What are the most commonly asked questions about bovine TB? And what are the misconceptions?
On this page we answer questions covering everything from the history of the disease and its spread to current government policy, such as:
You can find the answers to these questions and many more by clicking on the links below.
Bovine tuberculosis (bTB) is an infectious disease of cattle.
It is caused by the bacterium Mycobacterium bovis (M. bovis), which can also infect and cause TB in badgers, deer, goats, pigs, camelids (llamas and alpacas), dogs and cats, as well as many other mammals.
This disease is one of the biggest challenges facing the cattle farming industry today, particularly in the West and South West of England.
- Read more: TBhub
Bovine TB is spread from cattle to badgers and badgers to cattle.
This is known as the cycle of reinfection.
The links between badgers, cattle and TB infection were first suspected in the early 1970s and both experience and experimentation has subsequently proved them beyond doubt. Professor Sir John Krebs concluded in his 1997 report that there was “compelling evidence” that badgers transmit bTB to cattle.
In addition, both the Zuckerman and Dunnet reports to government came to the conclusion that the badger is the most important wildlife reservoir and it is involved in the maintenance and transmission of the disease to cattle.
There is still some uncertainty surrounding bovine TB and the way it is transmitted, but it is mainly a respiratory disease, caught by breathing in the M. bovis bacteria that cause bovine TB. This usually happens when animals are in close contact with each other, so animal density is a major factor in the transmission of M. bovis. Bacteria released into the air through coughing and sneezing can spread the disease to uninfected animals.
Direct transmission can happen, e.g. through nose to nose contact. There is also evidence that indirect transmission is possible, e.g. through contact with saliva, urine, droppings, pus from abscesses, etc. We know bovine TB is transmitted from cattle to cattle; from badgers to cattle and cattle to badgers; and badger to badger.
Results from research conducted by Crispell et al suggest that cattle are 10 times more likely to catch bovine TB from badgers than badgers are from cattle. Within-species transmission occurs at higher rates than between-species transmission for both.
The programme of trials that followed the Krebs report were designed to identify the most effective strategy for preventing bTB in badgers spreading into cattle populations.
Cattle movements are also part of the problem and have been linked to taking the disease to previously TB-free areas. However, evidence shows that, providing the wildlife is not also harbouring the disease, this doesn’t lead to a long-term TB problem. For example, Northumberland has had pockets of bTB caused by cattle movements, but the outbreak has been stamped out and there is no evidence of any wildlife reservoir of the disease in this area.
The vast majority of bTB outbreaks occur in the ‘hotspot’ bTB areas of the South West and the West Midlands, and in these high-risk areas up to 50% can be attributed to localised transmission involving infected badgers.
- Read more: Independent Scientific Review Group. 1997. Bovine Tuberculosis in Cattle and Badgers (Appendix 5)
The disease is spreading north and east across the country.
There are now areas where the incidence of TB in cattle is persistent and high. These are called ‘hotspots’. These are mostly centred in the South West and the West Midlands. However, as the disease is spreading there are more and more hotspots in places such as Cheshire, and increased areas across the East Midlands.
There has been a large increase in the number of cattle slaughtered because of TB in the last 20 years. According to Defra statistics, in 1998 there were 5,000 cows slaughtered due to bTB in England. In 2021, 27,581 cattle were killed.
Since the badger cull began in 2013 there has been a 36.2% decrease in the level of TB incidence within the high-risk area from 3,370 in January 2013 to 2,150 in January 2021. Currently 78.8% of land within the high-risk area and 16.2% in the ‘Edge’ area is involved in the badger cull.
TB in humans became a significant problem in Victorian England as industrialisation crowded people together in insanitary conditions in large cities.
At this time, many of the dairy herds that were kept in and around the cities to provide fresh milk became infected with bovine tuberculosis (bTB). The milk was a potent source of infection and many people died.
A law was passed making it illegal to sell tuberculosis milk and the tuberculin test, which could identify infected cattle before they showed symptoms, was developed. It was seen to have the potential to eradicate the disease and so the Attested Herd Scheme was introduced in 1935.
By 1950, herds that tested positive for the disease were compulsory slaughtered. This scheme involved regular compulsory testing of all cattle herds and the slaughter of bTB reactors, just as happens today.
It was at the NFU Conference in 1958 that the government announced, wrongly, that TB had been eradicated.
By the mid-1970s, all cattle herds in the UK were thought to have been cleared of bovine TB. However farmers in two areas, Cornwall and Gloucestershire, continued to see individual cattle test positive, despite having their herds cleared of the disease.
It is believed badgers harboured a reservoir of the disease and had begun to re-infect herds in those areas.
This situation continued at a low level throughout the 1970s. Unfortunately during the 1980s the number of cases started to rise again. This increase in number and geographical area has continued ever since so that bTB in cattle is once again widespread in England and Wales.
Read more: Download our History of bovine TB document
This disease situation has the potential to affect everyone, from those living in rural areas seeing the impact on farming neighbours first-hand, to people who enjoy great British beef and dairy products and want to see a thriving sector.
Everyone will be paying for the costs of bTB via the public purse, with costs set to rise to £1billion in the next ten years unless action is taken.
There is also the potential for bTB to spill over into other species. While there are still very few cases of bTB found in dogs and cats, it is on the increase in other animals, and particularly in alpacas.
Unless bTB is reduced in the environment it is likely that these cases will continue to increase as the disease is forced to find new hosts.
According to Defra, the estimated average cost of a bovine TB breakdown on a farm is £34,000.
Of this, it is estimated £20,000 is borne by the government, mainly as compensation for animals compulsorily slaughtered and the costs of testing, and £14,000 falls to the farmer as a result of the loss of animals, on-farm costs of testing, and business disruption because of movement restrictions.
It has cost the tax payer £500 million to control the disease in England in the last 10 years. It is estimated that the costs of bovine TB control will top £1 billion over the next decade, if no action is taken.
Farmers pay a significant amount with regard to bovine TB and in a variety of ways.
First of all they pay for the cattle control measures. Farmers in endemic areas routinely test their cattle every year, some every six months, and in a breakdown situation (when bTB is confirmed in a herd) they are testing every 60 days. Even for those without TB in their herds, pre-movement testing is required before any animal can be moved off farm.
It is estimated that the average cost of a routine bTB test for a farmer is around £350. Testing requires additional labour and causes significant stress, often leading to injuries to both stock and those people handling them, but also results in loss of income because cows don’t milk as well and beef animals don’t put on as much weight. It is widely recognised that the stress of handling can make animals more susceptible to other conditions and even cause pregnant cows to abort.
According to Defra figures, the estimated average cost of a bovine TB breakdown on farm is £34,000, although this figure can vary enormously from farm-to-farm. Of that, around £14,000 falls on the farm business itself as a result of the loss of animals, on-farm costs of testing, and business disruption due to movement restrictions.
An interim report published by the University of Exeter, looked at the costs of bTB breakdowns on eight case study farms from the South West of England.
One of the dairy farms used in the study, which lost 61 cows to bTB, estimated that the loss of these animals alone cost their farm £56,364 in milk sales. Consequential losses such as these are not recoverable by the affected farm business under the compensation scheme.
In addition, the money paid for animals which are slaughtered does not always truly reflect the value, particularly of breeding stock.
Herd restrictions put on trading animals after a breakdown can also be very expensive. Some farmers cannot sell animals and become overstocked, others cannot buy replacement stock to maintain their business and both situations can lead to big cash flow problems.
In addition, looking at the purely financial costs disregards the enormous emotional damage bTB does to farming families.
Read more - Allan Butler, Matt Lobley and Michael Winter, CRPR Research Paper No 30, Economic Impact Assessment of Bovine Tuberculosis in the South West of England
Read more - Farm Crisis Network report ‘Stress and Loss: A report on the impact of bovine TB on farming families’
In 2009 the FCN conducted interviews and found that ‘dealing with bTB causes considerable stress to both farmers and their families’.
Some 20% of those interviewed admitted that they were either ‘panicked’ or ‘devastated’ by the news of a new outbreak, and a further 50% were ‘upset” or ‘worried’. Farmers told the FCN:
“The worst thing was that cows very close to calving had to be shot on farm. We could see the calves kicking inside as they died.”
“I feel there is a constant dark cloud of uncertainty over me, causing stress, anxiety and fear. I feel weary, mentally and physically which results in pain in my body.”
“Financially it is very stressful. Cash flow is a huge problem. Having to keep animals when I would normally sell them puts more pressure on me, on my family, animal accommodation and feed costs. I don’t know how long we can keep going.”
The study found that many farmers were suffering financial impacts to their businesses, including a reduction in sales of beef and milk as a result of culled animals, increased labour and extra costs of feed and bedding, as they had to keep animals for longer.
Some farmers have become so weary and frustrated by repeated bTB outbreaks that they have decided to go out of beef or dairy production altogether.
The stringent testing regime, and removal of cattle for compulsory slaughter if they test positive for bTB, means that on-farm welfare implications for cows with bTB are kept to a minimum.
However the number of cows being culled because of bovine TB has increased four-fold in the past 17 years and has resulted in hundreds of thousands of cows being killed before the end of their productive life.
Read more: Defra statistics
The major cause of badger deaths - 50,000 each year according to the Badger Trust - is road accidents.
A study of tuberculosis in road traffic killed badgers on the edge of the bTB epidemic area found that 21% of roadkill badgers tested in 2014 were infected with bTB.
However, in the hotspot areas, up to one in three badgers are estimated to have bovine TB. (Source: Independent Scientific Group on Cattle TB).
Badgers spend most of their life below ground sharing the same air space, tunnels and chambers, which provides the perfect environment for the disease to spread within a social group.
As in cattle, the disease affects the lungs, but also the kidneys. Infected badgers experience more extensive development of TB lesions than cattle, and infected animals will lose weight and body condition and experience severe breathing problems which limit their ability to forage normally.
However, it has been shown that badgers can go through a period of ‘latency’ when the disease is present but makes little progress and it is their ability to live with the disease and to pass it on readily within the confines of their setts to other badgers and to cattle at pasture and around farm buildings that makes the badger an almost perfect host for bTB.
A badger with bTB can infect cattle in several ways.
The primary route is inhalation, with cattle breathing in the bacteria from the air.
However, infection from cows eating contaminated material is also an important route.
Clinical sampling of live badgers has shown that bTB bacteria can be isolated from sputum, faeces, urine, bite wounds and draining abscesses. Badger latrine sites, where badgers urinate or defecate in fields, can contaminate grass with bacteria, which can then be transmitted to the cows when they graze.
Similarly, badgers mark their territory by urinating and this is often spread across cattle pastures.
If a badger has TB infection in its kidneys it will excrete a very high level of TB bacteria on to the grass. If an infected badger eats or drinks from cattle feed or water troughs, they can spread TB bacteria through their saliva, which infects the cows when they eat or drink from these contaminated sources.
Infected badgers can also spread the bacteria through open cuts and wounds.
There is also the potential for direct transmission of bacteria through nose-to-nose contact between badgers and cattle.
This can occur when badgers visit farm yards and there is substantial evidence to show close contact in farm buildings as well as regular visits from badgers to cattle feed stores.
The Animal Health and Veterinary Laboratories Agency (AHVLA) reported in March 2014 that nine cats had contracted bovine TB in Berkshire and Hampshire in 2013.
Following screening of the people who came into contact with the infected cats, Public Health England and the AHVLA announced two humans developed bovine TB. This was the first documented case of cat to human transmission.
It is believed that the cats were infected with the disease after contact with wildlife, such as badgers or rats, although other methods such as cat-to-cat transmission cannot be ruled out.
There have been no further cases of bovine TB reported in the Berkshire and Hampshire area since March 2013. The disease is still uncommon in cats.
The evidence shows that bTB can be tackled successfully when the disease is tackled on all fronts at the same time.
This means using both cattle controls and badger controls in the hotspot areas -those areas where the disease is persistent and high.
Cattle herds in TB problem areas, and surrounding areas, are tested every six months and cows that react to the test are isolated and slaughtered.
The remainder of the herd is subject to strict movement restrictions, meaning cows cannot move off farm, unless it is for slaughter, until the whole herd passes two consecutive TB tests 60 days apart.
Despite these measures, huge numbers of farms are still closed down with bTB.
The number of cattle herds in England which were not officially TB free at the end of the period due to a bovine TB incident (non OTF herds) as of 31 December 2021 was 2,130. This was down 14% compared to the same time last year but is still having a devastating impact on the British beef and dairy sectors.
The evidence demonstrates that badgers do spread bTB to cattle and harbour a reservoir of the disease. In the TB eradication strategy published in April 2014 the government recognises the role badgers play in spreading the disease in areas where bTB is rife and makes a clear commitment to controlling the disease in badgers in these areas as part of the strategy. There is no nationwide culling strategy.
A strategy review was conducted by an independent panel, headed by Professor Sir Charles Godfray, in 2018. The findings reaffirm that badgers do transmit bovine TB to cattle and contribute to the persistence of the disease. He makes recommendations in relation to both culling and vaccinating badgers, as well as vaccinating cattle.
In response the government has released its next steps strategy for eradicating bTB and plans to increase vaccination in badgers, as well as continue culling, in areas where evidence shows that bTB is at its highest.
- Defra TB stats
- The strategy for achieving Officially Bovine Tuberculosis Free status for England
- The government’s policy on Bovine TB and badger control in England
- Garnett, B.T. Delahay, R.J. Roper, T.J. Use of cattle farm resources by badgers and risk of bovine tuberculosis transmission to cattle
- Crispell et al Combining genomics and epidemiology to analyse bi-directional transmission of Mycobacterium bovis in a multi-host system
- Godfray Bovine TB Strategy Review
Farmers are working hard to prevent potential disease transmission although it is very difficult for a farmer to prevent a wild animal from coming into contact with livestock out in a field.
The measures that farmers take include raising feed and water troughs off the ground, ensuring doors to feed sheds fit well, and are kept shut at night, storing feed in covered bins and fencing off badger setts and latrines. They also do all they can to make their buildings ‘badger proof’ by ensuring there are no gaps in, or under, doors or walls that badgers could get through.
The only way of totally preventing infection would be to house cattle day and night, for 12 months of the year in secure premises and to sterilise all feed brought in.
The NFU, together with Defra, the Welsh Assembly Government and Food Environment and Research Agency (FERA), developed a Bovine TB and Badgers - Improving Farm Biosecurity DVD which is used to promote best practice.
In November 2015 a cross-industry biosecurity campaign designed to help farmers minimise the risk of their herds getting bovine TB was launched.
All advice on bovine TB from government, farming experts, leading vets and agricultural colleges was made available on one single website - www.tbhub.co.uk.
The campaign also features a Biosecurity Five Point Plan to improve disease prevention on farm and in the cattle trade.
In April 2016, further cattle measures were introduced, including compulsory post-movement testing of cattle moving into the low risk area of England from the rest of England and Wales, to help reduce the risk of disease spread.
On April 1 2017, further new measures were introduced as part of the government’s TB eradication strategy. These measures included wider use of interferon-gamma blood testing in the High Risk Area; using ‘severe interpretation’ for skin tests on traced cattle; harmonising the scheduling of short interval tests in TB breakdown herds; and more effective control of the movement of cattle from one TB breakdown herd to another.
Farmers also have access to independent advice from various events run by veterinary groups.
On February 16, 2015, the Animal and Plant Health Agency (APHA) confirmed the award of contracts for the delivery of bTB testing in England, which changed the way bTB testing is delivered.
From 1 May 2015, all new bTB testing and other Official Veterinarian work has been undertaken by five regional suppliers, who are responsible for allocating local vets and ensuring testing is carried out to a high standard. APHA said the change would help to drive up standards and ensure the ongoing quality of testing for animal disease.
Previously, on-farm bTB testing was done by vets working for private businesses (usually farmers’ own vets) who were trained, appointed and paid for by the APHA to do the work.
Farmers and livestock keepers continue to be responsible for ensuring that TB testing is completed on time but now contact their regional delivery partner to make the arrangements. Delivery partners are then responsible for allocating the actual testing activity through their network of practices, and for assuring the quality of the work performed.
In recognition of the important relationship between farmers or livestock keepers and their vets in preventing and controlling disease and for ensuring the health and welfare of animals, the new contracts required delivery partners to offer testing work to eligible veterinary businesses operating within their geographical regions.
When making arrangements for tests, farmers and livestock keepers can express a preference to use a specific veterinary practice from within the delivery partners’ network to undertake their testing, and this preference will be honoured where possible. Farmers and livestock keepers who prefer to use a practice that is not part of the delivery partners’ network retain an option to pay for the testing privately.
Contract awards for two regions covering Wales were announced on January 27 2015 and came into force on April 1 2015. The changes do not apply in Scotland.
The government published itsStrategy for Achieving Officially TB Free Status for England on April 3 2014 in which it outlined its commitment to tackling TB using all the available options.
The then Secretary of State Owen Paterson re-emphasised that controlling the disease in wildlife is an essential part of the strategy.
During hisstatement to Parliament announcing the publication of the strategy, Mr Paterson also highlighted:
- A scheme forvaccination projects around the edge of the most badly affected parts of the country in an attempt to create a buffer zone of TB immunity to stop the disease spreading further;
- Acomprehensive farm-level risk management programme throughout the cull areas which will be available to all cattle keepers and will provide bespoke assessments and advice for farmers on how to protect cattle;
- An investment of £24.6 million over the current Parliament in the development of effective TB vaccines for both cattle and badgers. Large scale field trials for a deployable cattle vaccine are currently being designed and work is also being carried out on an oral badger vaccine;
- The stepping up of investment in the development of improved diagnostic tests to enable the identification and removal of only TB-infected badgers.
In April 2016, further cattle measures were introduced, includingcompulsory post-movement testing of cattle moving into the low risk area of England from the rest of England and Wales, to help reduce the risk of disease spread.
On April 1 2017,additional new measures were introduced as part of the government’s TB eradication strategy. These measures included wider use of interferon-gamma blood testing in the High Risk Area; using ‘severe interpretation’ for skin tests on traced cattle; harmonising the scheduling of short interval tests in TB breakdown herds; and more effective control of the movement of cattle from one TB breakdown herd to another.
In October 2017 theTB Advisory Service was launched for cattle farmers in the areas of England deemed at high risk from bTB or on the edge of the disease spread. The service aims to help maximise farm biosecurity and minimise the risk associated with cattle movements, with eligible farmers receiving an on-farm visit from an advisor at no cost. A telephone advice service is also available.
Professor Sir Charles Godfray and a team of experts were commissioned in February 2018, by the then Defra Secretary of State Michael Gove, toreview the government’s strategy. His report published in November 2018 found the below:
- Industry must take greater responsibility for on-farm controls, biosecurity and safe trading practices to stop the disease spreading.
- More can be done to help farmers make purchasing decisions reflecting the risks of cattle being infected
- Evidence shows that badgers do transmit bovine TB to cattle and contribute to the persistence of the disease.
- Disease reduction would benefit from greater flexibility and agility in adapting bovine TB control measures as new research findings emerge.
- A new independent body on disease control would be helpful to take over disease control operations from APHA, Natural England and local authorities (this recommendation will be considered by the government in light of the wider Dame Glenys Stacey review into farm inspections).
In March 2020, the then Secretary of State George Eustice published thegovernment’s response to Godfray’s recommendations. It sets out the approach planned for the next five years to achieve TB free status for England by 2038. The government’s top priorities are
- Increasing efforts to find a cattle vaccination in the next five years.
- Evolving the badger control policy with increased support for badger vaccination, following the wide-scale deployment of effective, industry-led intensive badger culling. The government envisages that the current intensive culling policy would begin to be phased out in the next few years, gradually replaced by government-supported badger vaccination and surveillance. Culling would remain an option where epidemiological assessment indicates that it is needed.
- Improving diagnostic testing to root out bTB more effectively, with deployment of more sensitive tests for surveillance supported by greater use of on-farm restriction of cattle with inconclusive test results.
In January 2021, the government launched a consultation on proposed changes to bTB policy. The Government also called for views on a range of possible future measures to accelerate bovine TB eradication in England, such as further improvements to TB testing, supporting responsible cattle movements and rewarding low risk cattle purchasing behaviour.
In May 2021, the government published its summary of responses which included making the following changes to bTB policy:
- Extending mandatory post-movement testing of cattle moving from higher TB risk regions of Great Britain into those parts of the Edge Area where herds are on annual surveillance testing
- Revise the current policy for the use of the Gamma test in the HRA and Edge Area
- New Badger Disease Control (intensive cull) licences will cease to be issued after 2022.
- New Badger Disease Control (intensive cull) licences issued in 2021 and 2022, could, after a minimum of two years of culling, be revoked after a progress evaluation by the CVO.
- The initial financial commitments for companies to apply for a Badger Disease Control licence will remain at four years’ worth of funding. However, the 25% contingency requirement will be removed.
- Supplementary Badger Culling will be limited to a maximum of two years, and the issuing of SBC licences for previously licensed areas or areas licensed for Badger Disease Control after 2020 will be prohibited.
The UK government decided on a multi-faceted approach because the science shows it will work.
In addition, there is evidence from other countries which have significantly reduced TB by tackling all aspects of the infection cycle.
For example, the government in the Republic of Ireland has been conducting a badger control programme. In 2008 Ireland had just under 30,000 reactor cattle. By 2015, the figure had fallen to 15,317. A reactive badger control strategy has been used, removing badgers in areas surrounding new TB herd breakdowns. This measure is partly credited for the 50% reduction in TB incidence that has been seen since 2000.
The government’s TB Eradication Plan, and the decision of successive farming ministers to include badger controls, is based on scientific experience from the Randomised Badger Culling Trial (1998-2007).
It demonstrated four keys areas which need to be achieved to ensure the badger culls are carried out safely, humanely and effectively.
- Controls need to cover a large enough area in order to reduce disease so the current government TB Eradication plan has said that no area under 150km² will be included. The most recent follow-up work published by members of the ISG (Independent Science Group) from the RBCT has shown that the size of area needed for an effective cull is not as large as initially thought and that the benefits can be sustained for a number of years after the cull has taken place.
- The RBCT said that bovine TB could increase outside of the cull area as badgers leave it, taking the disease with them. This is called the perturbation effect. So the current government TB Eradication plan has focused on using hard boundaries such a major roads, rivers and coast lines to ensure perturbation is kept to an absolute minimum.
- The report authors called for strict conditions to deliver an effective cull. The culls are licensed by Natural England under the Badger Act for the purpose of disease control. Licences are only approved once the licence criteria have been met by those applying for a licence.
- The report questioned the cost-effectiveness of a cull and so the farming industry is working with Defra, Natural England and professional contractors to deliver the cull from the grassroots, using local knowledge and local networks. An industry led, funded and delivered method will save money.
- Read more: Department for the Environment, Food and Rural Affairs, Bovine TB - Key conclusions from the meeting of scientific experts 4 April 2011
The Randomised Badger Culling Trial, or RBCT, was a large-scale field trial that was set up to quantify the impact of culling badgers on incidence of TB in cattle, and to determine the effectiveness of strategies to reduce the risk of a TB cattle herd breakdown.
The RBCT represents nearly ten years of work (1998-2007) and nearly £50 million of taxpayers’ money. It was started after the Krebs Review on Bovine TB in Cattle and Badgers which reported in 1997. It concluded that despite there being ‘compelling’ evidence that badgers were involved in transmitting infection to cattle, the development of a control policy was made difficult because the effectiveness of badger culling could not be quantified with the data available.
It therefore recommended that a large-scale field trial - the Randomised Badger Culling Trial, or RBCT - be set up to quantify the impact of culling badgers on incidence of TB in cattle, and to determine the effectiveness of strategies to reduce the risk of a TB cattle herd breakdown.
The results of this robust experimental trial are fully published and peer-reviewed and represent the most substantial and coherent evidence base for the evaluation of badger culling. However, while the design of this experiment was exemplary, some have questioned how effectively it was carried out - in particular, all culling operations were suspended for a year in 2001 because of the Foot and Mouth Disease outbreak - and have raised doubts about the validity of the results on this basis.
How did the trial work?
Thirty areas were grouped into ten sets of three, each called a triplet.
Within each triplet, one area was subjected to repeated (approximately annual) culling across all accessible/consent land (proactive culling). In another area the badgers were culled on a single occasion locally, on and near farmland where recent outbreaks of TB had occurred in cattle (reactive culling).
The remaining area received no culling (survey only) and acted as an experimental control with which the culling areas could be compared. Participating farmers were aware of the treatment being applied to their area (i.e. they were not blinded).
Results showed that from one year after the last proactive cull to 25 February 2011, incidence of confirmed breakdowns in proactive culling areas was 16% lower than in survey-only areas.
- Read more: Final Report of the Independent Scientific Group on Cattle TB Presented to the Secretary of State for Environment, Food and Rural Affairs in June 2007
- Read more: Department for the Environment, Food and Rural Affairs, Bovine TB - Key conclusions from the meeting of scientific experts 4 April 2011
Vaccination could be an important tool to help control bovine TB in the future.
But the evidence suggests it will not work on its ownand where both cattle and badgers are concerned, a realistic programme remains a number of years away.
Vaccination won’t work on an animal that already has bovine TB, and no country in the world where wildlife carries the disease has eradicated it in cattle without tackling it in wildlife too.
Vaccination and cows
There are calls for cows to be vaccinated against bTB.
However there is no legal vaccine available. Currently the only option is the BCG vaccine (Mycobacterium bovis Bacille Calmette-Guérin – ref 1,2,3,4,5).
The problem is that at present it is impossible to distinguish between a BCG-vaccinated and TB-infected cow. And for this reason it is currently illegal under EU law to vaccinate cattle with the BCG jab.
Work is underway to devise a DIVA test (ref 6,7,8) - a test that can Differentiate between Infected and Vaccinated Animals. But even when this has been fully developed, it will need to go through EU and international approval.
The government is accelerating work to develop a deployable cattle bTB vaccine by 2025.
On top of that, there’s evidence to suggest that the BCG vaccine and DIVA test will not eradicate bovine TB on their own. A recent scientific study (10) concluded that the efficacy of the BCG vaccine in cattle was between 56% and 68%.
We know the BCG vaccination reduces the progression, severity and excretion of TB, resulting in reduced transmission between animals, but it is not perfect. And for any vaccine to eradicate a disease it is necessary to ensure that 80% of the target population are immunised. The current BCG vaccine just does not shape up.
Scientists have said that vaccination has to be used in combination with other measures, which must include dealing with the disease in badgers. You can read more about bovine TB and cattle vaccination on the Defra website.
Vaccination and badgers
The government has set up the Badger Edge Vaccination Scheme (BEVS) to support badger vaccination projects in areas on the edge of the disease spread that are thought to be most at risk of the disease spreading from the endemic areas of the South West and West Midlands. However, in December 2015 the government announced that all badger vaccination projects in England were being suspended due to a global shortage of the BCG vaccine.
In July 2017, Farming Minister George Eustice announced that the BEVS would resume in summer 2018 and applications for grants from groups wishing to run projects would be accepted from late 2017.
The only vaccine currently available for use on badgers is in injectable form – and that presents problems.
You need to cage-trap the badgers to vaccinate them. And you have to do it annually for a period of at least five years.
The process is costly and needs to be carried out by people who have been on accredited courses. Every trap has to be visited early in the morning, every day.
The Welsh Assembly Government is carrying out a five-year badger vaccination programme in the Pembrokeshire hotspot area. In December 2015 the Deputy Minister for Farming and Food, Rebecca Evans, announced that the badger vaccination project in Wales was being suspended due to a global shortage of the BCG vaccine.
In May 2015, the report on the third year of the programme was published and showed that 1,316 badgers had been vaccinated at a total cost of £929,540, or approximately £706 per badger. During the second year of the programme 1,352 badgers were vaccinated at a total cost of £926,784, or approximately £685 per badger. The first year of the programme saw 1,424 badgers vaccinated at a total cost of around £943,000, or approximately £662 per jab.
There are also question marks over the efficacy of the vaccine.
The science suggests the vaccine is most effective in very young animals, and less so in older subjects (12). Young badgers spend their early weeks in the sett, making it impossible to trap and vaccinate them and putting them at risk of infection before they emerge.
There is also no evidence which shows that vaccinating a proportion of the badger population actually results in a reduced risk to cattle.
The government’s response to the Godfray study states that it will aim to phase out culling in the next few years and increase the use of badger vaccination, especially in areas that have intensively culled for four years. It also recognises that culling will still be necessary in areas of the UK where bTB incidences are still high. The Godfray report itself states that:
‘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.’
Read more: Gov.uk: Bovine TB and badger vaccination
As part of the badger cull, two methods are being used - controlled shooting and cage-trapping and shooting. Currently the only way to vaccinate a badger is via cage-trapping, using an injectable vaccine.
Bovine TB is endemic in the badger populations in large areas of the South West and West Midlands. Scientific evidence has shown that in these areas up to one-in-three badgers will have bTB. This means that vaccinating badgers in these areas will have no impact on the levels of disease. A vaccine cannot cure a diseased animal.
The badger culls are being managed, organised and funded by farmers and landowners.
The culls are being carefully monitored to test effectiveness, safety and humaneness. These monitoring costs are borne by the government. These culls are part of a legal, licensed and lawful activity to reduce disease as part of a government policy.
Policing costs associated with the threat of illegal action by anti-cull activists are paid by government.
In 2007, as part of its final report on the Randomised Badger Culling Trials, the Independent Scientific Group on Cattle TB reported a 40% infection rate among badgers in the hotspot areas where the RBCT ran.
The Badger Trust and anti badger cull groups quote the ISG as saying there was a 16% TB infection rate in badgers. However, this figure is based on initial post-mortems, rather than the final full post-mortem examinations.
The latter examinations did indeed find that 40% of the 1,600 badgers culled had visible TB lesions.
No. Badgers first became protected in 1973 following the introduction of the Badger Act.
Badgers are protected not because they are rare or endangered, but because of illegal badger baiting, which involves digging out setts and using dogs.
Subsequent laws have been introduced, such as the Wildlife and Countryside Act 1981, and have culminated in the Protection of Badgers Act 1992, protecting the sett as well as the badger.
A badger sett survey carried out by the Animal Health and Veterinary Laboratories Agency reported back in early 2014. It found that the number of badger colonies had doubled in the past 25 years.
There were at least 64,000 main setts in England in 2013, compared to 31,500 in 1988. The peer-reviewed study was published in Scientific Reports, a primary research publication from the publishers of Nature.
However, the researchers stressed that their remit had been setts and not badger numbers.
A study published in 2017 estimated that there are approximately 485,000 badgers in England and Wales combined. The results show a ‘marked increase’ in the badger population as a previous study carried out in the 1980s estimated the badger population to be 250,000.
Bovine TB is a chronic, wasting infection.
Animals (and humans) can suffer from it for many years before succumbing.
The nature of this disease is such that if it reaches the stages of chronic infection it will cause a debilitating and painful death to those animals that succumb to it.
However, it has been shown that badgers can go through a period of ‘latency’ when the disease is present but makes little progress. It is this ability to live with bovine TB and to pass it on within the confines of their setts, and to cattle at pasture and around farm buildings, that makes the badger an almost perfect host for bTB.
Operators are required to follow best practice guidelines, and undertake training and competence testing.
Best practice guidance has been published for the two permitted methods of culling:
- Controlled shooting
- Cage trapping and shooting
Read more about these methods at the Gov.uk website:
The requirement to cull 70% of badgers in a control area was established by independent scientists following results from the RBCT.
These results showed that on average across the 10 trial areas if you removed 70% of badgers there would be a significant impact on disease reduction in cattle.
The UK is a signatory to the Bern Convention of the Council of Europe which prohibits the local extinction of endangered or protected species. The Standing Committee of the Convention is satisfied that the planned control in England does not breach the terms of the Convention.
There is no simple way to determine whether a badger has bTB.
The only reliable method is by post-mortem examination. Failing that, as with cattle, by two tests separated by a number of days, which is completely impractical.
Badgers killed in the pilot culls were not tested for bovine TB. The pilot culls were to test to see if the process is humane, safe and effective. That said, the areas where culling is taking place are areas where bTB is rife so a significant proportion of the population will be infected.
Evidence from the Randomised Badger Culling Trials showed that bovine TB could increase outside of cull areas as badgers leave them, taking the disease with them.
This is called the perturbation effect. However, the latest peer-reviewed evidence of industry-led wildlife control demonstrates that the two areas which have completed four years of wildlife control, in Gloucestershire and Somerset, have not experienced a perturbation effect. The government continues to manage any risk of perturbation in any badger cull.
Decisions relating to bovine TB sit within the Welsh Government natural resources minister’s portfolio.
On March 20 2012, the Welsh Government announced a five-year badger vaccination programme in North Pembrokeshire.
During the fourth year of the programme 1,118 badgers were vaccinated at a total cost of £922,012, or around £825 per badger. The report on the third year of the programme was published and showed that 1,316 badgers had been vaccinated at a total cost of £929,540, or approximately £706 per badger. During the second year of the programme 1,352 badgers were vaccinated at a total cost of £926,784, or approximately £685 per badger. The first year of the programme saw 1,424 badgers vaccinated at a total cost of around £943,000, or approximately £662 per jab.
This could mean that, over the five-year period of the programme, vaccination could cost around £3,365 per vaccinated badger.
The Welsh Government has not been able to determine the proportion of the population of badgers in the area that has been vaccinated.
In December 2015 the Deputy Minister for Farming and Food, Rebecca Evans, announced that the badger vaccination project in Wales was being suspended due to a global shortage of the BCG vaccine.
Welsh farmers adhere to strict cattle controls. Measures include annual testing and pre-movement testing across the whole of Wales, stringent rules for restricted herds with regards to buying in replacements to make up for lost animals, and even tighter testing for herds neighbouring a bovine TB breakdown.
Statistics from Defra show that the number of cattle slaughtered because of bTB in Wales increased from 9,906 in 2016 to 10,053 in 2017. The number of new herd incidents of bTB rose from 711 in 2016 to 789 in 2017.
In June 2017, the Welsh Government announced the introduction of a strengthened approach to tackling bTB in Wales.
Low, Intermediate and High TB areas were established based on bTB incidence levels. Post-movement testing will be introduced in the Low TB areas and chronic breakdown herds in the High TB areas will have individual action plans specifically aimed at clearing up infection in cattle. In these chronic breakdown herds, where there is evidence of infection in the badger population, a range of options will be considered to reduce the risk of disease spread, including cage-trapping, testing and where necessary humanely killing infected badgers.
The Polymerase Chain Reaction (PCR) assay or test has the potential to be a rapid, inexpensive and very sensitive tool for identifying bTB infection. Click here to read more about this in a study by the Agri-Food and Biosciences Institute.
PCR detects small amounts of DNA from mixed samples, and this method is often combined with immuno-magnetic separation (IMS), which increases the concentration of the samples resulting in increased test sensitivity.
There is potential to use PCR with faecal and environmental samples. However, there has been limited validation work on PCR in badger samples. Research assessing the sensitivity of PCR in badger faecal samples was carried out in the Republic of Ireland.
Defra has funded research into PCR since 2007 to detect the M. bovis bacteria from environmental samples such as badger setts and latrines. While PCR has been demonstrated to identify M. bovis in spiked samples in the laboratory with 100% specificity (100% reliable that a positive test result means disease is present) and 97% sensitivity (97% successful at correctly identifying diseased samples), it has been found to be less sensitive for samples in the field.
In a smaller environmental study, real-time PCR was able to identify the disease in all 12 infected setts and latrines sampled. However, there has been criticism of using samples from the environment in this context. Infected badgers shed M. bovis intermittently which makes the interpretation of environmental samples more difficult.
The next stage is to determine how to apply the PCR assay for bTB surveillance of wildlife on a large scale.
Read more about PCR:
- An inter-laboratory validation of a real time PCR assay to measure host excretion of bacterial pathogens, particularly of mycobacterium bovis – Travis et al, 2011
- Environmental monitoring of mycobacterium bovis in badger faeces and badger sett soil by real-time PCR, as confirmed by immunofluorescence, immunocapture and cultivation – Sweeney et al, 2007
- The Strategy for achieving Officially Bovine Tuberculosis Free Status for England – Defra, 2014, p61-62
- Bovine tuberculosis: a review of diagnostic tests for M.bovis infection in badgers – Strain et all, 2011, p24
IDEXX antibody test
The IDEXX test has not yet been officially recognised by the EU but gained OIE (World Animal Health Organisation) approval as a supplementary test for TB in cattle in 2012. This means the APHA can use it in exceptional circumstances with approval from the herd owner. It is the third test used in chronic herd breakdowns after repeated skin testing and at least one round of interferon-gamma blood testing.
Enferplex antibody test
This is another blood test than can detect antibodies to the bTB bacterium in serum, and potentially milk, in infected cows. It also has been approved by the OIE as a supplementary test but has not been officially recognised by the EU yet. This test can only be used on a private basis with approval from the APHA as it has not currently been approved by Defra.
A bacteriophage, or phage, is a virus which infects bacteria. It does this by infecting its bacterial host by injecting its DNA into the bacterial cell, which is then forced to make new phage particles. Once the new phage are made, the viruses then rupture the bacterial cell. This releases the new phage into the environment, which in turn can infect more bacteria.
A specific phage capable of infecting specific bacteria, in this case Mycobacterium bovis, is used. The activity of the phage is used as an indicator that bacteria are present in a sample taken from an infected animal.
A recent study carried out by the test manufacturers estimated that Actiphage has a sensitivity of 95% and a specificity of 100%. However further trials are needed to confirm that accuracy and validity of the test.
The test can be used on a private basis provided the APHA has given approval.
Yes. Defra applies strict guidelines for processing meat from animals which have tested positive for bovine tuberculosis.
These EU-wide regulations are based upon internationally-agreed guidelines and are the same as those followed by many countries around the world, including Ireland.
Cattle slaughtered by Defra that have tested positive for bovine TB are allowed into the food chain provided they do not show tuberculosis lesions in more than one organ or body part.
The Food Standards Agency inspects this process and ensures these products are fit to eat. It states that there have been no documented cases where a person has caught bTB through eating meat and that careful safeguards surrounded the slaughtering and supply of meat to the food chain.
The European Food Safety Authority has described the threat of transmission through meat products as ‘negligible’. And Defra has categorised reports that humans could be at risk of contracting TB from eating meat as "irresponsible scaremongering".
Across Britain only 0.5-1.0% of human TB cases, fewer than 40 people a year, are related to Mycobacterium bovis. The majority of these cases occur in people over the age of 45 and, according to the NHS, were probably recurrences of decades-old infections contracted before milk pasteurisation and meat inspection were common in the UK.
No. The aim of the Natural England badger cull licenses is to cull 70% of badgers in a control area. This figure was established by independent scientists following results of the Randomised Badger Culling Trial.
These results showed that on average across the 10 trial areas if you removed 70% of badgers there would be a significant impact on disease reduction in cattle.
The licensing authority, Natural England, closely monitor the badger culls to ensure compliance, publishing an annual summary of culling operations.
The UK is a signatory to the Bern Convention of the Council of Europe. The Bern Convention is a binding international legal instrument in the field of nature conservation.
The current badger culls in England have been designed and are continually monitored to ensure robust compliance with this treaty.
The Standing Committee of the Bern Convention has been satisfied that the control in England does not breach the terms of the Convention, this position was re-affirmed within 2014.
The 2018 Bovine TB Strategy Review, often referred to as the ‘Godfray report’, was commissioned in February 2018 by the then Secretary of State for Environment, Food and Rural Affairs Michael Gove.
The purpose of the review was to reflect on progress being made with the implementation of the bTB eradication strategy and consider how to best progress the strategy. The review was to advise on what further actions might be prioritised now to ensure Defra maintain progress towards the target of achieving Officially TB Free status for England by 2038.
The review was to consider all the drivers for disease spread and how they might be addressed. The focus was on the bTB eradication strategy for England only and was not intended to revisit the rationale for current interventions in the Strategy. The strategy was charged with looking ahead, not reviewing current progress or the measures used as part of the strategy.
In October 2019, Downs et al published a study into the effects of four year intensive culling in the first three licensed badger cull areas, using data collected from 2013-17.
The first two areas, Gloucestershire and Somerset, had culled for four years and Dorset had culled for only two years.
Gloucestershire and Somerset saw reductions in bTB incidence rates in cull areas relative to comparison areas of 66% and 37% respectively after four years.
In Dorset, there was no change in incidence rates in cull areas relative to comparison areas after two years, but incidence dropped by 55% in the same period in the 2km buffer zone around the edge of the cull area.
In 2021 Defra published the Annual TB monitoring data and results for each of the badger control licensed areas and their buffer areas up to the end of 2020. From this data we have seen that on average after 4 years of culling there is a 54% reduction in disease.