Select Committee on Environment, Food and Rural Affairs Seventh Report

Badger Research at Woodchester Park[73]

The Scientific Study

22. In establishing the ISG and extending its remit, the Government committed itself to a wide-ranging scientific study of the factors that would allow "a sustainable cattle TB control policy ... to be implemented".[64] We were pleased to hear, during the course of our oral evidence sessions, broad support for the research that is going on: the NFU reiterated its support for the trials, called for "a more rapid development of vaccine", and wanted to see a bringing togther of "the best science we can find in the world";[65] the National Federation of Badger Groups wanted to see "a science-based policy";[66] and Dr Cheeseman wanted a "scientific underpinning of future policy".[67] We begin our review of the bovine tuberculosis science programme with a general assessment of the 'holistic approach' adopted by the ISG,[68] and then go on to look at a number of specific matters that were raised during the course of our inquiry.

23. Professor Bourne, its chairman, told us that the ISG had "achieved a lot in the last five years": in that time, with Defra, it had put in place in "substantive research programme".[69] Professor Bourne also identified a "complete culture change in attitudes towards TB" which was brought about by the ISG questioning the dogma in the debate about bovine tuberculosis.[70] These comments were endorsed by the Minister who believed that "we are taking the right action". He identified the Krebs trial, exploring the link between wildlife and cattle, epidemiology, cattle-to-cattle spread and vaccine development, and concluded that "I personally feel we are covering all of the areas that we need to cover without trying to be obsessed by any one reason".[71] Dr Cheeseman also believed that "Defra is probably doing all it can" although it could do more with more money.[72]

Since 1976 Dr Cheeseman has been investigating "the role of the badger in the TB problem in cattle". The project at Woodchester Park has provided information on:

• the population dynamics of badgers;
• the epidemiology of the disease in badgers;
• the way in which badgers and particularly diseased badgers behave;
• the involvement of other wildlife;
• badger genetics;
• the impact of removing badgers from the eco-system; and
• modelling.

He pointed out that:

"it does not follow necessarily that the more badgers there are the more disease you will get in badger populations; there is no linear relationship between the number of badgers and the prevalence of TB in the badger populations. Indeed, at Woodchester, we have got a population that has doubled over the period of study, the density of badgers has doubled, and the disease has cycled, with about a seven-year periodicity, and it has gone from highs of perhaps 10 per cent or more to lows of very nearly zero. And that is one of the puzzles, because I was taught, as most ecologists are, that diseases are usually density-dependent, the greater the density of the host species the greater the prevalence of disease; that is not the case with TB in badgers. So it is a complex problem, and that is one of the points I would like to make at this juncture, perhaps, for your understanding, it is not a simple issue that the more badgers there are the more TB there is";

"the disease [is] exacerbated by the disruption that takes place when you take badgers out. Because there is no doubt about it, if you remove a large component of a badger population the behaviour of the remaining badgers is highly disruptive, they move over greater distances, there are probably more interactions between badgers, and one of the critical factors in any disease is what is called 'contact rate'. If one animal contacts and gives disease to one other animal, at least, you have an epidemic on your hands; if it is fewer than one, the disease will decline to extinction. So anything that exacerbates, or promotes, contact is bad news, and the perturbation effects are something that exercises our minds at the moment".

24. However, despite his assessment of the progress of the whole bovine tuberculosis research programme, Professor Bourne and the ISG raised a number of detailed concerns about aspects of the programme. Other organisations and individuals also made us aware of a number of other concerns. In the following paragraphs we examine a number of those concerns: (i) progress in relation to the culling trial and other issues related to the culling trial; (ii) the epidemiological and pathogenesis work, including the road traffic accident survey and TB99 forms; (iii) diagnosing bovine tuberculosis and the piloting of the gamma interferon blood test; (iv) vaccination; and (v) other issues.

PROGRESS WITH THE CULLING TRIAL

25. The Krebs report said that the culling trial would have two key results: "First, it would provide unambiguous evidence on the role of the badger in cattle TB. Secondly, it would provide quantitative data for a cost-benefit analysis of the different strategies, including 'no culling'".[74] Dr Cheeseman argued that because all badgers have not been removed from the proactive culling areas and because of the disruptive effects ("when you remove badgers from the eco-system, the disease [is] exacerbated by the disruption"[75]) of the cull, "there is no way the trial will quantify the contribution of badgers to the TB problem in cattle". Nevertheless, he was strongly supportive of the trial because "it will tell us whether killing badgers has any impact on the disease in cattle, and it is absolutely crucial because that question has never been answered".[76] We believe that the research on badger ecology that takes place at Woodchester Park is a crucial part of the science that underpins both the culling trial, and the wider scientific programme overseen by the ISG.

26. In March 2002, the ISG reported to Defra that the effect of foot and mouth disease on the culling trial was not serious. Its assessment then was that "any extension to the trial to compensate for the time lost to FMD should not need to be more than 3 or 4 months in duration".[77] The ISG is currently updating its assessment of the impact of delays to the trial.[78] Professor Bourne told us that, with respect to the proactive cull, time lost due to foot and mouth disease has been regained "so by the end of 2005 we would have met the fifth triplet year target which was our pre-FMD target". He added the proviso that in two proactive areas, because of delays caused by the impact of foot and mouth disease, there was a possibility of data being "less vigorous because of badger migration". He still anticipated the proactive trial work finishing at "the end of 2005, possibly extending into 2006 by three to four months". However, in the reactive triplets, seven triplet years were lost as a result of no cattle testing in 2001-2002. This loss has been exacerbated by the delays to reactive culling.[79] This raises a concern about the integrity of the trial's results. However, Professor Bourne said that he was optimistic that "the reactive culling will be back on track by the end of the next year but there will inevitably be some extension beyond 2005 before we can reach the 50 triplet years".[80]

Reactive culling outside trial areas

27. However, the NFU told us that "given no further interruption the earliest the trials will be completed will be 2007" and argued that even if interim advice was published in 2005, this would be "too long to wait". It went on to call for reactive trapping in known TB hotspots outside the trial areas.[81] Professor Bourne confirmed that the ISG would be providing interim advice to Ministers in the next two months on vaccine scoping, progress of the trial, TB99 and the reactive strategy. He acknowledged that "we still do not know what proportion of the disease is caused by cattle transfer and what proportion is caused by wildlife". However, where policy has been developed or changed up until now, it has been on the basis of results from the ongoing research work.[82]

28. We asked the ISG about the NFU's proposal for reactive badger culling outside the triplet areas. In 1999, the ISG concluded that "killing badgers outside trial treatment areas should not be sanctioned".[83] Professor Bourne confirmed that the ISG's position was unchanged. He said that the trial was set up to answer the question of whether localised badger removal had any impact on cattle TB, and observed that if culling badgers is going to have an effect, "one would expect to see an impact, given we are working in hotspot areas, on national incidence of disease if it is going to be effective at all".[84] However, he concluded that, at present, "there is no evidence it has an impact, there is no evidence it does not have an impact; there is a suggestion that it could make it worse".[85] The Minister was more emphatic in his dismissal of the call for a badger cull outside the trial areas. He could "not see a shred of evidence to base that on"; he continued, "I think to start culling badgers outside the trial areas there would have to be very, very clear justification for that. I do not see that justification at the present time. I do not see the scientific case for it. I do not see the practical case for it. In some ways it seems based on folklore",[86] and "in the worse case it would simply be a placebo for farmers".[87] We understand the concerns of farmers. But we believe that the continuation of the culling trial is necessary to establish once and for all whether killing badgers has any impact on bovine tuberculosis in cattle. We therefore welcome the Minister's clear statement that the Government will not sanction culling outside the trial areas whilst the trial continues.

Epidemiology

29. In its Third Report, the ISG reported that it had developed and put in place a "wide-ranging epidemiological investigation into TB in both cattle and wildlife". The "multi-faceted investigation" includes:

• epidemiological investigation - a field trial and the TB99 questionnaire;
• laboratory-based and field studies into cattle pathogenesis to gain a better understanding of the disease in cattle, its diagnosis and spread; and
• other related research.[88]

However, progress in the various aspects of the epidemiological research has not been uniform and Professor Bourne highlighted his concerns before we met him.[89] We were therefore able to explore his concerns with him and his colleagues from the ISG before putting them to the Minister.

TB99 Questionnaire

30. The TB99 questionnaire seeks to identify and quantify risk factors, particularly associated with cattle husbandry, which "have been postulated as pre-disposing some farms to TB outbreaks". It uses a 'case control' study approach which requires three 'controls' for each breakdown.[90] The ISG regard the survey to be "of fundamental importance to the TB research programme" but told us that it "has been seriously compromised".[91] At 11 February 2003, within the trial areas, 561 TB99 forms had been completed for farms with TB breakdowns: but only 103 of those farms had even one control case and just 32 had three control cases.[92] Professor Bourne acknowledged that classical swine fever and foot and mouth disease had "reduced seriously the State Veterinary Service's capacity to collect the data required". However, he also reported that some data had been lost as a result of localised delays in completing forms that was not attributable to either disease.[93] The ISG continues "to urge" Defra to ensure that adequate resource is directed to the collection of TB99 over the next twelve months.[94] Mr Morley laid the blame for the low collection of data on foot and mouth disease, saying "basically the SVS could not cope". He also reported that ADAS[95] has been engaged "to speed up TB99".[96] The Government has previously said that it "is fully committed" to the TB99 questionnaire scheme.[97] However, it set time limits for the collection of TB99 forms that the State Veterinary Service was unable to meet even before the impact of classical swine fever and foot and mouth disease was felt. We hope that the appointment of ADAS will bring an improvement in the collection of data both from breakdown and control farms. We recommend that, as soon as practically possible in 2004, the ISG publish the number of TB99 forms collected in the current calendar year and an assessment of their suitability for analysis.

31. We heard concerns from some farming organisations about the length and complexity of the TB99 form. The NFU called for "a shorter, improved version",[98] and the CLA called for the form's "simplification".[99] However, the NFU accepted it was just an idea it had "floated", it did not have "the exact detail" of an alternative form.[100] Professor Gettinby told us that the ISG was aware of these general concerns but the Group "do not think it has been too demanding at the farm level", although he held out the prospect of shorter forms in future years, once interim analysis was completed.[101] Mr Morley pointed out that a more complex form yielded more valuable information.[102] He also noted that the design of the TB99 form would be considered in the interim analysis, and could be simplified although he added, "of course it is always possible they may identify additional questions".[103] We acknowledge that the TB99 form is complex. But its value in providing definitive information to complement that found in the culling trial and other scientific work would be diminished if it was peremptorily changed.

Road Traffic Accident Survey

32. The road traffic accident survey of badger carcases was re-introduced as a means of "collecting data on the prevalence of TB in badgers within and outside of trial areas".[104] Originally it too was conducted by the State Veterinary Service but was also affected by both classical swine fever and foot and mouth disease, the concerns of the Health and Safety Executive at the outset about the risks of contracting tuberculosis and the difficulty in organizing the logistics of collection. Defra has subsequently contracted the Central Science Laboratory to identify and collect badger carcases.[105] Professor Bourne reported that this "has improved the position and targets are nearer to being met, but the Group still has insufficient data for robust scientific analysis".[106] He conceded that the ISG did not know whether the survey would be a useful indicator of prevalence. However, he expected to meet the target of collecting 1,200 badger carcases per annum in the twelve months to June. A further year would elapse before the ISG expected "any useful analysable data".[107]

33. The NFU argued that the survey "could provide considerably more information if properly resourced and carried out more extensively, rather than only in the seven counties[108] recommended by the ISG".[109] The CLA also called for an extension of the areas covered by the survey.[110]

34. The road traffic accident survey is effectively a 'pilot' study.[111] This year it seems likely to collect enough badger carcasses for analysis to begin. We support the road traffic accident survey. If it is found over time to provide a good indication of the prevalence of bovine tuberculosis in badgers an extension to the survey should be considered.

Gamma interferon blood test

35. The existing tuberculin skin test used to identify whether individual cattle have bovine tuberculosis has its faults.[112] In particular, studies show that the sensitivity (i.e. the percentage of infected animals correctly identified) of the tuberculin test ranges from 77 per cent to 95 per cent. However, the specificity (i.e. negative animals correctly identified) is greater than 99 per cent.[113] As part of its autumn package, Defra announced a pilot project "to assess the effectiveness of the gamma interferon blood test in detecting bovine TB", and to discover whether its use would clear infection from herds more quickly.[114] However, the NFU pointed out that the test is much more sensitive but less specific than the skin test - that is "it gives you a lot of false positives".[115]

Gamma interferon pilot project[116]

The gamma interferon (GIFN) adjunct test pilot is a voluntary scheme for farmers with three or more reactors disclosed in a new TB breakdown. Disease must be confirmed in at least one of these by detection of typical lesions of TB at post­mortem examination. Herds will be randomly allocated to one of three treatment groups:

• use of GIFN as an adjunct to the skin test, 8 to 28 days after reading the disclosing test
• use of a more severe interpretation of the skin test at the first 'short interval test'; or
• a control group, in which the normal protocol will be applied.

36. Whilst the ISG has "strongly advocated work to refine the gamma interferon test", it was "disappointed that Defra proceeded with plans for a gamma interferon pilot and ignored the advice of the Group without any discussion." However, it reported that the Minister has assured the ISG that its concerns are being considered.[117] In oral evidence, Professor Bourne told us that "Defra appreciated that we were developing protocols for the gamma interferon tests. They chose to develop their own protocols without informing us that they were doing so and they took their protocols into the field without giving us the opportunity of discussing their protocols with them or indeed our criticisms of their protocols".[118] Defra told us that the ISG saw and criticised the first draft of the protocol for the gamma interferon pilot. The ISG also saw the revised protocol which "took account of their original comments" and wrote saying it was much improved.[119] The ISG also suggested other work to complement the comparative effectiveness of the tuberculosis test and the gamma interferon test.[120] The Minister also told us that the ISG's proposals were "very resource intensive" and raised "one or two ethical issues ... in relation to testing for cattle and whether they should be reported or not".[121] We welcome the fact that the ISG's concerns and "final proposals" are being considered by Defra.[122] One part of the ISG's remit is to advise Government "as requested, on related issues".[123] If it requests advice Defra should obviously allow the ISG adequate time to provide it. But Defra is not obliged to follow the ISG's advice: Defra is responsible for the decisions made. However, the importance of a harmonious relationship between the ISG and Defra is such that in this instance it would be helpful for Defra to clarify the differences between the protocol it adopted and the advice it received from the ISG and provide some commentary on the reasons for their different approach.

37. We also have concerns about the initial progress of the trial. Defra hoped to recruit over 600 herds, on a voluntary basis, over two years.[124] The NFU told us of the effect of the sensitivity of the gamma interferon test on one farm and the likely subsequent reluctance of neighbours to participate in the pilot,[125] and Mr Morley acknowledged that "recruitment is a bit slow".[126] We ask that Defra now provide an update on recruitment of herds to the pilot, detailing both the anticipated recruitment for each three month period of the trial and recruitment to date. Defra should also detail any changes it has made to the protocol in response to the ISG's comments, since 9 October 2002.

VACCINATION

38. A vaccine against bovine tuberculosis has been "ten years away" for a considerable time.[127] The NFU felt that a vaccine was "key" to the eradication of TB in both cattle and wildlife and called for "an increased emphasis [to] be placed on research into vaccines".[128] The Royal Association of British Dairy Farmers endorsed the call for increased Government investment in a vaccine,[129] as did the CLA.[130] The NFBG also believed that a cattle vaccine "must be part of a strategy to control bovine TB in cattle" but was concerned that Defra was increasing its focus on a badger vaccine.[131] The development of a vaccine is one aspect of Defra's TB strategy. Defra is investigating a number of approaches to vaccine development, including BCG, live attenuated vaccines, killed whole mycobacterial vaccines, subunit vaccines and heterologous prime-boost strategies.[132] Defra also reported that an ISG sub-group on vaccination was expected to report in March. It has the remit to:

"assist the ISG in advising Defra Ministers on the feasibility for pursuing a TB vaccination strategy for either cattle or wildlife. This should also include consideration of future research requirements in addition to those already in place".[133]

39. However, Dr Cheeseman pointed out that vaccination was not a panacea. Two factors, the efficacy of the vaccination and the proportion of the population that would receive it, had to be taken into consideration. He used these factors to highlight the difficulties of a vaccine-based eradication strategy in badgers and then pointed out such a strategy would be even more complicated for cattle because of export rules and because vaccinated animals would be identified as reactors by the tuberculin test.[134]

40. Professor Bourne told us that experimental use of the BCG vaccine in cattle has shown protection of about 60 per cent to 70 per cent. Although small-scale field trials have "indicated that it can be protective and effective", no effect has been shown on large-scale field trials. He then raised the question of whether the BCG could be used in a short time-frame to protect wildlife. He said this was "a possibility" and reported that Defra was supporting trials in Ireland that were "looking at the protective effect of BCG on captive badgers, badgers taken from the field and retained in captive facilities". He expected that work to end in about two years' time.[135] The Defra TB vaccine programme "consists of several linked projects located at the Veterinary Laboratories Agency (VLA) and the Institute of Animal Health (IAH)".[136] The VLA is working in collaboration with researchers from New Zealand.[137] The Ministry of Agriculture and Forestry in New Zealand is funding research to "develop and evaluate diagnostic tests and vaccines for control of bovine tuberculosis in cattle and possums".[138]

41. Professor Bourne reported that the vaccine scoping study was almost complete: "the bottom line is we believe that there is no potential vaccine that could be considered for use in cattle at the moment".[139] However, there was a possibility that the BCG could be used in a shorter time-frame to protect wildlife. Professor Bourne believed cattle vaccine could be a reality in the "long-medium to the long term" and a wildlife vaccine could be a reality in the medium-term.[140] He did not think funding private sector development would speed up the process.[141] Mr Morley also accepted that "at the moment there is no sign of a breakthrough and it is very difficult to predict how long it will be".[142]

42. The development of a vaccine seems as far off as ever. However, rather than being told it is ten years away, we at least now have an idea of the stages that need to be completed before a vaccine, either for cattle or wildlife, is a realistic possibility. We believe that the Vaccine Scoping Study will be useful in determining the Government's future strategy on the development of a vaccine. It is apparent that all interested parties would be willing to endorse the use of an effective bovine TB vaccine. Therefore, despite the long time-frame, research into the development of vaccines should continue. Moreover, other important lessons about the disease are likely to be learned from the vaccine research programme. However, the long time-frame means that the Government and others cannot afford to pin all their hopes on the development of a vaccine. It would be helpful if Defra could provide a statement summarising the present state of work worldwide on the production of a vaccine by the veterinary medicines industry. Finally, the private sector should be encouraged to play a part in the development of a vaccine.

OTHER ISSUES

43. We received a number of submissions that identified factors that potentially affected the incidence of bovine tuberculosis in the UK cattle herd. A number of submissions dealt with the role of the badger which, to us, emphasises the importance of the Krebs trial. Others mentioned trace element deficiency[143] and air quality in cattle sheds.[144] Professor Bourne told us that it is "extremely difficult" to undertake work on the influence of trace elements on the disease status of cattle or badgers. He added that he would "put trace elements research very low on my list. It probably would not appear".[145] Nevertheless, it may still be helpful to undertake a brief literature review of the influence of trace elements, particularly selenium, on the disease status of cattle and badgers. Although no specific work on the way in which cattle are housed was part of the TB programme, the pathogenesis programme was examining the route of transmission between cattle and whether it was nose-to-nose or across an airspace.[146]

CONCLUSION

44. In general, we are satisfied with the research programme that is in place, with the caveats and concerns outlined above. We heard that the NFBG was "still not confident that we have [a] broad-ranging research programme".[147] Having heard from the ISG and Dr Cheeseman, we are confident that the science strategy is broad enough. As Dr Cheeseman pointed out it would always be possible to do more. In the previous paragraph we identified some issues that are not currently under consideration. Part of the ISG's role is to take into consideration the changing science that underpins the research programme it oversees. We would therefore encourage the ISG to indicate why specified topics which have been drawn to its attention are not recommended for further study.

---

64   ISG, First Report, para 1.6. Back

65   Q 19 and Q 7. Back

66   Q 55. Back

67   Q 94. Back

68   Third Report of the ISG, An Epidemiological Investigation into Bovine Tuberculosis, July 2001, para 2.4. Back

69   Q 158. Back

70   Q 126. Back

71   Q 170. Back

72   Qq 116-117. Back

73   Q 87 and Q 89. Back

74   Krebs, 7.8.20. Back

75   Q 87. Back

76   Q 92 and Q 94. Back

77   Appendix, Annex 1, part 4. Back

78   Ev 45, para 38. Back

79   Qq 154-155. Back

80   Qq 155. Back

81   Ev 3, para 28. Back

82   Q 156. Back

83   Second Report of the ISG, An Epidemiological Investigation into Bovine Tuberculosis: Towards a Sustainable Policy to Control TB in Cattle, December 1999, Appendix E, para 27. Back

84   Q 156. Back

85   Q 157. Back

86   Q 190. Back

87   Q 191. Back

88   ISG, Third Report, paras 2.6-2.9. Back

89   Ev 32-Ev 33. Back

90   ISG, Third Report, para 3.20 and Q 139 [Professor Gettinby]. Back

91   Ev 32. Back

92   Ev 33 [Supplementary Memorandum]. Back

93   Ev 32. Back

94   Q 139. Back

95   ADAS is a consultancy and research organisation to the land­based industries, working throughout the UK and overseas. It was formerly the Agricultural Development and Advisory Service, which before privatisation was an arm of MAFF providing free advice to the farming industry. Back

96   Q 185. Back

97   HC (2000-01) 409, para 20. Back

98   Ev 2, para 24. Back

99   Ev 86, section 11. Back

100   Q 34. Back

101   Q 140. Back

102   Q 186. Back

103   Q 187. Back

104   ISG, Third Report, paras 5.15 and 5.16. Back

105   Ev 49. Back

106   Ev 33. Back

107   Q 143. Back

108   Cornwall, Devon, Gloucestershire, Herefordshire, Worcestershire, Shropshire and Dorset [Ev 49]. Back

109   Ev 2, para 19. Back

110   Ev 86, section 10. Back

111   Ev 16, para 78. Back

112   Q 153. Back

113   Krebs, paras 6.3.13-6.3.15. Back

114   Defra News Release 407/02, 9 October 2002. Back

115   Q36. Back

116   Defra News Release 407/02, 9 Octoer 2002. Back

117   Ev 33; see also Q162. Back

118   Q 153. Back

119   Q 175. Back

120   Q 153. Back

121   Q 161. Back

122   Q 161. Back

123   ISG, First Report, para 1.1. Back

124   Defra News Release 407/02, 9 October 2002. Back

125   Q 37. Back

126   Q 182. Back

127   Q 22. Back

128   Ev 3, paras 31-32. Back

129   Ev 81, Appendix 19. Back

130   Ev 86, section 9. Back

131   Ev 16, paras 66-67. Back

132   Ev 44, para 21. Back

133   Ev 44, para 19-25. Back

134   Q 97. Back

135   Q 132. Back

136   Ev 44, para 19. Back

137   HC Debates, 20 June 2002, col 474W. Back

138   See: www.maf.govt.nz. Back

139   Q 131. Back

140   Qq 132-133. Back

141   Q 143. Back

142   Q 182. Back

143   Ev 92-Ev 94. Back

144   Ev 95-Ev 96. Back

145   Q 148. Back

146   Q 146. Back

147   Q 55. Back

---

Prepared 9 April 2003