Thursday, November 15, 2012

This is encouraging..

It is always encouraging to find the opposition gathering their collective skirts and rushing headlong into a brick wall:  usually somewhat prematurely and for completely the wrong reasons.  We refer to the Badger Trust's broadside against the idea of using PCR (Polymerase Chain Reaction) technology to identify TB infected (or clean and healthy?) badgers. From their website:
DEFRA Secretary Owen Paterson told a Commons committee that he is exploring the possibility of using PCR (Polymerase chain reaction) tests to identify infected badger setts as part of a future badger culling strategy. However the Badger Trust warns that the use of such a test to detect the presence of bovine tuberculosis (bTB) cannot tell whether the infection came from cattle, badgers or any other wildlife. In addition, use of this test on its own carries with it huge risks of precipitate and counter-productive action. Finding the bTB bacillus close to a sett would not in itself prove where a particular sample had come from and localised culling also raises the risk of perturbation. Consequently the possible range of error in the field could be massive.
We think the Badger Trust would be better to grasp PCR to identify clean setts, prior to jabbing unscreened populations of badgers, but let that pass. It's Brian May's their money they're wasting.

But taking bite sized bits from a comprehensive 3 tiered plan, proposed by eminent scientists and also the European Union's DG SANCO is a tad premature we think. So we will quote what others have said.

 Firstly our Lords and Masters, the European Union. In its latest blast aimed at UK politician's non-policy for eradicating tuberculosis, DG SANCO pointed out that Defra should use the skill and knowledge accumulated by their own veterinarians. They said:
The TB eradication programme needs continuity and it must be recognised that success will be slow and perhaps hard to distinguish at first. There is a lot of skill and knowledge among the veterinary authorities and they must be allowed time to use it."
So the starting point of any strategy to eradicate tuberculosis must be maps of where reactors have been found. And that is any victim of tuberculosis, whether that is a cow, badger, sheep, pig, goat, bison, alpaca or domestic pet. Lord knows there are enough to choose from now. But bearing in mind that even in the worst affected counties, around 70 - 75 percent of cattle herds are still testing clear, then this is not a big ask.

Secondly, an overlay map of badger setts and more importantly their territories. And here we are most grateful to Lord Krebs and his co authors Dr. Rosie Woodroffe and Prof. Christl Donelley for their insightful proposals in 1996 which included the following statement on key features likely to influence the effectiveness of any strategy:
(i) The size of the area cleared, (including the extent to which this takes into account badger territory)

(ii) The efficiency of the badger removal operation (to ensure all infected badgers are removed and minimise any problem of perturbation associated with partial removal of social groups)

(iii) The prevention of recolonisation for a sufficient period.
That seems pretty sensible. So when these two maps are overlaid, and bait or fluorescent marking has identified badgers sharing tuberculosis victims' territories, then PCR could be used to confirm the previous two chunks of data? Interestingly, the authors of the Krebs report proposed exactly that in 1996, and of course, we are delighted to remind them of it - even if it is some 14 years later:
7.9.5 We also recommend that the scope for using modern DNA amplification techniques, such as the polymerase chain reaction (PCR), for diagnosis should be further explored. The PCR is quicker than microbial culture and can detect the remnants of dead bacteria in addition to living organisms. If sufficiently sensitive, we see two applications for such a test.

(i) It could provide rapid screening of samples from badger carcases. We suggest MAFF should consider whether this might be an alternative to culture. We estimate that existing assays could be optimised within one to two years.

(ii) MAFF could monitor the presence and distribution of infection by environmental sampling of areas used by badgers.
Sadly, that 'two year' lead in time has stretched a bit, but so many jobs depend on keeping this polemic rolling, and so many pensions rely on not identifying infectious (or healthy) badgers. Including it would seem, the arch protectors themselves, the Badger Trust. Now why would that be?

And it not just 'us' who wanted a targeted cull, involving carefully crafted badger territories, and using cutting edge technologies. Others proposed the very same 16 long years ago, including another signatory to the recent letter condemning the  'culling as planned' Son-of-Krebs shooting party  (apart from Krebs, Woodroffe and Donelley) and that was Professor Stephen Harris.

In 1996, Prof. Harris also proposed a much more targeted cull, relying on 'hotspot' identification, using reactor maps and badger territories. We quoted it in this posting.
So far from throwing this particular baby out with the bath water, we suggest the Badger Trust make use of PCR technology. It is an arrogant presumption that its use as a stand alone is proposed, and equally arrogant that its only use would be to identify infected badgers. It is just as important, in fact more so, to find and protect clean badgers, which occupy around 70 per cent of the cattle grazing areas, before tuberculosis overwhelms them too. Why shouldn't farmers enjoy healthy shiny badgers instead of the miserable, diseased specimens we fall over in Tuberculosis hotspots?

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