Randomised Badger Culling Trial: Impact, based on more extensive data
- Published
- Accepted
- Subject Areas
- Epidemiology, Infectious Diseases, Statistics
- Keywords
- bovine tuberculosis, badger culling, rbct
- Copyright
- © 2016 Hendy
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Randomised Badger Culling Trial: Impact, based on more extensive data. PeerJ Preprints 4:e2336v4 https://doi.org/10.7287/peerj.preprints.2336v4
Abstract
In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of the Randomised Badger Culling Trial (RBCT). Badgers were culled between 1998 and 2005 across 100 km2 (nominal) zones in the West of England. The results were based on a model of New Herd Incidence (NHI). It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas.
This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence.
Whilst the proactive culls substantially and sustainably reduced cattle TB in treated areas, such culls did not significantly increase TB in the surrounding areas. In fact NHIs between 2006 and 2012 dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the number of NHIs prevented since 1998, a break-even cost to complete a badger removal exercise was calculated to be £8,693 per km2. This figure may be under-estimated because it takes no account of any NHIs prevented after 2012.
The more limited reactive culls had no impact on both the treated area and outer 2km ring. Proactive culling only reduced confirmed TB with no significant impact on unconfirmed TB.
Conclusions in the RBCT Final Report, which were based on the results of a model of time-shifted early data, poorly reflect the greater benefits seen in this more extensive data. Badger culling is highly contentious in the UK and many press reports adversely report the effectiveness of badger culling in general and the culls which started in 2013 in particular. Unfortunately the RBCT conclusions are often cited to add credence to these press reports. In the RBCT, after the first year of substantial culling, this work found that 9 years of data were needed to clearly see the full extent by which TB dropped when plotted against calendar year. The impact of the culls, which started in late 2013, may not become clear until late 2023 after a 2-year reporting delay.
This work was restricted to looking at data showing total TB breakdowns over all triplets. Further work to examine breakdowns by triplet or groups of triplets should reveal more.
Author Comment
More detail has been added to the abstract to better explain what was done in previous work and to refer to further work.
The value of a calculation showing the benefit of culling has been adjusted slightly in the Discussions section to include the benefit seen in the 2km ring outside the treated area.
The Future Work section has been extended to describe another potential deliverable of studying data broken down by culling area.
Supplemental Information
Bovine TB RBCT data supplied by APHA on 15 March 2016 ATIC0693
This data was released by the Animal and Plant Health Agency, DEFRA and contains public sector information licensed under the Open Government Licence v3.0.
Provision of Information in response to information request ATIC0693
A document created by the ACCESS TO INFORMATION TEAM of the Animal and Plant Health Agency on 15 March 2016 referenced ATIC0693 in response to a request handled under the Environmental Information Regulations 2004, Regulation 2(c) and 2(f).