Select Committee on Environment, Food and Rural Affairs Written Evidence


Memorandum submitted by the National Federation of Badger Groups

BOVINE TB

1.  INTRODUCTION

  The NFBG welcomes the EFRA Committee's continued focus on the problem of bovine tuberculosis in cattle. This review is particularly timely. It comes in the wake of a prolonged media campaign driven by the farming unions, which aims to persuade policy makers and the wider public that badger culling is vital if bovine TB is to be controlled in the national herd.

  Regrettably, many farming correspondents in the media have lent weight to the farming unions' campaign by reporting on badger issues alone. This extraordinary and inexplicable bias has left many farmers feeling that there is no alternative to badger culling. But there is an alternative—the gamma interferon test—a highly advanced diagnostic test which is already in use from Europe to Australasia, but which appears to be poorly understood by farming unions, veterinary professionals and DEFRA officials alike in the UK.

  We hope that the Committee will take this opportunity to tease out:

    —  Why DEFRA has failed to assess the sensitivity and specificity of the gamma interferon test and wasted time and tax payers' money, instead, on a flawed trial which its own advisors warned would not provide adequate policy information.

    —  What the National Farmers Union and its allies know about the gamma interferon test (particularly with regard to its reliability), when they were provided with key information about the test and what steps they have taken to inform their members about the great opportunity offered by the test.

    —  On what evidence DEFRA claims that the gamma interferon test has a "lower specificity" and is "more costly" than the intradermal skin test (DEFRA, 2004), when DEFRA has not undertaken proper field trials or, so far as we know, conducted an up to date analysis of the cost benefits of implementing the test.

  Seven years after the hugely expensive randomised badger culling experiment began, we are still no closer to being able to measure precisely the role that badgers do or do not play in bovine TB in cattle. Indeed, after killing thousands of badgers at a massive cost to the public, we are now advised that Professor Sir John Krebs' grand trial will never provide the key answers that it initially promised.

  Instead, we find ourselves no further forwards than in 1998 when the Krebs trial began: the Government still has no coherent Plan B. Farmers and conservationists alike are trapped in an endless cycle of consultations about TB control strategies, in which DEFRA fails to provide an evidential basis for any particular policy approach and, in the case of gamma interferon, appears to be actively briefing against this test despite evidence confirming its potential.

  It is our view that DEFRA may have changed its name since its reform in the wake of foot and mouth disease, but it remains incapable of:

    —  implementing coherent, intelligent research strategies;

    —  analysing scientific research and advancing policy strategically; and

    —  communicating new information effectively to farmers and other stakeholders.

  The more that we have learned about the gamma interferon test, the more we are persuaded that DEFRA has been at the very least incompetent and perhaps, at worst, even negligent in assessing its potential. Bovine TB is spinning out of control whilst a likely control mechanism is available. We strongly urge the Committee to do all it can to alert Ministers and farmers alike to the potential of the gamma interferon test so that it is implemented before bovine TB is so endemic in the national herd that bringing it under control becomes prohibitively expensive.

2.  THE GAMMA INTERFERON TEST

  The NFBG has previously outlined its concerns over flaws in the tuberculin skin test and the lack of progress being made by DEFRA with the gamma interferon test (NFBG, 2003a). Whilst DEFRA has done little or nothing to report on the merits of the gamma interferon test, the NFBG has extensively researched the current research situation and the advantages of the test. We make the following observations:

2.1  DEFRA's gamma interferon field trial will not effectively inform future policy options

  Contrary to advice from the Independent Scientific Group (ISG), DEFRA's field trial is not assessing gamma interferon's specificity and sensitivity. These two factors are essential if DEFRA is to calculate the cost benefit of using the test in the UK.

  Sensitivity is the proportion of true positives detected by a diagnostic procedure. For example, if 100 infected cattle were tested and 90 detected, the test would have a sensitivity of 90%. The remaining 10% of infected cattle would be false negatives. Sensitivity needs to be high where bovine TB incidence is high, as it is in the south west, parts of Wales and the west Midlands, so as to remove as many infected animals as possible from the population being tested.

  Specificity is the proportion of true negatives detected by a diagnostic procedure. For example, if 100 uninfected cattle were tested and 90 were determined to be disease-free, the test would have a specificity of 90%. The 10% misdiagnosed by the test would be false positives. Specificity needs to be high where bovine TB incidence is low, such as in much of Scotland, northern, southern and eastern England, to avoid the needless slaughter of uninfected cattle.

  Most countries that are now using the test as a diagnostic tool first conducted their own trials to assess the sensitivity and specificity of the test under their environmental conditions. Such countries include Australia (Wood et al, 1991), New Zealand (Ryan et al, 1998), the US (Whipple et al, 1995), Italy (Dondo et al, 1996) and the Republic of Ireland (Neill et al, 1995; Monaghan et al, 1997). Yet no field trial has been undertaken in the UK, more than a decade after the test was first shown to be effective.

  It has been suggested that the gamma interferon test generates too many false positives and would lead to the needless slaughter of many livestock. This is a false premise. It assumes that the gamma interferon test is fixed in application. On the contrary, specificity can be "turned up" and sensitivity "turned down", and vice versa, according to the circumstances in which the test is being used, by using different antigens and different cut-off points.

  It is also important to understand that "false positives" may in fact be true positives, but technology does not allow us to confirm them as such.

  For example, false positives are defined as cattle that test positive to the gamma interferon test but, when slaughtered, are found to have no visible lesions on examination post mortem and M bovis cannot be cultured from tissue samples. However, the culture of bovine TB can be difficult and sometimes impossible even when livestock have been intentionally infected with large doses of bacteria.

  Therefore, a classically defined false positive result does not necessarily mean that the gamma interferon test was wrong. It can instead be the case that culture is not capable of confirming the result. This, in turn, causes specificity to be underestimated and the number of false positive cattle to be over estimated.

  This problem can be circumvented by determining the specificity of the test through field trials on uninfected herds, in non-TB areas. The trial must include thorough post mortem examinations. DEFRA's field trial, in stark contrast, is being conducted in herds with bovine TB.

2.2  DEFRA is making misleading claims about gamma interferon

2.2.1  DEFRA claims that the test "has slightly lower specificity than the skin test used in the UK" (DEFRA, 2004).

  Since DEFRA is not conducting trials to assess the specificity of the gamma interferon test in the UK, we fail to see how DEFRA can justify its assertion.

2.2.2  DEFRA claims that "it may, in time, be possible to increase the specificity of the gamma interferon test by including recently identified antigens in the test" (DEFRA, 2004).

  DEFRA's consultation document was published in February 2004, but research published as long ago as 2000 has reported that significant progress has already been made in improving the specificity of the gamma interferon test through the use of M. bovis antigens (Pollock et al, 2000; Van Pinxteren et al, 2000; Vordermeier et al, 2001; Buddle et al, 2003).

  For example, four years ago, scientists reported that the use of a specific M. bovis antigen (ESAT-6) increased the sensitivity of the gamma interferon tuberculin test from 88.3% to 99.2% (Pollock et al, 2000). Similarly, in November 2003, scientists (including two from the UK Government's Veterinary Laboratories Agency) reported that a combination of two M bovis antigens (ESAT-6 and CFP10) resulted in "significantly fewer false positive reactors . . . than with the standard gamma interferon test", but without reducing its sensitivity (Buddle et al, 2003).

  It therefore appears that DEFRA is either: (a) not keeping abreast of current research, even when some of the work is being conducted by its own scientists; (b) failing to understand the research, resulting in a failure to allow scientific progress to influence Government policy; or (c) intentionally briefing against the gamma interferon test in order to avoid incurring the cost of introducing the test.

2.2.3  DEFRA claims: "(the gamma interferon test) is more costly than the skin test" (DEFRA, 2004).

  The unit price of a single gamma interferon test may be higher than a single skin test, although DEFRA has not published up to date data to support this claim. However, to focus on the cost of testing an individual animal is highly misleading.

  When all the costs associated with herd testing are considered, the gamma interferon test can generate significant cost savings by:

    —  Reducing the length of time a herd is under movement restriction.

    —  Removing the need to visit stock twice, as required for the skin test.

    —  Reducing veterinary and labour fees by reducing the time spent on testing.

    —  Reducing the number of rounds of testing required clearing up infection due to the test's increased sensitivity (Wood and Jones, 1998).

  Costs can be further reduced as the number of tests increases economies of scale and by ensuring competition between laboratories conducting the test.

  The NFBG suspects that DEFRA's cost calculations from 2001 (DEFRA, 2001) are now out of date and have limited value. For example, a significant part of the economic cost of a TB outbreak is the detection of false positive cattle (Pollock et al, 2000). If, in its calculations, DEFRA used specificity data that were too low, the cost of an outbreak will be artificially raised.

  We would therefore urge the Committee to investigate why DEFRA has not conducted full and proper cost benefit analyses of using the gamma interferon test. We would be particularly interested to know whether DEFRA has calculated the cost of not implementing the gamma interferon test, given the recent alarming rise in the disease. How much money might have been saved already, had the test been introduced years ago?

2.3  The gamma interferon test has key advantages over the tuberculin skin test

  The sensitivity of the tuberculin skin test—ie its ability to detect infected cattle—can be relatively low and varies from 68-95% (Monaghan et al, 1994). The specificity of the test can also be low, resulting in false positive reactions in cattle that have been exposed to mycobacteria other than M. bovis (Snider, 1982). In Britain, specificity has been slightly improved through using the comparative skin test, where responses to M. bovis and M. avium are compared. However, the test remains crude and unreliable.

  Scientists have recognised for some years that more specific and sensitive tests are needed, particularly in countries where the incidence of bovine TB is low (Wood et al, 1991). The gamma interferon blood test was therefore developed in around 1990 (Wood et al, 1991). At that early stage, some thirteen years ago, scientists identified key advantages of the gamma interferon test over the tuberculin skin test. And as the test has been researched, developed and refined, these advantages have become clearer.

2.3.1  Key advantages of the gamma interferon test

    —  Detects cattle in the early stages of infection (Neill et al, 1994; Domingo et al, 1995);

    —  Detects infected cattle that fail to respond to the skin test due to repeated testing (Wood et al, 1991; Dr Chris Howard, unpublished data);

    —  Demonstrates higher specificity and sensitivity in trials, resulting in fewer "false positive" cattle, especially when using a cocktail of M bovis-specific antigens (Vordermeier et al, 2001; Buddle et al, 2003);

    —  High sensitivity means that the test is ideally suited to situations where bovine TB is spreading rapidly and the detection of as many diseased cattle as possible is desired (Wood and Jones, 1998);

    —  Can be used in parallel with the skin test to detect almost all infected cattle (Wood and Jones, 1998);

    —  Designed to test for M bovis and M avium at the same time (Wood and Jones, 1998);

    —  Cheaper in operation that the skin test, due to factors such as enhanced specificity and sensitivity; reduced length of time herds are under movement restrictions; and reduced veterinary time and labour;

    —  Reduces the costly option of total herd de-population (Wood et al, 1991);

    —  Distinguishes between cattle vaccinated with BCG and cattle infected with M bovis;

    —  Effective for large-scale field testing (Wood et al, 1991);

    —  Sensitivity and specificity can be adjusted according to the purpose for which it is being used (Wood et al, 1991);

    —  No second visit is required, reducing stress on cattle difficult to handle;

    —  Analysis of results is more precise, rather than a subjective assessment of a skin reaction by a veterinary surgeon;

    —  Test is non-invasive and does not compromise cattle immune system, so can be used repeatedly without delays. In contrast at least 60 days must elapse between skin tests due to its impact on the immune system;

    —  Test can be readily implemented by lay testers, reducing the cost of test to the Government.

2.4  NFBG recommendations

  The NFBG recommends that the Government:

    —  Conducts the current gamma interferon trial according to the methodology proposed by the ISG (ISG, 2002). This will ensure that data are collected on the specificity and sensitivity of the test in the UK and will enable the consideration of future policy options;

    —  Introduces the gamma interferon test for herds: (a) with multiple reactors, inconclusive reactors or persistent infection and (b) subject to pre-movement testing;

    —  Implements both measures above immediately, while simultaneously accumulating further data.

3.  THE BOVINE TB EXPERIENCE IN IRELAND

  Interesting developments are being made in both Northern Ireland and the Republic of Ireland, including the use of the gamma interferon test. The NFBG would therefore welcome an analysis of the experiences in both countries. In particular, we hope that the Committee will be able to draw out the coherence of the bovine TB control policy in the Republic of Ireland and be able to determine the extent to which individual control strategies are influencing the incidence of bovine TB in cattle.

  The NFBG is particularly interested in the extensive references to Ireland's Four Areas Badger Study, made by both farming unions and, more recently, the Godfray report. We were surprised to see Professor Godfray make such clear statements about research which is, as yet, unpublished in a peer-reviewed journal.

  We are also surprised at how others are apparently well informed about the study, given that Professor Dan Collins who heads it has refused to provide us even with the statistical methodology, let alone the results. We hope that a head of steam about the research is not being built up prior to its publication, in order to be released so as to obscure any balanced assessment of its possible deficiencies.

  The NFBG has attempted to investigate the Four Areas Badger Study and has obtained limited information from a number of sources. Regrettably, the individuals who undertook the research have declined to explain their methodology to us. Our main observations are as follows:

    (a)

    On 31 May 2003, the BBC Radio 4's Farming Today programme reported on the Irish study and quoted Dr Leigh Corner as follows: "If you take the year of the study compared to the average of the pre-study rate it (the reduction) is in the order of 70-80%. I think in one area it was 90% reduction in reactors." The NFBG was inevitably alarmed by these findings. They suggest that if enough badgers are killed, bovine TB can be virtually eliminated from cattle.

        We contacted Professor John "Dan" Collins and requested details about the scientific methodology of the study. In particular, we wanted to know how the statistical comparison was made between the "core" culling areas and the control "reference" areas where, ostensibly, no culling took place. Professor Collins refused to explain the methodology to us and told us that the results were due to be published in a peer-reviewed journal in June 2003. We understand that no such paper has yet been published;

    (b)

    The NFBG contacted the Irish Government for clarification. Margaret Good of the Department of Agriculture Food and Forestry in the Irish Republic confirmed to us that "badger removal operations" were also undertaken in the so-called "reference" (control) areas of the Four Areas Badger Study, during the course of the study (Margaret Good, pers com). The reference areas are ostensibly similar to the scientific "controls" in the no culling "survey only areas" in the Krebs trial. As badger removal operations also took place in these reference areas, they are not true scientific controls. It is unclear how the researchers will draw meaningful conclusions from the results of the study, unless they can accurately quantify the extent of culling in reference areas and make a valid statistical assessment of its implications;

    (c)

    The NFBG has also been advised that badger removal operations took place in some parts of some of the core areas prior to the start of the Irish study. In some areas, these removals were extensive. If these removals were similar to the reactive culling operations undertaken in the Krebs trial, then the level of bovine TB in those areas could have been artificially increased before the Four Areas Badger Study began. By implication, any subsequent reduction in bovine TB detected by the study would be artificially exaggerated;

    (d)

    The Independent Scientific Group on Cattle TB (ISG) also suggests that the Irish study may over-estimate the effectiveness of culling. The ISG also points out that the Krebs trial is a far larger-scale study than that undertaken in Ireland (Donelly et al, 2003);

    (e)

    Farming unions and others have been keen to claim that the Irish study reduced bovine TB by 90% through badger culling. However, thus far, no data have been published to suggest that the Irish have solved their bovine TB problem. Far from it: we have obtained data from the Department of Agriculture and Food on the number of herds under movement restrictions in each of Ireland's 26 counties. The figures were provided to the Committee last year (NFBG, 2003). At the time, we made two observations on these limited data:

      —  In the counties where the Four Areas Badger Study has been in progress, there has been no discernable improvement in bovine TB vis a" vis other counties;

      —  Nationally, 6.5% of herds were under movement restriction in 2002, compared to 3.3% of British herds in 2002 and 3.2% in 2003 (DEFRA, 2004b);

    (f)

    The NFBG has seen little reference to the welfare of badgers in published papers on the Four Areas Badger Study. In particular, we have received reports of snares set on banks—where badgers typically make their setts—with the results that badgers can hang by the neck on a wire noose for many hours prior to despatch. The Committee may wish to ask what independent assessment of the welfare of badgers in the Four Areas Badger Study has been undertaken and what are the implications for animal welfare if snares were to be used in the UK.

4.  BADGER CULLING IS NOT THE WAY FORWARDS

  Evidence is constantly accumulating to indicate that a badger culling policy will not control bovine TB in cattle or be cost effective (Delahay et al, 2003; Donelly, et al, 2003; EFRA, 2003a; Bennett et al, 2004).

  We noted with interest that, when the Krebs trial apparently showed that reactive badger culling increased bovine TB in cattle by 27%, the NFU's animal disease spokesman Anthony Gibson claimed that the NFU had long advocated a proactive badger-culling policy (Western Morning News, 2003), when the NFU's previous evidence to the EFRA Committee called for reactive culling (EFRA, 2003b). It seems that, as the scientific evidence mounts against their policies, the farming unions become more extreme in their demands. This culminated in the outgoing NFU President, Ben Gill, calling for the reintroduction of badger gassing. He produced his own "scientific" report which lacked any scientific justification for his proposals. Gill went so far as to claim that gassing was "humane" (Gill, 2004).

  We were even more surprised this month to see the Conservative spokesman on agriculture, Owen Paterson, campaigning for "targeted" badger culling in TB hotspots. We hope that Mr Paterson will precisely outline the scientific justification for his policy and its costs and benefits.

  Those who have already called for badger culling have been rather reluctant to justify the policy. In June 2003, the NFU led a number of organisations in publishing a "statement of recommendation" for the control of bovine TB, including "reactive" badger culling (NFU et al, 2003). We were surprised that professional veterinary bodies endorsed the statement and we wrote to all the statement's signatories, asking them to answer a number of key questions. These questions remain just as valid today but, so far, none of the statement's signatories have been prepared to answer the questions. The Committee may be able to secure answers to some of these questions in the course of its inquiry. A selection of the key questions can be found at APPENDIX I.

5.  BOVINE TB VACCINES

  The NFBG takes the view that TB vaccines must be part of a long-term strategy to control bovine TB in cattle. However, there are many questions that need to be addressed before a vaccine for cattle or badgers can be introduced. We therefore agree with the conclusions of the vaccine scooping study, published in 2003, which concluded that research on both cattle and badger vaccines should continue and that efforts be made to ensure that the work is funded in full (Bourne et al, 2003). We also agree that, in the meantime, other disease control measures should be implemented. The NFBG has outlined its proposals elsewhere (NFBG, 2003b).

  We understand that scientists are currently evaluating the use of two forms of BCG vaccine in cattle. The first involves neonatal vaccination of calves. The second involves "prime boosting"—vaccinating cattle with BCG then boosting its effect with M bovis DNA. Both forms of vaccine have shown promise in experimental trials but need to be further tested in natural transmission studies, followed by full field trials (Glyn Hewinson, pers com).

  Further work also needs to be conducted in developing a diagnostic test for TB in cattle that distinguishes between (a) infected cattle and (b) vaccinated cattle that have been exposed to M bovis. One reason for this being important is that a vaccine is unlikely to provide protection to all vaccinated animals.

  The vaccine scooping study also concluded that there are "significant scientific hurdles" to consider and overcome with a badger vaccine, even before it gets to the point of field trials. An obvious unknown is the likely effectiveness of a badger vaccine in controlling TB in cattle, when the role, if any, of the badger is currently unclear. And as with a cattle vaccine, a diagnostic test will be required. Progress is being made in this area with an improved ELISA test but specificity and sensitivity needs further improvement (Greenwald et al, 2003). We also believe that other factors such as ethical, economic and practical issues will also need to be resolved.

6.  ECONOMIC IMPACT OF BOVINE TB

  DEFRA has commissioned a study of the economic impact of bovine TB by researchers at Reading University (Bennett et al 2004). We are extremely disappointed that DEFRA has not widely publicised the results of the study and has not even issued a press release on the subject.

We noted, with particular interest, that the study concluded that a proactive badger culling strategy would be relatively very costly (even without attaching any value to badgers themselves) and such a strategy would have to result in very large reductions in the incidence of TB in cattle to be considered worthwhile from an economic (cost-benefit assessment) perspective.

7.  REFERENCES

  Bennett, R, Cooke, R and Ijpelaar, J (2004). Assessment of the economic impacts of TB and alternative control policies. www.defra.gov.uk/animalh/tb/

  Bourne et al (2003). Development of vaccines for Bovine Tuberculosis. Report of the Independent Scientific Group Vaccine Scoping Sub-Committee. July 2003. www.defra.gov.uk/animalh/tb/publications/index.htm

  Buddle, B M, et al (2003). Use of mycobacterial peptides and recombinant proteins for the diagnosis of bovine tuberculosis in skin test positive cattle. Veterinary Record 153, 615-620.

  DEFRA (2001). Gamma interferon feasibility trial. Objective 4. To evaluate the feasibility of using the gamma interferon test in reactor herds, as the basis for a larger field trial. APPENDIX to TB Forum paper TBF 62, January 2002.

  DEFRA (2004). Preparing for a new GB strategy on bovine tuberculosis. Consultation document. February 2004.

  DEFRA (2004b). TB statistics January-December 2003. www.defra.gov.uk/animalh/tb

  Delahay, R J et al (2003). Bovine tuberculosis in badgers: Can culling control the disease? Conservation and Conflict, pp 165-171, Westbury Publishing.

  Domingo, M, Liebana, E, Vilafranca, M, Aranaz, A, Vidal, D, Prats, N, Mateos, A, Casal, J and Dominguez, L (1995). A field evaluation of the interferon-gamma assay and the intradermal tuberculin test in dairy cattle in Spain. In: Griffin F and de Lisle G (ed) Tuberculosis in Wildlife and Domestic Animals. Otago Conference Series No 3. University of Otago Press, Dunedin, pp 304-306.

  Dondo, A, Goria, M, Moda, G, Cesano, L, Garanzini, A, Giammarino, M, Minola, G, Moriconi, E, Porta, G, Banchio, P and Marmo, G (1996). Gamma interferon assay for the diagnosis of bovine tuberculosis: field evaluation of sensitivity and specificity. Medicina Veterinaria Preventiva, 13, pp 14-19.

  Donnelly, C A et al (2003). Impact of localized badger culling on tuberculosis incidence in British cattle. Nature, 426, 834-837 Letters to Nature (18 Dec 2003).

  EFRA Committee (2003a). Badgers and Bovine TB. Seventh report of session 2002-03. April 2003. Oral evidence from Professor John Bourne, Chairman of Independent Scientific Group on Cattle TB.

  www.publications.parliament.uk/pa/cm200203/cmselect/cmenvfru/cmenvfru.htm£reports

  EFRA Committee (2003b). Badgers and Bovine TB. House of Commons Environment, Food and Rural Affairs Committee. 9 April 2003.

  Gill, B (2004). Bovine tuberculosis control—a scientific perspective: a report to the NFU.

  Greenwald, R et al (2003). Improved serodetection of Mycobacterium bovis infection in badgers (Meles meles) using multiantigen test formats. Diagnostic Microbiology and Infectious Disease, 46, pp 197-203.

  ISG (2002). Proposed trial of the gamma interferon test. TB Forum paper TBF 76. www.defra.gov.uk/animalh/tb/forum/findex.htm

  Monaghan, M, Doherty, M L, Collins, D, Kazda, J F and Quinn, P J (1994). The tuberculin test. Veterinary Microbiology, 40, pp 111-124.

  Monaghan, M, Quinn, P J, Kelly, A P, McGill, K, McMurray, C, O'Crowley, K, Bassett, H F, Costello, E, Quigley, F, Rothel, J S, Wood, P R, Collins, J D (1997). A pilot trial to evaluate the gamma-interferon assay for the detection of Mycobacterium bovis infected cattle under Irish conditions. Irish Veterinary Journal, 50, 229-232.

  Neill, S D et al (1994). Detection of Mycobacterium bovis infection in skin test negative cattle with an assay for bovine interferon-gamma. Veterinary Record, 135, pp 134-135.

  Neill, S D, Hanna, J, Clements, A, Cassidy, J, Pollock, J, Bryson, D G (1995). Diagnosing tuberculosis in animals. In: Griffin, F and de Lisle, G (ed). Tuberculosis in Wildlife and Domestic Animals. Otago Conference Series No 3. University of Otago Press, Dunedin, pp 300-303.

  NFBG (2003a). A paper submitted to the House of Commons Environment, Food and Rural Affairs Committee. Response to the Government decision to end badger culling in reactive areas of the "Krebs trial". 6 December 2003. www.badger.org.uk

  NFBG (2003b). The control of bovine tuberculosis in cattle in Great Britain. Submission to DEFRA's consultation on a bovine TB policy. October 2003. www.badger.org.uk

  NFU et al (2003). Industry bovine TB conference. Statement of recommendations to Ministers. TB Forum paper TBF 94. June 2003. www.defra.gov.uk/animalh/tb/forum/findex.htm

  Pollock, J M et al (2000). Defined antigens for the diagnosis of bovine tuberculosis: assessment in skin test-reactor cattle. Veterinary Record, 146, pp 659-665.

  Ryan, T J et al (1998). Tuberculosis control in livestock in New Zealand: the current situation and future directions. Proceedings of the Society for Veterinary Epidemiology and the Preventative Medicine. Ireland.

  Snider, D E (1982). American Review of Respiratory Diseases. 125, p 108.

  Van Pinxteren, L A H et al (2000). Diagnosis of tuberculosis based on the two specific antigens, ESAT-6 and CFP10. Clinical and Diagnostic Laboratory Immunology, 7, pp 155-160.

  Vordermeier, H. M. et al (2001). Use of synthetic peptides derived from the antigens ESAT-6 and CFP-10 for differential diagnosis of bovine tuberculosis in cattle. Clinical and Diagnostic Laboratory Immunology, 8, pp 571-578.

  Western Morning News (2003). "Scrap Krebs trial now", Anthony Gibson, NFU.

  Whipple, D L Bolin, C A, Davis, A J, Jarnagin, J L, Johnson, D C, Nabors, R S, Payeur, J B, Saari, D A, Wilson, A J and Wolf, M M (1995). Comparison of the sensitivity of the caudal fold skin test and a commercial gamma-interferon assay for diagnosis of bovine tuberculosis. American Journal of Veterinary Research, 56, pp 415-419.

  Wood, P R, Corner, L A, Rothel, J S, Baldock, C, Jones, S L, Cousins, D B, McCormick, B S, Francis, B R, Creeper, J and Tweddle, N E (1991). Field comparison of the interferon-gamma assay and the intradermal tuberculin test for the diagnosis of bovine tuberculosis. Australian Veterinary Journal, 68, pp 286-290.

  Wood, P R and Jones, S L (1998). Bovigam TM an internationally accredited diagnostic test for bovine tuberculosis. United States Animal Health Association: Proceedings 1998.

8.  APPENDIX I

  Questions asked by the NFBG of signatories to the "statement of recommendations", June 2003 (NFU et al, 2003).

  1.  You state that TB should be eradicated in both "cattle and wildlife". Since bovine TB is found in many wild animals other than badgers, how might TB be eradicated in wood mice, shrews, stoats, deer and the other mammals in which it is found?

  2.  Specifically, is it your view that the only way to eradicate bovine TB is to eradicate all the mammals which can harbour the disease?

  3.  You state that cattle movements should be allowed on the basis of individual farm risk assessments. Since you acknowledge that the TB test is not reliable, on what scientific basis could the risk of TB transmission from a farm in a known TB area be assessed?

  4.  You argue that counselling and financial advice should be made available to farmers to reduce the stress associated with a TB herd breakdown. Can you explain why this should be the responsibility of the taxpayer and not the farmer's union?

  5.  You call for reactive badger trapping in TB hotspots outside [Krebs'] trial areas. Can you explain:

    (a)

    By what proportion would bovine TB in cattle be reduced by such a reactive strategy, bearing in mind that claims lately made in Ireland have not been published in a peer-reviewed scientific journal?

    (b)

    What would be the financial cost of reactive badger culling in hotspots?

    (c)

    What would be the financial benefit (to farmers and to the taxpayer) of reactive badger culling in hotspots?

    (d)

    You state that TB is spreading in wild animals. What scientific evidence do you have to support this claim?

    (e)

    Specifically, what scientific evidence do you have that the disease is spreading between wild animals, rather than being introduced to new areas by infected cattle movements?

    (f)

    You state that badgers are known to have a role in the transmission of TB to cattle. What reliable scientific evidence do you have to justify your claim?

    (g)

    Since there is no reliable method for testing for TB in live badgers and you have consistently stated that you only want to kill "unhealthy" badgers, how would you ensure that only "infected" badgers were killed?

    (h)

    Since you have consistently stated that you do not want to eradicate badgers, what proportion of badgers in a reactive culling area should be culled and how would you know when the target proportion had been reached?

    (i)

    Since you acknowledge that widespread badger culling is politically unacceptable, why should the public purse rather than the industry pay for a reactive culling strategy?

  6.  You say that biosecurity advice should be based on proven scientific data. We agree. But how would volunteer demonstration farms generate scientifically valid data? It is already clear that the voluntary approach to the gamma interferon trial may not yield sufficient or robust data because an insufficient number of farmers are willing to take part.

  7.  You state that pre- or post-movement testing of cattle should be "encouraged". Since post-FMD breakdowns have confirmed the vital role that cattle play in transmitting bovine TB, on what scientific basis should pre- and post-movement testing not be compulsory? Any claim that it is "too expensive" for the industry is invalid unless your cost benefit analysis includes the cost to the tax payer of compensating farmers for TB breakdowns and—were you demands to be heeded—the cost of reactively culling badgers.

National Federation of Badger Groups

May 2004





 
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