Bovine tuberculosis; badgers finally in the clear

In the May 2023 issue of British Wildlife, I described the ‘weakened link’ between badgers and bovine TB (bTB) infection in cattle. Since that article was published. a further 45,000 badgers have been shot, bringing the total culled since 2013 to over 250,000 – largely healthy – adult and cub badgers, the killing of which has been supervised by Natural England and supported by public funds.

^{© H. Zell CC BY-SA 3.0}

Fifty years of hurt

Early meticulous research into bTB pathogenesis in cattle was highly successful, resulting in coordinated bTB disease control across Britain and Ireland in the 1950s and 1960s. Then, in the 1970s, badgers were suddenly accused of causing 50% of breakdowns in cattle. The connection between badgers and bTB gained political momentum in 1980, when a government review, with considerable input from the Ministry of Agriculture, Fisheries and Food, mistook bTB as badger TB, with cattle being cast largely as disease spillover hosts. A primitive model supporting the government’s view was produced, and subsequently countered by fresh investigative research (Dunnett et al. 1986; McIlroy et al. 1986).

While badgers took the blame, we now know that a so-called ‘hidden reservoir’ of the disease actually existed undetected in a proportion of young cows, capable of switching on and off the release (shedding) of bTB’s causative agent, Mycobacterium bovis, unpredictably and without clinical symptoms, as they aged. Infected calves and yearlings were considered low disease risk, yet short bouts of bacterial shedding may begin from birth and were impossible to monitor. This veterinary misunderstanding, together with changes to the ways in which cattle were housed and tested, has led to billions of pounds of public and farmer finance being lost on unsuccessful disease control since 1980.

These nuances were overlooked in the design of the Randomised Badger Culling Trial (RBCT) (Krebs et al. 1997;, Bourne et al. 2007), which allowed free movement of cattle of variable disease burden into and out of RBCT test areas. A fatal problem with the study was a lack of a detailed analytical statistical protocol, and use of unnatural methods that have rendered its key proactive cull analytics (Donnelly et al. 2006; Mills et al. 2024a, 2024b) flawed when concluding that RBCT proactive badger culls reduce cattle herd TB breakdowns. Concerns focus on the measure of time for which study cattle herds were ‘at infection risk’, and large differences in the number of herds between the study areas during the experiment. Scrutiny has considered what are known as information criteria;  the carefully constructed applications that test the respective ability of statistical models to represent the data in a verifiable way. In 2025, the RBCT progressed from a position of strength, to weakness, to invalidity.

It may be a surprise to some that the RBCT-derived reports and peer reviewed publications are fatally flawed, including cost-benefit analyses. Defra now argues that the RBCT is just an old reference study, no longer of any significance. However, given that its faults impugn most subsequent government publications, and the entirety of current bTB control policy and strategy, it is important that its flaws are recognised.

Bovine tuberculosis control

While the rate of bovine TB incidents (disease prevalence) has dropped since the introduction of annual tuberculin testing from 2010 in the most infected areas, it is clear that the 2038 target for reduction to TB-Free (OTF) classification in England and beyond is now highly unlikely to be met and would require a massive input of national resources were it to be attempted.

^{© Richard Croft CC BY-SA 2.0}

While large modern dairy herds with robotic milking and cleaning are different to the average small to medium European herd, the difficulty in removing bTB with standard tuberculin testing is well known. Alternative testing approaches have been showcased in a recent documentary focusing on trials at Gatcombe farm in Devon.

Moving forwards

Collectively all the evidence suggests that intensive and supplementary culling of badgers has been a distraction, contributing to a waste of over £1 billion of public funds since 2013.

The current strategic direction to replace badger culling with badger vaccination is, like culling, also a distraction. The Godfray policy review update this year has been unhelpful in suggesting that one or the other is needed. Government badger surveys over the last 12 months are likely to show badgers recovering numbers rapidly in culled areas and continuing their long-term recovery across much of the county. This is not at all surprising given their known resilience to heavy localised road traffic deaths. There is no evidence to say that culling in Low Risk Areas provides benefit to bTB suppression, and yet approaching 2,000 badgers have been shot (2018-present) in Cumbria and Lincolnshire, where there have been only a handful of breakdowns. The last cull area no. 73, in Cumbria, started in autumn 2024 and remains the last vestige of the failed RBCT-related culling policy. A cull in Lincolnshire has shot 523 badgers in an area with a low density of herds and very few bTB breakdowns.

The Westminster Hall Debate on 13th October 2025, in response to a Protect the Wild petition by over 100,000 members of the public, consolidated Labour’s intention to stop the ‘ineffective’ badger cull, and to pursue non-lethal interventions, while at the same time revealing Defra’s position that badger interventions are necessary. Coming so soon after the September 2025 review, and with further important publications to consider, it may make time for the newer and better interpretations of the science to filter down into policy.

Defra’s interest in ‘Test Vaccinate Remove’ (TVR) approaches looks unlikely to be adopted. This is the method that was abandoned by Wales due to unreliable testing techniques in 2021, having spent £1,352,000 (2017-2020) removing a total of 68 badgers at a cost of nearly £20,000 per badger, only 13 of which were confirmed as bTB positive. Any further view that Whole Genome Sequencing (WGS) offers more than tentative estimates for transmission pathways and rates, requires close scrutiny. Care will be needed to make sure that WGS does not repeat the same mistakes of the past, using bad modelling to pursue a real-time emergency.

The evidence suggests that any attempt to progress more or less on the current trajectory will see bTB rise. Resource reallocation would need completely new approaches and authoritative implementation. Thus, while the badger ‘blame game’ is over scientifically, those responsible for deciding the path forward now have a choice as to whether they will support bTB control actions that actually work and would free farmers, cows and badgers from decades of failure.

By Tom Langton