Select Committee on Agriculture Fifth Report



III. THE KREBS REPORT

33. On 23 July 1996 Douglas Hogg MP, then Minister of Agriculture, Fisheries and Food, responded to growing concern over Government policy on bovine tuberculosis by announcing an independent scientific review under the chairmanship of Professor John Krebs, Chief Executive of the Natural Environment Research Council. Five reasons were later given for the initiation of the review: (a) the link between badgers and bovine TB remained unproven; (b) the only reliable method for showing that badgers have bovine TB involved killing them first as the blood test on live badgers was insufficiently sensitive; (c) there was still little sign of a successful vaccine against bovine TB in badgers which had long been seen as the solution; (d) the effectiveness of badger culling remained doubtful; and (e) bovine TB was spreading.[80] These reasons more than justified the setting up of an independent inquiry on this scale. As the Minister currently in charge of the policy commented to us: "it is a tribute to the previous Government they had set up the Krebs inquiry, because if they had not we would have had to do something similar."[81]

34. The terms of reference of the Krebs review were: "To review the incidence of tuberculosis in cattle and badgers and assess the scientific evidence of links between them; to take account of EU policies on reducing and eliminating the incidence of tuberculosis in cattle; to take account of any risk to the human population; and accordingly to review, in the light of the scientific evidence, present Government policy on badgers and tuberculosis and to make recommendations".[82] The NFBG and others suggested to us that the focus on badgers coloured the inquiry and prevented the team addressing other issues.[83] However, Professor Krebs told us that the terms of reference had been discussed before they were finally agreed by Ministers and that all members of the group were satisfied with them. The group regarded the terms of reference as "enabling rather than proscriptive ... we felt free to range quite widely in looking at the scientific issues related to the bovine tuberculosis problem".[84] We agree with Professor Krebs that the terms of reference were appropriate and not restrictive, but we understand the concern of the conservationists about the fact that the title of the review was "Bovine tuberculosis in Cattle and Badgers".

35. Five other experts were appointed to the Review Group, all academics. They were assisted by Dr Simon Frost and Dr Rosie Woodroffe, then from the Departments of Zoology at the Universities of Oxford and Cambridge, respectively. None of the group had direct veterinary experience. A call for written evidence resulted in 68 submissions from organisations, academic institutions and individuals. Six presentations were heard from other interested parties, including MAFF and academic experts, and meetings were held with representatives from the farming industry, veterinary interests and wildlife organisations. The group also made site visits to farms and to the MAFF Wildlife Unit and the Woodchester Park Badger Research Station and held discussions with representatives of the appropriate government departments from Northern Ireland, the Republic of Ireland and New Zealand, countries with a similar problem with bovine TB in cattle. This extensive programme of consultation and research may have contributed to the delay in the timetable for the report. When the review was announced, it was expected that the group would report in early summer 1997. In the event, they held a meeting to discuss the main questions to be addressed in the final report on 25 June 1997 and the report itself was published on 16 December 1997.

36. The Krebs report is an impressive document. Well-written and researched, it covers a wide range of issues and provides much useful analysis of the history of Government policy on the control of bovine tuberculosis and of the current scientific understanding of the epidemiology of the disease. It concentrates on evidence of TB in badgers and the transmission of M. bovis from badgers to cattle but, as the NFBG acknowledge, it goes "beyond [the] terms of reference" to "highlight the other possible contributory factors to the TB problem - including other wildlife, climate and poor animal husbandry".[85] Of its many conclusions, the one which was frequently repeated in evidence to us was that: "The sum of evidence strongly supports the view that, in Britain, badgers are a significant source of infection in cattle".[86] Krebs went on to state that "Most of this evidence is indirect, consisting of correlations rather than demonstrations of cause and effect; but in total the available evidence, including the effects of completely removing badgers from certain areas, is compelling". He added two caveats: "it is not, however, possible to state quantitatively what contribution badgers make to cattle infection" and "it is not possible to compare the effectiveness of [previous policies for killing badgers]; nor is it possible to compare any of them with the impact of not killing badgers at all, because there have been no proper experiments".[87] His primary conclusion was that "The control of TB in cattle is a complex problem and there is no single solution. We recommend a combination of approaches on different timescales".[88]

37. The Krebs report contains 16 pages of conclusions and recommendations. The latter were grouped into four categories: those aiming to understand the causes of herd breakdown, to evaluate the effectiveness of currently available strategies to reduce herd breakdowns, and to develop improved strategies to reduce herd breakdown, and other recommendations which were mainly concerned with the Government's approach towards the commissioning and use of research.[89] MAFF summarised the main recommendations as:

    1. The development of a cattle vaccine, considered to be the best long term option to control TB;

    2. Major research initiatives aimed at achieving a better understanding of the causes of TB, and developing improved strategies to reduce outbreaks;

    3. A randomised culling trial to test the effectiveness of different strategies and to provide unambiguous evidence of the role of badgers in cattle TB, the trial to be overseen by an expert group; and

    4. That the Government should work with the farming industry to improve husbandry methods to minimise contact between cattle and badgers. [90]

The research proposals included epidemiological work to look at the local correlates of risk to cattle, more research to establish transmission routes, investigation of other potential wildlife reservoir species, spoligotyping as a possible way of identifying a link between TB in badgers and in cattle, and the reinstatement of the survey of badgers killed in road traffic accidents. All the measures were presented as a package but the culling trial has naturally drawn most attention and criticism, and it is this part of the report which is often meant when reference is made to the "Krebs experiment".

38. For the culling trial, Krebs recommended that ten groups of three areas in TB hotspots, each measuring 10km by 10km, should be the basis of a field trial. At the time this covered most of the main hotspot areas. In each triplet one area would be subject to proactive culling of badgers, another to reactive culling following the identification of TB in cattle, and the third to survey work only. The Krebs group undertook a statistical power analysis (see Glossary) on the rate of breakdown and concluded that the proactive strategy could provide clear results within one year but a full quantitative assessment which could provide a sound basis for future policy would take longer.[91] In evidence to us Professor Krebs described his design as set out in the report as "sketching out a concept rather than writing an implementation plan".[92] For this reason, we can divide the factors that made many witnesses claim that the trial was "fundamentally flawed" or "significantly flawed, and unnecessary"[93] into objections of principle, process and practice. In the next section we discuss the latter two which relate to the implementation of the trial by the Bourne Group and MAFF. Here, we consider whether Krebs was right in principle to recommend such an experiment.

39. The aim of the culling trial is "to quantify the impact of culling badgers".[94] As Krebs himself pointed out, among the opponents of the recommendation "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 know that the badger is completely innocent".[95] Evidence to us reflected this dichotomy of opinion although significantly more organisations expressed the first view than the latter. While it is perhaps to be expected that the RCVS or farmers should judge that the badger was already proven to be the source of bovine TB in cattle,[96] it was less predictable that the Wildlife Trusts should adopt the same view on the link and that even the NFBG would accept the connection.[97] However, their agreement on the futility of the trial resulted from very different propositions. The RCVS had wanted Krebs to recommend "action that would result in the removal of all badgers in infected areas",[98] while the Wildlife Trusts believed that "to kill 20,000 badgers or whatever in order to find out for certain whether there is a link seems to us a waste of badger lives".[99]

40. This difference illustrates the need to put badger culling on a scientific footing. Until there is a clear and quantitative understanding of the link between badgers and cattle TB, it is impossible to develop an effective and rational policy on its control. The disappointment and frustration of both farmers and wildlife groups that Krebs was unable to come up with a definitive answer to the problem is natural and to some extent can be seen as the inevitable result of a clash between scientists who want real scientific proof and practitioners who want action, as most clearly evidenced by the attitude of the RCVS. However, we accept Professor Krebs's conclusion that the evidence of a link between badgers and cattle TB is compelling but not conclusive and that a field trial is required to test and quantify the link between badgers and cattle.

41. It has been argued by several witnesses that the trial is unnecessary as the link has already been established by previous culls, especially those at Thornbury, Gloucestershire from 1975 to 1981 and East Offaly in the Irish Republic from 1989 to 1995.[100] These examples of large scale badger clearances, together with two further instances at Hartland in Devon and Steeple Leaze in Dorset, are described in the Krebs report.[101] In addition, we are grateful for a memorandum from the Irish Government on the outcome of the East Offaly project. In all four cases, where badgers were cleared the incidence of TB in cattle fell significantly. However, the difficulty with these results is that in none of the cases were adequate experimental controls in place. As Krebs commented, "badger removal might have caused the observed fall in herd breakdown rates, but the possibility remains that some other unidentified factor could have been responsible".[102] The study of the Irish experiment concluded: "As this study involved just a single area with high badger numbers and a high cattle density, it is not possible to directly extrapolate from the outcome to other areas. Further studies will be required to confirm the conclusions".[103] The Irish Republic has instituted a new trial involving four areas, each consisting of an area designated for complete removal of badgers and one for more limited removals, the results of which will be reviewed in December 2002.[104] Their action in establishing this trial following the East Offaly experiment underlines Professor Krebs' argument that these previous clearances provided "pretty strong circumstantial evidence" but that in order to convince the doubters it was necessary "to address it more rigorously".[105]

42. One factor in deciding whether the culling trial is justified in principle is the number of badgers likely to be killed in order to implement it. Media headlines have repeatedly cited as fact the figure of 20,000 badgers.[106] This is based on an estimate made by the NFBG[107] and is at odds with Krebs' own estimate of 12,500, which has been accepted by the Government.[108] The discrepancy is largely accounted for by differing views on badger densities in the trial areas. The figure given by Krebs also reflects varying totals of badgers culled during each year of the trial, ie 7,500 to establish the proactive and reactive triplets in the first year and around 1,250 for each subsequent year. To put both estimates into perspective, however, in the last year of the interim strategy (1997) 2,447 badgers were killed in official programmes,[109] and every year some 50,000 badgers are killed on the roads.[110] Our concern for animal welfare extends not just to wildlife but to domestic animals as well. We conclude that, seen in context, the number of badgers likely to be culled in the trial will not substantially affect the overall UK badger population and is justified in pursuit of a soundly-based policy which should save unnecessary slaughter of both badgers and cattle in the future.

43. The emphasis on the culling trial has deflected attention away from Krebs' other proposals. Professor Krebs told us that "We clearly said at the beginning that this is a multifaceted problem; it is complex; there is no simple, quick fix"[111] and we believe that his report reflects this complexity. It goes some way towards setting out the holistic approach called for by the NFBG and others, while reflecting the balance of evidence that the badger has a part to play in the transmission of bovine TB to cattle, a fact that justifies the particular attention paid to the badger. It was suggested to us that the lack of a theory of causation invalidated the trial and that it would be preferable to abandon the trial in favour of molecular testing.[112] Both Professor Krebs and Professor Bourne were adamant that while molecular testing may have developed sufficiently in a few years' time to help identify transmission routes and indeed the Krebs report contained proposals for using this method, it was not feasible that "we could put in place now molecular epidemiology which would negate the need of doing the trial".[113] On balance, therefore, we conclude that Krebs' approach of combining a culling trial with other research is the correct one and we see no reason why any of the Krebs proposals should be abandoned. We agree broadly with Krebs' conclusions and recommendations.

44. Nevertheless, we have reservations about the priority Professor Krebs awarded to one particular area of interest. From the evidence we have received, we are convinced that more attention should have been paid to the role played by husbandry in preventing TB breakdowns.[114] The Krebs group did briefly touch on this subject in the report and suggested that areas outside the trial would be suitable for an experimental comparison of proactive husbandry methods. They recommended that the farming industry itself should take the lead in this "comparison of the impact of simple husbandry techniques", aided by advice from MAFF. Krebs concluded that "Husbandry may well play an important role as part of the long-term solution".[115] However, the weight of this finding is not balanced by analysis in the report itself which we find disappointing in this respect. Professor Krebs explained that "we did not write a great deal about it because we did not have the expertise" and the group also wished to complete their work in good time.[116] We understand this explanation and acknowledge that the introduction of the subject was at the instigation of the group since it did not fall into the remit given by the Government, but we regret that Professor Krebs and his colleagues were unable to review the literature relating to this important area with the thoroughness of the rest of the report.

45. Our one remaining concern about the Krebs report is that it failed to consider the situation of the farmers in areas outside the hotspots chosen for the experiment. As we have seen, the problem is worsening with the result that, as the NFU told us, "when Krebs came out the ten triplet areas that he had proposed would have covered at least 75 per cent of affected areas and in this period where we have gone on it now covers less than 50 per cent".[117] Of course, Professor Krebs is not to blame for the delays in implementing his recommendations but in any case he offered farmers outside the triplets only the chance of participating in the limited husbandry experiments and he strongly recommended that no culling should be carried out in these areas.[118] In this way, he took no account of the need for short term containment measures while the long term strategy is developed. At the moment, badger-culling is the only measure for which there is any evidence of short-term effectiveness. In the treatment areas, this is recognised since the trial itself is a control measure as well as a source of data but farmers in the other areas face continuing problems with TB with no means of addressing them.

Conclusions on the Krebs report

46. On the whole, notwithstanding the reservations expressed above, we congratulate Professor Krebs and his team on his cogent report. His findings have been accepted by the vast majority of witnesses to our inquiry, while the NFU told us that the report "represents the only real method of finding a lasting answer to this problem in the management of TB".[119] The TB situation has become even more urgent in the 16 months since Professor Krebs published his report, with the continuing rapid increase in the number and spread of herd breakdowns. We turn now to the progress made by the Government in implementing his recommendations.


80  Government response to the Krebs report, para 6. Back
81  Q 669. Back
82  Krebs, 1.1.1. Back
83  Eg. Ev. p.40. Back
84  Qq 2, 3. Back
85  Ev. p.38, para 20. Back
86  Krebs, Executive summary, para 5. Back
87  Ibid, paras 6 and 7 Back
88  Ibid, para 1. Back
89  Krebs, Chapter 7, pp.135-7. Back
90  MAFF Factsheet C4. Back
91  Krebs, 5.6.25-5.6.27. Back
92  Q 76. Back
93  Eg. Ev. pp.175, 189. Back
94  Krebs, Executive summary para 9. Back
95  Q 41. Back
96  Q 424; Ev. p.123. Back
97  Qq 352, 292. Back
98  Ev. p.123. Back
99  Q 352. Back
100  Ev. pp.186, 189-90, 193, 231. Back
101  Krebs, pp. 30-1. Back
102  Krebs, 2.5.11. Back
103  Unprinted evidence. Back
104  Krebs, 2.5.12. Back
105  Q 45. Back
106  For example, see the Guardian, 12 April 1999. Back
107  Q 282. Back
108  Krebs, 5.6. 29, 5.6.30. Back
109  HC Debates, 24 June 1998, col. 549w. Back
110  Q 283. Back
111  Q 31. Back
112  Ev. p.175. Back
113  Qq 3-4, 203-4. Back
114  See paragraphs 106 to 113 below.  Back
115  Krebs, Executive summary, para 15. Back
116  Q 110. Back
117  Q 396. Back
118  Krebs, 5.6.35. Back
119  Q 400. Back

 
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