Scottish Government

Preparing for a new GB strategy on bovine tuberculosis

PART ONE

3. Review of the TB Strategy

3.1 What is the current approach on bovine TB?

3.1.1 Krebs report: In 1996 the Government asked Professor Sir John Krebs to review scientific knowledge on bovine TB. Recommendations were published in December 1997. One of the main recommendations was to set up an experiment to quantify the impact of culling badgers on incidence of TB in cattle, to be overseen and analysed by an independent expert group. The Government has done this. Another recommendation was that outside hot-spot areas the farming industry should investigate the impact of simple husbandry techniques. The Government's role was to provide advice. This has since been done in the form of guidelines to farmers on good husbandry practices to minimise the transmission of TB (Golden Rules for a Healthy Herd, Farm Biosecurity, TB in Cattle: Reducing the Risk). The review also recommended a programme of research which has now been implemented. Various other suggestions on the procurement and co-ordination of the research programme have also been taken on board with a large proportion of the research placed now going to open competition and all proposals being subjected to rigorous peer review. The outputs of the current research programme are intended to be fit for policy purposes and provide scientific evidence and tools to underpin future strategies.

3.1.2 The Krebs report made clear that the control of TB in cattle is a complex problem with no single solution. The report recommended a combination of approaches on different timescales. To take forward the recommendations of the Krebs Report, the Government set out a 5-point plan of action:

• Protecting human health;
• Developing a vaccine;
• Research into how TB is spread;
• Cattle testing and controls; and
• Badger culling trial (Randomised Badger Culling Trial - RBCT).

3.1.3 Independent Scientific Group (ISG) on Cattle TB: This Non- Departmental Public Body was set up in February 1998 to provide advice on the implementation of the Krebs report on bovine TB in cattle and badgers. The Terms of reference given to the Group were:

'To advise Ministers on implementation of the Krebs report on bovine TB in cattle and badgers by:

• overseeing the design and analysis of the RBCT to test the effectiveness of badger culling as a means of controlling TB;
• regularly monitoring the progress of and outputs from the trial and assessing any important differences in results between treatments;
• monitoring data on the M. bovis situation in areas and species outside the trial;
• reporting to Ministers on progress; and
• advising as requested, on related issues.'

3.1.4 The Randomised Badger Culling Trial (RBCT) started in 1998 and is due to be completed by 2006. An independent scientific review of the RBCT (and associated epidemiological research) is being conducted. This is due to report in early 2004. Reports of the ISG can be found on Defra's website http://www.defra.gov.uk/animalh/tb/isg.

3.2 The Regulatory framework

3.2.1 Control of bovine TB is a fully devolved matter in Scotland and Wales. However, as GB forms a single epidemiological unit the Scottish Executive and the Welsh Assembly see advantages in working with Defra to common GB policies. A list of legislation pertaining to bovine TB is at Annex B. The key elements are:

• Existing European Union (EU) and domestic legislation govern routine testing of cattle for TB, notification of disease, slaughter, valuation and compensation and the restriction of the movement of affected herds.
• Domestic legislation governs TB in deer. Any deer (alive or dead), wild or farmed, suspected of having TB must be reported to the appropriate Divisional Veterinary Manager (DVM). The legislation also provides for compensation for farmed deer slaughtered for disease control purposes. There is no statutory requirement for deer to be tested for TB, although it may provide trade benefits for the deer farmer.
• Food safety legislation requires that raw cows' and buffalos' milk shall come from animals belonging to a herd which is officially TB-free. Milk that does not satisfy this condition must be heat treated before being sold for human consumption. In Scotland the sale of non-heat treated cows milk has been prohibited since 1983.
• Also under food safety legislation, the Meat Hygiene Service inspects all cattle carcases for visible signs of TB. Where localised lesions are found in more than one organ or area of the carcase, then the whole carcase is condemned. However, if lesions are localised and do not affect other parts of the carcase, the affected area is removed and the rest of the carcase may be passed as fit for human consumption.
• The Protection of Badgers Act 1992 makes it an offence to kill, or take a badger, or attempt to do so except under licence or in circumstances defined in the Act, or injure, ill-treat or dig for one.

3.3 What is the current status of the 5 point plan?

Protecting Human Health

3.3.1 Guidance on tuberculosis was issued to Health Boards, Health Trusts and copied to Local Authority Chief Executives in October 1998. This guidance is currently being reviewed and the draft text will be sent out for consultation before being finalised.

3.3.2 The increase in bovine TB in cattle has not, to date, been coupled with an increase in the incidence of human disease in the UK caused by M. bovis. Most human cases of TB are now due to M. tuberculosis. The Scottish Centre for Infection and Environmental Health (SCIEH) monitors all human cases of bovine TB. All cases of TB within an agricultural setting, or where M. bovis is cultured are followed up with a questionnaire. The proportion of isolates cultured in the UK attributed to M. bovis remains low at around 1%. These infections occur predominantly in older Caucasian people in whom they are thought to represent reactivation of infection originally acquired when human M. bovis infection was more common in the UK. While evidence to date is that the risk to public health from bovine TB in cattle is very small there are several reasons not to be complacent about the risks to human health from increases in TB in cattle and wildlife:

• M. bovis is difficult and slow to grow in the laboratory, so cases may be being missed;
• many years may elapse between acquisition of TB infection and progression to clinical disease; and
• the extent to which an increased risk of direct human exposure to infected animals increases the risk of transmission of infection is not known.

3.3.3 Health and Safety Executive guidance on occupational zoonoses recognises the risk of transmission of infection from animals with respiratory tract lesions or infected carcases to groups such as farmers, veterinarians and abattoir workers.

3.3.4 Heat treatment of milk and milk products, and meat inspection in slaughterhouses have a major role to play in consumer protection, in conjunction with cattle testing and control measures.

3.3.5 Divisional Veterinary Managers notify the relevant Chief Environmental Health Officer and the Consultant in Public Health Medicine when disease in a herd is suspected, when a reactor is found and when disease free status is restored.

3.3.6 Results of research carried out on behalf of the Food Standards Agency (FSA) into the detection of M. bovis in edible parts of the carcass from slaughtered reactor cattle have been considered by the Advisory Committee on Microbiological Safety of Food (ACMSF) and the European Food Safety Authority. The ACMSF concluded that the research results did not alter their previous advice that the risk, if any, to human health from eating meat from M. bovis infected cattle is very low. The European Food Safety Authority conclusions will be published in due course.

3.3.7 The UK Zoonoses Group (an interdepartmental body) maintains a watching brief on the potential for M. bovis to infect humans through the UK food chain and other zoonotic routes. It also provides an overview of existing and emerging zoonotic infections to help ensure overall co-ordination of public health action in the UK. Copies have been distributed to interested bodies and details are available on the Defra website www.defra.gov.uk

Testing cattle for TB and putting controls in place

3.3.8 Bovine TB is an infectious disease affecting cattle. Figure 1 illustrates the increase in incidence by comparing maps from 1997 with 2002. The level of TB in cattle has been increasing since 1988. Currently some four per cent of the GB national herd of 99,000 registered herds is under TB movement restrictions. In Scotland 0.8% of herds are under movement restrictions and the main disease incidence "hotspots" are in South-West England, the West Midlands, Powys, Monmouthshire, Stafford-Derbyshire, East Sussex and South-West Wales; for example some 15 per cent of herds in Cornwall have been affected, whilst in Gloucestershire the figure is 25 per cent of herds. In addition, Cumbria has been sustaining greater than usual numbers of TB incidents. The rate of incidence is increasing in Great Britain at around 18 per cent per annum for herds. This is most significant in the Southwest of England but it is spreading to other parts of the country including the Southwest of Scotland.

Figure 1 Bovine TB incidence in GB 1997 and 2002

Notes

• Each map shows confirmed incidents commencing during a twelve-month period
• The area enclosed by the circle is proportional to the number of skin test reactors

3.3.9 The disease is managed through regular testing of herds and slaughtering those animals that test positive. In addition, in a herd suffering a breakdown enquiries are carried out to find the origin of the disease, movements off are traced and tested and contiguous premises are tested. Routine testing is carried out at intervals of one to four years depending on local circumstances. Where TB incidents are high annual testing is the norm. In 2002, nearly 44,000 herd tests were carried out involving more than 4 million animals.

3.3.10 The backlog in testing, arising from the suspension of testing in 2001 because of the Foot and Mouth Disease (FMD) outbreak, has been radically reduced from 27,000 at the end of 2001 to the position in July 2003 where there were just over 3,330 overdue tests (of which 195 were in Scotland) - roughly the level before the onset of FMD.

3.3.11 Animals reacting positively to the test (known as reactors) are separated from the herd and sent for slaughter. Animals whose test result was inconclusive are also separated from the rest of the herd until a follow-up test shows either a positive reaction leading to slaughter or a negative reaction at which point they can re-join the herd. On average, the number of reactors per TB incident in 2002 was 4.7 (although this figure is likely to have been influenced by the limited TB testing carried out in 2001 during the FMD outbreak); this compares with an average of 1.9 reactors per TB Incident in 1997. In 2002 some 22,000 reactor animals were slaughtered, at a cost of some 31 million. This included 177 reactor animals in Scotland at a cost of 207,000.

3.3.12 If TB is found in a herd, restrictions are imposed on movements onto and off the premises until all animals in the herd have been tested and been found clear on two consecutive occasions, or one test in the case of animals tested and infection was not confirmed. In Scotland the only exception to the movement restrictions is to allow animals to be sent straight to slaughter under licence.

3.3.13 The average length of time that a herd remains under restriction has risen steadily over the last 10 years and this increase is paralleled by the increase in average herd size. Between 1997 and 2002 the average duration of a herd restriction due to a confirmed incident of TB has increased from 215 days to 292 days (the average duration due to an unconfirmed incident over the same period has increased from 113 days to 149 days).

Developing scientific knowledge of bovine TB

3.3.14 Three of the five points in the 5 point plan related to research (developing a vaccine, carrying out research on how TB is spread and the RBCT). These have been carried forward in the research programme which is focussed on improving our understanding of TB in cattle and wildlife, trialling disease control options and development of new tools to fight the disease. The research programme is funded by Defra but supports GB as a whole and includes research work undertaken in Scotland.

3.3.15 Full details of the current GB research programme are available on the Defra website at http://www.defra.gov.uk/science/TB_Review. There are plans to publish a new research requirements document in May 2004, taking on board ideas from the wider scientific community and main stakeholders. Research contractors who are successful in their bids will be funded within the available budget from April 2005.

3.3.16 Total expenditure on research associated with bovine TB (excluding the RBCT, TB 99 and Road Traffic Accident (RTA) studies) amounts to 6.8 million in 2003/4.

3.3.17 Where appropriate, research programmes are carried out in collaboration with researchers in other countries. This has been particularly important in carrying forward research on possible vaccines against bovine TB, where collaboration with researchers in the Republic of Ireland and New Zealand has been established.

3.3.18 The results of research are disseminated to stakeholders through presentations of research findings and through the publications by the contractors in the scientific press, and those of the Independent Scientific Group, including their open meeting. Information is also made available on Defra's website.

Improving our understanding of TB in cattle and wildlife

3.3.19 Studies have been commissioned in Scotland and England to determine the routes of infection in cattle, the infective dose, the development of lesions of TB and immunological responses following exposure and infection, the occurrence of shedding of M. bovis and the rate of transmission from experimentally and naturally infected cattle under controlled conditions. These studies will both improve our understanding of how the disease may be spread between cattle, and provide information and experimental models for the development of new diagnostic tests and vaccines.

3.3.20 Research intended to identify all the relevant negative effects of TB at the farm level and for the GB economy together with the relevant costs and benefits associated with selected control strategies is ongoing. In addition, studies aimed at determining the value of badgers to society are in progress in order to allow a complete assessment of the economic effects of bovine TB and possible control measures.

3.3.21 A large scale case control study of farms which have TB breakdowns, the TB99 survey, is intended to determine whether there are risk factors associated with bovine TB, with a view to providing effective advice to farmers on how to reduce the risk of their herd becoming infected.

3.3.22 Epidemiological studies on the occurrence of M. bovis in both cattle and badgers, including studies using strain typing, to help to establish how the disease is spread on a larger scale are also being carried out. We have taken the opportunity afforded by the FMD epidemic of studying the disease in restocked herds.

3.3.23 Studies of badger populations and the effects of disturbing badgers through culling are in place. In addition, Defra are collecting and examining badger carcases from road traffic accidents in seven counties to establish whether this method is useful in determining the prevalence of bovine TB in wild badger populations.

3.3.24 As well as being found in cattle, bovine TB is also found in a wide variety of other animals, e.g. badgers, foxes, deer, and even domestic cats. In order to complete the picture of the epidemiology of bovine TB, there are two studies to determine the range of wildlife species other than badgers which may be naturally infected with the disease. Whilst final reports are yet to be produced, preliminary findings are that researchers have found a very low prevalence of bovine TB in the smaller species such as voles and mice and in the carcases of larger mammals. Bovine TB has been found in five of the six species of deer in GB.

The randomised badger culling trial (RBCT)

3.3.25 The RBCT was established in 1998 to investigate whether culling badgers, either proactively or reactively, is an effective means of controlling the spread of TB in cattle. The trial was not undertaken in Scotland as there is no evidence to suggest that TB in badgers is widespread or is being transmitted to cattle. Expenditure on the trial has been 25 million to April 2003, and the cost is currently about 7 million per annum. The trial involved three experimental treatments:

• proactive culling, which aims to reduce badger densities to very low levels across entire trial areas,
• reactive culling, which sought to remove only those badgers geographically close to recent cattle TB outbreaks on particular premises, and
• no culling (survey only).

3.3.26 On 4 November 2003 Defra announced the suspension of badger culling in England in reactive areas of the Krebs trial. This decision was taken on the basis of interim scientific findings from the ISG. The ISG advised Defra Ministers that its interim analysis of trial data so far indicated that there was a 27 per cent increase in the number of cases of bovine TB (breakdowns) occurring in reactive culling areas compared with the related survey-only areas where no badger culling took place. The proactive and control elements of the trial will be continuing. The RBCT is due to be completed in 2006. The Independent Scientific Group (ISG) will report to Ministers thereafter.

Developing new tools to fight the disease

3.3.27 Work which may lead to the development of vaccines or of new tests for bovine TB is being taken forward. A significant breakthrough in this field was the sequencing of the genome of M. bovis.

3.3.28 In 2003/2004 the spend on vaccine related research is 1.6 million. Progress to date is more or less in line with the timetable which Professor Sir John Krebs envisaged in his report on Bovine Tuberculosis in Cattle and Badgers. The key achievements in the development of a cattle vaccine to date have been:

• A vaccine candidate has been identified that could be more effective than Bacillus Calmette-Guerin (BCG) though no work in the field has yet been done;
• Diagnostic antigens have been identified that differentiate between BCG vaccinated and M. bovis infected animals and assays developed that predict the outcome of infection; and
• Neonatal vaccination is known to be more effective than vaccinating 6 month old calves.

3.3.29 Small scale field studies could be taken forward during the next 3 years, but legislative and licensing hurdles need to be overcome before large scale field trials could be carried out.

3.3.30 Progress has also been made towards the development of a badger vaccine:

• Immunological tools are being developed for the purposes of 1) surveying the population to determine prevalence of infection and risk of transmission, 2) performing badger-side diagnosis, 3) underpinning a badger vaccination strategy by monitoring vaccine 'take'; and
• An experimental BCG vaccination/challenge study is underway.

3.3.31 Small scale feasibility field studies could be possible in the next 3 years in collaboration with the Republic of Ireland. Large scale field trials await the outcome of the RBCT and resolution of licensing issues.

3.3.32 The report of the Vaccine Scoping Study Sub Committee of the Independent Scientific Committee was published in December 2003.

3.3.33 Research intended to improve diagnostic tools includes the development of new antigens for the existing test methods (skin testing, gamma Interferon and Enzyme Linked Immunosorbant Assay (ELISA tests)) in order to improve their sensitivity and/or specificity and the adaptation of new test methods such as polymerase chain reaction (PCR) for use with M. bovis. Test development will be an integral part of the vaccine development programme; as it is unlikely that any vaccine will be 100 per cent effective in protecting animals against infection, tests which can distinguish between vaccinated animals and infected animals will be necessary before a cattle vaccination programme could be contemplated.

3.4 What is it costing?

3.4.1 The cost to the Scottish Executive (who are responsible for valuers fees and compensation payments) and the UK Government associated with control of bovine TB in GB is forecast to be 71 million in 2003/4. Details are set out in the table 1 below. Costs borne by the UK Government include extensive surveillance testing in cattle using the tuberculin skin test, payment of valuers fees, transport to slaughterhouses of TB reactors, slaughterhouse monitoring, compensation to farmers, cost of slaughter net of salvage value of any animals not unfit for human consumption, laboratory examination of samples taken in slaughterhouses, and costs associated with disease control measures in herds with reactor cattle. The Government also invests in a wide ranging research programme.

Table 1 Government expenditure on TB

3.4.2 Legislation provides for farmers to be compensated for the market value of reactor animals that are slaughtered under disease control measures. The consequential losses/costs are borne by the farmer and are difficult to quantify. Industry estimates made in the late 1990's put average on-farm costs at around 36,000 per affected farm, although this disguised a very wide range between farms. Current research based on a farmer survey is likely to suggest a lower figure but also indicates wide variation in costs. The majority of breakdowns involve a small number of reactors and the financial implications appear to be much lower than the 36,000 figure which is often quoted. However, there are a small number of cases, generally involving larger herds and larger number of reactors, where the costs are considerable. This research is due to be completed and a report sent to Defra by January 2004. A summary of the report will be published on Defra's website in spring 2004.

3.4.3 A report by the National Audit Office Wales published in July 2003 estimated that, in 2002, compensation was at least 50 per cent higher than underlying market prices for both commercial and pedigree animals. A similar situation exists in England with differences between TB valuations and market prices being greatest since the 2001 FMD outbreak. Due to the much lower incidence of TB in Scotland there is little evidence to conclude that a similar position exists. It is envisaged that new valuation arrangements will be put in place as a result of the consultation on rationalisation of compensation arrangements across animal diseases, which was issued on 27 October 2003.

3.4.4 These costs must be considered against a background of a GB agriculture industry with a value of 6.7 billion (measured in terms of Gross Value Added at basic prices). There are more than 3.3 million breeding cows in Great Britain - 1.9 million dairy cows and 1.4 million suckler cows. In Scotland the there are 199,000 dairy cows and 489,000 suckler cows, showing that the beef sector is more important to the Scottish economy. In 2002 almost 1.9 million cattle were slaughtered for meat. The national herd includes some 62,500 beef herds and 22,500 dairy herds. Equivalent Scottish figures are over 10,000 beef herds and about 2,160 dairy herds. Dairy herds tend to be much larger than their beef herd counterparts - almost 70 per cent of dairy herds contain over 100 animals compared to only 24 per cent of beef herds containing the same number.

Impact of CAP reform on cattle farming

3.4.5 In developing a new TB strategy we will need to take into account the structure and economics of the cattle farming industry, including the impact of CAP Reform. When the full effects of the CAP Reform agreed at Luxembourg in June 2003 have worked through they are expected to deliver significant economic benefits for the UK as a whole. Decoupling or breaking the link between subsidies and production, is the central element of the Reform Agreement and presents a significant change for the farming industry. The Agreement also includes a number of options for the final shape of the Reforms and these are currently subject to consultation in Scotland. Further details are available on the Scottish Executive's website:- http://www.scotland.gov.uk/about/ERADA/AgriPol/00017653/Home.aspx.

3.4.6 In implementing the Reform, a new Single Payment Scheme will apply from January 2005. There is concern about the possibility of reduction in the Scottish suckler herd as a result of decoupling. Various economic analyses indicate that the drop in beef production could be around 5-10%, with greater reductions possible in the more remote parts of Scotland. This could have implications for the environment and rural communities which have a higher dependence on agriculture within the economy. However, some parts of Scotland, such as the North East, may increase production, or switch marginal arable land into to grassland; some concentration of production may also take place.

3.4.7 In the dairy sector, proposed cuts in support prices for dairy products are only partially compensated by the introduction of direct payments. However, other factors affecting the dairy sector will also play a part in any future restructuring in the sector. Early decoupling of the dairy direct payments should bring dynamic benefits to the dairy sector and allow it more easily to restructure to meet the challenges posed by the lower price environment likely to result from the reforms. There is the option to bring forward the decoupling of dairy direct payments from 2007 to 2005. However, a final decision will not be made until February/March 2004, once the current consultation has closed and decisions are taken.