Monday, October 08, 2007

60 per cent bTb 'reservoir' in cattle?

The 290 pages produced by the ISG as its Final Report of the RBCT Badger Dispersal Trial concluded, after a torurous passage through a 'simple mathematical model', with 'assumed' data weighted 2:1 towards cattle influence, that 40 per cent of the spread of bTb was down to badgers. And thus, 60 per cent must be due to cattle?

In a long piece from which we quote the first section below, John Daykin and Dr. Lewis Thomas, explained in the Veterinary Times last week, why they believe that this 'simple mathematical conclusion' voiced by the ISG chairman, is quite wrong.

"In his conclusions, the Chairman, Professor Bourne, ventured the opinion that a maximum of 40% of cattle breakdowns could be ascribed to badger transmission. Therefore, by his own admission, he thinks that 60% of breakdowns are due to cattle to cattle transmission . This is not predicated on any scientific data in the public realm, and can only be based on assumption and opinion. We challenge this view in the strongest possible terms and point out that SVS and LVI opinion is quite to the contrary. Indeed, as long ago as 1995, the then CVO reported that his staff attributed about 90% of breakdowns to an ultimate badger source (1). We suggest that this opinion 12 years ago was based on rather sounder data than Professor Bourne’s current view. Veterinary Officers of the SVS and cattle practitioners believe that the vast majority of cattle breakdowns in endemic areas originate from badger contact, and these form the bulk of all new breakdowns."
It may be timely to point out here that the diminutive Prof. went into this ten year prevarication exercise clutching the express instruction that a badger, he may not target. Thus any conclusion it arrived at was bound to be somewhat slanted. The RBCT conclusion does what it says on the tin - or in this case, on Professor Bourne's Ministerial recipe sheet.

Neverless, ten long years (and £50 million later) Mr. Daykin and Dr. Thomas point out paragraph 56 of the 1985 Dunnet Report:

“The evidence is unchallengeable that badgers can be infected
by M.bovis and can become infectious…………We believe
that it is not necessary, and indeed would be a waste of
resources, to seek further confirmation for the transmission
of tuberculosis from badgers to cattle”

Why, then , more than two decades later, have we just spent nearly £50m on a flawed project that a government report clearly advised against all those years ago? [ .. ] Clearly other factors are involved in our failure to control the current epidemic.

This is most certainly true. But the authors may not, we venture to suggest, have realised the extent of the ministerial input into the dynamics of this expensive jolly - input which Professor Bourne was proud to trumpet to the EFRAcom, as seen in our post (link above).
Mr. Daykin, and Dr.Thomas continue:
No evidence was presented to convince us that the RBCTs have provided a sound scientific basis for the control of bTB. Indeed, quite the opposite, in that we are now even more convinced of the basic flaws evident throughout the protocols that have guided these Trials.
They point out the increase in bTb through the cattle herds (some of which would have been like the authors of this site, - closed to cattle contact and on regular testing for many years) during the course of the ISG’s stewardship of the bTB epidemic. But cattle slaughtered as reactors, inconclusive reactors and dangerous contacts have increased from 6191 in 1998 to 30672 in 2005, and new herd breakdowns have increased from 1518 to 3512 over this period (3.93% of all herds), despite the ever more rigorous application of cattle controls. 6.54% of all herds were under TB2 restrictions at some time during 2006.

Which is 6.53 percent more than OIE Tb free trading status permits.

(Ed- As this Opinion piece is so packed with information, and thus a tad long, to do it justice, we will split it up into separate postings. More on the 'trial' culling efficiency and gamma IFN to follow.....)

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