Tag Archives: Torgerson et al

Randomised Badger Culling Trial Unsprung – the uncertainties grow

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The continuing questions over uncertainty in the published outcome of the Randomised Badger Culling Trial (RBCT) have rumbled on over the summer of 2024, and were reported on (here). 

Why are the statistical elements of the RBCT so important? Because the government badger cull policy rests all but entirely on them. It was the science that DEFRA has used to create policy and in court to defend their decisions to experiment with badger culling. The RBCT claimed badger culling can reduce bovine TB in cattle; very many subsequent studies are heavily derived from it, to the point that if it is wrong, it will send a wrecking ball through dozens of publications, reports and reviews. The stakes could not be higher.

Disease benefits claimed for badger culling by civil servants and politicians are in reality, far more likely due to implementation of additional cattle measures. But there is continued inference that badger culling is a cause of disease reduction because such benefits might be “predicted” from the results of the RBCT.

The chronology of published and pre-printed science on the statistical analysis of the RBCT as it relates to proactive culling is growing, so here is a summary with clickable links:

16th February 2006, “Positive and negative effects of widespread badger culling on tuberculosis in cattle” was published in Nature by Donnelly et al.. 

10th May 2019, “Badger Culling and Bovine TB in Cattle: A Re Evaluation of Proactive Culling Benefit in the Randomized Badger Culling Trial” was published in the Journal of Dairy and Veterinary Sciences by Langton.

13th December 2022, “Absence of effects of widespread badger culling on tuberculosis in cattle” was posted as a preprint on Research Square by Torgerson et al. .

12th May 2023. A revised version of “Absence of effects of widespread badger culling on tuberculosis in cattle” was pre-printed in Research Square, and submitted to Nature Scientific Reports by Torgerson et al…

15th July 2024. The final version of “Absence of effects of widespread badger culling on tuberculosis in cattle” was published in Nature Scientific Reports by Torgerson et al..

18th August 2024. Interim report on the August 2024 pre-publication response to the July 2024 re-evaluation of evidence and analyses of proactive culling (published in 2006), as a part of the Randomised Badger Culling Trial (RBCT), 1998-2005. Independent pre-publication report on the Mills et al papers to be published on 21.08.2024.

21st August 2024. “An extensive re-evaluation of evidence and analyses of the Randomised Badger Culling Trial (RBCT) I: Within proactive culling areas”  and “An extensive re-evaluation of evidence and analyses of the Randomised Badger Culling Trial II: In neighbouring areas” were published in Royal Society Open Science by Mills et al..

16th September 2024. A ‘Comment’ response to the new Mills et al. 2024 papers was submitted to the Royal Society Open Science: “Randomised Badger Culling Trial lacks evidence for proactive badger culling effect on tuberculosis in cattle: comment on Mills et al. 2024, Parts I & II” by Torgerson et al.. This was pre-printed with bioRxiv on 20th September.

The ‘Comment’ submission to the Royal Society Open Science is an extensive response to the two new Mills et al. (2024) papers which reproduced much of Torgerson et al.’s models, whilst re-interpreting the results.

The abstract of the Torgerson et al. ‘Comment’ is as follows:

Abstract
Re-evaluation of statistical analysis of the Randomised Badger Culling Trial (RBCT) by Torgerson et al. 2024 was rebutted by Mills et al. 2024 Parts I and II. The rebuttal defended the use of count rather than rate when considering bovine tuberculosis herd incidence. The defence makes biologically implausible use of Information Criterion for appraisal diagnostics; overfits data; and has erroneous Bayesian analyses. It favours ‘goodness of fit’ over ‘predictive power’, for a small data set, when the study was to inform application. Importantly, for ‘total’ bTB breakdown: (‘confirmed’ (OTF-W) +‘unconfirmed’ (OTF-S)), where modern interpretation of the main diagnostic bTB test better indicates the incidence rate of herd breakdown, there is no effect in cull and neighbouring areas, across all statistical models. The RBCT was a small, single experiment with unknown factors. With respect to the paradigm of reproducibility and the FAIR principles, the original RBCT analysis and recent efforts to support it are wholly unconvincing. The 2006 conclusion of the RBCT that “badger culling is unlikely to contribute positively to the control of cattle TB in Britain” is supported, but the route to such a position is revised in the light of modern veterinary understanding and statistical reappraisal.

The new Comment, that has not yet been peer-reviewed, highlights what is described as selective reporting, misleading interpretation, implausible model selection and coding anomalies. It will be of interest to Ministers, Civil Servants, scientists and politicians who currently,  under the new Labour administration, are ‘refreshing’ the bovine TB strategy, and policy. 

The two Mills et al. papers were published just a few days before the Intensive and Supplementary badger cull licences were issued for 2024, providing a rationale for culling to continue.

Why are we waiting?

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Things are starting to become slightly clearer as we near the point of discovery over the future of badger culling in England and beyond. Consultees to the online Defra Consultation  questionnaire of 14th March were told this Monday (5th August) that an analysis of Consultation responses will be published in the autumn (Sept-Nov?) giving more time for policy development without badger culling. But there is no reason now to delay clarification on the big 56% lie surrounding the ineffective badger culls.



 

Notably, the NFU appeared fully taken in by the spin from the Animal and Plant Health Agency paper by Colin Birch and Defra, that badger culling ‘is working’. Birch et al. follows on from a paper published in Veterinary Record in 2022 that showed quite neatly how recorded bovine TB levels (recorded OTF-W incidence)  peaked after the introduction of annual tuberculin testing in 2010 and began dropping in the High Risk Area from 2013 in some counties and generally by 2015. And, at a steady rate that did not increase once badger culling started (and that was more widespread from 2018), showing no evidence that badger culling had contributed to a slow decline of around 6% per year. 

Steve Barclay, and previous Environment Ministers before him, had made wild claims of a culling benefit of around 50%, based on APHA parroting the claims made since the 1970s that this is the badger contribution to cattle TB. This has always been a poorly evidenced, lame and far-fetched claim, making a mockery of professional epidemiology.

Not to be fooled, Labour are onto the problem and have firmly labelled badger culling as ‘ineffective’ in their manifesto. They have highlighted the need to work with farmers and scientists which is now the helpful – but not very specific – new Defra mantra.

The Birch paper makes it quite clear in two places that the cause of the welcome decline in bTB first identified formally in 2022, cannot be attributed to any particular intervention, be it better testing, different tests and more frequent tests, better biosecurity or badger culling. It is just a crude before-and-after effort with no controls, showing what was already known in a slightly clunky way. This is no help at all, as Professor Macdonald at Oxford pointed out in his November 2023 ‘state of the science’ review. However, the unfortunately misleading abstract for the Birch paper transmutes opinion into ‘fact’, to give the casual  reader a misinformed overview of the findings. How very CVO.

So what are we left with as we approach the time of Labour’s big reveal this month? Firstly, an increased interest in badger vaccination with Defra organising a media spree with its dutiful contractors to suggest a direction of travel that Natural England seem to think is appropriate.

Also, news from Oxford, where a 50,000 signature petition to the School of Biological Science, organised by the Oxfordshire Badger Group calling for increased academic engagement seems to be working. A response to the Torgerson et al. 2024 paper on the choice of models for analysis of the Randomised Badger Culling Trial data, published  recently in Scientific Reports is imminent. The Torgerson paper wallowed rather oddly for 18 months in peer review, emerging little changed, so plenty of time for the RBCT folk to have prepared.

How the 50 something % cull benefit lie has been peddled in recent months and years:

Farmers Weekly: Badger culling policy reduces cattle TB by 56%, study shows 

Farmers Guardian, Farming matters: Lord Robert Douglas-Miller – ‘The science is clear that the tide is turning on bovine TB’ 

Shrewsbury Conservatives, DANIEL KAWCZYNSKI MP MEETS WITH MARK SPENCER, THE MINISTER OF STATE FOR FOOD, FARMING, AND FISHERIES, URGING HIM TO TAKE TOUGHER ACTION TO REDUCE CASES OF BOVINE TUBERCULOSIS:  

Parliamentary Question response from Mark Spencer: To ask the Secretary of State for Environment, Food and Rural Affairs, what assessment her Department has made of the (a) effectiveness of badger culls in tackling bovine TB and (b) reliability of the TB test used to identify cattle for slaughter; and what estimate her Department has made of the (i) annual cost of bovine TB in Shropshire and (ii) level of bovine TB in that county. 

 

Labour and Badger Culling?

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In 2019, when Jeremy Corbyn was the leader of the Labour party, their manifesto stated clearly that, if elected, badger culling would stop. Labour under the leadership of Keir Starmer had a less clear position on badger culling, until Reform UK split the Conservative vote, and in the recent election manifesto it was said that Labour would “work with farmers and scientists on measures to eradicate Bovine TB, protecting livelihoods, so that we can end the ineffective badger cull”.

How will Labour work with farmers and scientists?

Since the election, Steve Reed, the new Secretary of State  for Environment, Food and Rural Affairs, and Daniel Zeichner, the new Minister of State in the Department for Environment, Food and Rural Affairs, have been busy making their presence felt amongst the farming community. They seem to have been rubbing shoulders every other day with the NFU for the last two weeks, and yesterday (18th July) were at the National Farmers’ Union Summer Reception in Parliament in front of dozens of MPs, where Zeichner said:

“And I know the culling debate is a really, really hard one. Very, very contentious. Huge passion on both sides of the argument. But let me tell you, the Secretary of State has been clear: the current round of licences will be honoured. I absolutely believe we’re only going to eradicate bovine TB by working closely and constructively together to use all the science and everything that we’ve got to beat it. We are going to beat it. I tell you, I’ve already said to the department, that is my top priority. So, you have my assurance.”

So who will be working closely and constructively together? Zeichner is fulfilling his commitment to meet with industry representatives. How about meeting with the scientists? And other stakeholders shut out by Government for a decade or more? He may be talking to the scientists who have spent the last 20 odd years presenting work from their own Randomised Badger Culling Trials (RBCT) as the best evidence of the role of badgers in bovine TB, but they are definitely not talking to published scientists who have found that culling badgers has no role in the management of bovine TB in cattle (Langton et al 2022 and Torgerson et al 2024).

Are Labour taking ‘evidence’ from only one side of the debate and filtered through the lenses of civil servants? The civil servants seem to be doubling down to keep uncertain and flawed science that they have propped up for two decades. Will Labour keep in place the really dreadful  Bovine TB Partnership that is made up largely of those with the commercial interests of farming and cattle vets, to advise on badger culling. Mostly not scientists. With a new scientific paper out this week (here) that shows that there were no measurable effects of widespread badger culling on tuberculosis in cattle in the RBCT, will there be better thinking from Labour? Will they drop the unscientific inference (from Birch et al.) regarding the 56% reduction in breakdowns (2013-2020) being due to badger culling rather than from cattle testing? (See what Professor David MacDonald says about this here). If they will not stop culling now, with yet more science suggesting badger culling is ineffective, then when will they, and can the law let them?

Ineffective badger cull?

It was heartening to see in Labour’s manifesto that they agree that the badger cull is ineffective. It would have been good to see a little more detail on why this is their view. We would like to hear more on this. But surely, if culling is ineffective, it is illegal under Section 10 of the Protection of Badger Act 1992? Culling badgers would only be permitted under licence if it could prevent the spread of disease  – which it cannot if it is ineffective? So is Labour talking in riddles, or poised to backtrack and go back on its first manifesto pledge? We are about to find out.

We can end the ineffective badger cull?

‘We can end’ the ineffective badger culls’ they say, but when? Millions of people voted Labour because they hoped and believed that Labour would end the culls on coming into power. Why wouldn’t they, they are ineffective? Or do they believe they are effective, as Defra Vet Christine Middlemiss has been telling them, with the fake ‘56%’ nonsense that is now under legal challenge. Newly published science shows that there can be no measurable benefit from continuing culling. They cannot be continuing them because of contractual obligation to culling companies, because the Derbyshire cull that was cancelled in 2019 was legally challenged by the NFU, but the judge found that the government had a legal entitlement to make a political decision about culling. So they could make a political decision, and a scientific one, to stop all culling straight away if they wanted to. So why don’t they? This is now the big question that they need to answer next week before they pack up from Parliament for the summer.