Wednesday, March 08, 2006

And the Earth is Flat.......

As the bitter polemic develops over whether or not to control tuberculosis in wildlife in general and badgers in particular - statements are flying which can only be described as 'fanciful'. Science they are not.

We quote an extract from the Gwent Badger Group's meeting with John Bourne:

27 Feb 2006

"Gwent Badger Group Organises Talk by Top TB Scientist
On Friday 24 February at University of Wales, Caerleon Campus, badger groups, farmers, conservationists and other interested parties gathered for a presentation by Professor John Bourne, the highly respected Chairman of the Government’s Independent Scientific Group (ISG) on Bovine Tuberculosis (bTB). The event was organised and funded by the Gwent Badger Group.

Professor Bourne stood at the lectern for over two hours, firstly delivering the detailed findings of the ISG’s in depth research and then taking questions from the floor.

Although he acknowledged that badgers are clearly involved in the transmission of bTB, he also stressed that cattle to cattle transmission is a prominent factor in the spread of the disease and suggested that a neighbouring farm is more of a threat to the average farmer than badgers are. “Problem herds are contributing massively to the TB problem” he added. With around 13 million cattle movements a year, stricter controls on this infectious disease were vital he argued, including pre-movement testing. “There are far too many infected animals in the national herd which transmit the disease nationally and locally” said Professor Bourne.

One of the main problems of bTB persisting in herds is that the widely used Tuberculin skin test failed to detect many infected animals. Large numbers of skin test negative, yet visible TB lesion positive, cattle can be detected by the improved gamma interferon (g-IFN) test. The g-IFN test can detect infected animals earlier than tuberculin test and despite the pleas of the ISG the government refuses to sanction its widespread use. Computer modelling of the infection rate of the disease has suggested that even a modest improvement in diagnosis would bring the epidemic under better control.

There was no solace for those still under the misapprehension that a widespread badger cull would be a straightforward, simple solution to the bTB issue.

Firstly, he explained “If you disrupt badgers by culling them they range further afield.” This effect was clearly demonstrated in collected data given to Government Ministers in September 2005, which showed that during badger culling trials there was a 19 per cent decrease in cattle TB incidence in the culled areas but outside the culled areas there was an increase. It was 29 per cent higher up to two kilometres outside.

Secondly, Professor Bourne concluded that widespread culling would have some impact on bTB but it would be logistically difficult and hugely expensive to carry it out and maintain it and he would only expect a twenty per cent reduction in bTB by eliminating badgers over huge areas of the countryside. When questioned on whether areas needing to be culled would be as large as 300 – 400 km2, he replied that badgers would need to be removed areas the size of the South West of England.

There are and probably always will be pockets of unculled land which greatly reduce the effectiveness of any cull. This can be, for example from farmers or other landowners unwilling to have badgers culled on their land.
It all adds up to evidence, if it is needed, that culling is not the quick fix, foolproof solution some pretend it to be, quite apart from the unacceptable end result of practically decimating one of the best loved species of British mammal which already has a sad and sorry history of persecution"

Reading that from the standpoint of the Badger Groups would be manna from heaven. The fact that it is factually inaccurate, ignores herds to which his hypothesis does not apply and has a scaremongering skew on any possible solution, is a sad reflection on Bourne's idea of 'science'.

* The "13 million cattle movements a year ", we have clarified below as movements of data - at least two, and up to four per bovine trip. The figure for bovines moving 'On' to another farm is 2.7 million. (and the number of cattle in the UK is just over 10 million - not the 3.2 )

*The perturbation found in Krebs' data was predicted by Professor Stephen Harris ( amongst others) It was inevitable given the constraints of cage trapping and using 'map' and not 'badger' or clinical bTb boundaries. The quote is applicable to only the first year's data. The second year achieved a quite different balance, which Bourne (or the report?) fails to highlight.

*The intradermal skin test is the primary diagnostic tool worldwide. It's limitations are a latancy 30 - 50 days before the actual test as the body mounts the 'immune response' which it measures in the skin. And if that body is overwhelmed by Tb and has no immune response, that too will fail to show. Such cases in a herd test, are very rare and only 288 animals tested positive for Tb after being flagged up at slaughter (not by the test) last year out of a kill number of +/- 4 million cattle.

*In the absence of a wildlife reservoir, gamma interferon blood testing will show incubating cases earlier and it is used in other countries to that end. But if the drip feed of infection is from a wildlife source, what is the point? It may also take out cattle with an immunity to m.bovis, having had slight exposure and developed the anti bodies that this blood test measures. Arguably the very animals which should be kept.

*The only badger cull which would be effective is an area the size of SW England, in blocks 300 - 400 sq km. Sheesh, when Bourne couldn't cope with 100 sq. km? So make it bigger?

No - make it different. Using the information available from herds testing clear, only target the setts harbouring Tb, and leave healthy groups intact to prevent peturbation. Monitor the off sets carefully, and action again when they become inhabited. The badgers causing the most havoc, are the individuals that their own group have excluded. The super excreters, dispersers - they have acquired all sorts of names but the pictures we have shown are all of badgers in the latter stages of this dreadful disease. Talk of 'wipe out' is emotive and destructive. It is unacceptable, counter productive and takes the emphhasis away from the disease itself. But as we've said before the polemic which has developed on its back, is keeping several 'beneficiaries' in - the manner to which they have become accustomed.

But the main problem with Bourne's 'science', is its flat, blanket, computer driven assumptions.

This site was started by 6 farmers and a microbiologist, whose PhD was developed in the field of epidemiology and the postulates needed for the spread of disease. Four of the farmers had cattle who had been on the receiving end of long periods of Tb restriction, and to whom none of Bourne's statements apply. That he still announces them with such vigour, is of no value whatsoever if they are ... wrong.

And it is under those circumstances (no bought in cattle and no cattle contact) that we remind our readers :

"the onus must be on those disputing the role of the badger as a signifiant reservoir of infection to hypothesise other sources of infection for such herds, especially where when investigated, the majority of badger populations in the area have been found to be infected".

This last snippet, we quote from Dr. Clifton-Hadley's most excellent paper, 'Badgers, Bovine Tuberculosis and the Age of Reason". (British Veterinary Journal - Guest Editorial 1996)

We find it quite bizarre that Professor Bourne can make such generalised and factually incorrect statements which are gathered and recycled unquestioningly, ignoring the (many) herds which do not fit his hypothesis or computer model, and still call it 'science'.

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