Badgers, Cows and Evidence-based Policy

It would have been hard to miss the news this week that the government-planned badger cull has been ‘postponed’. For many campaigners this is very welcome as the badger has had a stay of execution for at least another year. But the government, on the surface of things, seems adamant that this is just a postponement, not a cancellation.

The bTB debate has interested me for a couple of years. I have followed the to-ing and fro-ing between farmers, vets and scientists with interest, not because I am a badger lover or a farmer, but because I have a keen interest in evidence-based policy. It appeared to me that policy was once again set to fly in the face of the evidence.

The badger cull is rare in that it is one of the few policies for which real scientific field trials have been performed in order to establish its efficacy. Peer-reviewed journals detailing the results of these trials conclude that culling badgers is, for the most part, ineffective as a remedy for bTB.

I’m writing this blog post to consider the two main sides of the scientific debate in an attempt to circumvent some of the cherry-picking of evidence that appears to have gone on. There are two main trials worthy of note that are often quoted by both sides of the debate. The first is a large trial conducted in the UK called the randomized badger culling trial which ran from 1998 to 2005. From the analysis of data obtained from this trial, Donelly (Nature, 2005) concludes that ‘culling reduces cattle TB incidence in the areas that are culled, but increases incidence in adjoining areas’.  The study found that badgers migrate during a cull, further exacerbating the spread of the disease.

The second trial which is most often cited in support of a cull was conducted in Ireland from 1997 to 2002. The purpose of this trial wasn’t, as is often stated, to establish if culling badgers reduces TB but was, rather, to establish if indeed badgers are responsible for the spread of the disease. The researchers achieved this by preventing the perturbation of the disease from roaming badgers by carefully selecting areas of the countryside where the geography made migration difficult. The researchers found that, when perturbation was prevented, removing badgers did indeed significantly reduce bTB. As such, this allowed them to conclude that badgers do spread the disease. However, they end their report by stating ‘Although feasible, we acknowledge that widespread badger removal is not a viable strategy for the long-term control of tuberculosis in the Irish cattle population’. The researchers recognised that preventing perturbation effects using geography is not something that can be done across the countryside as a whole.

The government’s proposal for a shooting trial is very similar to the Irish one, where natural features such as rivers are used to prevent perturbation. However it needs to be noted that the aims of the study are to establish whether culling by shooting is an effective means of reducing bTB. Considering the two trials mentioned above, it is clear that yes, bTB will be reduced in the cull area as in Ireland but the results cannot be applied to other areas of the country where the geography does not prevent badger migration. The government is wrong to suggest that the outcome of the shooting trial can be used to establish the effectiveness of culling in other areas of the country and so is ultimately misguided and unscientific. It could be argued that we already know the effectiveness of culling from the randomised badger culling trial conducted already.

I am pleased that our party is committed to tackling bTB using scientific evidence to inform its policy but I am very disappointed that it appears to have decided to ignore the body of evidence which is already available from the most extensive scientific field experiment of its type. Rather than supporting a cull next year, the Liberal Democrats should instead push for a policy which worked for the UK in the 1950s where there was no systematic culling of badgers. In the 50s, a stringent programme of TB testing and monitoring of cattle movement was used to achieve a near-eradication of the disease. Coupled with the development of a vaccine for both cattle and badgers, hopefully government, scientists and farmers can work together towards a solution which is truly based on evidence and will ultimately result in the end of bovine TB.

Dr Craig Brown is an Aldes committee member, space mission designer and Lib Dem activist in Haringey. He tweets at @CraigLD.

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