On the 23 August the BBC broadcast Brian May: The Badgers, the Farmers and Me. BCVA has written this response to the content of the programme, focussed on evidence, and reflecting the experience of farm vets who face the realities of this disease and see the devastating impact on herds and farmers.
When considering bTB it is essential to take an evidence-based approach, so the key points to be made are that the programme failed to present the latest evidence, and that this evidence shows clearly that that badgers do transmit TB to cattle.
It is important to recognise that whilst several farms featured in this programme the content was largely based on the results from one farm’s experience and the opinions of one celebrity and one vet. Opinions aren’t facts. Certainly, any suggestion that there is a new, singular, and revolutionary explanation for the reason TB spreads is a stretch. BCVA is disappointed that emotive and biased language was used throughout the programme, including the use of the word "killing" when referring to culling of badgers.
BCVA is particularly disappointed that whilst the programme referred to the Krebs report, newer evidence was not referenced. BCVA recognises that the results from the Krebs report raised concern that badger culling could result in both increased and decreased TB incidence in cattle. It is recognised that the randomised badger culling trial, from which this report was written, involved culling badgers over small areas and this was associated with a perturbation effect. By omitting the peer reviewed studies on the more recent badger control policy, an opportunity was missed to shed light on this disease and stimulate informed, scientific and evidence-led discussion.
Here is some of the evidence missing from this television programme … The two most recent studies, Downs 2019 and Birch 2024, report the results of the badger control policy in England which started in 2013. The cull areas in this policy were much larger than those in the randomised badger culling trial. Downs 2019 reported data from the first 3 licensed cull areas. After 4 years of culling, bovine TB incidence decreased by 66% and 36% in Gloucester and Somerset respectively compared to comparison areas.
The Downs report also showed that in the 2km buffer zone surrounding the cull area there was a 36% reduction in bovine TB incidence and no change in incidence in Gloucester and Somerset respectively. The more recent Birch report includes data from 52 cull areas and shows a 56% reduction in TB incidence in the fourth year of culling.
BCVA acknowledges that during that time, other factors such as increased more sensitive testing and improved biosecurity may also have contributed to the reductions in TB incidence and BCVA therefore believes that the Birch and Downs reports give evidence that badger culling in combination with more sensitive testing and improved biosecurity reduces incidence of bovine TB and that TB control policies must be holistic including all evidenced measures of control; more sensitive testing, improved biosecurity and badger culling.
The factual inaccuracies mentioned in the programme must be addressed. It was claimed that the Single Intradermal Comparative Cervical Tuberculin Test (skin test) has a sensitivity of 50%. This is incorrect. It is important to highlight that the skin test sensitivity actually ranges between 50-80% (Karolemeas 2012, Nunez-Garcia, 2018) with an average test sensitivity at standard interpretation in England of 80% (APHA 2024).
It was implied during the programme that badgers do not play a part in bTB. Published evidence shows that badgers do transmit TB to cattle (Crispell et al 2019). It was also said that "we" say that badgers are "the" problem when it comes to bovine TB. BCVA would like to make it clear that we recognise, given all available evidence, that badgers are part of a multifactorial problem which includes wildlife spread, a less-than-ideal screening test sensitivity and a lack of appropriate biosecurity, in some cases. In the farm vet profession and in UK agriculture, there is not a narrative that says that badgers are the only cause of TB transmission to cattle.
There was also a claim in the programme that badgers culled did not have TB. TB is tested for in culled badgers by performing postmortem examinations, looking for visible lesions and taking cultures from lesions. It should be noted that lesions in TB positive animals are not always seen during postmortem examinations and M.bovis is a very difficult organism to culture. It is, therefore, difficult to confirm that badgers culled during the badger control policy did not have TB.
In the programme, it was discussed that cattle were identified as shedding M.bovis bacteria in their faeces. BCVA feels it is important to highlight that the faecal PCR used to determine this is not a validated test and as such care should be taken when interpreting results of the test.
BCVA believes the programme was misleading in its reported success of controlling bovine TB on the study farm. Although mentioned in writing on the screen at the very end of the programme, BCVA feels it was not made clear enough that after becoming clear of bovine TB, the farm had three TB breakdowns in five years.
Another claim in this television programme was that bTB in Devon is static and has plateaued, this is not reflected in the reported data – in the 12 months up to March 2024 there were 6,667 tests on officially TB-free herds in Devonshire, resulting 528 new TB breakdowns, a decrease of 8.7% since the 12 months up to March 2023 (TB Hub).
BCVA has worked hard to bridge the relationship between private veterinary surgeons (PVS), farmers, vets and Defra, aiming to help farmers understand the necessity for the skin test and where it works well, gamma test and government policy. We are now seeing a successful decline of the disease across the UK (TB Hub), and we know from the very clear evidence that it is the result of collaborative efforts of everyone working in livestock agriculture, using all the tools in the box. So, now we have seen this decrease in TB incidence it is crucial that we bank those lessons and build on the benefits of taking a multi-tool approach to managing this disease. This means that the conversations that take place around this devastating disease need to be useful, based on evidence and proven facts.
The ‘control the controllable’ phrase is a constant when it comes to bTB, and good biosecurity and cleanliness is important for all disease control. As scientists, farm vets will always be interested in seeing some valid, peer reviewed data relating to slurry management. However, there is nowhere near enough evidence to demonstrate fully how TB bacteria behave in slurry and any claims that managing slurry alone is a complete answer is not based on credible evidence.
TB control requires a multi-tool and individual approach to each farm's unique situation. So, whilst we welcome contributions to the public conversation about this disease, this kind of attention is problematic in terms of the impact it will have on those people who live with the threat of bTB on their farms. The farmers and herds who are suffering with TB month after month can feel alone and helpless – targeted blame or shame could prove devastating. Not to mention the public reaction - who may well be attracted to a much-loved celebrity sharing his personal views which are not backed by evidence.
We wish there had been an opportunity to share the science and evidence that the badger culls, along with a range combined strategies, have contributed to the 20 year all time low that we are currently experiencing.
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Useful References
http://apha.defra.gov.uk/External_OV_Instructions/TB_Instructions/Skin_Test/index.htm
Birch, C.P.D., Bakrania, M., Prosser, A. et al. Difference in differences analysis evaluates the effects of the badger control policy on bovine tuberculosis in England. Sci Rep 14, 4849 (2024). https://doi.org/10.1038/s41598-024-54062-4
Downs, S.H., Prosser, A., Ashton, A. et al. Assessing effects from four years of industry-led badger culling in England on the incidence of bovine tuberculosis in cattle, 2013–2017. Sci Rep 9, 14666 (2019). https://doi.org/10.1038/s41598-019-49957-6
Joseph Crispell, Clare H Benton, Daniel Balaz, Nicola De Maio, Assel Ahkmetova, Adrian Allen, Roman Biek, Eleanor L Presho, James Dale, Glyn Hewinson, Samantha J Lycett, Javier Nunez-Garcia, Robin A Skuce, Hannah Trewby, Daniel J Wilson, Ruth N Zadoks, Richard J Delahay, Rowland Raymond Kao (2019) Combining genomics and epidemiology to analyse bi-directional transmission of Mycobacterium bovis in a multi-host system eLife 8:e45833 https://doi.org/
Katerina Karolemeas,Ricardo de la Rua-Domenech,Roderick Cooper,Anthony V. Goodchild,Richard S. Clifton-Hadley,Andrew J. K. Conlan,Andrew P. Mitchell,R. Glyn Hewinson,Christl A. Donnelly,James L. N. Wood,Trevelyan J. McKinley Estimation of the Relative Sensitivity of the Comparative Tuberculin Skin Test in Tuberculous Cattle Herds Subjected to Depopulation Published: August 21, 2012https://doi.org/10.1371/journal.pone.0043217
Nuñez-Garcia J, Downs SH, Parry JE, Abernethy DA, Broughan JM, Cameron AR, Cook AJ, de la Rua-Domenech R, Goodchild AV, Gunn J, More SJ, Rhodes S, Rolfe S, Sharp M, Upton PA, Vordermeier HM, Watson E, Welsh M, Whelan AO, Woolliams JA, Clifton-Hadley RS, Greiner M. Meta-analyses of the sensitivity and specificity of ante-mortem and post-mortem diagnostic tests for bovine tuberculosis in the UK and Ireland. Prev Vet Med. 2018 May 1;153:94-107. doi: 10.1016/j.prevetmed.2017.02.017. Epub 2017 Mar 6. PMID: 28347519.
https://tbhub.co.uk/preventing-tb-breakdowns/about-bovine-tb/bovine-tb-statistics-and-epidemiology/
