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This publication is available at https://www.gov.uk/government/publications/a-strategy-for-achieving-bovine-tuberculosis-free-status-for-england-2018-review/bovine-tb-strategy-review-summary-and-conclusions
Bovine TB is an infectious disease that spreads between cattle that is unlike any other endemic disease afflicting the livestock industry in England. The prevalence of the disease in parts of the country, coupled with the test and slaughter strategy that is the basis of disease control, makes the risk and consequences of infection one of the greatest factors affecting the livelihoods of numerous farmers. In writing this report we are acutely aware of the burden this disease places on the welfare and well-being of farmers and their families. We do think more can be done to control this disease, and hopefully eventually eliminate it, but we would be offering false hope if we pretended this will be other than a protracted campaign.
The disease is also unusual in that it infects an iconic wild animal, the badger, and there is transmission to and from badgers and cattle. Culling of badgers to reduce infection in cattle is seen as unconscionable by some sections of society and currently the Labour Party has pledged that culling will not be part of its bovine TB control strategy (and Wales also currently has a no-cull policy). The deeply held beliefs of people who cannot countenance culling badgers deserve respect, as do the beliefs of people who argue that sacrificing badgers is justified to reduce the burden of this disease on livestock and farmers. The decision whether or not to cull badgers must be informed by evidence which provides important information on likely outcomes. However, final decisions have to take into account the irreconcilable views of different stakeholders and so inevitably require judgements to be made by ministers.
Our interpretation of the evidence is that the presence of infected badgers does pose a threat to local cattle herds. This interpretation reflects the broad consensus amongst epidemiologists who have studied the disease. Reducing this threat, by culling or non-lethal intervention, will thus help lower the incidence of the disease in cattle. If a decision is made not to cull, and if non-lethal interventions prove less effective, then progress towards eliminating the disease will be slower and complete elimination may be even more difficult.
A very unfortunate consequence of the controversy around badger culling and the politicisation of the debate has been a deflection of focus from what can be done by the individual farmer and by the livestock industry to help control the disease. In particular, the poor take up of on-farm biosecurity measures and the extent of trading in often high-risk cattle is, we believe, severely hampering disease control measures. All the industry bodies we spoke to recognised this as an issue and saw the need for industry to take more ownership of the problem. Implementing better control measures on the livestock side will mean short- to medium-term costs to the industry to achieve the greater goal of bovine TB elimination. The degree to which the industry as opposed to the state or the consumer bears these costs is a decision for ministers but 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.
Bovine TB is a notifiable disease and exactly how it is monitored and controlled affects our ability to trade. The complex statutory underpinning of surveillance and control, involving both national and European legislation, makes agile and adaptive management of the disease very difficult. We believe this legal and administrative viscosity hampers better disease control. We report at a time when the UK is negotiating to leave the EU but when the final settlement of our trading relationship and regulatory alignment with the EU is yet to be agreed. The disadvantage of this timing is that detailed cost-benefit analysis of the consequences of the different control options we discuss is not possible. The advantage is that with the inevitable restructuring of our agricultural governance arrangements there is the opportunity to explore better disease control interventions. We urge that the opportunity to re-fashion the regulation on bovine TB is not missed.
The main body of the report, Chapters 3-9, explores a wide range of interventions that we believe should be considered in attempts to control bovine TB in England. We have attempted to broaden the discussion of interventions from a narrow focus on epidemiology, and tried dispassionately to weigh their advantages and disadvantages. In many cases we do not recommend a specific course of actions. This is for a number of reasons including:
- many decisions require ministerial judgement, for example those involving ethics or costs
- further more detailed cost-benefit analysis and modelling is required than has been possible in this study
- we do not know the final post-EU arrangements
In this chapter we summarise our conclusions and highlight the factors that we believe should be at the front of decision makers’ minds when determining future policy.
We believe that there is a strong argument that current governance arrangements poorly serve bovine TB control. They have resulted in too little industry ownership of the disease and a widespread implicit belief that bovine TB is government’s problem alone. Within government and its agencies, multiple bodies share responsibility for different aspects of the disease, and the ability of the system to adapt rapidly to new epidemiological evidence or new technologies is inadequate.
In New Zealand, bovine TB control efforts are led by the industry and this has produced very good results. There is also a major wildlife reservoir species in New Zealand, but this is the introduced Australian brush-tailed possum; culling possums has agricultural and conservation benefits and is relatively uncontroversial. We do not think adopting this governance model in England would be possible as giving industry as great a control over policy concerning the disease in wildlife would be unacceptable to many, while partial responsibility would be unattractive or unacceptable to industry.
We see many advantages of retaining high-level policy making in Defra but devolving much of the disease control operations to a new body that would take over functions currently performed by APHA, Natural England and local authorities. Centralising functions in this way would be more efficient, avoid duplication and allow greater co-ordination and agility. Separation from government would make it easier for the new body to work collaboratively with industry and other stakeholders, encouraging shared ownership of the problem. We have discussed these issues with Dame Glenys Stacey who is currently leading a review for Defra of the broader issue of farm regulation and inspection and are aware this proposal aligns with some of her likely recommendations.
An important part of farmers taking more ownership of the disease is ensuring that they receive the best advice (for example on safe trading practices, on-farm controls and biosecurity) from trusted sources. Existing information available on the web (TB Hub) is very good, though obviously farmers must be motivated to find and make use of it. We believe the role of private veterinarians in providing advice is particularly important and should be supported, taking into account the true costs of its provision for veterinary businesses. Study of best practice in the Devolved Administrations and the Republic of Ireland (RoI) will be very helpful in designing support for farmers in England.
Consultation with industry and other stakeholders is an important part of bovine TB control and of achieving shared ownership of the problem. Nevertheless, we believe that the current frequency and granularity of consultation is cumbersome and counter-productive. Concern over ‘consultation fatigue’ was expressed to us by many stakeholders. We see advantages in consulting at a higher level on broad strategy and principles of adaptive management. This will enable operational decisions to be made more swiftly and more flexibly as circumstances change and new evidence emerges. We are aware that changes in the nature of consultation will involve some legislative amendments.
Surveillance and diagnostics
If a test is not sensitive enough it will miss too many infected animals, while if it is not specific enough it will produce too many false positives. There is often a trade-off between sensitivity and specificity. The test we use in the United Kingdom (UK) and the RoI (the Single Intradermal Comparative Cervical Test, SICCT) has high specificity but lower sensitivity than that used in continental Europe (the Single Intradermal Cervical Test, SICT). There is some evidence that the sensitivity of the SICCT under operational field conditions is lower than that estimated in formal trials.
Policy makers need to balance the disadvantages of low specificity (more cattle sent to slaughter and herds placed under provisional restrictions) and low sensitivity (infections going unrecognised). We see a strong argument for moving to a more sensitive test (probably the SICT) for surveillance in the High Risk Area (HRA) and Edge Area (EA) to enable the detection of infections in these regions as early as possible. In the Low Risk Area (LRA) the numbers of new infections detected would not justify the increased number of false positives. Such a change would be allowed given current EU rules. Once outside the EU, there would be scope to use either the SICT or caudal fold test (CFT) for herd screening and to retest reactor animals with the interferon gamma test to reduce the number of false positives detected by the more sensitive screening test.
Were this change to be made, the number of herd breakdowns would in the short term go up as more infections are revealed. It is very important that policy makers and all stakeholders understand this epidemiological reality and do not misinterpret it as a policy failure.
Once infection is discovered in a herd it is important to identify all cattle infected with the bacterium. There are a number of circumstances where there is particular premium on removing infections from herds as quickly as possible. These include herds with persistent and recurrent infections, herds in badger cull areas where it is important to avoid re-infecting wildlife, herds in the EA where preventing geographical spread into the LRA is a high priority, and emerging hotspots of infection within the LRA. Here, combining a skin test, the interferon gamma test and the IDEXX ELISA serological test, should be considered as each test detects some infected animals that the other tests miss. The costs of testing would increase, but the epidemiological benefits in these critical cases would be substantial.
The current SICCT, SICT and interferon gamma tests rely on tuberculin – essentially a cocktail of proteins derived from the bacterium that is difficult to standardise. We see a strong argument for investing in better tuberculin quality control. In the medium term, and requiring efficacy and safety tests, the aim should be to replace tuberculin by defined antigens. Such tests would also provide a DIVA (differentiating infected from vaccinated animals) function.
There is intensive research on TB testing and diagnostics in both the human and veterinary science worlds. A number of promising tests are in development. Other innovations include the possible bulk-testing of milk for evidence of infection. We see it as very important to make sure that an efficient pipeline is developed to assess the value of new innovations, to carry out field efficacy and safety tests, and where justified to deploy them rapidly. We realise, of course, that the administrative burden of changing test protocols, as well as any consequences for trade, have to be taken into account.
Currently, M. bovis, the bacterium responsible for bovine TB, is genotyped using information from specific regions of its genome. Recent advances in molecular biology make it now feasible and cost-efficient to move to whole-genome sequencing which we believe should be used routinely. This technique allows disease transmission pathways to be identified with greater accuracy (though cannot of course resolve all issues in identifying sources of infection).
Vaccination and genetic resistance in cattle
The BCG vaccine available for cattle provides some but not complete protection against bovine TB. However, vaccinated cattle often test positive for current tuberculin-based tests for the disease and the widespread use of BCG in cattle would compromise surveillance (and affect trade in live cattle and dairy products).
In our view, the goal should be for testing to move to DIVA tests. Once these are available, then the possible advantages of different models of vaccination deployment should be re-examined. This should involve a cost-benefit analysis that takes into account implications for international and UK trade and business. Recent studies in humans and other primates have explored the potential of improving BCG vaccines and vaccination protocols. Investigation of whether these and future advances carry over to cattle is worthwhile.
Progress has been made in understanding the genetic basis of bovine TB resistance in cattle enabling genetic selection for higher resistance. This sensible approach that will in the long term make a modest but valuable contribution to disease control should, we believe, be supported.
Defra and the livestock industry are currently investing in the Livestock Information Service (LIS) which will provide information on the movements of all cattle in the UK linked to electronic identification tags. LIS will have multiple functions, of which providing information that can be used in bovine TB control will be one of the most important. We place a very high priority on supporting and implementing LIS, and strongly advise that considerations of how it can be used to combat this disease are taken into account at the design stage.
It is now routine to mark horses and pets with microchips and we believe further investigation of the feasibility of this for cattle is warranted. It would reduce the opportunities for fraud and improve traceability. We understand the need to avoid microchips entering the human food chain.
Relatively crude indices of the risk of infection of cattle have already been developed and LIS will enable more sophisticated measures. There is, we believe, a very strong argument that these measures should mandatorily be available prior to purchase and at market ring-sides.
The number of cattle movements in England is very high and will inevitably be a risk for disease spread. We have not been able to do a full analysis of the regulatory and economic drivers of this level of trading with the time and resources available. We recommend such an analysis is carried out to discover whether there are perverse incentives for movement and if these can be changed as part of post-EU agricultural reforms. The analysis should also test whether movements that increase the efficiency of the industry provide sufficient benefits to outweigh the negative externality of disease spread.
Farmers are currently compensated for slaughtered cattle (or might in the future take out insurance against the risk). We believe that there is a strong argument for disincentivising risky trading by reducing compensation (or insurance payments) to reflect trading behaviour. Such adjustments would need to be relatively large to change behaviour.
There is evidence that mandatory post-movement testing has reduced the movement of cattle from high- to low-risk areas. Policy makers should consider extending this to at least the EA and to mandate the use of the most sensitive test. We consider that the increased costs of trading that will be borne by the industry is justified by the likely reduction in disease spread.
Disease in wildlife
The evidence shows that badgers do transmit bovine TB to cattle and contribute to the persistence of the disease. Ministers have to decide whether the real but circumscribed benefits of culling to the farming industry outweigh the animal welfare and environmental concerns of other stakeholders. This decision must be informed by scientific evidence but inescapably involves a judgement call by ministers.
There is evidence that culling badgers perturbs the animal’s social structure leading to increased risks of herd breakdowns in adjacent non-culled areas – the perturbation effect. If a decision is made to cull, then carrying it out over sufficiently large geographic areas to reduce the relative effects of perturbation and utilising natural barriers to badger movement, as is done at the moment, is in our view correct. Experience from the Randomised Badger Culling Trial suggests that the benefits of widespread culling repeated annually for four years persist for some years after lethal control stops, and hence we see periodic culling as a more promising strategy than continuous culling beyond four years.
Moving from lethal to non-lethal control of the disease in badgers is highly desirable. Though research into other options should continue, we believe that the injectable BCG vaccine is the only viable option currently available. At the moment there is limited information about the relative effectiveness of vaccination and culling on incidence of the disease in cattle, though the results from small-scale vaccine projects in England and large-scale deployment of vaccination in the RoI will help address this. We believe it is very important to maintain flexibility in policy over control of the risk of transmission from badgers to be able to respond to the changing evidence base.
If uncertainty about the relative effectiveness of vaccination and culling is not resolved by analysis of the outcomes of existing interventions (in England and elsewhere) then we believe government should address this need. Culling is currently being carried out, or being planned, in 32 areas, chiefly in the west of England. On the assumption that this goes ahead and that periodic culling rather than continuous culling is adopted), we suggest that after four years of culling government should consider a programme in which badgers are vaccinated in half of the areas and, after a two-year pause, intensive culling resumes in the other half. The outcomes should be monitored and adaptively managed so should it become clear that vaccination is providing comparable benefits to culling then all areas should adopt it, with the opposite happening if vaccination fails to provide protection.
The evidence does not suggest that other wild or feral animals (for example deer, fox, wild boar) pose a substantial national threat to cattle but any opportunity to increase our knowledge of disease prevalence in these species should be taken.
The disease in non-bovine managed animals
Bovine TB occurs in other farmed animals, though is less of a problem than in cattle. Defra has recently consulted on improvements in regulations concerning non-bovines (particularly South American camelids such as alpacas) and we support their implementation.
The evidence base about which particular biosecurity measures work is not strong because of the difficulties of carrying out formal experiments for each of multiple different options. Nevertheless, there are many relatively cheap things a farmer can do to separate cattle from badgers, cattle from other cattle on neighbouring holdings, and potentially infected from uninfected cattle. These are ’no regret’ biosecurity options whose take up is disappointingly low. In our view, the issue here is not the availability of information but motivation to discover what can be done and to implement the measures. Above we stress the importance of the industry taking greater ownership of the disease, and we hope this leads to greater uptake of biosecurity. We also underline the importance of farmers’ trusted advisors, in particular private veterinarians, giving clear and unambiguous advice on biosecurity.
A number of accreditation schemes mandate biosecurity measures while supermarkets also lay down rules for their suppliers. Unifying all these rules relevant to bovine TB in a single guidance set would, we believe, be helpful for farmers and stimulate uptake. Were the single bovine TB authority we discuss in chapter 9 to be created, this would be the natural body to coordinate.
Farmers are at present partly compensated for losses due to cattle slaughtered for reasons of disease control. We have examined the relative merits of compensation versus insurance and recommend further exploration of the latter. Because of the issues of adverse selection, government would need to be involved in setting up an insurance programme (as, for example, it has been in flooding insurance) and in information provision. We envisage a compulsory insurance programme partially supported by government (replacing compensation) with premiums and compensation designed to incentivise and reward behaviour that reduces the risk of disease.
We note recent evidence that the potential for bovine TB to be dispersed by spreading slurry or manure on the land may have been under-appreciated. We believe obtaining more evidence on this transmission route, and then if appropriate mitigating it, is important.
British farming after the CAP
In September 2018 the government published the Agriculture Bill and a policy statement on The Future for Food, Farming and the Environment both of which outline a vision for British agriculture outside the Common Agriculture Policy (CAP). A clear direction of travel from indirect subsidy (Single Farm Payment) to “public money for public good” is indicated. The next decade will see arguably the greatest change in British farming since the 1940s and ensuring these changes facilitate bovine TB control will be critical to successful elimination of the disease.
Current incentives to hold agricultural land for investment has increased the amount of land rented out for grazing. New rules introducing Temporary Land Associations mean that a farmer renting the land is not required to record cattle movements as long as they are less than 10 miles from his or her farm’s central location. We have not been able to analyse fully the extent of this movement but are concerned about the role of short-distance movement in disease spread. We hope that the introduction of the LIS will enable data to be collected on this movement easily without excessively burdening the farmer. Policy makers should consider whether, even with our imperfect current knowledge, reducing local movements in the most critical places for spread (the EA) is justified. Looking to the future, ensuring post-CAP arrangements reduce incentives for local movements would be helpful, though we realise may impact upon the industry.
There has been recent discussion about the extent of short-term tenancies in British farming and the disincentive this introduces to investment to increase productivity. We note that these investments include those to reduce the risk of bovine TB and that disease control would also benefit from measures to encourage long-term investment.
There are many areas, some outlined in this review, where research has played a valuable role in the battle against bovine TB. The specific need for more research, such as in novel diagnostics, vaccines, genetic resistance and around farmer behaviour, is identified in this report. Research in this field is funded by a variety of bodies and occupies the whole spectrum from largely fundamental to highly strategic. This diversity is a strength. Nevertheless, we believe there would be a benefit from setting up a forum that would better link research funders with the needs of customers of the more applied research. This would ensure that the research had the highest possible impact and value for money.
We conclude with two broad observations. TB is a complex and difficult disease to control, both in humans and in animals. Research over more than a century has provided many insights into the disease and tools to help combat it, and future research will be equally informative. In designing a strategy to control bovine TB in England and progress towards elimination 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.
Second, we most always remember that this is a disease control campaign with a clear objective and, unfortunately, requiring sacrifices to be successful. Because of the complexities and multiple consequences of the disease – epidemiological, economic and social – it is inevitable that a large series of rules and regulations have had to be put in place. This can foster a philosophy of living with the disease (and the regulations) rather than being part of a disease control campaign. Today, bovine TB incidences in England, definitely in cattle and possibly in badgers, are at best roughly stable. This cannot be allowed to continue. There are no easy answers to reducing disease levels and what is required is new drive and a concerted and concentrated effort by all sectors involved.