September 22, 2021

I, Science

The science magazine of Imperial College

It’s a debate that’s got everyone talking; animal rights activists, farmers, scientists and politicians. Yes, it’s about the dear old badger, and Government plans to tackle the spread of tuberculosis in cows through culling. Bovine TB has become a serious problem for British livestock and currently costs the taxpayer £100m a year. It is well-known that badgers act as a reservoir of infection, and farmers are desperate for measures to control badger populations and help prevent their livestock from becoming infected. So the Government has in the last few weeks confirmed that they are to go ahead with pilots for allowing farmers to use marksmen to shoot badgers in their areas, with wider use planned for 2013.

One of the most interesting points about this debate is how polarised people’s views are on the plans. People either love or hate badgers, which then dictates their opinion on the culling plans. Animal rights groups are obviously up in arms, and polls also suggest that the general public is against the policy. This is unsurprising when we think of how the animal is embraced in British culture, as many a much-loved character from popular children’s books, television programmes, and bizarre internet virals about dancing badgers (“badger, badger, badger!”). And aside from the threat to their livestock, farmers and rural communities have other reasons to hate badgers, seeing them as irritating pests that cause crop damage.

As much as people may either love or hate the thought of badgers being shot, it’s dangerous to use these lines of argument in forming an opinion on a separate issue, which is on the method of tackling a harmful disease. Instead, the questions we need to ask are whether badger culling can stop Bovine TB, whether it’s cost-effective against what we’re already spending on the disease, and what robust scientific evidence there is for the Government to base this policy on.

Unfortunately, despite the Government’s recent decision on the badger cull pilots, we are still yet to see any genuine scientific basis for this policy. So in the next few postings of this blog, we will run through how the badger control policy has been developed, and see how the ‘science’ referred to by successive Governments is, at best, shakey, and at worst, the manipulation of scientific advice for political purposes. The badger debate is a classic example of how Governments are given authoritative and professional advice, but then make a final, and arguably ill-advised, decision to appease certain members of an electorate.

Let’s start by looking at the only available data on the impact of badger culling on Bovine TB. The Randomised Badger Cull Trial (RBCT) was carried out for 8 years by DEFRA in 30 high-risk TB areas in England. The study was under the guidance of an Independent Scientific Group (ISG) consisting of a range of experts in fields such as animal health, epidemiology, immunology and agricultural economics, and overseen by an independent statistical auditor. The trial measured the incidence of TB in cows following the use of two badger cull methods; ‘proactive culling’, where culling was carried out across all available land, and ‘reactive culling’, where badgers were only culled near farmland where recent Bovine TB outbreaks had occurred.

With proactive culling, while a 23% reduction of TB incidence was observed inside the cull area, there was also a 25% increase in TB incidence on neighbouring un-culled land. This was due to the ‘pertubation effect’, which is when culling disrupts badgers’ social organisation, making the blighters run away and carry the TB bacterium to other farms. And with reactive culling, the effects of pertubation were so disastrous that it led to a 27% increase in incidences of the disease, forcing Ministers to suspend this part of the trial due to concerns for livestock safety.

So, in June 2007, the ISG delivered their final report and advised the then Labour Environment Secretary, David Miliband, that “badger culling can make no meaningful contribution to cattle TB control in Britain”, and instead suggested that cattle-based control measures alone would reverse the disease. Seems simple, doesn’t it? So how can culling possibly now go ahead in the face of such strong evidence?

Well, the ISG’s conclusions sparked outrage from the farming and veterinary professions who had long supported badger culling. Then a month later, Sir David King, the Government’s Chief Scientific Advisor, submitted his own report with a re-interpretation of the RBCT data, concluding that the removal of badgers could make a significant contribution to the control of Bovine TB. Quite a change of stance. Could this convenient change of opinion have been in response to the negative reaction from farming communities? Whether this was an honest new interpretation of data or coercion by political forces is unclear. However, there are several facts that ought to be considered. Firstly, the King Report was subject to neither peer review nor independent statistical auditors. Secondly, the ISG experts were not made aware of the King Report until it was published. And finally, despite the authority of his position, Sir David King’s profession was as a physical chemist, and not a biologist or epidemiologist. It therefore begs the question why anyone, especially a Government, would choose this rushed re-interpretation of data over the well-considered advice of the field experts in the ISG.

The scientific community’s response to the King report was one of outrage, with the science publication Nature even commenting that the mishandling of the issue by David King was an example to governments of how not to deal with scientific advice.

The official reason behind these differences in opinion was that, while the ISG were tasked with presenting Ministers with scientifically-based policy options which would be “technically … and economically acceptable”, King’s brief did not extend to considering economic or other practical issues. But experts stress how relevant such factors are in determining how, where and on what scale badger culling could be conducted, and therefore absolutely critical in determining whether culling could reduce TB.

Clearly, any risk, such as that of the pertubation effect, could be overcome if culling was implemented using unlimited resources to the extent that every infected badger was culled. So, by allowing King to work within such a wide scope and exclude consideration of major issues, the Government was able to gain the ‘scientific’ endorsement of any desired option, even though there would have been insufficient resources for badger culling to produce the desired effect when actually implemented. And according to the ISG, “Ministers severely hampered [David King’s] ability to inform policy development.”

And that’s just the beginning. In my next post, we’ll see how the current Coalition Government continues to skew the science behind the cull …