Monday, May 30, 2005

Cattle / Cattle : A Critical Analysis.

In the same edition of 'Nature' as the work by the Oxford team, (see post below) is a critical analysis in rather more readable form by Mark Woolhouse of the University of Edinburgh's Centre for Infectious Diseases, who concludes;

" In a further analysis, (of Spatial multiple logistic regression), Gilbert et al, found that cattle movements played a more obvious role outside the 'core' areas where bTb is already established, implying that movements are more important for the spread of disease than for its persistence. Indeed there are regions where bTb occurs only sporadically despite regular imports of cattle from infected areas. Some other necessary factor seems to be missing - which brings the discussion round to wildlife reservoirs and especially the badger".

At the risk of being disrespectful, we would also flag up the another apparently 'missing factor', referred to and reported by Matthew 4 in the post below. That is the collective brain cell of the Oxford team in totally ignoring the obvious.
A point so eloquently picked up by Mark Woolhouse who continues:

"Badgers are known to carry bTb, but Gilbert and colleague's study is equivocal (that's a a polite way of saying dubious, of double meaning, questionable etc.) on the animal's role in the epidemiology of the disease in British cattle. Proximity to known badger locations does appear in their analysis - but it is not prominent".

"To better understand the role of badgers in the persistence of bTb, we need to turn to experimental studies such as the Four Counties trial in Ireland, the results of which were published this year. (and Offaly, and Thornbury, Steeple Leez and Hartland)

Mark Woolhouse concludes that the Four County trial with a reduction of up to 95 percent in cattle Tb relative to its reference areas "is the clearest demonstration to date of a link between badgers and bovine tb in cattle. Given the incidence of bovine tb in Britain is expected to remain high, or even increase further, the sooner that effective control measures are introduced, the better. "

We agree. But would add a caution; that any attempt to clamp down on cattle movements by either pre / post movement testing must be for disease control reasons and not political expediency, and run concurrent to and simultaneous with the clearance of bTb from all known wildlife reservoirs.

Infectious bacteria do not respond to political bullying - they just spread..................

Boys and Their Toys...

We closed the previous post with the observation (based on years of cynical involvement with the relationship between animal diseases and political expedience) that neither politicians nor politically motivated vets should be seen within a mile of any infectious bacteria. To that group we would add the new breed of animal, "Spatial Ecologists, using Mutiple Logistic Regressions", or Statistical Modellers as they are now quaintly entitled.

Readers may remember this new breeds first salvo into the murky world of animal disease and politics when, led by Townie Blurrs' chief scientist, Sir David King, the computers whirred and clanked and 11 million animals died in unholy circumstances for the want of some real expertise in genuine disease control. Ignored were Prof. Fred Brown and his Smart Cycler, (that was American for God's sake - what did you expect?) and world experts on FMD such as Dr. Simon Barteling, both of whom were imploring the Government to identify candidate infected animals with the PCR cycler and vaccinate the rest. Instead Bliar appointed this new scientific animal, a Statistical Modeller in the shape of Prof. Roy Anderson, who had no previous experience of animal disease control, but on the strength of computer input, 'modelled' to death over 8 million healthy animals in an illegal contiguous cull.

Now computers are great, but if in the input is wrong (spot the deliberate mistake in the previous paragraph - or was it?) then it's a case of 'crap in = crap out'. Which brings us to the much publicised piece in 'Nature' last week, which pumped cattle movements from the Cattle Movement Service (but little else) into a computer - and concluded in language which seemed to have been written with the serious intent of preventing anyone else understanding it, that cattle movements have caused the explosion of bTb.

Music to the ears of a Minister for Inertia (Margaret Beckett) who obviously paid a great deal of money for this paper which says much but means little - and of course the lovely Elaine King.

The paper starts with the staggering observation that bovine Tb's "Transmission pathways remain poorly understood".

We would point out with the greatest respect of course, that from 1895 (and that is not a typing error) the 'transmission pathways' of Tb have been explored, logged, and experimented with. Firstly in 1895 by Professor Koch of the London Public Health Laboratory, and during the whole of the last century by a raft of experts in infectious diseases. We know from answers to Parliamentary Questions, how much Tb bacteria is carried in badger urine, and the dosage needed to infect cattle in various ways. We know the survival rate of this bacteria under various circumstances, what carries it and the influence of environmental factors - and for those answers (all archived) as ever, we are most grateful. The collective brain cell of the Oxford team was obviously not party to all this 100 years of research, even though one member was influential some of it.

So what was entered into this exercise of 'spatial modelling' of bTb?
Cattle movements from the CTS database 2000 - 2003, and then backwards from 1997 - 2003. using the same data . This because " spatial and temporal patterns of movement were shown to be consistent from year to year". One might enquire, if such movements were 'consistent from year to year', what other variable was the cause of the rise in cattle Tb?
However, the paper goes on "Processing constraints and the current structure of the CTS database, prevented movement data to be generated on the fly during the simulation process as a function of the previous year's simulated distribution: it was therefore necessary to identify a surrogate variable for animal movements from previously infected areas".

You couldn't make that up - or could you?. Do we read this, that if data was unavailable from CTS, then a 'surrogate variable ' was substituted? Well, well, well. And they call this 'science'?

As well as cattle movements a few other hopefuls (out of a possible list of 100) were entered as predictor categories, including a "broad range of anthropogenic, biological, demographic, climatic and topograhic variables". The team describe "the mean of normalised deviation vegetation index". That sounds good doesn't it? Haven't a bloody clue what it means but..
Another gem, " encapsualted in Fourier-processed satellite imagery in modelling the distribution of bTb in Great Britain".

At least they 'paired' the movements, so they had caught up with one 'Off' and one 'On' equalling just a single movement. But did they exclude a movement to slaughter? The paper does not say.

The bits which this site finds most interesting - apart from what was left out of the modelling exercise - is the statement totally missed by industry commentators thusfar:

"the pattern of spread of bTb between 1984 and 2003 shows an expanding core.."
"short distance spread can be viewed as contagion to adjacent or nearby farms located within a few kms. by direct contact or bourne by wind, insects, rodents or alternative hosts".

"movements are more important for the spread of infection than for its persistence.".


M. bovis although a tenacious little bug may arguably be excluded from all but two of the hypotheses given for contagions by the Oxford teams which is confirmed as "short distance spread from an expanding core".

The paper continues, "long distance jump-spread can be viewed as contagion occurring between locations separated by large areas of disease absence, and caused by the movement of infectious individuals or material".

Fairly profound that one, but we get the picture. But let's not forget the translocation of the other part of the infection cycle - to parts of the country where they are not likely to be ' persecuted'. It's not just cattle that move. Badgers translocated in cage traps are a disease opportunity - a Tb takeaway.

Despite the attention grabbing headlines of this 'work', another observation conveniently ignored by the mainstream media concerns such long distance movements of cattle;
"It should be pointed out that ...there are several regions into which many animals are imported and where the disease appears regularly but does not seem to persist. Potential explanations include ...the imported animals remain there only a short time before being slaughtered, and that suitable wildlife reservoirs do not exist in those areas or the conditions necessary for the establishment in those species are not fulfilled".

So they got there in the end. But conclude that their work has 'established a clear requirement for further examination of cattle movements to define the critical movement categories.."

Are they are asking for more money?

BCMS confirm that our Matthew 5 has had 'No 'ON' movements of bought in cattle ' onto his farm. The farm, as with two of our other editors is ring fenced to prevent cattle / cattle contact, yet we have all watched that "expanding core" of disease creep nearer and engulf our herds. And stay there.

The headline of the Oxford work is 'Cattle Movements and Bovine tuberculosis in Great Britain'.

What part of 'No 'ON' movements' do these people not understand?

Sunday, May 22, 2005

A Prolonged Wringing of Hands.

We referred (in the post below), to the profound witterings of the Chief Veterinary Officer Dr. Debbie Reynolds at the launch of Defra's Animal Health Report 2004 - this in the context of an increase in the pile of dead cattle as Tb reactors by 30 percent in the first 3 months of 2005, which she was happy to oversee. The dear lady also announced that "The industry will be putting forward proposals for Tb control strategy that would involve badger culling" , and it would be presented to the Minister, (our own Ben Bradshaw, Minister for Conservation and Fisheries. Yup the parcel stopped on his chair) in the next few weeks.

We assume that this refers to the Minister's request that the 'industry' comes up with a plan, to halt the scourge of bovine tb through the cattle herds, to which we have also referred, and which is presently doing the rounds of 'discussion'.

Dr. Reynolds went on "We want a sustainable long term solution on the wildlife component. The scientific evidence base for future changes is very important. As laid out in the strategy, if wildlife measures are to be adopted they need to be effective, cost beneficial, take account of animal welfare and be socially acceptable".

She described such a policy as "a major investment to find a sustainable way to deal with wildlife".

We'll deal with those points one at a time, but we will not refer to anything Defra touches as 'science' - in the true meaning of that word.

Cost beneficial. The minions at Page street have added up Krebs, divided by a not- very- large pile of trapped badgers - (arguably the wrong ones) and remember 57 percent of the traps were interfered with, and 12 percent went AWOL, and come up with a figure of £'X'000 per badger, to control Tb - which frightened them to death. The minions not the badgers. The sad thing is that they actually believed this rubbish, and fed it all into the regulation 'computer model' ending up with zillions of £'s which far outweighed the donations from PAL and the 'animal welfare' charities. Sp whatever the core discussion group comes up with, cage traps are not a likely candidate. They are indiscriminate, far too slow, open to abuse and hence very expensive.

Animal Welfare. By this we assume the lady means the welfare of any targetted wildlife, and not the piles of dead cattle - about which she appears to care not one jot. Game management specialists are already employed by Defra on their 'deer management' strategy. With night vision stalking rifles, that is as good as it gets. Their class 1 'Game management ' qualification ensures they are excellent marksmen with a wider appreciation of deer habitat and laws governing their control. They keep numbers under control for a given area, taking out the old and the weak. Her own 'wildlife' teams are in the main, well versed in wild animal control, habitat and management. She could do a lot worse than listen to them. What must be avoided is the stirring up or perturbation of a group of badgers, leading to territorial aggression, which spreads their endemic Tb through bite wounding. We would favour mapping a strong vibrant sett in an area of cattle testing clear, in a density of about 1 adult per sq. km as described by the late Earnest Neal, as "abundant", - and gas the dispersers, and single hole 'problem' sets and sets disturbing sensitive wildlife habitats, houses and gardens, farms and cattle, using carbon monoxide. This was suggested by Dr. William Stanton of the Somerset Wildlife Trust in 1999 and described in our post below. To continue with the 'animal welfare' bit, simultaneously we would use BCG vaccines to protect the cubs in that main set, and continue to monitor all the outlying sets in the area, to pick up the 'badgers which the badgers have excluded' from their main group.

Socially acceptable. Defra have a library of pictures of badgers suffering from advanced Tb. It is much less than honest not to show that suffering. Landowners are seeing in increasing numbers the results of the total protection that this delightful animal 'enjoys' and it is mendacious to pretend it isn't happening. Honesty and politics are unlikely bedfellows, but the lady could do worse than 'tell it as it is' - before the tabloids print pictures of what ramblers and walkers are likely to trip over - any time now. Emaciated, mangy and boasting abcessed sores which ooze highly infectious pus. The press is keen to sieze on animal cruelty stories and Defra's deliberate abandonment of a wild animal species to an the endemic zoonosis 'Tuberculosis' is an accident waiting to happen.

But while Dr. Reynolds is pacing time hand in hand with 'the Industry', she is also saying that she will let Krebs run its course. Another 2 years? 3? The next election? And while she "regrets" farmer anger, and shares their "frustration" she is not going to be hurried into any decision.

"There is a serious problem, and I share the frustration. If it were possible to bring forward the decision, I would".

We deliberately entitled this post 'A Prolonged Wringing of Hands'. We would also add that politicians and 'political' vets should not be seen within a mile of infectious bacteria.

Saturday, May 21, 2005

To Test or not to Test?

Last year in answer to the exponential rise in Tb cattle slaughterings, our Ben - bless him he's back with the poisoned chalice again after the election - set up a couple of committees. One was the Pre-Movement testing committee, which had a remit from Defra to discuss - just that, 'Pre Movement Testing'.. Not whether pre movement testing worked or was effective as a disease control method - just do it. Sounds good though doesn't it? And cost didn't enter because the farmer was going to pay. Generously, our Ben agreed to pay for the tuberculin. That's 25p against the farmer's share of about £25 for the vet - twice.

We've told you several times on this blog, about severe cattle measures applied both in Ireland and the UK which have made not a dent in cattle Tb, if the reservoir in wildlife was not tackled simultaneously. And we (as ever) are most grateful to Captain Ben for the answers to Parliamentary Questions (archived) which confirm that "in the absence of a wildlife reservoir, regular testing (of cattle) and slaughter (of reactors) is all that is necessary".

But reporting to Defra this week the Pre Movement Testing Group, having cogitated, pondered and meditated their extraordinarily restrictive remit, expect Defra to implement some type of pre movement test next year.

Speaking at the launch of Defra's Animal Health 2004 report (not doing too well at that are they - cattle slaughterings up 30%? Not very well at all.) Chief Veterinary Officer Debbie Reynolds said "Tb is a regional problem and we need to keep clean areas clean. This depends on rigourous implementation of cattle controls and pre-movement testing would play a fundamental part in this".

That's easy then. Rigourous cattle controls and all the tb just - goes away? Errr no. It does not, as Ireland found in the 'Downie' era and certain DVM's found to their cost in the UK. (see posts and comments below)

But pre movement testing can be downright dangerous as farmers purchasing cattle so tested will assume, quite wrongly that they are 'clear' of tb. The skin test is not at fault, its implementation in this situation, combined with the expected industry 'exclusions' is.

We will explain;

1. The skin test has a latency of 30 - 50 days from exposure to m.bovis to the provoking of a skin reaction from that exposure.

2. The industry is likely to want at least an 8 week window from a pre movement test to selling, in which to arrange sales.

3. The industry is likely to ask for exemption for calves under 8 weeks, and slaughter stock which is probably OK, but also for store animals up to 15, 18 or even 20 months - which is risky.

4. The skin test is an 'excellent herd test' - John Bourne says so, so it must be. But on a single animal tested just once it's accuracy falls to under 70%.

So what have we got so far? 1 + 2 + 3 + 4 = a whole lot of 'missed' potential reactors.

The latency and 8 week exemption window add up to 4 months. That's 30 percent of reactors missed on an annual testing regime. Store animals exempt up to some 'teenage' cut off point, even though SVS tell us that 50 percent of reactors are in such young stock, would leave only a third of the animals tested reasonably covered by any pre movement test - and that compromised by the 'single animal' factor. Under conditions described above, we reckon about 60 percent of potential reactors would be missed.

But from Defra's Page Street disease control centre - it sounds good, and of course Defra isn't planning to pay.

Tuesday, May 10, 2005

Cattle Slaughtered - up nearly 30 percent.

In the first three months of 2005, cattle slaughtered as Reactors, Dangerous contacts or Inconclusives after a Tb test leapt by a staggering 29.5 percent compared with 2004.

You will remember of course that our number- crunching Minister of Fisheries and Conservation in the last government, (Rear-Admiral Ben) tried to tell the electorate and parliament that the bTb 'epidemic' had plateaued - compared with 2003 that is. Which is the very thing his department told everyone else not to do. Compare with 2003 that is, or 2002 either, because of FMD in 2001, the following years were absolutely 'not to be used for comparative purposes'. And yup - as we've pointed out many times on this blog, our Ben went and did just that. And then tried to tell us it was under control.

Well it isn't.

Figures now released (and available on the Defra website show a huge rise in cattle slaughtered, and also in herds under restriction Jan - March 2005. Glos., Devon, Hereford & Worcs. and Cornwall all have between 11 and 15 percent (of herds registered) under restriction because of a reactor found at TT testing. Wiltshire and Somerset are both in excess of 5 percent.

In a letter to the Daily Telgraph May 6th. Cornish farmer Margaret Miles, of St. Mawes described watching Tb creep into the Roseland peninsular towards her closed herd. She tells readers that since 1966, the herd has bought in no dairy replacements, only a stock bull once every 10 years or so. Four in 40 years. Geographically the farm has a secure border on 3 sides so thought the herd was fairly safe. Not any more. At a routine (annual) test last October reactors was found, since when this herd has lost 40 percent of its cattle in successive 60 day tests over the past six months. And no doubt contributes to the figures quoted above. (The last purchased bull had been on the farm for his allotted 10 year span, and had been tested every 2 years and then annually- all clear. Last summer 5 or 6 dead badgers were found on the farm.)

Ms. Miles has calculated that based on the this spring's figures from Defra, and if no action is taken on the wildlife reservoir, within 6 years ALL of Cornwall's herds will be under restriction.

As Glos. and Devon are actually worse than Cornwall, with a higher percentage of herds under restriction - that situation shouldn't take so long for them.

In 1986, GB had less than 100 herds under restriction, and were mortified to have slaughtered 686 cattle - in a whole year. At the end of March 2005, 6,334 herds were under movement restriction and in just 3 months Defra slaughtered 8,429 cattle.

Well done Ben. What a legacy. And despite your slippery pole tactics - yup, you've got the problem back in your 'new' job. Welcome back, Captain Ben.

Monday, May 02, 2005

404 - and rising.

In a letter to the Veterinary Record (23rd. April), senior vets from Devon, Glos, Bristol and Sussex give an update on the letter addressed to the Secretary of State for Agriculture, requesting urgent action on the reservoir of bTb in badgers.

What will not be lost on the CVO (Chief Veterinary Officer) is that the signatories were SVS personel of the highest level, all specialists in bovine tuberculosis, but now unfettered by government employment restrictions.
The 'Official Secrets Act' clause we expect, would impede their successors' ability to "tell it as it is" - which is exactly what it is meant to do.

Describing the letter as;
".... the result of total exasperation that a government department, statutorily charged with the responsibility to eradicate a serious disease such as bovine Tb, and in full knowledge of the cause, can allow its control to deteriorate so rapidly that the number of outbreaks now equates to that last seen 40 years ago.

They continue,
"Over many years peer-reviewed articles, written by State Veterinary Service (SVS) staff and MAFF biologists and agreed for publication by the then SVS Directorates, have elaborated the role of the badger as a maintenance host for bovine Tb in Britain, and the effect this disease was having on the species. Has the Directorate made the Minister aware of these findings?

Over half the adult badgers found dead in fields or farm buildings were shown to have generalised Tb with emaciation. Insidious lung disease in wild badgers was found to continue for a year before death. But where renal Tb developed following generalisation, death was accelerated. Tranmission of infection from one social group of badgers to another was found generally to occur through immigration of diseased individuals. But in disturbed populations, and those with a particularly high population density, territorial defence was found to result in fights, which frequently led to the disturbing phenomenon of bite wound transmission of infection.

They remind the Minister that..
"Where strategic culling was undertaken the disease was successfully controlled until 1986, since which time piecemeal efforts, followed by the cessation of all control, have led to an unfettered progress of the disease across much of the endemically infected area. Tb has become a serious threat to the wellbeing of the species.

While primarily a disease of the badger, infection is not only spreading to other badgers, but spilling over into the environment to affect other species. Cattle, being abundant and fully susceptible are frequently acting as sentinels of badger disease. Testing and slaughter of reactors largely averts the devlopment of overt disease in most cattle, but this wretched disease continues unabated in the maintenance host.

Infection in all 5 species of wild deer in this country has now been confirmed and a worrying development of infection in rural cats has been recognised more recently. (See our post: The Cat's out of The Bag - archived.)

Treatment of diseased wild animals is not feasible, and culling such communities is unfortunately necessary to stop the remorseless spread of this serious notifiable disease to cattle and man. We feel attempts to raise the immune status of apparently healthy badgers should also be made, using BCG. Wide scale trials of vaccination of badgers are a positive measure that should be attempted to protect the species as far as possible. Or do we continue with current policy, and watch the problem become completely out of control? One certainty is the complete failure of control measures directed against cattle alone, the policy advocated by the ISG. Just killing more and more cattle was the approach we used 40 years ago before we knew that the badger was a maintenance host. Then it was understandable, now it is incomprehensible.

The Minister has announced that action against this problem will await the completion of the hopelessly flawed Krebs trials, which have been more to do with political procrastination than science. All signatories to our letter expressed 'no confidence' in these trials, and considered them completely discredited. Professor Godfray, Imperial College, London found the statistical method to be flawed, and has questioned what benefit might be gained from their continuance following the highly successful Four Area Trials in Ireland. In Parliamentary Questions it was admitted that trapping efficiency in the Krebs trial was from 30 - 80 percent. Additionally, there have been problems of non-compliance and interference. At the end of the excercise the results are likely to be inconclusive and unreliable, despite a spend to date of £31 million, and a projected further £7.4 million of public money.

We feel that this charade should cease immediately, allowing effective control to be started forthwith".

404 veterinary surgeons and members of the RCVS, have now signed the letter indicating their 'total exasperation' with current non-policy on bovine tb. The one sided approach. - that is just slaughtering more and more cattle, with no action on the wildlife reservoir of the disease - they point out was the approach used 40 years ago, before the badger's role was known. (And when, as David Denny points out (see post below) cattle contact and spread of bTb was successfully prevented by 2 strands of wire 6 feet apart).

Their comment on this approach is scathing: " Then it was understandable, now it is incomprehensible".

We agree.