November 13, 2018

expert reactions to an independent review on the bovine TB strategy

Reactions to an independent review on the bovine TB strategy as published by Defra. 

Prof Malcolm Bennett, Professor of Zoonotic and Emerging Disease, University of Nottingham, said:

“The Review is thorough and makes a number of interesting and potentially useful points, particularly concerning the governance of the disease.  Few will disagree with the statement that “the current governance arrangements poorly serve bovine TB control”, and that there has been “too little industry ownership of the disease and a widespread implicit belief that bovine TB is government’s problem alone”.   Nor will there be much argument with “the ability of the current system to adapt rapidly to new epidemiological evidence or new technologies is inadequate”.

“Much of the review emphasises how little we still know about the disease or its transmission: our diagnostic tests are inadequate and our surveillance – in both cattle and wildlife – inadequate.  There is the interesting suggestion that more sensitive skin tests be used in cattle – as they are in most parts of the world – along with other more sensitive tests still, and recognition that too many infected cattle are left on farms.  Despite it being a recommendation of the Krebs report some 20 years ago, this review also points out that our understanding of the role of badgers in the infection of cattle remains poor.

“Many readers heading straight for the wildlife chapter will be disappointed to see that the review supports culling badgers – although it appears to do so more with regret than appetite, makes it a ‘judgement call’ for politicians, and points out how little research on the effectiveness of vaccination in terms of its effect on the disease in cattle (after all – that’s why badgers are vaccinated) has been done.  And it makes some useful observations and suggestions on what should be done after culling – and indeed how culling and vaccination might be more integrated.

“The review concludes by returning to its governance theme, that “it is important to be flexible and set up systems that ensure new insights from surveillance and research are efficiently incorporated into policy and implementation” and a call to cut through the red tape – the accumulation of rules and regulations that “can foster a philosophy of living with the disease (and the regulations) rather than being part of the control campaign”.  While there is an argument that bovine TB is a disease of industry and policy, and should be handed over to industry to sort out (an oversimplification, but only just, of how the Australians and New Zealanders got the disease under control), this review seems rather to be a call for government and industry and all the other stakeholders to treat bovine TB seriously, as we would other notifiable diseases, to focus research on getting the evidence needed to inform policy, and then to ensure that policy is agile enough to adapt to the evidence.”

Dr Colin Butter, Reader in Bioveterinary Science, University of Lincoln, said:

“The Godfray report is a welcome and thorough review of Bovine TB in the UK.  Its deficiencies are primarily due to a lack of robust data in some critical areas.  For example, although there is consensus that badgers can transmit TB to cattle, the relative importance of badger control, compared with other possible interventions such as increased biosecurity and vaccination of cattle is left unresolved.  This would seem a critical issue when there appears to be little public support for the present badger cull, though the report is clear on the desirability of non-lethal control of the disease in this iconic wildlife species.

“The report correctly highlights the need for further research, particularly with a funding landscape that has seen a substantial reduction of DERFA research spend in the past five years (£3.9M in 18/18 compared with £5.6M in 14/15) and an unsure future of UK access to EU funding.”

Prof Rob Smith, Emeritus Professor of Population Dynamics,University of Huddersfield, said:

“This is a forward-looking review of the UK strategy to control the disease bovine tuberculosis (TB), which currently costs the UK taxpayer an estimated £70M and UK farmers another £50M annually.  Previous (and current) Defra strategies have been controversial and have failed to satisfy different stakeholder groups.  The new review emphasises the complexity of the problem and is realistic in its appraisal of the options – there are no quick fixes and it is unlikely that the conflicting demands of stakeholders can be resolved.  So how useful is this new review?

“The authors have done a very good job overall in a relatively short (six month) period of time.  Their report is wide-ranging and describes the different elements of the problem very clearly.  They identify many uncertainties and data gaps and emphasise the need for “greater flexibility and agility” in adapting strategy as new data appear.  Will Defra be flexible and agile in its response to new science?  Who knows, but the review points out in a number of places that decisions require value judgments by elected politicians, i.e. decisions are (unfortunately) not based on science alone.

“The need to think about the control of bovine TB at a landscape scale is well recognised and is emphasised in various parts of the review.  It is clear that the increase in the geographical area affected by bovine TB over the last 30 years (Figure 1.2(b)) cannot be a consequence of badger movements and is related to the movement of infected cattle.  The very high level of movement of cattle in the UK is described in its own chapter and is apparently economically rational.  It does, however, seem crazy that, for example, cattle are generally moved from the west to the east of England where crops for cattle feed are grown because it is cheaper to move cattle to the feed rather than vice versa.  Surely, considerations of both animal welfare and disease transmission tell us that this is plainly wrong?  The review does consider various options for reducing the spread of TB through greater control of movement of cattle, including additional, selective testing and the use of microchips to replace ear tags.

“The review discusses the controversial area of badger culling along with vaccination in relation to options for the future for controlling the disease.  Although culling in some form is almost certain to continue under the present government, there are biosecurity measures that can be implemented (at a cost) by individual farmers and that could be required before a cull license is granted.  The review is to be commended for considering the economic and social context of disease-control measures and for examining approaches in other countries.”

Dr Steven Van Winden, Senior Lecturer in Production Animal Medicine, Royal Veterinary College, said:

“The document is balanced in content, robust in its approach, and gives useful guidance and direction for future disease (bovine TB) control policies.  As bTB is a complex disease with a complicated method of spread, the document addresses the relevant areas of disease detection and control, whilst respecting the different points of view, which especially in the role of badgers in the disease pathway can be laden.

“I expect this document to be the basis of many directions of policy making and informing decision support on farm.  The focus is much on disease detection and spread between farms, via cattle, badgers, or otherwise, but lacks the importance of disease control once bTB has entered the farm.  Once bTB has arrived on the farm, external disease incursion routes may well be less relevant than herd mates that are infected.  It is good to see that this is to a degree addressed in the testing strategy, where the more sensitive single intradermal cervical test could be used to pick up infected individuals more effectively.  I am confident that this document will help finding a way to control bTB more effectively in the future.”

Prof Lord John Krebs FRS FMed Sci, Department of Zoology, University of Oxford, said:

“The Godfray Report is a valuable, impartial, summary of the current evidence on the control of TB in cattle.  The report does not focus on the question of whether or to cull badgers, but takes a much broader view.  Its key conclusions are that in order to control and eventually eradicate the disease, farmers need to take more ownership of the problem themselves and there is an urgent need for a better test for TB in cattle.  Currently, much of the spread of TB in cattle arises from a combination of three things: disappointingly low uptake of measures to prevent cattle coming into contact with badgers, trading of infected cattle, and the low sensitivity of the standard skin test for TB, which means that there is likely to be a hidden reservoir of infection in many cattle herds in high risk areas.  Unless the Government and the farming industry tackle these problems now, TB will not be eradicated or controlled.”

Prof Rosie Woodroffe, Senior Research Fellow, Institute of Zoology, Zoological Society of London, said:

“This report presents many strong and bold proposals to improve cattle TB control, including testing cattle with a more sensitive test (even though this might produce more false positives as well as more false negatives), and reducing compensation for farmers who adopt risky trading practices.

“The report is very clear that cattle are more likely to acquire TB from other cattle than from badgers.

“While the report does not call for an end to the controversial practice of badger culling, it does state repeatedly the desirability of replacing culling with a nonlethal alternative, if such an alternative could be found.  Specifically, it emphasises the need for a proper evaluation of badger vaccination.

“The report authors propose a trial to evaluate badger vaccination as an exit strategy from culling.  After the four-year culling licence is completed, they propose that half of the areas should then receive annual vaccination, and half culling every two years.  This approach is helpful to compare exit strategies, but on its own it will not provide a proper evaluation of vaccination, because prior culling will undermine the effectiveness of culling.  There are two reasons for this.  First, culling weeds out the animals that are easily captured and so, after four years of culling, it will be more difficult to capture badgers for vaccination.  Second, vaccination works by protecting animals which have not yet been infected, but culling increases infection prevalence and, correspondingly, reduces the number of animals that can be protected by vaccination.  For these reasons, vaccination may perform less well on recently culled populations.  It would be helpful to know if, say, culling for four years and then vaccinating for four years would be more or less effective than just vaccinating for eight years; the latter would certainly be less costly to implement.  Given the desirability of a nonlethal approach to TB control, it would be well worth including a third treatment, where vaccination is implemented from the start, without any culling.

“The report also discusses the potential for TB control to be overseen by a new body, separate from APHA and Natural England.  This proposal is worrying, because the badger is a protected species, and decisions about its management need to be taken by an organisation tasked with conserving wildlife, rather than one which views it simply as a pest.  The suggestion that government might consult less often on TB control measures is also cause for concern.”

Prof Matt Keeling, Professor of Populations and Disease, University of Warwick, said:

“On the whole this is generally well balanced report, that tries to outline the underlying science without getting involved in the emotive issues.  In this respect the authors have done exceptionally well, providing a broad over-view of the science and its implications for policy.  The ‘Summary and Conclusions’ are an excellent consensus of the science and the complexities of bovine TB control; the problem will be ensuring that the interested parties take the full breadth of the conclusions and do not just pick the points that most closely agree with their own pre-conceptions.

“I’m slightly surprised that there isn’t a wider economic over-view of the problem – in terms of current costs and the likely costs of future control options.

“I’d pull out two main points from the review, which talk to the controversy about the role of badgers: “Our interpretation of the evidence is that the presence of infected badgers does pose a threat to local cattle herds” – (although the scale of this threat is difficult to quantify); and “… it is wrong, we believe, to over-emphasise the role of wildlife and so avoid the need for the industry to take measures that have in the short- term negative financial consequences.”  Taken together these clearly say that infected badgers do play a role, but this is far from being the whole story and other action needs to be taken.

“The review provides a strong review of the evidence for other control options: risk-based trading (preventing the spread of infection by stopping the movement of cattle likely to be infected); farmer-led biosecurity; control of infection in badgers or control of the badger population; improved surveillance and diagnostics (such that more infected cattle are identified earlier).  These have huge policy implications for DEFRA.

“I’ll finish with a personal perspective on this problem.  Both cattle and badgers play some role in the spread and maintenance of bovine TB, placing a huge burden on affected farmers.  It is difficult if not impossible to disentangle the relative contribution of each species, and it is likely to vary across the country.  Therefore while culling of badger could play some role in reducing cases of bovine TB in cattle, it cannot be the only measure.  Finally, if bovine TB was being spread by rats rather than badgers, then the options would be much more clear – we would be culling rats around each farm, as well as taking other action.  The question is therefore how much we value badgers as an iconic wild animal — the higher the value we put on these animals the less sense it make to include culling as part of the control measures.  This is not a question of science, but is an issue for society.”

‘Bovine TB strategy review, Report to Rt Hon Michael Gove MP, Secretary of State, Defra’ by Professor Sir Charles Godfray FRS (Chair) et al.was published by Defra at 00:01 UK time on Tuesday 13 November 2018.

Declared interests

Prof Malcolm Bennett: “My background/interests/conflicts are that I work on infectious diseases that jump species, especially when wildlife are involved, and including bovine TB in badgers on the edge of the current epidemic.  This project relies on the active engagement of a range of stakeholders including farmers, vets and wildlife groups, and was core-funded by Defra.”

Dr Colin Butter: “No conflicting interests.”

Prof Rob Smith: “I am retired and do not have paid employment nor am I in receipt of any external funding.  I have previously been an independent member of the UK Advisory Committee on Pesticides, the UK Committee on Toxicity and the EFSA Panel on Plant Protection Products and their Residues.”

Dr Steven Van Winden: “None that I can think of.”

Prof Rosie Woodroffe: “I was on the team which designed and oversaw the Randomised Badger Culling Trial and have received research funding from Defra. I have also collaborated extensively with one of the report’s authors.”

cuNone others received.