oral evidence to our review. We spent quite a long session discussing his ideas with him. I have not seen the document that you are referring to where he has written that down. I guess that was probably in response to the review. He obviously is in the group of people that is convinced that killing badgers is both an effective and a cost effective method of control. As I said earlier on, there is a spectrum of debate from people who say, "The issue has been resolved; get out there and kill badgers. That is fine. That is a way of controlling TB" and Harris is saying, I guess, "Kill them in the hot spot areas. That will sort the problem out". At the other end of the spectrum, there will be people who will say, "There is no evidence whatsoever that the badger is implicated. Killing badgers is a complete red herring." Harris takes the one end of the spectrum and that is his view. I believe, as the report fully explains, that the evidence, whilst extremely strong, is not strong enough for MAFF to go ahead with a policy that says, "We will kill badgers everywhere where there is a high risk as a method of control" because they do not actually know for certain whether that is going to work. Harris thinks it will but I would say where is the evidence. It is not there.

  52. That is certainly one aspect of what he suggests. I think you are right in characterising his evidence as that, which is to tackle the hot spots with a will now.
  (Professor Sir John Krebs) That is not his evidence; that is his suggestion.

  53. The additional elements are obviously some additional research on the epidemiology.
  (Professor Sir John Krebs) That is what we have been discussing.

  54. That is consensual; and also improved husbandry practices as well, on which scepticism has been expressed already.
  (Professor Sir John Krebs) Again, we recommended that husbandry could be part of the picture. We felt that the farming industry should take the lead in looking at husbandry. When you talk, as I did and I am sure many of you have done, to farmers, again you hear a spectrum of views. I went to one farmer, I remember, in Gloucestershire who had had numerous outbreaks of TB on his farm and he said it was simply a waste of time talking about husbandry. He was not prepared to implement any husbandry practices. He did not think it was at all relevant. Another farmer a few miles away was very keen to talk about husbandry -- for example, fencing around badger setts to keep the cattle away -- so there is a spectrum of opinion out there in the farming industry. I think the industry should be more proactive in looking systematically at husbandry effects. As I said earlier in response to Mr Marsden's question, by analysing the factors that contribute to risk in this complicated statistical analysis, we will get pointers towards which particular husbandry practices might be helpful. I agree with Harris that husbandry has a role to play. Epidemiological analysis has a role to play. Where I disagree with him, and my review group disagreed with him, was in saying that the case is so open and shut that killing badgers controls TB so effectively and cost effectively that we do not need to do any further work on it. He is of that view and I am not.

  55. How robust is the badger population taking an area, as he is suggesting, of complete elimination of badgers from hot spots? What evidence is there of the speed at which a badger population would be restored, presumably disease free, in the future?
  (Professor Sir John Krebs) It will depend on the size of the area. The bigger the area you clear, the longer it will take to recover. I cannot give a blanket answer, but I could say two things. First of all, that the badger population in Britain as a whole appears, from the evidence that was presented to us, to be increasing quite rapidly. There is no national threat to badgers. They are not an endangered species. In terms of local immigration into a cleared area, it depends on the size of the area but I would imagine that, with a reasonably sized area such as the ones that we proposed in our culling trial, the immigration and recovery of the population will be in an order of years rather than weeks or months. It may be five or seven years, but that is only a guess because it depends very much on the size of the area.

  56. On the epidemiology, a new questionnaire has been issued by MAFF. Have you seen that questionnaire?
  (Professor Sir John Krebs) I have not, no.

  Chairman: There has been some criticism of it in written evidence.

  57. How long does the problem linger in the dunging that we were talking about earlier and the demarcation of territory? Does that linger on after the badgers have gone?
  (Professor Sir John Krebs) The simple answer is we do not know. We do know that the bacterium can survive for quite long periods in the environment. We also know that badger setts are quite good incubators to keep the bacterium going. They are cool, a fairly constant temperature with no environmental extremes. What we do not know is how long the bacterium, when surviving in the environment, retains its power to infect.

  58. Are we talking about minutes, hours, days, weeks?
  (Professor Sir John Krebs) Days to weeks.

  59. Just days?
  (Professor Sir John Krebs) Days to weeks. It is quite long lived.