Tuesday, April 22, 2008

His master's voice - GammaIFN

We have deliberately not posted much about the gamma interferon blood test, pending the result of a court ruling. The case sought a Judicial Review into some quite extraordinary results of its use experienced by some farms, unlucky enough to have it inflicted on their cattle herds.

One such was the Somerset based Higher Burrow Organic Farmering Partnership, where over 430 animals were tested late last year. Of those, 14 had a positive skin test result. But in accordance with Defra policy of using the newly approved blood test as a herd test in such cases, the cattle underwent parallel GammaIFN testing. The results showed that 86 were positive, while eight results were indeterminate.

Concerned farmers in several herds so affected, requested the primary skin test as backup, as the disparity between the blood test results and intradermal skin test was so great. Defra said no and ordered slaughter. So for months several farms have been snarled up with hundreds of cattle awaiting the results of last week's request to the High Court for a Judicial Review into that apparent disparity.

Newspaper reports which covered the story quote:

Hugh Mercer QC, for High Burrow, who said the two sets of tests showed "a massive disparity". Slaughter without re-testing would be "unlawful, irrational and disproportionate".
The case has been adjourned once already, so that reams of "evidence" could be cogitated and digested, but in one fell swoop, last week, sitting judge, Mr. Justice Mittings dismissed the request saying "the policy is lawful".

He said: "The policy is lawful. The outcome – unhappy and potentially disastrous though it may be – flows from it."
So what of this policy? Where did it have its roots and how was it trialled in the UK?

Defra will say that the blood test was "developed in Australia in the 1980's", but what they are not so keen to explore is that Australia achieved Tb free status ahead of its licensing, using the intradermal skin test - and a clearance of feral cattle and water buffalo, acting as a maintenance reservoir of tuberculosis. Australia also has a hugely different environment from the UK, with many less contaminants to affect the test results.

But in 2006, Defra began a pilot study known as SB4021. They snuck under the radar of 24 farms in 3/4 year testing areas, using bloods from other testing regimes, and tested for bovine Tb. In these areas they would not have expected to find anything at all, but they did. In fact seven percent of samples proved positive. As this test was not a recognised diagnostic test at the time, they could not confirm their findings with slaughter. Specificity and sensitivety of any diagnostic test are interlinked values, but the authors of the report had a much better idea. Chuck out omit any results which didn't fit the expected result. These included cattle from areas of high Tb incidence which may have encountered a sniff of m.bovis , and also postives - up to 25 per cent in a few herds - to another micobacterium which was subsequently identified as M. kansassii (5.4).

The pilot study indicated vastly differing results for length of time in transit of bloods, possible co contamination with recent skin tests, and several other known contaminants including skin granulomas, the precence of antibodies or vaccinates to Johnnes disease (M. avium paratuberculosis) and certain mosses - as well as M. kansassii.

No post mortems were carried out to confirm their results, but Defra presented this ragbag of selectively culled information to the the Standing Veterinary Committee of the EU for approval as a secondary diagnostic test for bTb.

As a secondary test, a gamma negative animal still requires a primary intradermal skin test to regain its status, yet in the bizarre world inhabited by Defra, a postive result means the chop. And this is at the root of what the farmers challenging official Defra policy last week in the High Court were asking for. Parity for both animals, particularly as the bloods had shown such, err - disparity, of results.

Mr. Justice Mittings described Defra's decision to slaughter the animals as
"not only lawful but mandatory".
Mandatory under EU law, based on a small "pilot study" which excluded or ignored results which it did not expect? Rock solid science then.

The blood test was sold to an unsuspecting industry as "flexible in interpretation", but we see little sign of that, with a fixed cut off point now applied and no allowances made for other known contaminants. It was also described as picking up "very early cases". But that too turns out to be somewhat of an exaggeration. The difference between the latency of the intradermal skin test and gammaIFN is about two weeks, with the skin test averaging 42 days and gamma 28 in experimentally infected animals.

But a delicious twist has given one farmer in the queue for a re-test using the primary intradermal skin test, exactly what he wanted. While the cattle at Higher Burrow await their fate, 31 cattle at Tom Maidment's farm in Wiltshire have been retested. Mr. Maidment and his vets had engaged in long correspondence with Defra (London) and Defra (Veterinary Laboratories Agency) but not the clerks at the local AHO who, very obligingly, when the 60 day re-test was due, ordered Mr. Maidment to - err, retest his cattle.

Only too keen to oblige, Mr. Maidment's cattle were skin tested and the results interpreted under severe interpretation. All were clear. All passed. No lumps. Anywhere. Not one.

Which makes Mr. Justice Mittings' statement:

there was no evidence that those blood tests might, if retaken, prove negative...
rather timely. (Or had the learned judge not realised that the last thing the farmers were asking for was another blood test, but the primary skin test?)

And which is probably why, when assessing the relative accuracy of the gammaIFN blood test, Defra are not so keen to reveal that while about half (48 - 51 percent)skin test reactors slaughtered show VL (visible lesions) from the cattle's exposure to M. bovis, at post mortem, 81.4 percent of cattle slaughtered as gamma reactors show no sign of disease whatsoever.

Thursday, April 10, 2008

Devil in the detail?

We mentioned that phrase in relation to our posting below, on the Welsh Assembly's announcement this week of a pilot cull of badgers in an as yet undefined ' hotspot', and a more thorough examination of the full announcement has churned out a couple of 'devils'.
We believe that the most effective measure to address both sources of infection and cross-infection, subject to strict regulation and meeting a number of requirements, would be a targeted cull of badgers in TB high incidence areas. To take this forward we will prioritise the establishment of an intensive action pilot in an area which has been identified as a TB hotspot. No final decision has yet been made about a location capable of satisfying these criteria but I anticipate it would be in a defined high incidence area for the disease and subject to strict conditions. Additional areas will not be considered until the implementation and robust review and a proper evaluation of the cull and the other measures in the intensive action pilot area has been undertaken.

'Strict regulation and meeting of requirements' sounds suspiciously like a number of bureaucratic boxes must be ticked conditions must be met prior to any action on a wildlife reservoir on tuberculosis. And if, after the pilot cull takes place, these conditions cannot be met in other areas? What then?
The paper continues:
Action by government alone will not eradicate bovine TB. I want to reform the compensation regime to encourage herd owners to follow best practice. By the end of 2008 plans will be published to amend the current system to ensure compensation arrangements encourage herd owners to comply with legal and best practice requirements. I will also take action to further address the concerns about the abuse to the TB compensation system as highlighted by the report of the National Audit Office in 2003.

That sounds like tabular valuations are on the way, and any compulsory purchase monies will be dependent upon an assessor's opinion of a farm's biosecurity. But the really big 'devil' is in the final sentence of this next paragraph.
We will also be taking forward other measures such as the development and promotion of improved husbandry and biosecurity practices to make sure that cattle owners know what to do to reduce the risk of the introduction of the disease onto their farms, or to manage existing disease. This will include from 2009 the publication of infected farms and the compensation paid.

So, publication of the farms under Tb restriction. A death knell to a pedigree breeder selling bulls or top notch breeding females? So, it looks to us like the Welsh Assembly have used a very big stick of possibly reduced compulsory purchase monies which will be totally dependent upon increased biosecurity and the threat of the publicity of both, should infected stripeys break through the cordon.

Like our own beloved Defra, the Welsh Assembly speak of 'partnership' but are more than willing to use any means possible to beat the industry into submission, in this instance over a situation not of their making, nor under their control. Defra used the tabular valuation paperwork in England to obtain a farmer's signature prior to slaughter of a reactor and knowledge of amount of compulsory purchase monies paid, and it looks very much as if the Assembly will follow suit. Even to the extent of 'no signature means no payment at all, and if you sign it will be published'. A very unequal partnership we think, and at a time when many farmers are pushed to the brink of emotional overload by the restrictions imposed by a Tb breakdown.

It would seem to us that the various sides (and there should be only one) in this debate are posturing through the motions. The Badger Trust rocking their pram and throwing out unsubstantiated, emotional rubbish at a gullible public, and the farming unions playing along with what may turn out to be an unworkable political mishmash in the hope of implanting a backbone into the wavering frame of our own Hilary Benn.

A link to the Welsh Assembly full statement (pdf) is here.

Tuesday, April 08, 2008

From 669 to 7905 in ten years.

Those figures are for cattle slaughtered in Wales as reactors to the Tb test. A corresponding rise in the expense associated with the disease is reflected by the compulsory purchase figures: up from £1.3 million in 1999/2000 to a staggering £15.2 million in 2007. As the bandwagon of testing, slaughter, transport, postmortems, sampling, culturing samples, paperwork and tracing trundles on, the final tally of the disease to the Welsh Assembly is approaching a figure which is unsustainable. And today, they have called a halt.

The Rural Affairs Minister, Elin Jones, announced a pilot badger cull in the worst affected areas BBC Wales reports.

Commenting that tackling the disease has become extremely contentious, the minister also announced a 'one off' test of all Welsh cattle herds "to assess the extent of infection."

After that, a pilot badger cull would be carried out within 'hard' natural or man made boundaries - as yet undefined.

Commenting on the present situation at a press briefing today, the Chief Veterinary Officer for Wales Christianne Glossop said:
... bovine TB was out of control and the current policy was not working.
Incidents had increased dramatically over the last decade. Compensation payments to farmers have risen from £1.3m in 1999-2000 to £15.2m in 2007-2008, and last year 7,905 cattle were slaughtered in Wales, up from 669 in 1997.

We have not posted the Tb figures for 2007, but inevitably with a non-policy of an annual cull of sentinel cattle masquerading as 'eradication' of a disease housed comfortably in a wildlife maintenance reservoir, they are up. England had a total of 8.5 percent of its cattle herds under restriction 'due to a Tb incident' at some time during 2007, while Wales posted 10.8 percent.

In both regions, certain areas bore the brunt of the cattle carnage and movement restrictions. The West region of England recorded 18.6 percent of its herds affected with Gloucestershire and Hereford / Worcs. recording 27.5 percent and 26.4 percent respectively. Devon and Cornwall at 23 and 19.5 percent followed.

The Welsh problems are worse in the far West, with Dyfyd having 15.4 percent of its herds affected last year: North Wales recorded 3.7 percent having a restriction due to a Tb incident. Gwent and South Powys are also high and all areas are rising.

One wonders what description Elin Jones and CVO Christianne Glossop would award to the English figures, particularly the area around the river Severn, so spectacularly flooded last summer? Glos and Hereford / Worcs record up to 27 per cent of herds affected. The worst area of Wales is 15.4 percent and considered 'out of control' ... but we digress, our Minister is considering the situation and our CVO has yet to comment.

As well as a blanket sweep of cattle testing across Wales to ascertain the scale of the problem, the Welsh Assembly also announced:
a reform of the compulsory purchase regime for farmers whose infected cows were slaughtered to "encourage herd owners to comply with legal and best practice requirements".

Not sure exactly what that means. Wales is not on tabular valuation, and still operates a valuer system. Time will tell, and devil may be in the detail.

Ms. Jones pointed out that bTb in Wales would cost more than £30m by 2012 if it grew at the present "unsustainable" rate. The coalition deal between Labour and Plaid Cymru in the Welsh Assembly Government has led to a commitment to attempt to eradicate TB in cattle, with £27m being allocated over the next three years for this purpose.

The comments attributed to this announcement were predictable, with NFU Cymru and the Farmers Union of Wales welcoming plans for a proactive approach, while 'conservationists' - of Tb infested wildlife? Sheesh, what's to conserve in an animal riddled with tuberculosis? - and of course the Badger Trust, threw teddies out of their respective prams, describing their chosen species as 'victims of modern intensive farming'.

More on this story from The Times
Critics argue that culling trials have shown that the approach simply prompts badgers to move to new areas, spreading the disease. The RSPCA also condemned the decision and said it flew in the face of sound scientific judgment. Rob Atkinson, its head of wildlife science, said: “We are not a bunch of badger-huggers. Our opposition to a badger cull is based on solid science, not sentiment.”

That would be the 'solid science' which led to the RSPCA being censured by the Advertising Standards Authority in 2006 and the Charity Commission in 2007 for publishing misleading information its Back Off Badgers campaign? And certainly the RBCT Badger Dispersal Exercise showed us all how NOT to deal with infected badger communities. Eight nights hit-and-run visits using cage traps, repeated very occasionally, if at all, was the sole reason for the predictable chaos and the spread of disease. The Times article continues with the view of the Welsh CVO:
But Christianne Glossop, Chief Veterinary Officer for Wales, who announced the decision with Elin Jones, Welsh Rural Affairs Minister, said that “doing nothing was not an option. We know there’s a link between infection in cattle and infection in badgers. It’s true in Great Britain and it’s true in Ireland,” she said. “The aim is healthy cattle, healthy badgers and healthy people.”

Amen to that.

Wednesday, April 02, 2008

VAWM's reply to EFRAcom.

We are grateful for sight of the press release from VAWM (Veterinary Association for Wildlife Management) in reply to the long awaited EFRA committee report into bTb.
Given the conflicting conclusions on how to tackle bovine TB in this country from the Independent Scientific Group and the former Chief Scientist, Sir David King it is perhaps hardly surprising that a committee of MPs has recently produced a comprehensive, 67 page report that encompasses all the options for tackling the disease (Fourth report of the Environmental, Food and Rural Affairs Committee, 2007-08). However at least it brings the most important option into play – the necessity of tackling the huge reservoir of infection in the badger population. But it is a pity that it has been fogged by all the other options such as more and more cattle testing, biosecurity and vaccination, two of which together, cattle testing and biosecurity, have been shown to be wholly inadequate in tackling the disease to date. And there are good reasons set out in our last statement why vaccination of cattle is unlikely ever to be a realistic option.

We would remind readers just how "inadequate" waste-of-money-useless
and all-been-done before cattle measures in isolation from action on the maintenance reservoir of bTb actually is. But VAWM takes no prisoners, describing bTb as "not a complex disease".
In spite of what some, including EFRACom, would have one believe, bovine TB is not a complex disease. It is caused by a single organism Mycobacterium bovis and the major wildlife reservoir of infection in this country is the badger. It was almost eradicated in the mid 80s by a sustained policy of cattle testing using the intradermal skin test and slaughter of reactors, accompanied by a policy of culling infected badger populations. And there is no reason why the same approach cannot succeed two decades later in spite of the hugely increased scale of the problem that has been allowed to develop. As the Irish have shown where there’s a will there’s a way.

They continue:
We have already given our support to the 7 point plan recently set out by the NFU and other farming interests but it is now hard to envisage how this has much chance of success given all the constraints recommended by EFRACom on any badger culling and the knowledge, revealed in the report, that the Government has abdicated all responsibility for logistical support – hardly the commitment by Government to fight the disease, declared elsewhere in the report.

VAWM conclude with a point that has puzzled and astonished us in equal measure. EFRAcom has interviewed the so-called 'sides' of this debate to distraction. The Badger Trust have been wheeled out to spar with the NFU and the ISG to educate the politicians as to the difference between 'science' and 'political science'. The RSPCA make regular visits - as do representatives of numerous universities, all of whom benefit from the taxpayer's largesse. But to our knowledge, no-one with hands on experience of bTb in the field has appeared to give evidence. In fact disappointingly, EFRAcom turned down an offer from two leading scientists / epidemiologists with a wealth of experience some weeks ago seemingly preferring to listen to desk jockeys with electronic abacuses to play with.
Finally we are astonished to note that the committee does not appear to have consulted any veterinary organisation outside of DEFRA and the VLA. Instead they have sought the opinions of two non veterinary, single issue organisations the Badger Trust and RSPCA, who have no apparent concern for the insidious disease that is endemic in parts of the badger population, one of which, the RSPCA, was censured by the Advertising Standards Authority in 2006 and the Charity Commission in 2007 for publishing misleading information on the transmission of bovine TB.

For further information see: www.vet-wildlifemanagement.org.uk

A superb overview we think. 'Conflicting' science, 'fogged' by more dead cattle and a both-hands-tied approach to controlling bTb in badgers, leading to 'constraints' designed to prolong the status quo.. And all brought about by trying to placate the people least affected by the disease and kick government responsibility for a notifiable zoonosis firmly into the long grass.