Wednesday, July 13, 2011

Short memories

Professor, Lord, Sir John Krebbs has popped up again. He of the original RBCT protocol in the mid 1990s. He is reported as saying that a cull of badgers'would not work' in this weeks' Farmers Guardian.
The scientist who instigated the 10-year Randomised Badger Culling Trials (RBCT) has insisted that a badger cull would not be an effective way of controlling bovine TB (bTB). Professor Lord John Krebs said the results was commenting on the publication of a Defra report suggesting that, based on the findings of the trial, culling badgers would reduce bTB incidence in cattle by approximately 12-16 per cent over a nine year period.

“You cull intensively for at least four years, you will have a net benefit of reducing TB in cattle of 12 per cent to 16per cent. So you leave 85 per cent of the problem still there, having gone to a huge amount of trouble to kill a huge number of badgers. It doesn’t seem to be an effective way of controlling the disease.”
He's right of course, if the result of a cull was 16 percent or any other number dreamed up by a mathematical modeller. But that is not what the man said in his observations or report which instigated the RBCT two decades ago.

We read this report cover to cover at the time and some snippets arein this posting where Krebbs observes, quite correctly, that:
7.8.3 The gassing and clean ring strategies, in effect, eliminated or severely reduced badger populations from an area and appear to have had the effect of reducing or eliminating TB in local cattle populations. The effect lasted for many years after the cessation of culling, but eventually TB returned
That's 'eventually' as in more than a decade in most cases, by the way.

Krebbs then (in his original paperwork)went on to describe a list of dos and don'ts with regard to any cull of badgers. A sensible list which Bourne and the ISG turned completely on its head when the trial began. In 2007, Bourne gave the following reasons for this in oral evidence to the EFRA committee.

What followed was an indignant Krebbs, spitting feathers at how his trial had been tweaked for political gain, which was entertaining for a short while. But he soon saw the future prospects light, and engaged in a group hug with the ISG in general and Professor John Bourne in particular. As our co-editor wryly remarked in a joint posting at the time, Krebbs was following the cash. To the FSA, to Climate Change committees and any other lucrative rewards appointments likely to be thrown his way.

So where did that '9 -16 percent' benefit originate? What was the data input responsible? The RBCT Badger Dispersal Trial, carried out by Bourne and the ISG, as later management of it showed, had an ongoing beneficial result according to Christl Donnelley's electronic abacus, of around 32 percent, and that extending beyond the cull areas, negating the wholly predictable 'perturbation' halo achieved earlier by the trial.
So 32 per cent (at least) is recorded data for culling badgers, very occasionally, for just 8 nights using cage traps, over a number of years.
At the other end of the spectrum, is Thornbury and the earlier Clean Ring clearances, where gassing took place for a few weeks. Months in the case of Thornbury (not years), and gave a 100 percent benefit to cattle herds for more than a decade.

The averaging of that actual data (not guesses, estimates or simple assumptions) and discounting the different operating procedures, would give a thumb nail benefit of 65 - 70 percent ?

But then we have no 'agenda' to follow and no 'expectations' to look forward to. Just more testing and more dead cattle.

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