by Rebecca Nesbit, press officer at the Society of Biology
‘Marmite debates’ were a common theme at the food security meeting hosted by the BBSRC last week. Just like reactions to Marmite, opinions in debates about GM crops and the badger cull tend to be polar opposites. This is in sharp contrast to the science in such debates, which often shows arguments in both directions.
Speaking at the event, Angela Cassidy from Imperial College pointed out that little of the Bovine TB debate focusses on facts about the cull. Differing images of badgers have far more influence over attitudes towards culling: are they emblems of our countryside or vermin which need controlling?
With that in mind, I went back to a briefing prepared by my colleagues in the Society of Biology policy team to learn more about the science behind the cull.
The government’s original plan for culling was based on the results of the ‘Krebs’ trial, a randomised badger culling trail run by the Independent Scientific Group on Cattle TB. This trial has to rank amongst the UK’s largest field experiments, costing £50m over 5 years of culling and 4 years of follow-up studies (1998-2007).
Despite the size of the experiment, the results were inconclusive and showed that culling can have a positive or negative effect on the incidence of Bovine TB. This lack of a clear result was partly as a result of two major interruptions: the 2001 foot and mouth outbreak disrupted the trial, and reactive culling was suspended when it led to a rise in TB infections.
However, the results demonstrated that the effect of culling varied depending on the situation. They suggested that, if certain conditions are met, culling can reduce disease incidence by 16% over 9 years. To slow the spread of the disease more than 70% of badgers in an area should be eradicated, but if it was less than 70% the spread of TB could increase. This is because killing badgers disrupts social groups and as the badgers move to establish new groups they can carry TB with them- something known as the ‘perturbation effect’.
The Government made the controversial decision to go ahead with culls in 2012, but this has since been postponed until 2013, partly because it emerged that there are up to twice as many badgers in the culling zones than previously thought, which sharply increases costs.
Bovine TB is clearly a huge challenge which the farming and life science industries need to tackle. The cost is huge to both farmers and tax payers; each outbreak of Bovine TB within a herd costs an average of £30,000 per farm, of which around £10,000 falls to the farmer. This has made the idea of a cull very popular. However, there is no simple answer to whether a large scale badger cull is economically efficient, morally right or scientifically sound.
So what are we left with? Defra is planning to invest a further £15.5m in vaccine development over the next 4 years to continue to develop both an oral vaccine for badgers and a vaccine for cattle. But it will be several years at least before these measures are of use. Wales has chosen to go ahead and begin a trial vaccinating badgers by injection.
The Society of Biology will be responding to the inquiry by the Commons Select Committee about vaccination of badgers and cattle. If you are an expert in this area we would very much like to hear from you. Please email Jackie Caine.
There’s more information in our previous blog post and on the Defra and Nature websites.