Friday, June 09, 2006

More on the RBCT. A vet's view.

In response to letters to the veterinary press by Professor John Bourne, defending (or trying to) the badger 'culling' trial carried out by his ISG group, Worcestershire veterinary surgeon, Jessica Thornton, MRCVS weighs in with a robust critique in this week's Veterinary Times:

"The "results" of the Randomized Badger Culling Trial (RBCT) have been continously upheld and used by the ISG, Badger Trust and RSPCA to sway political and public opinion against a badger cull. It's unbelievable that Prof. Bourne is so blinkered by his scientific tunnel-vision that he has no capacity to see the blatant weaknesses of the RBCT.

He is not only insistent about denying the faults of the trial, but he denigrates fellow scientists and insults veterinarians who have worked on the frontlines of the bTB battle for years, in some cases decades."
Ms. Thornton then makes the following points:

* "The trial may have been rigorously implemented, but it was not well implemented.

*Sixty-nine percent of traps were interfered with - 57% had interference while 12% went missing (Parliamentary Questions 8, December 2003, column 218W [141971]).

* Treatment groups were not treated similarly. For example, in the reactive groups 36% of TB breakdown notifications received no culling while the remainder received partial or full culling.

*Foot & Mouth Disease (FMD) disrupted culling in proactive areas, which were supposed to be culled every 5-9 months.

* Only 2 proactive areas were culled in this time frame, while the other 8 areas ranged from 12-25 months between intitial and first culls.

*Several proactive areas' follow-up culls resulted in more badgers being culled than in the intial cull. Was this due to inadequate culling to begin with? Interference with badger traps? A long delay between culls?

It is safe to say that culling of badgers in the RBCT was a failure, and so the very aim of the study was missed. It doesn't matter how "robust" statistical analyses are or what world renown magazines published the study. There is no way that such a large amount of interference and variation within treatment groups could result in a reliable outcome.

Perhaps this 'peturbation' effect is actually the reuslt of inefficient badger culling, and not localised badger culling.

Another concern raised is this issue of peer review. A peer reveiw is scrutiny of a scientific paper by an independent, anonymous specialist. As Deputy Chair of the ISG, Prof. Donnelly would not be eligible to peer review the ISG's report, as he is neither an independent nor anonymous specialist. After putting so much time and effort into the RBCT, it would be very difficult for any member of the ISG to be unbiased enough to peer review the report.

In addition, I am confused as to which "past, failed TB control policies" Prof. Bourne is refering to in his May 13th letter to the Veterinary Record, and May 22nd to the Vet. Times. History shows that the 1950's TB outbreak was controlled using the tuberculin skin test and mandatory slaughter of reactors. Present day success in the other EU states have successfully reduced/eradicated bTB with the same method.

Prof. Bourne then argues that cattle-based TB control measures need to be more vigorously adopted and applied. One main difference between then and now is the large wildlife population acting as a bTB resevoir (namely badgers, but also deer and other mammals). Cattle-based controls alone will not reduce TB incidence in cattle when there is a high disease incidence in a wildlife reservoir population.

The disease in the wildlife resevoir must be reduced as well. If it is clear that badgers contribute to TB in cattle, then what does the ISG propose we do about this wildlife bTB reservoir? Ignore it? That's a great plan. Or why don't we waste another decade and £millions in taxpayer's money to set up another scientific research trial to determine the effects of ignoring bTb in the wildlife reservoir?
(don't give them ideas Ms. Thornton - ed)

Unfortunately, the RBCT has not made the "extent to which badger culling can be reduce TB incidence in cattle" any clearer. The fact is, the longer we stand by jostling between ourselves, the worse the TB situation is getting for everyone involved, badgers included!

It would be disheartening for anyone who has worked on the RBCT to admit that circumstances within and outside their control have resulted in no conclusive evidence in regards to badger culling and its effects on bTB in cattle. Perhaps working so closely to the project has made it difficult for some to see the trial's weaknesses, making any criticism personally offensive.

However, as men and women of science we must be responsible and mature enough to be self-critical of our own work and to consider humbly the criticism given by our peers. Otherwise our "scientific results" may wrongly influence those unable to deterimine whether science is good or bad, as well as take advantage of the faith they place in science and scientists alike. "

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