The law of unintended consequences

Or as we say - Sod's law. As the barricades go up once again on livestock farms across the country, cattle farmers are counting the cost of preMT in spades.

When FMD (Foot and Mouth Disease) was discovered on a farm in Surrey, early August, all livestock movements came to a halt. The outbreak, traced back to the Pirbright site operated by Merial Laboratories and Defra's flagship Institute of Animal Health is well covered by the indefatigable warmwell , but as a consequence of the industry 'shut down', cattle pre-movement tested for sales during August have not moved.

When trading between farms resumed for the briefest of windows mid September, many of these preMT tests were 'time expired'; that is to say the selling opportunity was breached as the testing had been done more than 60 days ago. Some farmers tested again that week - if they were lucky enough to get a vet at very short notice - only to be stopped again by the discovery of healed lesions and FMD antibodies in livestock at Egham.

Auctioneers and farmers are telling us that thousands of head of cattle are stuck on farms, needing yet another preMT before sale. But now, as routine autumn testing starts in earnest, veterinary practises are several personel short, having loaned vets to Surrey. And they are telling clients that they cannot cope with extra preMT until at least November.

September is the traditional 'hand over' time when farms change owners or tenants, and this too, is now put on hold, due to snarlups in the trading system. Late October / November, which is Defra's new window for loosening up trading restrictions, (assuming no new FMD cases pop up) is the wrong time of the year for autumn suckled calf sellers to sell. And the delay in moving stock puts horrendous pressure on dairy farms, regularly trading calves and newly calved milking cattle. And it comes at a time when wheat, maize and other starch prices are rising at an extraordinary rate.

So a double whammy of an FMD 'leak' in Surrey, combined with the costly, bureaucratic and cumbersome 'comfort blanket' of preMT has led to severe overstocking and consequential feeding and possibly housing problems, on livestock farms who are on annual or two year bTb testing regimes.

The eyes of the media are on Surrey, but the law of unintended consequences, is alive and kicking on thousands of cattle farms from Staffordshire to the tip of Cornwall.

Comments (and errors)

Some of us are computer literate, and some - are just a bit 'challenged', I think.

After being inundated with 'Anonymous' comments, reluctantly, we deleted that option - and apparently zapped all comments options. That was clever. So, Matt 5, read the book, and reinstalled 'Any Comments', but on scrolling down the blogger tool kit to verify the change, altered the next box to 'Allow No Comments' - at all. That was really clever. And not intentional.

About as good as the ISG's simple mathematical model which received an exclusive, professional brief peer review in our posting below.

Our modeler also challenged the ISG computer's maths on the incidence of New herd breakdowns, which were calculated as doubling 'every 4 and a half years'.

Incidence of New Breakdowns (7.21) on p148 - error on the first line
[The ISG quote] a compound IR of 15% - I’d be happy with that.
Compounding annually at 15% means it would double in 5 yrs not 4.5.
That’s out by 10%. A fairly big error straight off.


The maths: 1 x 1.15^5 = 2.01136

1 x 1.15^4.95 = 1.99735

Ten per cent is a lot to be adrift by - but hey, the ISG did describe their model as 'simple'.

Another 'error' was found by our eagle eyed contributers, in the recently published SE 3013 Pathogenosis project report. The stats on Gamma Interferon use within the trial we found odd, as was the conclusion of the mathematical calculations. Were some of the conclusions, including, possibly, this one, used to fuel a 'simple modeling exercise' too?

We quote from the point made to VLA on their figures for the IFN trial:

If 23 out of 96 tested negative to both of two tests, then logic dictates that at least 23 must have tested negative to either one of the two tests. So the figure of 9 in the last sentence quoted doesn't square with the earlier statement. But the higher figure of 30 reactors with unconfirmed bTB which tested positive could be correct. If so, 42% of reactors with positive IFN results but no confirmed bTB seems a large proportion.

And the answer confirmed our query:

"Thank you for identifying this error for which I am responsible: "23 out of 96 tested negative to both tests" should read " 6 out of 96 tested negative to both tests" . 23 out of 96 animals tested negative to either test".

So, 23 out of 96 (23.958 per cent) becomes 6 out of 96 (6.25 per cent)- an error of almst 18 per cent. Our modeler described the ISG's mathematical error of 10 per cent as 'fairly big". We can't begin to guess how he would react to a gaff of 17.708 per cent.

So when considering veterinary and epidemiological options based on these multi million £ research projects, readers would be wise to keep a firm handle on their brains and common sense, and if a conclusion looks odd, to question both the conclusion and the manner in which it was reached.

"A simple mathematical model"

We are grateful for the over view of a mathematical modeler, with an MSc degree in the subject, self employed and freelance in his profession.
He has looked at the basis of the ISG data for us, and comments thus:

"One of the more telling sentences is the penultimate one of section 7.19: "

“The ISG chose to use a relatively simple model rather than a more complicated and potentially more realistic model because the objectives were to reach rather broad conclusions, and because the more realistic models require the specification of many essential unknown features”.

"In mathematical modelling terms, this basically means:"

a) It is a simple model – therefore not even close to modeling a ‘realistic’ scenario. Waste of time basically.

b) The objective was to reach a broad conclusion – ie nothing of substance again.

c) There were many essential unknown features – again the more realistic model that might be of some use can not be used as they don’t have the information.

Our modeler continues:

How can this model, using such basic assumptions and missing key information (because of unknown but essential features) be relied upon for real world decisions that affect people and livelihoods?! It is fine for an academic discussion but that is where it should be kept.

So, it would appear that by opting for a simplified, broad brush model into which to put generalised assumptions, the ISG has turned an embryonic mathematical 'science' into an art form which can be tweaked to achieve their intended answer We would add, that to see the eminent professor actually appear proud of his acceptance of such a political bridle in which to 'work' was quite extraordinary. Illuminating, but extraordinary.

But we digress: in modeling terms, our independent expert describes such input as ;

"simple squared equals stupid". Referring to the fact that the ISG have used a simple model to which they have applied simple assumptions.

We referred to such blind faith in the machinations of skewed input into computers in our post here and also drew our reader's attention to one such extremely broad 'hypothesis', on the relative importance offered to the sacred machine of 2 parts cattle v. 1 part badger, which extruded 50 per cent cattle to cattle transmission - and the inevitable cattle carnage. This input data could have been much more accurate, if information from the Tb 99 tomes had been used. Lord knows we spent long enough filled the goddamn things in.

We note that the ISG have recorded manure spreading as a factor encountered on the vast majority of breakdown farms. Yes. Cows do have that unfortunate habit, and the resultant organic manure is spread. And?

Using the 'science'.

We have, and will continue to be highly critical of the politically skewed RBCT Badger Dispersal Trial. It told us little that we did not know ten years ago, except to reiterate how not to deal with a serious, zoonotic disease situation in a wildlife reservoir.

But the further one delves into the ISG 290 page final report, the more snippets emerge which, although not highlighted by the authors, do not support the unequivocal conclusions of its chairman. (that badger culling, as it was conducted in the 'trial', has no place in the control of bTb).

A comment from Jim on a posting below first drew our attention to the published results of the cull areas of the trial, but in much more detail;

I've done some "mathematical modelling" (based entirely on the data in the ISG Report), and this "suggests" (to use modellers' language) that, if you take a cull area of 800km2 (as opposed to the RBCT area of 100km2), then the net number of herd breakdowns saved (i.e. the number of breakdowns prevented in the cull area minus the number of breakdowns induced by the perturbation effect in the 2km ring outside the cull area) would be 121.9. This is to be compared with the RBCT figure of 1.4 net breakdowns saved per 100km2 (or 11.2 for eight separate areas of 100km2 each). This result is simply a (mathematical) function of the fact that the area culled is proportionately larger when compared to the perturbed area just outside the cull area.

and the really important bit, on which the ISG did not dwell;

I've also taken account of the fact that the ISG found that the beneficial effect of proactive culling was about 50% in an inner core area 4 - 5km from the trial boundary - see para. 5.15 and fig. 5.1B - though this doesn't seem to be a finding they are keen to highlight

.
So should the data that the centre of Bourne's cull areas managed to avoid the problem of his 'edges' - or any other part of the man - have been given more prominence? That depends from where the political steer was coming. Our commentator continues:

Surely, if the mathematical modellers are saying that something would have a beneficial effect (i.e. culling over a larger area), then it's up to the politicians to find the will and the means to achieve that (or not, as the case may be). Instead, no doubt they'll hide behind the good professor, who has assured them it isn't practicable - and in the meantime they've conveniently sacked all the people with the necessary expertise.

Jim stresses that he is not advocating much larger cull areas as the only or even the necessary way forward, preferring a more targetted approach, but he points out what can be achieved through the use of mathematical modelling.

"If you take the ISG's own figures at face value, the question for the politicians is why not devise a way to carry out a cull over larger areas, as the mathematics shows that this will have a significant beneficial effect? "For the avoidance of doubt", as they say, (a) in setting my calculator to work on the ISG data I'm not accepting that their report is anything other than fatally flawed, (b) if anyone thinks my maths is wonky, feel free to say so (though it appears to be in line with paras. 5.39 to 5.42 and fig. 5.4 of the ISG report), and (c) I realise that questions of badger ecology might influence the effects of a cull over a larger area (I'm just trying to show how a bit of number-crunching can affect one's conclusion

Another observation, this time from Dr. Nick Fenwick in his evidence to the Welsh Assembly makes the same point;

"There is a graph on page 99 of the ISG report in which the beneficial effects of what we would regard as not exactly efficient badger culling are plotted against the distance from the outside of the culling area. The closer you are to the outside of the culling area, the more significant the perturbation effect would be, because that is where the badgers are travelling in and out of the culling area. The badgers from outside the culling area are too far away to travel to the core of the culling area. So, ultimately, perturbation is not a problem in those core areas.

The relationship between the beneficial effect and the distance from the perimeter of the culling area is plotted. The average figure for the effect over five years is in the early twenties: there is around a 23 per cent or 24 per cent reduction in TB. However, in terms of the core areas, where we can ignore perturbation, the reduction in the incidence of TB is down to 50 per cent.

In addition to that, it is worth bearing in mind that, on that same page in the ISG report, there is also a plot of the effect after each year of culling. After the fourth year, the reduction in the incidence was some 32 per cent — I am estimating these figures from the graph. There was a 32 per cent beneficial effect, compared with around an 8 per cent negative effect on the periphery of the culling area. If you combine those two aspects, one might ask what the reduction in the incidence of TB in the core area was after the fourth cull, because that figure of 50 per cent is likely to be increased significantly.

So, in the fifth year of culling, you could imagine perhaps a 60 per cent or 70 per cent reduction in the incidence of TB, which would be a major breakthrough in TB control and would reverse the decline in our TB status that started in 1986."

We agree, but would suggest that annual culls are merely a way to prolong this agony. An intense targetted cull of weeks, would draw out dispersers from other social groups, thus leaving a 'clean ring' of badgers for probably several years. Do not forget that the length of time from exposure of a sentinel cow to a skin test flag up reaction from UK strains of bTb is 221 days. Just 7 months. (Not the seven years the strains take to manifest in Australia) There is absolutely no reason to suppose that the UK system of two 60 day skin tests plus a follow up six month check test for a herd, will not clear the problem, providing the source of infection is identified and removed.

And although they may not appreciate our pointing it out, the ISG final report has shown a huge reduction in cattle Tb at the centre of the cull zones, even and especially given their ineffective, irregular 8 night hit-and-run visits. And no cattle controls either, apart from regular skin tests. How odd, that they felt unable to share this.

"This is the answer ....

... now, what was the question?"

The ISG final report from the RBCT Badger Dispersal Trial was categoric in its recommendations. Badger culling, in the way that it was conducted during their trial, has absolutely no place in the GB armoury against bTb - unless as he said in our posting here it was to act as an inducement for the cattle measures which Professor Bourne openly told veterinary colleagues at the start of the excercise, would be their only option, at the end of it.

We have explored the difference between the trial protocol as described by Professor, Sir John (now Lord?) Krebs here
and how it differed substantially and critically from what the ISG delivered in practise. And from the Welsh Assembly's examination of various industry reactions to the report's findings, we quote this gem from Mr. Rooney, speaking for the CLA:

" Perhaps I might preface my remarks by saying that I was brought up as a scientist; it was not in this discipline, but scientific principles hold, whatever the discipline. One of the things that I was taught was that, in designing an experiment to try to address an issue or a problem, you may not like the results, but you accept them. I find it deeply shocking that responsible scientists should have been prepared to undertake a research study having been told at the outset that there is a conclusion that they are not allowed to reach. I find that utterly disgraceful".

Mr. Rooney concludes, in robust fashion:

"In my more bitter moments I see its approach to the wildlife issue as having been a most impressive exercise in creative prevarication. The excuses for not doing anything have been most imaginative".

The reflections by the ISG on their trial protocol from the ISG in public are somewhat inconsistant. While they assert that it was 'their protocol', when pressed on the specifics, the answer is somewhat different.
Professor Bourne to the EFRAcom (18/06/07)

The Irish "...have less welfare considerations than we forced to give to the trapping that we carried out on the trial"

'Forced? John Bourne? Exactly who had him in an armlock, one wonders? He continues;

"Very importantly, there was 100 % farmer co operation and we did not get that.The other thing is that there is no badger group in Ireland".

and:

"Let us go back to 1999 when we started our work. It was made very clear to us by ministers of the day - and they have not refuted it since - that elimination of badgers over large tracts of countryside was not an option for future policy".

A horrified Geoffrey Cox, MP intervened "Is it not the function of science..." but the diminutive Prof. was in full spate. He was not to interrupted and continued:

It was on that basis that we (note that we - ed) designed the trial. We also had to take into account welfare considerations with respect to culling used, and limitations on culling with respect that cubs were not killed or died underground [ ] Those were clear political limitations that we operated under; I have no reason to believe that those political limitations have changed".

Geoffrey Cox, MP then asked Bourne to clarify the report's findings and its conclusions in the light of his statement describing a political steer in what should have been a scientific exercise. Professor Bourne replied thus:

"We repeatedly say "culling, as conducted in the trial." It is important [that] we do say that. Those limitations were not imposed by ourselves. They were imposed by politicians."

and he concluded the session:

"At the end of the day I think you have to accept that it is the price society puts on a badger. [ ] In this country there is a price on a badger and on badger welfare".

An astounded Mr. Cox, whose constituency houses some of the worst hotspots in the country replied:

"I beg your pardon: they put a price on it in terms of the suffering of families, and the slaughtering of tens of thousands of cattle?"

Professor Bourne, now condescendingly patiently explains to Mr. Cox, the difference between 'science' and 'political science':

"Whatever has driven that I do not know [ try copious multi million ££ donations to political parties? - ed) but the fact is that a price has been put on the badger in this country which related to the way we were able to carry out our scientific work. That is exactly what we report".

So there we have it. As the fallout from this expensive farce continues, one may safely assume that Professor Bourne and the ISG, having ignored Krebs original protocol and its clear warnings, grabbed a politically skewed methodology, conveniently labelled "This is the answer, now phrase the question".

That it was an 'exercise' in prevarication is beyond doubt, but to label it 'science' in the same breath as reading how it was steered, is stretching the imagination.

An epitaph to the RBCT

We have been alerted to a recently published comment piece in the broad sheets, which describes the folly of leaving one's brains behind while acccepting exactly what any computer programme extrudes, regardless of input.

As an epitaph to the hallowed computer modelling which fuels so much of the politically 'in the difficult file' decisions which have taken over veterinary and epidemiological policy in recent years, we reproduce it below, with thanks.

It is taken from an article by Tom Stevenson in the Daily Telegraph last week on this summer’s upheavals in the stock markets. He takes issue with the claim that “highly remunerated rocket science can be a short cut to above-average returns with below-average risk”, and continues:

“The two are as incompatible as they always have been and no spurious cocktail of calculus and Greek letters can change that fact…The admission by the biggest and most powerful investment banks that their ‘quantitative’ rocket scientists got their sums wrong undermines the claim…that ‘number crunching is leading decision makers to make different and, by-and-large, better choices’… Garbage in garbage out. If you lend money to people who cannot afford to borrow it, no statistical model or clever repackaging of the debt will make the resultant waste any less toxic. There are no short cuts…[This] kicks away support from the false idea that human experience and judgment are less important than a terabyte-crunching, mechanistic view of the world.”

The ISG final report is full of 'assumptions' and 'hypotheses', but its conclusions, built via a 'simple' mathematical model, on the back of these are now described as 'hard scientific data'. Yet the consequences explored in the report, of various policies are apparently based on the assumption of "equal risk" given to "roughly the same importance" of:

" all sources of infection for cattle, local infection for example across farm boundaries, infection from animals bought in, particularly but not only, from high incidence areas, .... and infection from wildlife, especially badgers."[ 7.24]

In the case of almost every farm, on onsite veterinary officer from local AHO could, in a couple of minutes discount two of those "rough, equal risk 'hypotheses'" and for any badger cull to proceed, should have to do so.

We liked the final paragraph of Tom Stevenson's piece, and particularly his conclusion, describing statisticians modelling of unsustainable debt which, after it had made passage through a mathematical abacas, indicated above-average returns with below-average risk. The fallout from this, its consequential share value switchback ride has finally kicked away "support for the false idea that human experience and judgment are less important than a terabyte-crunching, mechanistic view of the world.”

Not at Defra it hasn't. And if you change the stuff about the consequences of lending to people who can’t afford to borrow, to killing cattle without dealing with all sources of infection, this would make a perfect epitaph to the RBCT Badger Dispersal Trial.

A Trojan horse

At a recent meeting of the EFRA committee, Professor Bourne gave the following insight into his cattle control measures, and possibly how they may be achieved. We take this from the uncorrected transcript of evidence, which is of far more use than a draft which has been re-written and tweaked half a dozen times. It does what it says on the tin.

In its final published version, the RBCT Badger Dispersal Trial report roundly rebuffed the “at least 40 per cent” contribution that badgers make to the disease progression and despite admitting “there is no dispute about the fact that badgers do contribute to the cattle disease disease” . The diminutive Prof. then went on to outline the only option that was feasible which, in his opinion, was more (and more draconian) cattle controls.

This was ‘bourne’ of simple mathematical modelling undertaken by Prof. Donelly, who having tortured some unidentified (by the reader) data, weighted heavily - 2: 1 - in favour of cattle and against badgers (that bit was published) extruded a figure of 50 per cent of herd breakdowns attributable to cattle. We think. And it is on this illusive figure that Professor Bourne has fastened. He was questioned, including the progression of the disease through the 1960’s to the present day, and he came up with the following gems:

On the use of the tuberculin skin test:

“It was developed as a herd test. The obvious way to use a herd test is, if you find an infected herd, to take it out.”

On the increase in cattle Tb after the late 1980’s into the 1990’s.

“I suspect cattle testing was relaxed"

(It wasn’t, but badger culling in response to Tb outbreaks most certainly was –ed)
On cattle movement:

“Statistics show that there is a great deal more cattle movement because of wider trading activities of cattle farming”

(More than what? Drover’s roads from Wales and the Midlands to London, with herds stopping every ten miles or so? Cattle trains from Cumbria to the south? Just because a scientist hasn’t realised that a thing happened, it does that mean that prior to his Damoscene moment, it did not happen – ed)

And on ‘opposition’ to badger culling in ireland as opposed to the UK.

"There is no Badger Group in Ireland"

(And? bTb is a grade 3 zoonosis.)

On larger cull areas.

"Mathematical modelling in extrapolation from the trial data suggests that if you cull over a large area, you would ultimately get positive gains with respect to the area culled, relative to the area you were not culling"

.
(So that’s a yes?)

Er – no.

"I also stated [] that there would be extreme logistical difficulties in achieving this with respect to culling over a large area repeated regularly over a large period of time, and it could only be considered as a policy option, if there had been an adequate cost benefit analysis.”

(He means farmer’s would pay for cage trapping – ed)

Define difficulties?

“...the logistical difficulties of getting a trapping force into the fields, to do culling across the whole piece at the same time and continuing it for this very long period. ... Government have stated very clearly that they would not do this themselves. They would not be responsible for this, but farmers would in fact have to do this off their own bat..”

And is it possible, with such farmer participation?

“As an extrapolation, as a modelling exercise that was correct, but we are bound to write caveats to that, which I thought would have been a clear message to message to Ministers of the difficulty of doing that and the liklihood that the whole thing would not be achievable”

(That’s a No then –ed)

So could badger culling have any effect at all on cattle Tb in the UK? And here we get the Trojan Horse, and the cattle measures that this open minded scientist has preached all along, while accepting political strictures from day 1, on his badger culling dispersal trial..

“What we are saying is that badger culling in the way it can be conducted in the UK, we believe, cannot possibly contribute to cattle TB control, and in using the word ‘ meaningfully’ what we mean there, is that if it is the only inducement that would encourage farmers to co-operate fully, and introduce effective cattle controls, it could have an effect”.

(Whaaaaat? - ed)

This was echoed, somewhat more politely by the EFRAcom Chairman:

“Can I make quite certain that my ears did not deceive me a moment ago, when you said with your almost impish smile, “Left to its own devices, culling is not the silver bullet but if it induced some other activity as a quid pro quo, it might have a role to play?”. Is that what you are saying to me?”

Prof. Bourne:

“It would be most unfortunate if that happened but that is exactly what I was communicating to you, because farmers have made it clear they will not co operate unless thay can kill badgers. Farmer co operation is absolutely essential to get this disease under control. It will be appalling thing for us if farmers were given the opportunity of knocking off a few badgers, just to get their co operation.”

Well that’s pretty clear, is it not? If government offer a few sacrificial badgers, at the same time as extra cattle controls, then a ‘package’ may be agreed?
A quid pro quo, the man said. Yes? The last industry 'package' was unceremoniously shattered by Defra, who are very adept at taking the 'quid' while failing to deliver the 'pro quo'.

So, cattle measures: in order that there is absolutely no illusion about what the good Prof. is proposing, the ISG final report (p.24 – 29) illuminated his audience with exactly what he had in mind as those extra cattle controls. They included:

* Pre and post movement testing, both combined with gamma interferon.(IFN)

* Strict animal movement control (zoning) of animals from high risk areas into low risk, and even between farms of the same status within a zone.(10.64)

* Gamma interferon widespread in low risk area breakdowns.

* Severe animal movement controls and only licensed to farms of the same status(10.71)

* In breakdown herds in high risk areas, one or two reactors at disclosing skin test and no recent history of infection would merit IFN in parallel use to the skin test.

* Within multiple reactor herds, with a previous history of persistent disease, slaughter of the whole herd or cohorts within it. It is advisable to be rigourous in these situations, and whole herd slaughter should be more readily excercised option for heavily infected herds.

* Expect a hard core of 5 per cent or more multiple reactor breakdown herds in high risk areas which have been difficult to clear; these pose a substantial disease risk and should be considered for whole herd slaughter.

And the contribution of infected badgers? Not a thing, except a throw away line that a few may have to culled, as a Trojan horse for what Bourne wanted all along. The draconian cattle controls which have so spectacularly failed in the past. And that delivered with a smirk "impish smile" to the Chairman of the EFRAcom, who remarked that he could not "be certain that his ears had deceived him".
Believe it. There's an election coming.

Shamb-les

(Updated 23/08)

The situation at the Skandavale sanctuary in West Wales, does not appear to be going away any time soon.

After the much publicised demise of Shambo, the sacred bullock, who proved positive for bovine tuberculosis, the sensitivety of previous test reactions was ratcheted down to include two more animals who, now assessed under ' severe interpretation', await slaughter at the Minister's pleasure.

But a further herd test last week has apparently revealed more problems.
ic Wales , the internet based Welsh news company reported that four water buffalo and a cow gave an inconclusive result to last week's test.

The sanctuary is also home to several goats, deer and an elephant.

At what stage of an unresolving bTb outbreak we wonder, would the ISG's proposal for whole herd slaughter, which we discussed in the posting below, be initiated?
We aren't supporting this option in any way, but on the table for discussion, it most certainly is.

23/08/2007.
After delays in serving slaughter notices due to FMD standstills, the two animals now in reactor status at the Skandavale 'sanctuary' have been slaughtered.

Under a headline 'More Hindu cattle to be slaughtered", Farmers Weekly describes the animals in question as a yearling water buffalo and "a 16-year-old Jersey bullock, which has been unable to stand for a year".

There are times when words fail me.

Matt 5

Opportunism?

The Veterinary Record last week contained two letters of interest to this site. And as we like to end on a cheerful note, we quote a lightweight piece of political opportunism first.

This came from the president of the BVA (British Veterinary Association), David Catlow, who explained that his organisation had deliberately taken the time to digest the contents of the ISG RBCT Badger Dispersal Trial 'Bible'.

The implication is therefore that veterinary colleagues who have already commented, had not digested the report? But we digress.

Mr. Catlow wants to know where the report "fits with our existing bovine tuberculosis (TB) control strategy". Well that is quite easy. We don't have one do we? Haven't had for some time. He continues: "What is quite clear is that the report gives no clear direction on how best to progress the control of bovine TB".

Actually, it does. The ISG confirmed that badgers do give cattle tuberculosis, and told us how NOT to deal with it. Mr. Catlow points out that the ISG report states "that bovine TB infection from badgers to cattle in endemic areas could account for up to 50 per cent of cases". This curious figure may have its roots in the methodology of the ISG mathematical modelling as described in 7.19, where they describe the choice of a "simple model, highly idealized but intended to capture key features of the epidemic". Fast forward now to 7.24 of the ISG 'Bible', where the explanation of such modelling informs the reader thus:

"The effect of changes cannot be assessed directly from available data but simple mathemetical models, combined with the large amount of data now assembled do allow some very tentative predictions. The infection rate concerns all sources of infection for cattle, local infection across farm boundaries, infection from animals bought, in particular but not only, from high incidence areas, and infection from wildlife especially badgers."

And then the crucial bit. Far from using the cumbersome TB99 and local AHO knowledge on breakdown farms available, including mapping in the case of shared boundaries, and BCMS / CTS records for bought in cattle, the modellers of the ISG describe their 3 choices for comparison of risk thus:

"All these are important, but their relative importance and that of cattle-badger transmission, cannot be estimated directly. In the following calculations we assume all three souces to be roughly equally important"

So, "tentative predictions" made on "rough assumptions" of transmission opportunities at the rate of "2 cattle : 1 badger" were pumped into the modelling computer's abacus? Is that right? Of course the relative causes of breakdown herds could and should have been more refined than that. It was too much goddamn trouble to ask. So out extrudes a deliberately vague reference, not supported by the CVO's previous annual reports which attributed up to 90 per cent of cases to badgers.

On that side of this unequal 'rough assumption", the BVA have this to say:

"It remains the BVA's view that addressing this transmission from wildlife is an essential part of a bovine TB control policy in endemic areas. It is evident from the spiralling incidence that cattle controls alone are inadequate to control the disease. Obviously, the vaccination of cattle/badgers is desirable, but since no effective vaccine is yet available, more immediate steps need to be progressed.
We have suggested and discussed the feasibility of a study for designing an efficient and humane badger culling programme, within the constraints identified by the ISG report, with appropriate consideration given to addressing the 'edge effect', compliance, social and political acceptance and cost. Other suggestions include developing PCR technology in order to identify and selectively cull only infected badger setts".

OK as far as it goes. Nowhere near robust enough, but then these were the chaps who were defending to the hilt, practising veterinarian's 'rights' to Tb testing. They publicly and vehemently opposed lay testers, on the grounds of losing cattle vets from their practises. And once again in this letter, their constant but consistant political opportunism appears. Having given credence to the unique 'edge effect' that Bourne experienced, the BVA then parrot the ISG's demands of extra cattle controls, 'bourne' of the modelling excercise described above;

Reducing the spread of the disease remains an essential part of any strategy, and the BVA discussed with TBAG what further refinements in cattle controls might be beneficial and therefore warrant further examination. These include:
 Exploring what potential exists for extending the role of the gamma interferon ( -IFN) test;
 Altering the frequency of bovine TB testing - whether the frequency of tests could be reduced in some areas to allow deployment of increased resource in others;
 Developing the concept of pre- and postmovement testing;
 Enhancing speed of removal of reactors from farms;
 Developing the concept of risk-based cattle movements. Herds of similar risk might trade relatively unrestricted but higher-risk movements might be subject to further assurances to reduce the cattle spread of disease into new herds and regions;
 Developing the role of the LVI in order to facilitate the tracing process of infected animals.

Straight from the ISG Bible. The only thing they've missed out is whole herd and cohort slaughter. How could they miss that? They said they had 'deliberately taken time to digest the report' did they not? But it's there in all its gore glory, both in 'low risk areas' and 'high incidence'

10.67 .. slaughter of the whole herd or cohorts of animals in affected herds. It would be advisable to be rigourous in these situations, and whole herd slaughter should be a more readily excercised option for heavily infected herds". (This for low risk areas)

and

10.74 Previous testing history will reveal a hard core, possibly 5 per cent or more of these multiple reactor breakdown herds in high risk areas which have been difficult to clear of infection. These herds pose a substantial disease risk and should be considered for whole herd slaughter or slaughter of cohorts with a history of infection.

But ever consistant in sourcing veterinary opportunities, the BVA have ignored this little gem and cherry picked concentrated on the testing part. They have also ignored the restocking options. Do they really think that after whole herd slaughter, Defra are going to allow cattle back onto that farm to be reinfected from a 'non-bovine source' as they so quaintly describe it? Already farmers in that position are being advised, 'respectfully' of course, that a cattle restock option would not be wise, due to infection from such 'non bovine sources'. But as we have said, the BVA are happy to cherry pick the ISG Bible for veterinary opportunities, and propose more frequent testing. More frequent than what? every 60 days for years? Sheesh. Pre and post movement testing, zoning of areas and the inevitable extension of veterinary expertise to accomplish this. Piling up dead cattle higher and quicker then. With approximately 5 per cent of the herds in Wales and the West region (Defra figures to May) slaughtered out altogether. That's 180 herds who won't need a cattle vet then?

The BVA were involved in the last government strategy 'package'. They have learnt nothing. You do not play political trade offs with politicians.

By unquestioningly grabbing at these lightweight LVI opportunities, the BVA must have made government's day. They can go ahead with the tacit agreement of (some) veterinarians along the lines of the ISG 'Bible's' cattle carnage 'science' which has already told them that this alone will reduce bTb by 15 per cent per year. But if the president of the BVA thinks he can offer these sacrificial lambs (or in this case, calves) in exchange for a badger policy at the same time, history and bitter experience suggests he may have to think again. "We won't know which is working" will be the clarion call, "so one strategy at a time gentlemen,- but obviously with cattle measures first". Cynical? You bet we are.

The other letter which the Veterinary Record published, carried a more positive embrace of veterinary responsibility for diseases in wild animals, their transmission and the welfare of sufferers. It came from Mr. I.F. Keymer, a former government veterinary employee, whose interest extends beyonds the politically acceptible. He congratulates Defra on recognising the importance of diseases and zoonoses in wild animals and their transmission to domestic stock. Mr. Keymer's letter concludes:

"I hope that Defra with its new responsibilities, will now take more positive action to tackle the welfare problem of bovine Tb in badgers. The infection has now spread to several other species of wild mammal. Urgent action is therefore required to prevent further spread, especially to cattle".

Yes, it is. But with opportunism as exhibited by the BVA's letter above, it won't come anytime soon.

"I've gone off the ISG people"

We are grateful to the Small Farms Association for a copy of his critique of the RBCT Badger Dispersal Trial, written for them by Dr. John Gallagher, which we publish below.

TB and those culling trials – the ISG final report.

After spending the most depressing day for many years listening to the full findings of the so called Independent Scientific Group (ISG) on the culling trials and TB problem in cattle, just how badly the trials had been carried out started to dawn on me. I had been working in the Putford / Holsworthy area at the time and talking with farmers and seeing what they were reporting made me realise that the trapping was going badly. But to listen to the slick ISG presentation describing these trials as the “only robust scientific data on which policy can be formulated” you would have thought they had been conducted in an impeccable manner. We were told culling badgers did not work and whilst it could result in modest reductions in numbers of cattle herd outbreaks in the culled areas, in the surrounding areas a rise in outbreaks was found as a result of infected badgers dispersing. This they claimed was an inevitable effect and an insuperable problem of culling. But what we were being told didn’t add up. You were left wondering just how robust was this science?

The ISG’s report is some 280 pages long and most of the data they have used on which to base their conclusions derives from the Randomised Badger Culling Trials. But there were huge problems with these trials. DEFRA Wildlife staff were tasked with trying to catch the badgers in cage traps yet trapping was continued for only an average of 8 days per annum, of the 15,666 traps set, 8,981 (57%) were tampered with and 1,827 (12%) were stolen and trapping was carried out when least likely to be effective during November to January in 16 of the total of 51 culls. Indeed one of the DEFRA trapping managers was so concerned about the poor trapping efficiency and procedural interference by the ISG that he submitted a written submission to that effect to the EFRA Select Comittee, 2006. All these problems as well as landowner refusal to participate added up to a disastrously low culling rate confirmed by DEFRA of from 20% to 60%. This means from 80% to 40% of infected badgers were dispersed to spread their infection making this more a study in dispersal of TB rather than a culling trial to control it. However, in a vigorous defence the ISG assert they removed from 32% to 77% !

But in all other trials in this country (Thornbury, Avon; Steeeple Leaze,Dorset and Hartland, Devon) and in the Republic of Ireland (East Offaly and the Four Counties) culling success has been over 80%. In the trials using gassing in the mid 70’s, 100% removal was achieved resulting in complete cessation of TB cases over 10 years before other infected badgers moved in to start the problem again (Thornbury) and 7 years in the other (Steeple Leaze). At the latter the farming group switched to arable after that time.

Culling efficiency is everything when dealing with a wildlife reservoir host such as the badger which is organised into hierarchical social groups. Due to the confined air space in the sett, mutual grooming, communal sleeping and the gregarious nature of badgers, once there is a diseased badger in the sett all inmates will become infected. Most infections remain in a dormant phase with maybe only one or two developing progressive disease straight away. But the dormant cases may break down and develop disease as a result of stress caused by malnutrition, intercurrent diseases or social disruption. This is how poor culling approaches spread disease. So culling must always be aimed at complete removal of all the social group or sett occupants.
When the trials were set up there were to be three areas each of 100 sq.Km. One was to be a no action area, acting as a control, whilst reactive culling was to be carried out the second as and when outbreaks occurred. In the third all the badgers were to be culled to see whether that halted outbreaks in the cattle, the proactive cull area. But in this last area the ISG decided not to cull out the badgers but rather to reduce the population and keep it “suppressed” throughout the trial. Surely this was a certain formula for disrupting and dispersing social groups? On studying the trial data it was apparent that 5 of the first culls in these 10 areas were carried out in the Winter (4 in Dec/Jan and 1 in Nov). It is well known that Winter is the least successful time of the year for trapping thus giving worrying doubts as to what the ISG were attempting to do ?

Consciously choosing such a course of action ensured this first cull removed minimal numbers of badgers and maximised social disruption and subsequent dispersal. At site B, Putford, N Devon the second cull was also in the Winter exacerbating the disruption. Overall 16 of the 51 culls were conducted at this time. Were they actually trying to turn this into a study of the effects of social disruption and dispersal in the spread of TB ?

We have long known that poor culling rates can spread infection and the initial cull must always attempt to maximise the removal of as many sett inmates as possible to avert this problem.

The last large cull, using the same cage trapping method as used in the RBCT, was at Hartland, N Devon, in 1984 and resulted in a fall in confirmed herd outbreaks of TB in cattle from 15% of herds to 4% in 1985. Thereafter annual incidence declined and held at around 1%. In excess of 80% to almost 90% of badgers were removed which required protracted trapping efforts in some of the area, sometimes for about three months. No evidence of significant dispersal of infected badgers was found here.

However, waiting for badgers to emerge at dusk and chance catching them using traps or shooting them makes the likelihood of complete removal of social groups poor as well as logistically hugely more difficult. And the one unequivocal finding from the ISG is that if culling is not done completely disruption of badger groups and their dispersal will result.

Since badgers live in underground tunnel systems the obvious approach is to try and dispatch them whilst still asleep underground, during the working day, by a toxic gas. Carbon monoxide mixed with dioxide from petrol exhaust fumes would seem the obvious choice but DEFRA have only recently started to test this approach and the trials and licensing of the method seem almost a year away. Whether, in the light of the ISG’s report they will continue with this work is debateable. Cyanide had been used previously but whilst very effective there were concerns about humaneness and obviously other connotations to its use. But it is only the gassing approach that has resulted in a certain and complete dispatch of all the sett inmates.

The culling method is crucial in eliminating infected groups and stopping spread to other badger groups and eventually cattle and the several other species that may pick infection. To date this includes deer, alpacas, lamas, sheep, pigs, cats, ferrets and a dog. Infection of man is an accident waiting to happen.
In the MAFF annual report of 1995 the Chief Veterinary Officer stated that 90% of outbreaks were considered due to infected badgers and this was also affirmed by MAFF’s Senior TB Epidemiologist. Indeed, in the two gassing trial areas the complete cessation of TB in cattle following removal of the badgers indicated that they were the sole source of infection. Thus there and throughout the areas where TB infection is endemic in badgers cattle have been acting as sentinels of active disease in the badger But the ISG say they have been unable to quantify the role of badgers in cattle outbreaks although they do admit they can be a source of infection for cattle. However, they consider that cattle to cattle transmission is greatly more important !

Test, test and test again and then use the blood test as well. This is the only way forward according to the ISG. They consider there is a huge reservoir of undiagnosed infectious cattle out there and more “rigorous testing” will more effectively cull out all infected cattle and new herd infections will reduce, so they tell us. But I see no sense in killing cattle this way as they are the innocent sentinels of active disease in badgers. The TB test may not be perfect but repeat herd testing and slaughter of reactors has eradicated TB from all other Member States in Europe other than the UK and Ireland. And in Ireland a combined policy of control in cattle and culling infected badgers has resulted in a 42% fall in reactors since 2002. We are the only country with a deteriorating problem. And from their recommendations based on their dubious work, the ISG would appear to be quite content with that. But the Minister has yet to decide what to do.

So £45 million later with no end to the carnage of our cattle and the human and economic costs involved, there is still no intent to face the reality of this serious disease which is becoming even more entrenched in our badger population.

I must admit I’ve gone off the ISG people."

This very easy-to-read piece is substantially what the Irish scientists have said, but in rather more scientific language which we covered in our posting, here
But, as Dr. Gallagher points out, the ISG have offered a seductive morsel to ministers in the shape of a drop in cattle Tb if they adopt more cattle based measures. We have attempted to point out that this may be the triumph of hope over experience , but this view is 'bourne' out by the £2.8 million Pathman project which failed to find a single mucosal cattle sample testing postive for onwards transmission of bTb - even from reactors with lung lesions.

Those trials again.

The report into the RBCT Badger Dispersal Trial has provoked a strong reaction from a farmer (not one of us) unfortunate enough to have taken part.
In a letter to the Western Morning News Mr. Dennis comments that the way the culling was carried out was chaotic and fractured, and the ISG's conclusions on this, that cattle measures alone will cure the bTb problem, are 'nothing short of lunacy'.

The report on the problem of bovine TB published on June 18 by the Independent Scientific Group is neither independent nor scientific. As so often with so-called "independent" reports, it bears the heavy imprint of a Government which has made it clear that it is totally opposed to any form of badger culling and would much prefer that farmers were culled instead.The fact that there has been an increase in bovine TB outbreaks around areas where culling has taken place is not surprising, for the method of culling was fatally flawed and the scientists should have been intelligent enough to recognise that. If, during the Krebs trials, badgers had been culled by gassing instead of being trapped, the outcome would have been very different.

My farm was one on which culling took place during the trials. On one occasion the traps were set in place in November and removed just before Christmas. Within a few days of the traps being removed, badgers had returned to the sett, digging furiously.

Badgers are not stupid animals and when they see one of their fellow badgers caught in a trap and then disappearing, they become trap-shy and move away from the sett, subsequentially increasing the risk of bovine TB spreading. Gassing the badgers in their setts would have eliminated that risk.

The suggestion by the ISG that cattle should be targeted more intensively with no action being taken against infected badgers is quite appalling, and raises some serious questions about its intelligence and understanding of the problem.

When there is a major infectious disease problem in both the domestic cattle and wildlife population, targeting one sector and leaving the other major sector untouched is nothing short of lunacy.

Ivor Dennis, Holsworthy

PCR in use

In the outbreak of FMD in Surrey last week, the first mention was made of the in-field use of rt-PCR.

This is not laboratory based technology but 'soldier' proof, in the field, fast diagnostics, yielding results in minutes not days. We have been 'banging on' about it for several years now, as our commentators have pointed out. And we will continue to do so until on-site rapid diagnosis, (rt- PCR) such as that given such successful trials by Warwick last year and those developed in the UK with taxpayer's money by Enigma diagnostics, are ratcheted up governmental agendas.

This technology, already in use elsewhere in the world for animal diseases and now widely used in UK hospitals, will allow any necessary euthanasia to be both humane and absolutely targeted. It could also defuse the whole, horrible, polarised "debate" between those who want to save their cattle and those who want to protect badgers. Both sides speak from the best of motives. But we have the technology to deal with bovine TB without a mass cull of either species.

Anyway, it looks like Pirbright are taking an opportunity to 'validate' their magic box. Defra say in their FMD epidemiological report:

"The third premises had one RT-PCR postive in 22 cattle, but there was no evidence of clinical disease"

See page 2 of the pdf file on the Defra website.

Other snippets on the use of this amazing technology, include its ability to identify (FMD) disease in milk, days ahead of clinical symptoms. One of its main proponents Roger Breeze, predicts its widespread use within a year.

Much more on PCR technology can be found on warmwell

Not only, but also.

Pirbright Institute of Animal Health, currently in the news as a potential source of the FMD outbreak reported last week, is also in the news for a bTb 'escape'.

During a routine HSE inspection in February this year, it's facility at Compton, near Newbury, Berkshire, was found to have problems with the air conditioning unit. A major experiment into the benefits of vaccinating cattle for bovine TB was halted, fifteen cattle taking part in the trial were culled, and part of the laboratory was closed down.

An IAH spokesman said "The airflow systems in the building were not working as they should, therefore the experiment was terminated".

The Health and Safety Executive (HSE) who discovered the fault, were concerned about the safety of workers on the site, who it was feared were in danger of inhaling contaminated air. The cattle had been inoculated with BCG vaccine, and then 'challenged' with bTB bacteria. They were being monitored in the laboratory to see what if any, response was noted.

The IAH spokesman explained that alternative arrangements had been made at another site, so that the experiment could continue and that it had only caused ' a short delay, or maybe no delay at all' in the wider programme of bTB vaccine research.

In the light of this week's news however, it does raise questions about the state of biosecurity surrounding the IAH's facilities. And we should be grateful that at least the HSE takes exposure to tuberculosis bacteria seriously.

As a postscipt, given the comments we have received on 'leaving badgers infected with tuberculosis alone', we wonder how much public money may have to be spent on vaccines for other susceptible species, other than the sentinel cattle mentioned above? Will the taxpayer have to fund BCG for cats? free range pigs? camelids and deer? and of course every child would have to be immunised again.

Viewpoint

Published in this week's Vet. Record, (Aug. 11th.) the 'Viewpoint' of the Irish on the results of the RBCT Badger Dispersal Trial.

Does reactive badger culling lead to an increase in tuberculosis in cattle?
S. J. More, BVSc, MVB, DipPM, PhD, FACVSc, DipECVPH1, T. A. Clegg, BSc, MSc1, G. McGrath, BA, MSc1, J. D. Collins, MVB, MVM, MS, PhD, MRCVS1, L. A. L. Corner, BA, BVSc, MVSc, PhD, MACVSc2 and E. Gormley, BA, PhD2
1 Centre for Veterinary Epidemiology and Risk Analysis, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
2 Badger Vaccine Research Laboratory, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland


"The conclusion from the randomised badger culling trial was that localised badger culling not only fails to control but can actually increase the incidence of bovine tuberculosis in cattle. Professor Simon More and colleagues from University College Dublin question that conclusion, arguing that the data do not provide sufficient evidence to rule out alternative hypotheses.

BADGERS play an important role in the epidemiology of bovine tuberculosis (TB) in Ireland and the UK. A range of control measures are in place or have been under consideration, including badger culling. In the UK, there is a concern that reactive badger culling may be counterproductive, leading to increased TB incidence in associated cattle and the residual badger population. Although these concerns had been raised previously (Swinton and others 1997, Krebs and others 1998, Rogers and others 1998), results from the randomised badger culling trial (RBCT) provide the first detailed data with which to test this hypothesis. In the RBCT, an increased TB incidence associated with localised reactive culling was reported in cattle (Donnelly and others 2003, Le Fevre and others 2005). A similar finding was reported in herds in areas adjoining proactive culling areas (Donnelly and others 2006, 2007). Further, proactive culling was associated with an increased prevalence of TB infection in the residual badger population (Woodroffe and others 2006). A cascade of adverse events following badger culling has been proposed (Macdonald and others 2006), whereby badger culling results in substantial changes to the spatial and social organisation and the territorial behaviour of badger populations (these steps are collectively termed 'perturbation'), which in turn lead to increased contact and transmission of infection between badgers, increased contact between cattle and the disturbed badger population, and increased infection risk in associated cattle.

The proposed cascade is theoretically valid. Further, the first steps in the cascade, that is, perturbation following badger removal, are well documented in both Ireland (O'Corry-Crowe and others 1996, Costello and others 2006) and the UK (Tuyttens and others 2000a, 2000b). However, we question the evidence from the published RBCT results in support of the latter stages of the hypothesised cascade, that is, perturbation leading to increased risk of cattle TB breakdowns. Two aspects of the RBCT are relevant to this cascade: the effects of reactive culling inside RBCT areas and effects of proactive culling adjoining RBCT areas. In this article, we raise concerns about specific aspects of the interpretation of these data, in particular the biological plausibility of measured effects, the precision of these effects and the timing of biological processes, and of the accuracy of spatial data.

THE RBCT RESULTS
In keeping with the fundamental principle of causality, the effect of reactive badger culling can only be examined during periods when such effects are biologically plausible, in a setting where all factors are controlled apart from the issue under study, and after sufficient time has elapsed to allow an effect to be detected. These issues will be considered in turn.
In their analyses, Donnelly and others (2003) and Le Fevre and others (2005) attribute the effects of reactive culling during periods when we consider such effects are biologically implausible. To illustrate, the Independent Scientific Group on Cattle TB (ISG) (2007) concludes that 'reactive badger culling induced an estimated increase of 22 per cent in the incidence of confirmed cattle herd breakdowns (95 per cent confidence interval [CI] 2·5 to 45) (P=0·025)'. However, this analysis encompasses two adjoining observation periods: from the completion of the proactive cull until the first reactive culling operation in each triplet (42 per cent of the total observation period), and from the first reactive culling operation in each triplet until November 4, 2003 (58 per cent), when the reactive cull ceased. A measured effect during the latter of these two periods could potentially be related to reactive culling; however, a similar effect during the former could only result from factors not related to reactive culling. This former period represents a substantial proportion (42 per cent) of the total period under observation (Fig 1). Furthermore, in the analysis, data are included from triplets A to I before the start of the reactive cull, and all data from triplet J, where reactive culling was never implemented.
[... we have omitted illustration - can't scan - ed]

An increase in TB incidence in cattle in association with reactive culling has been presented on several occasions (Donnelly and others 2003, Le Fevre and others 2005, ISG 2007). During the period from the first reactive culling operation in each triplet until November 4, 2003 (that is, while the reactive culling was being conducted), an 18·9 per cent increase (95 per cent CI -5·4 to 49·5) (P=0.14) was reported (ISG 2007). However, the ISG (2007) also reported a very similar, and also imprecise and non-significant, increase (23·7 per cent; 95 per cent CI -10·7 to 71·5) (P=0·20) during the period immediately preceding the start of the reactive cull. This raises several noteworthy points. The imprecision and lack of significance of the results do not justify the conclusion that 'localised badger culling not only fails to control but also seems to increase TB incidence in cattle' (Donnelly and others 2003). It can reasonably be argued that the observed increase was a consequence of pre-existing area differences in TB incidence that were not controlled with randomisation, and was not the result of any effect of reactive culling. These data do not provide sufficient evidence to rule out alternative hypotheses, including the possibilities that reactive culling had either no adverse impact, or indeed was protective.

[Much as we hate to break into this 'hypothesised cascade', we would point out that we would have been grateful if the WLU had turned up more than once in 3 years - if at all - and we think the next paragraph makes the point - ed]

The hypothesised cascade is a chain of consecutive events, which collectively will take time to complete. Therefore, there will be a time lag between its start (badger removal) and end (increased detection of confirmed TB in associated cattle) (Godfray and others 2004, Griffin and others 2005). Although the duration of this time lag cannot be defined with certainty, it must be sufficiently long to enable completion of each of the key events within the cascade; namely, disruption in badger social organisation leading to increased transmission of TB among badgers, dispersal of badgers infected with Mycobacterium bovis, contact between cattle and the disturbed badger population leading to cattle exposure, the establishment of infection in cattle, the development of responsiveness to tuberculin following establishment of infection, and the completion of the annual herd test. Although the timing of several of these steps has been estimated by Le Fevre and others (2005), much of this is based on data from experimental infections and holds limited relevance to events occurring under conditions of natural transmission. The RBCT analyses considered change in cattle herd incidence during a range of time periods (as discussed previously), but none allowed for any delay to enable all elements of the cascade to take place. For example, the ISG (2007) reported the effects of reactive culling inside RBCT areas from the start of the reactive cull, and the effects of proactive culling outside RBCT areas from the end of the initial proactive cull. In addition, the effects of proactive culling outside RBCT areas were only significant (P=0·052) between the initial and first follow-up cull, an average of 1·26 years. Following this period there was no significant effect (P=0·22).

Spatial accuracy is of particular importance in the interpretation of the RBCT results, given that key findings, for example, adverse effects in association with proactive badger culling (Donnelly and others 2006, 2007) were observed within defined geographic areas. These authors have suggested that expanded badger movement patterns (the first steps in the hypothesised cascade) will be observed in reactive culling areas, and also on farms neighbouring proactive trial areas. Two different data sets (VETNET and RBCT) were used to conduct this spatial analysis. Although both data sets are a representation of the same land, there is evidence of substantial inconsistencies between them, as reflected in the reported results.

Using equivalent analyses, the number of herds in reactive culling areas with confirmed breakdowns compared with no-cull areas was reported as either 28·2 per cent (if the RBCT data set was used) or 17·8 per cent (VETNET) (Le Fevre and others 2005). Similar differences were observed when analysing data from the proactive trial areas (Donnelly and others 2006, 2007, ISG 2007). In addition, farms were represented as a single point in space based on 'the centre of the largest land parcel' (Donnelly and others 2006), without account being taken of the potential impact of farm fragmentation (Ferguson and others 2001). Errors in farm location and allocation will affect the interpretation of results concerning TB in cattle (Donnelly and others 2003, 2006, 2007, Le Fevre and others 2005), but not in badgers (Woodroffe and others 2006)"

CONCLUSION
Bovine TB remains a very serious concern for government and industry in both Ireland and the UK, and it is essential that all policy options are considered as part of a broad control and eradication programme. We raise a number of questions relevant to the current interpretations of the RBCT results. It is important that interested policymakers and the general public are aware of varying perspectives surrounding this topic.

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TUYTTENS, F. A. M., MACDONALD, D. W., ROGERS, L. M., CHEESEMAN, C. L. & RODDAM, A. W. (2000b) Comparative study on the consequences of culling badgers (Meles meles) on biometrics, population dynamics and movement. Journal of Animal Ecology 69,567 -580
WOODROFFE, R., DONNELLY, C. A., JENKINS, H. E., JOHNSTON, W. T., COX, D. R., BOURNE, F. J., CHEESEMAN, C. L., DELAHAY, R. J., CLIFTON-HADLEY, R. S., GETTINBY, G., GILKS, P., HEWINSON, R. G., MCINERNEY, J. P. & MORRISON, W. I. (2006) Culling and cattle controls influence tuberculosis risk for badgers. Proceedings of the National Academy of Sciences of the United States of America 103,14713 -14717

Published: Veterinary Record 11 Aug 07, Vol 161, Number 6, page 208, as a 'Viewpoint'.

"From Tb bacilli - everywhere.."

A little light relief in the a letter to the Veterinary Record this week, offers a grotesque but accurate slant on the bizarre 'Pythonesque' situation surrounding TB eradication in Great Britain. The letter, from H.Fraser, Oban , Argyll and Bute, offers grateful thanks to John Bourne and the ISG on behalf of all Tb bacilli.

"Oh goody, goody! We can go forth and multiply. We and our progeny are really grateful to that nice Independent Scientific Group, which is to provide us with a secure future. What a relief that those nasty vets and cattlemen are to be prevented from removing our expanding habitat. So we can now continue to spread. Sadly, when this spread is to cattle, we risk death by fire or brimstone when they use that nasty skin test. And, when we spread to humankind, they try and kill us off with those nasty antibiotics; some of my mutant friends have learned how to avoid this fate and many are quite taken with this idea.

But at least now we can expect to be safe in the badger. Some of us can remember those bad old days in the 1960s, when we were almost exterminated, but no more. As you know sir, we are not in the least fussy where we live, and now that kind Professor Bourne will allow us to spread and colonise unmolested, at least in badgers.
Signed; Tb bacilli everywhere."

Another letter in the same issue from Dr. Richard Yarnell, CEO of the Badger Trust predictably (happliy?) quotes the ISG tome at length, seemingly unaware of the total failure of past efforts based solely on cattle controls. He also ignores the lack of evidence of the spoligotype spread which would show a different colour pattern - or none at all - if cattle were plastering the countryside with different strains of Tb. It's all cattle he says. So it must be, but at least the Tb bacilli are happy.

Not so the badgers, infected with them though. A robust letter from Dr. Lewis Thomas points out:

"But the recommendation to bear down more and more on the disease in cattle, whilst ignoring the huge reservoir of infection in badgers, defies all logic. It also ignores the chronic welfare problem for the badger."

One would imagine that the "chronic welfare problems" of badgers should be of concern for the Badger Trust as well, or at least its members. But by denying the result of Tb infection and its transmission opportunities in their chosen species, by ommission they support Mr. Fraser's letter quoted above.

And the death or welfare of any species is not a problem for the Tb bacilli. They now have the opportunity to thrive, transmit and expand their host base. And as the letter from H. Fraser says, this is thanks to John Bourne and the ISG.
Epidemiological logic has flown out of the window, past mistakes are likely to be repeated, spill over transmissions are inevitable but the upside of all this is of course, is the TB bacilli are very, very happy.

A humerous letter with an iron-hard message, we think.

Lord Rooker - again

We have been reminded that in our posting below, which highlighted farmer's response to the devastation of flooded areas of Gloucestershire and the surrounding areas, and their comparison with the ongoing scourge of bTb, of Lord Rooker's most extraordinary comment.

"We have to close down every possible route. I cannot for the life of me understand why some farmers in non-hotspot areas are buying cattle from hotspot areas without getting them tested,” he said.

Now far be it for us to remind Hizonner, Lord Rooker, but testing - as in pre movement testing - has been in use in annual and two year testing parishes, or as he would describe them 'hotspot areas', for the last sixteen months. And thanks to a comment on the posting below, the appalling extent of this can be seen on Defra's map of GB. The reason why these tests do not show up on Defra's direct Tb budget, is that farmers pay for them. They were part of a package agreed with the industry two years ago. PreMT was introduced along with tabular valuation, but the third part of the package Defra reneged on. We agree that post movement testing is by far a better disease protection, but preMT is what Defra wanted, so that is what Defra got. So it really is adding insult to injury that having delivered on its obligations, the industry's leaders seem totally unaware of farmers' commitment to stopping cattle moving with bTb, at their own expense, and with absolutely nothing offered in return.

News from Gloucestershire

On a visit to flood-hit Gloucestershire this week, farming minister, Lord Rooker was told in no uncertain terms that although the floods were devastating, they would recede. Bovine tb, without Government intervention would not.
Farmers Guardian reports that Lord Rooker asked affected farmers what help they needed from the Government, only to be told that their main concern, despite the devastation, was not the floods but bovine TB.

"The disease was rife in the area and the resultant movement restrictions were destroying livestock units by preventing farmers from buying and selling cattle, NFU Tewkesbury chairman Carl Gray told him.

“We will recover from the floods but what we really need help with is TB,” said Mr Gray, who questioned whether the Independent Scientific Group (ISG) on bovine TB was either ‘scientific’ or ‘independent’"

And adding his considerable experience to the debate is Gloucester veterinary surgeon, Roger Blowey who, in a letter to the Vet. Record (July 14th) queried the difference between past policies and present, and more importantly their results.

Mr. Blowey outlined the remit of the ISG and quoted from its most recent report:

"First, while badgers are clearly a source of cattle Tb, careful evaluation of our own and others' data indicates that badger culling can make no meaningful contribution to cattle Tb control in Britain. Indeed, some policies under consideration are likely to make matters worse rather than better".

With the ISG's initial conclusion we would agree, and with the latter comment, especially if John Bourne's observations encompass the RBCT's 'policy' of badger dispersal. with that we would wholeheartedly agree.
With the middle bit, we do not.

Mr. Blowey continues to quote the ISG report;

"Second, weaknesses in the cattle testing regimes mean that cattle themselves contribute significantly to the persistence and spread of disease in all areas where Tb occurs, and in some areas of Britain are likely to be the main source of infection. Scientific findings indicate that the rising incidence of disease can be reversed and geopgraphical spread contained, by rigid application of cattle-based measures alone".

Now those are strong words from a 'scientist', and from one who has obviously not read or understood the excellent spoligotype work or even the previous carnage wreaked on cattle nailed firmly to the floor by his predecessors; one William Tait and in the Republic of Ireland, the Downie era. Both of these government veterinary officials were equally certain that they too could "reverse rising incidence of TB", and "prevent geographical spread", and they killed a lot of cattle in their single minded pursuit. Both spectacularly failed. But how piling more dead cattle higher and faster, can mitigate the transmission of m.bovis from even Bourne's, now acknowledged, source of the disease in badgers, Professor Bourne does not explain; he merely throws a safety net to a gullible government.

After listing the Tb eradication strategy in GB from 1900 -1970, Mr. Blowey brings us up to the present day thus:

1975 - Strategic control of infected badger communities. Gassing of setts began, that is elimination of whole setts, thus avoiding the 'peturbation' effect.
1980 - Almost four fold drop in confirmed outbreaks down to about 60 herds nationwide, mainly in the south west.
1981 - Gassing stopped due to concerns about the use of cyanide and badger welfare.
1984 - Reactors still down at 400 hundred cattle slaughtered per year.
1985 - Dunnet committee on TB reports (para 56) "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" - but badger culling was reduced.
1986 - Intensive and prolonged cage trapping was stopped as considered too expensive. Number of confirmed outbreaks now increased to 84. Minimal trapping policy started, restricted to within farm boundaries, but cattle tb is increasing.
(The land available for trapping was reduced from 7 km down to 1km and limited to the farm concerned, within its boundaries and preferably on land grazed by the reactor - ed)
1990s - Badger control shown to effective in reducing the incidence of TB (Clifton-Hadley and others, 1995 [ Thornbury, Hartland, Steeple Leez, East Offally etc.- ed])
1997 - All badger trapping stopped during ISG trial: from then on Tb increases dramatically.
2005 - Massive increase in TB reactor cattle culled. from 400 a year in 1980s to 30,000 in 2005.
2006 - Triplet badger cull trial finishes. interim report by Defra states that the sucess in removal of badgers was only 20 - 60 percent. TB culls reduced to 23,000.
2007 - Published papers confirm that the ISG trial only culled between 32 per cent to a maximum of 77 per cent of badgers in the control areas. (Smith and Cheeseman 2007)

The culling trial has now been described or re-titled by the ISG as merely a 'population reduction'. Well they did that for sure. Culled on 8 nights only, trapped the main group leaders of what was assumed to be an infected population, and then disappeared. Sometimes for years, but with the interruption of FMD, certainly for two years in every triplet, to leave a fractured and highly infectious population to scrap and fight as it regrouped. Pretty smart that was, given the warnings issued by Professor Krebs when he set up the methodology in 1997, its carnage confirmed by their own WLU manager.

But we digress: the letter from Roger Blowey concludes with a question:

"Very little has changed with the TB testing. We are using essentially the same skin test that brought Tb under control in the 1960s, 1970s and 1980s (and in my case, the same vet!), and it is the same skin test that has been successfully used in other countries in the EU and throughout the world. So, could someone please explain to me why, in the UK, the disease is spiralling out of control? This despite the introduction of premovement testing and ever more stringent restrictions imposed on cattle movements. Some of us might just think that there could be an external source of infection leading to these increased breakdowns. If this is true, what other disease is there where we have attempted control by culling test positives without tackling the reservoir of infection?"

Also writing from the swamplands of Gloucestershire, is ex member of the old Badger panel, Martin Hancox of Stroud. (in the Vet. Times).
Having roundly castigated the 'farcical Tb debate' by denying that badgers are anything at all to do with Tb, and that cattle are the only true cause, Hancox continues:

"Annual testing is so effective in cattle that it reduces cattle to cattle spread so that nearly half of herd breakdowns comprise only a single reactor. Putting herds under immediate movement restriction stops the export of latent TB carriers which would otherwise go off and cause further herd breakdowns. The third result of intensive cattle controls is that some two thirds of cases are caught so early that it is not possible to confirm that they do, in fact have TB (NVL and few m.bovis presents so hard to confirm, PCR would help)"

With that we have no quarrel at all. Good stuff. "Annual testing is so effective [] that it reduces cattle to cattle spread" But has it been so long since the Badger Panel sat, that Mr. Hancox didn't realise that annual testing is the norm now from Cheshire to Cornwall? And that movement restrictions are slapped on by the disclosing veterinary surgeon, at the time of reading the test? And that subsequently 60 day tests are conducted ad infinitum until at least one reveals the herd is clear - two if lesions and / or culture confirms disease? And that after that clear test a 6 month check test is completed to confirm no latent infection? (This because the GB strains of tb have a maximum incubation period of exposure to skin test flag up of 221 days) And if under all those circumstances and no bought in cattle are implicated - where does Mr. Hancox assume infection is coming from? And coming from? And coming from?

He continues:

"It is important to realise that untraced movements of such unconfirmed and undetected true Tb cases is why Tb persists both here and in Ireland."

Not if there are no bought in cattle it isn't. And movement restrictions imediately stop any ongoing cattle sales except direct slaughter, and traces follow up everything sold from 2 months prior to the last clear test. Sheeesh.
And Mr. Hancox concludes;

"The Badger Trust is misguided in pushing so hard for IFN blood tests .... yes, they do pick up early NVL cases, but miss later skin test positive ones, which is why EU rules are only for IFN as a back up test."

Yes. But the ISG recommend it. Your point?

The other observation we would offer from Gloucestershire - and all other areas experiencing such devastating floods - is what do our readers think is happening to the badgers? Householders were reporting seeing stranded rabbits and foxes in their gardens and if the badgers haven't drowned, then survivors will have packed their water wings and struggled to higher, drier ground. And what will they find there, already occupying the territory? Other social groups. So, a peturbation opportunity in the making, just as FMD was and just as the last two summer's extraordinarily dry conditions made food sources more scarce, these floods will have a dramatic effect of badger habitat, and thus movement of 'peturbed', and in Glos. highly infectious, badgers.

£2.8 million - The Pathman project.

In October 2000 Defra instigated a project to investigate the 'Pathogenisis and diagnosis of tuberculosis in cattle - complementary field studies". Known as the 'Pathman project', this work was designed to investigate the undiscovered reservoir of cattle Tb missed by the skin test - or so it seems to us. The correct term, is " to advance the understanding of cattle-to cattle transmission of bovine tuberculosis in Great Britian'. But its core result seems to have escaped notice.

200 tuberculin reactor cattle at standard interpretation of the skin test, were collected ex farm and paired with 200 in contact animals. Blood samples were drawn and nasal mucous samples were collected; then the animals were slaughtered and subject to a two hour (at least) thorough postmortem examination. The bloods were sent for trace element testing, as were liver samples which are much more accurate, and also immunological assays to check past disease exposure.

The in-contact animals were kept on farm at the Boxworth research establishment for seven weeks, in isolation. During this time several bloods were drawn, and up to seven nasal swabs taken to "detect early stage disease and m.bovis excretion". At the end of the holding period, another skin test was performed and then the animals slaughtered under the same procedure as the reactors.

(3.4 TB50)The results were only slightly better than those performed in 8 minutes by SVS postmortems, in that just over half the reactors had VL (55 per cent) and thus half did not and would record NVL. The in-contacts recorded 14 per cent macrospopic lesions and on the 7 week skin retest, 15 of these 200 animals had become reactors at standard interpretation. The site of lesions most commonly found were in the thorax of the cattle, with head lesions second. Very few were found in the abdominal cavity, (3.2) and even less if lesions were not apparent elsewhere.

32 animals in the study were found to have lung lesions, and the range of postmortem VLs was much higher (89 per cent) in yearlings and calves than in other classes. Dairy cattle had the lowest confirmation rate at 34 per cent, a point noted by the investigative team. (Table 5)

Investigation into other inputs such as vaccinations or exposure to other diseases gave mixed results. (table 10) Having antibodies to Johnes disease (m.avium paratuberculosis) was associated with confirmed bTb in both dairy and non dairy reactors but in the in contact animals it was thought to be "not statistically significant". Antibodies to Leptospira, were strongly associated with bTb in in-contact dairy cattle - but the opposite in non dairy contacts. In reactors there was no association. Having antibodies to liver fluke was associated with lower risk in all categories.

Selenium and copper were investigated and it was found that levels of selenium tended to be higher in dairy animals than non-dairy. The conclusion was that a lower liver level was associated with an increased risk of bTb, but that the association 'was not statistically significant'. (table 12) Other categories found a slight correlation. Dairy animals were significantly and consistently "less likely to have bTb confirmed by culture, than beef or other production classes" involved in the study. (4.8)

Considering the amount of emphasis placed on cattle to cattle transmission by the ISG, it is interesting to note that in the Pathman project, not a single one of the 1543 nasal mucosal samples of which 1006 proved clear of contamination - including those from the 32 reactors found to have lung lesions - proved positive for m.bovis, a point missed by the ISG when describing the project in their final report. How could John Bourne have missed that, one might ask? It was mentioned at least four times (4.6) (3.6)the executive summary and the conclusion.

"M.bovis was not detected by bacterial culture in any of the nasal mucus samples." and "The results suggest that large concentrations of M.bovis are not present in the nasal passages, and the shedding of M.bovis, if it occurs, is rare in naturally infected GB cattle."

To be fair (and why should we be?) the paper points out that the researchers 'have not looked at transmission through mouth respiration and coughing', and they conclude, rather strangely we think, 'that these could remain potential sources of disease transmission'. We think they would like to do another trial; but think about it. Cattle graze and eat with their heads lower than their gut, thus any mucous in the lungs passes towards the exit - which in all the cattle we've known is the nose and not the mouth. Cattle with pneumonia will pant for sure, but any discharge from an excess of mucous in the lungs exits from the nose and not the mouth. Hence, as cattle keepers, not scientists, our cryptic comments.

But also making a cryptic observation in this week's Veterinary Record, are R.M.Q.Sainsbury and Dr. John Gallagher, both remarking on the lack of onward transmission from these 1006 samples, and others in a complimentray study not noted by the ISG. They point out that the final report of the ISG "used data somewhat inconsistent with those in the recently published 'Pathogenisis and diagnosis of tuberculosis in cattle - complementary field studies'".

"In total over 1500 nasal mucus samples were taken in order to ascertain whether tuberculosis (bTB) was passed from cattle to cattle via the respiratory tract. Micobacterium bovis was not isolated from any of these samples despite lesions being found in the lungs of 32 of the cattle. Also quoted in the study are the results of an ongoing, separate longitudinal study of reactor animals [SE3033]where no bacilli have been detected in approximately 1000 nasal mucus samples from a further 40 reactors [ taken at varying time intervals]"

Returning to the ISG final report, the letter continues:

"In appendix 1, the ISG report does mention the pathogenisis and longitudinal studies, but appears to play down the significance of their results despite the fact that both studies confirmed 'on the ground' experience of many working in this field, that is, that cattle-to-cattle spread is uncommon on infected farms."

The writers emphasise their point thus;

"This point is crucial. In the ISG report it is stressed that infected cattle have 'serious implications for the maintenance and persistence of the disease in infected herds, and for the spread of the disease to neighbouring herds and to other parts of the country'. This is used to justify the recommended further rigorous movement controls and additional testing (recommendations 21 - 29) and would inevitably lead to the slaughter of many more cattle."

And they conclude:

"The overall conclusions of this Defra published report have increased our grave concerns regarding the ISG recommendation that controls on cattle alone would be relied upon to reduce the incidence and the spread of bovine Tb. We believe the ISG has seriously overstressed the importance of cattle-to-cattle spread, and the adoption of this recommendation will not control the disease. Progress will only be made when the original source of cattle infections is addressed and that means facing the reality of the large reservoir of Tb in wild badgers."

We agree with that conclusion, and have already pointed out the crass futility of repeating such cattle-only measures, attempted by greater men than John Bourne and with such stunning success

And after £2.8 million, Professor Bourne missed the histology conclusion on those mucus samples completely. They were all negative. Every one.

It may be churlish to point out the obvious, but we will point it out nevertheless; that is, if micobacterium bovis wasn't plastering the pastures and cattle feed troughs of GB, then the disease status of those cattle unfortunate enough to fall over it would not be called into question. But as it has been, surely the negative-for-onward-transmission results of every mucosal sample taken, deserves a higher profile?
See SE3013 here