Badgers not a key source of bovine TB

Back in 2016 a request was made by the University of Nottingham for dead roadkill badgers to test for BovineTB, the cattle disease that has ultimately led to more than 150,000 badgers being killed to protect the dairy industry. Teams from the Universities of Nottingham, Surrey and Liverpool wanted to find out whether badgers living in counties around the edge of the expanding TB epidemic in cattle were infected and were therefore important vectors in the spread of the disease.

The study, known as the Badgers Found Dead Study (BFDS) was to be led by Professor Malcolm Bennett from the School of Veterinary Medicine and Science, who said at the time that: “Using road-killed badgers is a valuable way of studying disease and conservation issues in wildlife that makes use of an otherwise wasted resource. The prevalence and geographic distribution of TB in badgers on the edge of the cattle epidemic is currently unknown yet of obvious importance to future TB control policy. While there is a wealth of evidence to inform cattle-based control measures, the role, if any, of badgers in the spread of bTB in the edge counties is not yet clear so we are keen to address this.”

A network of farmers wildlife groups and other stakeholder organisations would be established to collect the badger carcasses for examination at the collaborating universities, using special kits and protocols to ensure both the safety of those doing the collecting and that the carcasses are suitable for the study.

Whilst the study was launched in 2016 and was based on badgers found dead between 2017 and 2018, the results have only just been announced. Badgers are not a key source of bovine TB, just as conservationists have been saying all along.

These results tie in with data from a study of culled badgers from the first ten cull zones in 2016, which found a prevalence of bTB in badgers of only 4.6%. Although a higher percentage of badgers were infected in the centre of the Cumbrian cattle outbreak in 2018, this was known to be caused by the movement of cattle from Ireland, and by 2019 overall bTB prevalence in culled Cumbrian badgers was less than 1%.

In the meantime, hoping to sway public opinion by disguising the slaughter by using the euphemism ‘cull’, contract killers spent the whole of this summer killing badgers on a massive scale on behalf of Defra and the dairy industry…

 

The Badger Trust has today welcomed the long awaited release of the Badgers Found Dead Study (BFDS), with results that clearly support the Trust’s view that badgers are not a reservoir host for bovine TB, but rather a spillover host. These latest results support those of a previous survey of culled badgers in 2016, which found less than 5% of culled badgers tested positive for bovine TB*.

The BFDS, commissioned by DEFRA in 2016, investigated the prevalence of bTB in ‘found dead’ badgers in Edge Areas ( of England, covering the northern counties of Cheshire, Derbyshire, Warwickshire, Nottinghamshire, Leicestershire and Northamptonshire; and in the southern counties of Oxfordshire, Hampshire, East Sussex, Buckinghamshire and Berkshire. It was carried out by the Universities of Nottingham and Surrey for the northern and southern areas respectively. The results of the study were presented in two separate reports.

A total of 372 badger carcasses underwent post mortem examination and sampling. In all five southern counties only three M. tuberculosis complex bovis (MTCB) positive cases were identified, all from Oxfordshire, giving a prevalence for Oxfordshire of 3.8% (3 out of 79), and an overall prevalence for these counties of 1.0%.

In the northern counties approximately 100 carcasses were tested from each county, and overall 8.3% were culture-positive (confirmed by PCR) for M. tuberculosis complex (MTC). Cheshire (13.5%), Leicestershire (12.4%) and Warwickshire (9.8%) had the highest infection rates, with Derbyshire (4%), Nottinghamshire (4.9%) and Northamptonshire (4.1%) showing the lowest.

Almost all badgers in the northern study showed no clear signs of tuberculosis lesions at post mortem examination. Of those confirmed culture positive only two had widespread tuberculous lesions, and a further two had limited bTB lesions. The University of Nottingham Final Report states therefore that ‘the majority (92%) of MTC positive badgers might be described as ‘latently’ infected – i.e. not showing symptoms and non-infectious.

No lesions typical of M. bovis infection were observed in any of the badgers examined in the southern counties.

Jo Bates-Keegan, Chair of the Badger Trust, stated:

The BFDS data supports our view that badgers are not in fact a reservoir host for bovine TB, but instead simply a spillover host. The government’s justification for culling in Edge areas such as Derbyshire is based on highly inaccurate estimates of the number of new herd breakdowns (where a herd loses its officially TB free status due to bovine TB being suspected or confirmed) to have been caused by badgers.’

She continued: ‘The APHA Risk Pathway Assessments (intended to determine the route by which infection may have entered the herd) are entirely subjective and unscientific as an approach and cannot be relied upon. It is clear from this study that few badgers are even infected, let alone infectious, a fact that points us squarely back in the direction of the real issues. Namely an ineffective cattle test that leaves infected cattle in the herd, and a complete lack of emphasis by DEFRA and the APHA on any number of other potential factors – from a lack of biosecurity measures to infected slurry or watercourses’.

The BFDS results tie in with data from a study of culled badgers from the first ten cull zones in 2016, which found a prevalence of bTB in badgers of only 4.6%. Although a higher percentage of badgers were infected in the centre of the Cumbrian cattle outbreak in 2018, this was known to be caused by the movement of cattle from Ireland, and by 2019 overall bTB prevalence in culled Cumbrian badgers was less than 1%.

The BFDS is reported to have cost almost half a million £GBP, and the results from the work undertaken in 2016 and 2017 was only released in October 2020, despite both reports being dated to Summer 2018.

Badger Trust, Brockbase press-release, 03 Nov 2020