Naked Science Forum
Life Sciences => Cells, Microbes & Viruses => Topic started by: thedoc on 25/09/2012 18:38:07
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I've been a big fan of your show for a few years now and really enjoy how you explain everything scientific so that anyone can understand.
When it came to a friend of mine, who is a farmer, talking about the UK Badger cull and the Badger TB crisis I couldn't get my head around all the arguments. Would it be possible for you to explain the science behind why we need the cull? And what ways we could help both the badgers and the farmers?
Asked by Christina
Visit the webpage for the podcast in which this question is answered. (http://www.thenakedscientists.com/HTML/podcasts/show/20120923/)
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The science behind a badger cull is not terribly clear.
I think it is a subject that could prove to be a fascinating study into the use of "annecdata" and lobbying in the formation of public policy. I think a second study of the general public's reactions to the treatment of iconic megafauna would also be terribly interesting.
The original link between badgers and bovine TB (bTB) was made 90 years ago because the south west of England has the highest incidence of TB positive badgers and the highest incidence of bTB in cattle. Most of the studies have focused on this hypothesis.
The limited culling trials in the 1990's found that TB levels fell by around 15% in the cull areas - confirming some link - but also suggesting that the issue is far more complicated than simply the presence or otherwise of badgers. The same studies found a small increase in TB levels outside of the cull areas which has been attributed as being caused by disruption of the badger population.
It is interesting to note that in 2011 Lord Krebbs who reported these findings to Parliament criticised the large scale cull planned, suggesting it would be ineffective and money would be better spent on developing a vaccine. This has been countered by saying that the trial cull areas were too small and that a larger area would see greater reduction in incidence and proportionately less “perturbation” problems from disrupted badger populations. For obvious reasons this has not be scientifically studied (to date) and has been criticised by some ecologists, although these ecologists are more likely to be critical of modern intensive farming practice.
Badgers are not the only carriers of TB, with vermin and deer also carrying it.
Some research from Ireland suggests that is TB in healthy Badgers is not particularly infectious. Similar studies have noted that the condition of the cattle - vitamin levels, immunity levels being a factor which are primarily dictated by the weather and the intensity of the farming - was an important factor. Cows in good condition are less likely to become infected. However, when bTB infects a herd, it spreads much more rapidly. It is not inconceivable that poor biosecurity at livestock markets may also be a factor in the spread of the disease. This links to another possible issue is modern agricultural practice, which can see animals moved all around the country. For example to be called “Scottish Beef” the animals only have to be finished for a relatively short time in Scotland – they do not have to be born/ raised there.