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. 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.”
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”. The NFBG and others suggested to us that the focus on badgers coloured the inquiry and prevented the team addressing other issues. 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”. 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”. 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”. 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”. 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”.
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. 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. 
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. 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”. For this reason, we can divide the factors that made many witnesses claim that the trial was “fundamentally flawed” or “significantly flawed, and unnecessary” 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”. 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”. 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, 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. 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”, 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”.
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