Saturday, April 22, 2006

Krebs - A study in badger dispersal?

In our post below, we quoted from a Wildlife operative's submission to the EFRA committee which described his experiences trying to catch badgers for the Krebs RBCT, and he warns observers not to take any Krebs results seriously.

http://bovinetb.blogspot.com/2006/03/robust-basis-of-krebs.html

The whole basis of Krebs was to compare methods of ..... errr, culling badgers.
And it appears that on that basic premise the trials failed, so what of any conclusions drawn from this trial in 'peturbation'?

A letter printed in this week's Veterinary Record from Dr. John Gallagher and others follows:

TB policy and the badger culling trials.

With reference to last weeks letter (Bourne et al. 2006 ) from the Independent Scientific Group on TB (ISG ) we feel the catastrophic problems surrounding the current TB policy are such that this requires a response.
The raison d’etre for the formation of this Group was to carry out the badger culling trials as recommended by Krebs (1997). Despite the huge logistical difficulties encountered and problems with animal rights activist interference, intimidation and lack of cooperation compromising its efficacy, it is understandable that the ISG wish to defend the findings of their trial.

However, DEFRA staff carried out the trapping as determined by the ISG and it is DEFRA which admitted that the overall trapping efficiency was remarkably poor at between 20 and 60 per cent (DEFRA 2005). The consequential social disruption and dispersal of infected badgers was found to have been very considerable . Thus these trials have been so badly compromised that extreme caution is required in their interpretation.

It is unfortunate that the ISG have disregarded earlier work on this subject but understandable as to admit the veracity of this work would have made the Krebs culling trials unnecessary. But it is folly not to heed such work as it was carried out to more exacting standards with regard to culling efficiency, being virtually 100 per cent in both the Thornbury and Steeple Leaze trials and over 80 percent in the East Offaly Trial and Hartland clearance (Gallagher et al 2006). The ISG’s trial was envisaged as a culling trial but as a result of the many problems encountered it turned out to be virtually a study of disruption and dispersal of badgers.

Based on many years of practical experience of tuberculous disease in cattle and badgers and its control we disagree with the ISG over their conclusions based on their trials and their recommendations for future control of TB in cattle. The ISG should be aware that TB has been eradicated from cattle in 23 of the 25 Member States of the European Community by test and slaughter. It was almost eradicated in this Country in 1986 when only 84 confirmed outbreaks were recorded before effective strategic culling of infected badgers ceased. Only Britain and Ireland have a problem and Ireland is making encouraging progress in tackling theirs. Whilst the huge carnage of cattle taken as TB reactors continues it is quite irrational for the ISG to assert that cattle to cattle transmission is the real problem.

We can assure this Group that until the badger maintenance host is effectively dealt with TB in cattle will not be controlled and certainly never eradicated.

This is also the agreed opinion of over 420 veterinarians mostly from the problem areas in the South West, South Wales and Sussex and dealing on farm with this problem. Considering there are now only about one thousand veterinarians in farm animal practice this represents a considerable body of informed opinion. These views were expressed in a jointly signed letter to the Secretary of State for DEFRA in February and June 2005. We consider that this problem is too serious to be put off track by views based on a trial with highly questionable results.
J. Gallagher
R.H. Muirhead
A.T.Turnbull
J.I.Davies
W.L.G.Ashton
J.Smith
J.M.Daykin
A.McDiarmid



Dr. Gallagher refers to Defra observations of the number of badgers caught in the Krebs triplets as "remarkably poor, at from 20% to 60%". It is our understanding that this figure is calculated using the amount of land available to the RBCT, and John Bourne has said that as much as 50% of that was 'unavailable' in some areas. Whether that included the RBCT's own 'exclusions', i.e farms already under Tb restriction at the start of the 'trial' or just land whose owners refused access, we do not know. Neither do we know if the Defra figure factored in the RBCT trapping efficacy as described in Parliamentary Questions:

8th Dec 2003: Column 218W
Mr. Paterson. To ask the Secretary of State for Environment,Food and Rural Affairs in how many cases badger traps laid by or on behalf of the Department in the TB culling trial have been interfered with or removed without authorisation. [141971]
Mr. Bradshaw. Interference with badger traps laid in the Randomised Culling Trial is variable between operations. It is usually quite geographically localised and repetitive within a culling operational area. Management records indicate that - over 116 culling operations, across 19 trial areas, between December 1998 and October 2003 , during which 15,666 traps were sited - there were 8,981 individual occasions where the trap was interfered with, and 1,827 individual cull sites when a trap was removed.

We make that 57% opened or trashed, and 12% went AWOL altogether.
So out of a 100% cage traps set, 69% were unavailable to catch anything at all. And we suspect that this figure was attributable to in some cases on only 50% of land available and mapped in the RBCT, some of whose boundaries changed over the time of the 'trial'.

Amazing stuff this 'science'. You couldn't make it up.

3 comments:

Gonzo said...

The reason the Krebs trials were set up was not to test the efficacy of culling methods - it was to "test the effectiveness of badger culling as a means of controlling bovine TB" (the ISGs own words). It is true that the methodology used only provided a cull rate of 20-60%, and as a result of this it became impossible to establish a) what the link was between badgers and infection of cattle by bovine TB and b) whether badger culling would be an effective method for controlling bovine TB. It is equally true that a badger culling strategy at any scale larger than a small cluster of farms, will be equally unlikely to be effective - for the very same reasons - interference by animal activists and landowner's refusal of access to cull badgers. The Government has already stated it has no intention of changing powers of entry to land for the purposes of culling badgers. The consequence is clear - there will always be refugia for badgers to recolonise culled areas.

As you have regularly pointed out it only takes a lone infectious badger to create an infection episode and these animals are the ones that tend to roam beyond normal badger territories anyway, and are more likely to enter unprotected farm buildings to find food and water. Although the Kerbs trials failed to answer the questions for which it was set up, it has provided useful data on the perturbation effect - an effect that was first described over 20 years ago. A less than complete cull would disperse badgers, including the small proportion of infectious ones, either forward into previously uninfected areas, or back into previously culled areas.

I think you will find that those case studies mentioned in Dr Gallagher's letter eg Thornbury, East Offaly, Hartland etc were either very small, had a high level of landowner compliance, included physical geographical barriers against badger recolonisation, or a combination of these factors, working to help deliver a near complete badger cull. It is highly unrealistic to expect these factors to be relevant across the large areas now suffering from endemic TB infection in cattle in the eg south west.

Badger culling as currently being proposed by the Government and farming industry is simply not going to deliver the reductions in cattle herd breakdowns everyone wants. There may well be scope in the future to use PCR to detect disease in setts and cull badgers in a very tightly targeted way, but this is still theoretical and would need testing. Similarly work on badger and cattle vaccines is promising (but as you say has been promising for many years)but still some years off. So what can be done now? Pre and post movement testing of cattle will help reduce cattle-cattle transmission, and improved biosecurity, though you scoff, will definitely help, but only if it is taken seriously. How long did it take for biosecurity to be taken seriously following the first FMD outbreak? Far too long, by which time it was too late for many farms. How long will it take for biosecurity to be taken seriously by farmers, farm contractors, hauliers, and anyone else who travels from one farm to another, as a tool for reducing bTB infection. Where are the disinfectant baths on (currently) uninfected dairy and beef farms? I haven't seen any.

Matthew said...

Thanks for that Gonzo.

We think the way forward is to use 'badger' technology to identify the 'loners' and deal with them. It's true that Thornbury, Hartland etc. worked and it is also true that Krebs will show nothing new, except how not to do a 'trial'. In past clearances, small or large, the Wildlife teams went back several times and over a much longer period than just 8 nights annually as in Krebs.

You are also right in saying that Government have no intention of altering the law re power of entry, and it is our opinion that they have no intention of dealing with bTb in the wildlife either. The Wildlife unit staff are on notice to quit.

Recolonisation is ongoing with any species. But it is the badgers that the social group has hefted out that do the most damage (to cattle) and we favour a targetted cull of these leaving a healthy main sett in place, and gassing outlying setts to pick up these old, sick and excluded individuals. By doing that, the main group, although it may a few contain individuals with bTb, will not do as much damage as these loners, who enter farm buildings and whose infectivity is off the scale.

PQ's have told us that these individuals roam further, and behave atypically, i.e they wander around in the day, disorientated and dribble urine over pastures and in feed troughs, rather than use group latrines.

You say that "badger culling is not going to deliver the reduction in cattle tb that everyone wants". Not the way the RBCT went about it certainly. But in the SW is a group of nearly 30 farms which has practised the methods described above. They have badgers. They have healthy badgers. And those 30 farms have been clear of bTb for 7/8 years now. If Warwick University's PCR identification could be lifted from its dusty shelf, then a more targetted approach still, could be used. But as we said, do turkeys vote for Christmas? For if this was to happen many at Defra would be out of a job.

Bio security and bTb is a sticky one. As we've said, 4 of us writing on this site had no bought in cattle. That did not protect us. Matt 5 is answering you here and personally, we found it extraordinarily difficult to keep badgers out of the buildings. They climb, dig and slither under gates. They run through covered yards, to get at cattle feed. Our main clamps were sheeted down after use, and gradually the whole building complex was fenced around with netting and barbed wire underneath to ground level. Mains electric fencing at 6 inches was across the concrete driveways and with the help of one of the last 'reactive' culls before that part of Krebs was abandoned, we went clear in the spring of 2005, after nearly 5 years. The last two badgers the team caught were horrendous (they said). A huge sow with suppurating bite wounds in her back and mangy bag of bones, very emaciated. And our setts were all empty. These were not 'our' badgers.

Bio security at farm gate level, certainly did apply to us as no personel or lorries entered the building complex other than via a dedicated entrance off the road which was not used by cattle.

Pre movement testing we have discussed at length as being an expensive and potentially dangerous illusion. Post movement tests would be better, but that said, as we showed on the Irish work with adult cattle in housed contact with bTb positive cattle, transmission between cattle is very difficult, and takes longer than 6 months, and sometimes longer than 12. The level of infectivity in bovine lesions, we understand is usually very very small. Compare that to the 300,000 units of bTb bacteria found in 1ml of urine from a badger with kidney lesions, and the dosage of just 70 of those units needed to infect a cow (produce a reaction to the skin test) and you can see the problem. Combine that with 30ml of urine dribbled at each 'void', a third of which is indiscriminately left across pasture and the problem becomes clearer. Add to that a badger's 'flight / fright' reaction when surrounded, cornered or trapped by curious cattle having a sniff at him, and that aerosol urine spray plus the spitting reaction is quite enough to negate any disinfectant footbath at the farm gate.

Anonymous said...

Farmer at heart of badger battle says Hands off Brock (27 Apr)
A farmer whose cattle were the first in Britain to be linked to the theory that bovine tuberculosis comes from badgers has rubbished the connection – and declared his land a "no-kill zone".

A government announcement – and a green light for the biggest cull of Britain's half-million badgers – is expected shortly, but Gloucestershire farmer Len Ballinger is vowing to keep the killers off his land.

"I'm standing up for Brock - they've been before and wiped out every badger, yet the disease has continued. Brock's a soft target and he's clearly no more than a bystander in this growing problem of bovine TB."

Len grazed beef cattle on land adjoining Alderley Farm near Wotton-under-Edge in Gloucestershire when, back in 1971, Ministry of Agriculture vets investigating positive TB readings in his cattle discovered a dead badger. Subsequent tests detected TB and spawned the theory that cattle might catch the disease from badgers.

But 35 years later and with £43m spent on an extensive badger-culling trail, no scientific evidence has successfully proved the link. Indeed, the government's own scientists have now indicated that the way to address the disease is to reapply the strict TB testing and movement controls in cattle which were disrupted by the recent BSE and foot and mouth epidemics. Nevertheless, to assuage hardline anti-badger factions in the National Farmers Union and the Countryside Alliance, which represents anti-badger, shooting interests, the cull is likely to be sanctioned.

Len is adamant that badgers are being scapegoated: "My own suspicion even in 1971 was that intensification was to blame. My cattle grazed on land next to a highly intensive dairy unit, where the cows were kept indoors permanently and the slurry was pumped out onto surrounding fields. I was convinced my own cattle had caught the TB via that route - and in all likelihood, so had the badger - they love rooting through cattle manure for beetles and worms."

Mr Ballinger joins a growing list of farmers refusing to participate in the cull. In Devon, dairy farmers David and Patsy Mallet, who have a herd of 80 milkers on 200 acres of Dartmoor, say the move will wreak untold damage on consumer relations: "This isn’t a case of sentimentality over fluffy badgers," says David, "Something is deeply wrong with our agriculture if we are resorting to wiping out whole species. If farmers allow this, there will be a massive public backlash – basically, consumers will think ‘stuff you’!"

Badger expert Martin Hancox, who sat on the government's Badgers and Bovine TB panel, says any cull would be pointless: "Tuberculosis in cattle is caught from other cattle," he says, pointing to the fact that the disease is now appearing in areas of the UK, such as Cumbria, which had been TB-free for 10 years – and sometimes even longer. "The badgers were there all the time, so are they supposed to have sat around for a decade and then one day decided to infect cows?" he says.

"Since the chaos inflicted on the industry by BSE and then Foot and Mouth, TB controls and movement restrictions on cattle, which controlled the disease so well in the past - with no killing of badgers - have become a farce. Badgers don’t travel up the M5, but cattle do."

The answer is staring everybody in the face, but the fixation with badgers is blinding them to it."