Saturday, November 20, 2010

Vaccination myths

We should be used to the grammatical gymnastics of the Badger Trust by now, so many may be blown out of the water by a simple read through of the paperwork they love to misquote.

We saw it here and here and posted the correct information so that our readers could make up their own minds. So when a 'proper' journalist starts throwing his teddies with a polemic rant about 'controlling landowners', and vaccinating badgers it is, er disappointing.

After his rant about cattle farmers, whom he seems to hate as much, or more than the badgers he claims to want to protect, George Monbiot the Graudian's Great Moonbat offers this gem:
As for the badgers, they should continue to be trapped in cages, but vaccinated and then released, as this prevents their social structures from being disrupted. By 2015 an oral vaccine for badgers could be ready to roll, which will be far cheaper than the current options.

This is straight of the Badger Trust website where they offer a press release claiming:
Laboratory studies showed that injections of BCG significantly reduced the progression, severity of cattle TB and excretion of bacilli. A key finding of a four-year field study in more than 800 wild badgers in Gloucestershire was a 74 per cent reduction in the proportion of wild badgers giving positive results to TB tests.
Well that's fine then. A jab of BCG and a 74 percent reduction in badger TB? Excellent. What's to misunderstand?

A lot. A great big, huge lot. As is explained in the operating procedure for all these vaccine trials, released with impeccable timing by Defra last week. The one which should be of interest to cattle farmers is use of BCG on a headline figure '800wild badgers', in this paper. But these badgers were screened. Not 'wild' as in of unknown disease status. They were trapped, then subject to three tranches of blood assays to try and ascertain disease status prior to vaccination. That is a far cry from launching into the TB hotspots of the UK with hope, and a long needle, on two night forays.

So what was the result? The Badger trustsays 74 percent. Er, no. At least not until a huge proportion of the candidates were shaken out of the selection process by our old friends the mathematical modellers. On page 33 of the Appendix which readers may have missed, the text tells us:
"However, the numbers of animals eligible for analysis was sometimes very small, although larger than in the interim analysis as a result of the additional observations from two further trapping campaigns in 2009. For instance, for the StatPak test, 47% of the groups analysed have three or fewer individuals. This was 45% for the Gamma and Culture test individually and for StatPak and Culture tests and all three tests combined. As a result, the scale for proportions is very coarse (e.g. 0%, 33%, 66%, 100% for n=3) and this leads to very high variability where group size is small. "
Conclusion:
This additional analysis has shown that there were differences in the proportions of cases of new incidences between groups A and B (treatment A showed a reduction of between 19% and 74% in the proportion of cases of new incidences, depending on the outcome of interest). Two of these differences were found to be statistically significant at the 5% level (StatPak on its own and StatPak and Culture combined.)
Never miss an opportunity to grab a headline, do they? Nobody mentioned the mathematical modelling, the pre screening, the shakeout to a small 'high variability' group using all three blood assays, or the need for annual vaccination. And no-one mentioned the crucial "between 19%", which preceeded the 74% mis quote.

The actual figures of pre-screened, annually vaccinated badgers showing a possible reduction in TB at subsequent blood screening was around 25%, with 41.5 per cent of non vaccinated badgers proving positive to a dose of m.bovis on all the blood screens and 31.1 percent of the vaccinated badgers.
For all three tests combined (total number = 262), there was a reduction from 41.5% cases (95% confidence interval: [28.0%, 56.3%]) of new incidence in group B down to 31.1% cases (95% confidence interval: [22.7%, 41.0%]) of new incidence in group A
But the crucial postmortems have not been done, to check for transmission opportunities.
Vaccine efficacy in the context of BCG vaccination of badgers may be defined either as a reduction in the incidence of uninfected badgers becoming infected with M. bovis or a reduction in the progression/severity of TB in badgers that do. The effect of vaccination is measured with reference to a non-vaccinated control group. According to this definition it was not possible to estimate the efficacy of BCG vaccination in this study as the decision was taken not to subject study badgers to post-mortem determination of infection. However, it was possible to use the tests employed in this study (IFN╬│ EIA, Stat-Pak, culture) in live animals as surrogate measures of vaccine efficiency

So far from that gallopingly wild headline, adopted by all and sundry - and Moonbat - of a 74 per cent reduction in TB of the 800 wild vaccinated badger trial group, the conclusion on p 9 of the Appendix, opines that
"it is not possible to to estimate efficacy of BCG vaccination, in this study"
And by that, the researchers, whose names have been blanked out of the paper, indicate that they would like more cash to do it all again.

No badgers were injured during this trial.

19 comments:

Anonymous said...

Badger culling is no 'silver bullet' either.
House of Lords
Tuesday, 16 November 2010.


www.publications.parliament.uk
http://tinyurl.com/398gjrb

Bovine Tuberculosis
Question
2.48 pm

Asked By Lord Krebs

"I ask the Minister two questions. First, does he agree with the estimate
of his own officials that, based on the results of the randomised
badger-culling trials, long-term intensive culling of badgers would lead
to a 16 per cent reduction in the incidence of TB in cattle over nine
years? Even this modest reduction, which would leave 84 per cent of the
problem unaffected, would be achievable only with highly effective,
large-scale, long-term culling. Otherwise, culling will make the problem
worse. Secondly, does the Government's Chief Scientific Adviser, Sir
John Beddington, agree with the policy of culling?

Lord Henley: My Lords, on the first question, I accept what the noble
Lord has to say, but ongoing monitoring since the end of those trials
indicates that the positive impacts on herd breakdowns within the culled
areas have lasted for a considerable number of years after the culls
have ended and that those areas have seen a reduction of some 28 per
cent in the incidence of TB."

So badger culling gives at best 28% reduction - at a (high) £££

What about the other 72%?

Anonymous said...

It would appear that Anonymous above is as big a tosseur as are both Monbiot & Krebsy-baby.

“So badger culling gives at best 28% reduction - at a (high) £££”

We’re talking here of a totally bodged-up (un-scientific) ‘exercise’

Cull the sick badgers – cull the infected cattle - and keep on culling

Matthew said...

Anon 9.46

We are aware of Lord Krebs change of direction from his original trial protocol. We are also aware, as is Bourne, of how it impacted on 'success' rates for the proactive RBCT cull.
Krebs' original operating procedure is on site (Krebs v. RBCT posted July 2007) as is Bourne's 'culling badgers the way we did in the RBCT' is ineffective and expensive. Evidence to EFRAcom July 2007 ("This is the answer.. post)
The fact that the RBCT subsequently achieved anything at all, after an 8 night occasional foray with cage traps is quite remarkable.
Thornbury achieved 100% after a cull of little over 6 months. And that lasted over a decade.

Matthew said...

This comment came into the blogger mailbox, but did not appear on site. We are posting for the Anon, concerned.
Matt.

"It's not often I find myself agreeing with something in the farming press, but we have witnessed the failure of bovine Tb policies over many years, and we seem no closer to a solution now than we ever were. So perhaps it is time for a radical rethink along the lines proposed below.

UK - Bovine TB and Badgers, The Reply!

www.meattradenewsdaily.co.uk
http://tinyurl.com/27ujtcq

19 Nov 2010

Dear Sir or Madam, we read, with interest, your article dated 18/11/10
'UK - Bovine TB and Badgers.

Killing badgers will not be a quick fix and no one really knows if it
will work. The Government has persistently failed to adequately justify
the need for the existing expensive, archaic and draconian bovine TB
policy, either on the grounds of human or animal health or even on
economic grounds. Farmers are getting desperate. A new direction is
needed - and now.

We wonder if you would be able to address the root of the problem in
future articles? It is clear that we need a total re-think on policy. We
can provide refs to facts below if required but much of the information
is from good sources, including the articles in 'Mycobacterium bovis
infection in Animals and Humans' by Thoen et al 2006.

No other country with wildlife reserves has been able to eradicate
(eliminate!) the disease. Those countries that claim to have eradicated
the disease using the skin test (which is not accurate enough to be
anything other than a herd test - see flaws of this test further below!)
have only done so by the complete depopulation of all herds where any
animal reacts to the test and re-stocking is then delayed. In Russia
even soil was removed!


The current policy, which has been operating for over 50 years) is NOT
meeting the aims set by the Government (see
http://www.bovinetb.co.uk/article.php?article_id=27).

To prevent bovine TB spreading to other cattle or other animals FAILING
To make sure that cattle do not suffer because of TB FAILING
To protect human health - pasteurisation and cooking of meat is
sufficient - see 'Public Health and bovine tuberculosis; What's all the
fuss about?' by Paul R and David J Torgerson.

Download the article here:
http://www.meattradenewsdaily.co.uk/pdf/Torgerson.pdf

Matthew said...

"What is all the fuss about?" say the authors of Anon's piece which we posted above.

Tuberculosis?
Zoonosis?
A statutory duty to protect public health?

What they have not caught up with, is the huge increase in what Defra politely call 'environmental' contamination. By that they mean bacteria capable of developing TB in the environment and available to any mammal, left around by badgers.

Look on the tested slaughtered cattle as sentinels of that contamination and then follow the progression of the dramatic increase in their numbers.

TB is now affecting many other mammals, including and especially, some which are up close and personal with their owners. And this 'contamination' is not coming from cattle. They're dead, way ahead of ability to transmit in the majority of cases. And in some areas of GB, all the cattle herds have gone. Sold up, but leaving sheep, alpacas, lifestyle pigs and domestic cats / dogs to roam and pick up disease.

We are told by AH that it is those TB victims which now queue to fill in VLA's spoligotype maps. Not cattle.

So with respect, the article's authors have totally missed the point. Tb is not about badgers and it is certainly not about cattle, or their meat / milk. It is a zoonosis which affect all mammals. It is doing, and it will continue to do so, until the source is cleared.

The authors are also wrong re other countries and TB.
New Zealand is well on the way to becoming TB free having managed its infected possum population.
Australia tackled its wildlife reservoir in their BTEC scheme. They are trading TB free.
The USA is tackling TB in white tailed deer, and bison in the national parks.

Uniquely, the UK is pratting about killing off its tested sentinels, and leaving the source to fester. And now the TB overspill from that source is killing hundreds (yes, HUNDREDS) of other mammals.
And it will continue to do so.

And that is the point.

Anonymous said...

“So badger culling gives at best 28% reduction - at a (high) £££”

If a farmer in an endemic area who is able to reduce their breakdown by 30% this is hugely significant! High Cost? If you spread the cost of a cull over the number of farmers likely to be involved within a 150km area its reasonable in comparison to the costs of having the disease in your herd, and thats using Defra figures!

Lets not forget that we will still have cattle controls in place and its likely that some of these will be tougher when the Gov produce their eradication plan for england - which they have said they will.

Wouldnt be a bit surprised if we see some of the Short Interval Testing lengthened to 90 days.

As for the vaccination trial - were these the 'wild' badgers kept at Woodchester park? Those same ones that go in and out of traps 3/4 times a year?

Matthew said...
This comment has been removed by the author.
Dr Dan Holdsworth said...

Rather than invest money in trying to make the BCG vaccine actually work worth a damn on badgers, I think that a much more fruitful avenue of approach would be to look at making a contraceptive vaccine or vaccines work in badgers.

The problem with culling badgers is twofold: firstly, the animal rights numpties object strongly to it, and secondly it isn't all that easy to target badgers with a toxin that'll only hit them, and not clobber scavenging domestic dogs (which have quite catholic tastes if they live with humans; peanut butter would be the bait of choice for badgers, but some dogs would find it highly palatable).

An oral contraceptive vaccine, by contrast, only inhibits conception and is quite species-specific. Such a bait can therefore be used quite freely, since even if non-target species do consume it, it doesn't cause them much damage. The health and safety aspects of it are reduced quite markedly also; you can safely allow relatively untrained personnel to distribute the stuff. If a UV fluorescent marker is added to it, then bait uptake can be checked by shining a UV lamp onto badger latrines.

If used over a big enough area, then the effects of a contraceptive bait would be minimal in the first few years, and would subsequently accelerate over time as the badger population in the area grew old and died off without much recruitment to the population. On an economic basis, such a bait would be a very useful thing to develop, firstly as there'd be a pan-European market for a badger-specific bait, and secondly as the underlying technology would be very useful for deploying against a range of nuisance species across the world (camels, rabbits and horses in Australia, for instance).

Matthew said...

Anon 9.41

What these stats are counting is a road-map of the RBCT, Confirmed NEW Incidents (CNI) only. As in reduction of. Taken literally, if all farmers in one of these areas were already under restriction, then there would, on the available data be no 'benefit', as there would be no CNIs ! That's how skewed it is..
This method ignores the fact that evry farmer under TB restriction is costing the taxpayer 6 tests / year instead of one, plus the cost of slaughter and removal of reactors and is indefinite until the source is removed.
Factor the 'benefit' to those such herds in and the data would appear quite different, we suspect.

In the RBCT, herds already under TB restriction at the start, were specifically excluded from the 'trial'. They had to be clear at the beginning of it, to be counted.

The 800 'wild' badgers were collected from areas where neither badgers nor sentinel cattle had shown evidence of TB. But it was from 110 setts in Gloucestershire, so make of that what you will. They were kept in groups similar to the capture structure, blood screened and identity marked, vaccinated and then released near where they were trapped. This continued for 4 years. Sometimes the same badgers were retrapped for their annual shot, some were different. Over the four yaers, data relates to just over 200.

One years' intake (2008?) were subjected to a dose of m.bovis.
This trial was to ascertain the 'safety' of BCG, when administered in this way to badgers, rather than its efficacy. That was an afterthought.

The efficacy results to which we refer are in the Appendix. (Link in the posting)

Yes, cattle measures are all that are available in order to comply with European directives on an eradication policy for TB. Which by statute, GB must have.

Matthew said...

Dr. Holdsworth.
We believe contraception may be allowed under the Bern convention, but previous work, notably White and Harris have estimated that without a parallel cull to clear latent infection, the time scale could be up to 20 years.
It will soon be nearly that since they wrote the piece.(1997)

http://www.jstor.org/pss/51109

Anonymous said...

Does anyone really believe that 'farmers' will be any more efficient at badger culling than DEFRA?

I think not.

If the proposed licensed culling goes ahead it will almost certainly be as big a pig's ear as DEFRA's efforts with the possible result of an even worse situation.

Anonymous said...

Matthew says: "What they have not caught up with, is the huge increase in what Defra politely call 'environmental' contamination. By that they mean bacteria capable of developing TB in the environment and available to any mammal, left around by badgers."

Yes you're right the environment is full of bacteria looking for a suitable host. If you removed all mammals (yes all) bovine TB bacteria would still be in the environment.

Your 'left around by badgers' is a sorry reflection on farmers beliefs. There is no silver bullet!

Matthew said...

Anon 3.12

Bacteria may still be in the environment - but not in the quantities needed to effect the onward transmission of disease. Deadend hosts will always be around. The amount of bacteria badgers are able to excrete, while still living relatively 'normal' lives makes them unique maintenance hosts of TB..

Removing infected badgers from the equation is not a 'farmer belief' it is a peer reviewed, well practised certainty.
And it worked here, on my farm, on my cattle - when the RBCT finally turned up to 'react' to a notified breakdown..

Can't comment on how 'farmers' will carry out any cull. It isn't them who will be doing it, as operating protocol demands very stringent licensing. And anybody who thinks a landowner can grab a shotgun and let rip is mistaken.
If the culling period is as the RBCT, (8 nights very occasionally, with cage traps, leaving a fragmented group (1997 - 2004)) then we agree. It will be the chaos we saw before. If however social groups are identified and removed intact (as after 2004), then the results may be different. The timing of any cull is crucial, as is its length.

Anonymous said...

Matthew can't comment on how 'farmers' will carry out any cull, and tells us that it isn't them who will be doing it. He also talks about badger social groups being identified and removed intact.

OK, farmers may choose to use contractors but
the government's preferred option is to license farmers/landowners who may engage and pay contractors of their choice.

And where does this social group idea appear in the proposals? OK, so the large areas will contain many social groups - but why identify them?


Oh yes - that reactive culling Matthew - that would be like was abandoned in the RBCT because it was making things worse, albeit not for you.

Matthew said...

Anon 4.41

You missed the FAC bit of a 'farmer controlled cull. That means a Firearms Certificate, not a shotgun license. A rifle. Using fragmenting bullets. All of which need special prescriptive permissions and control. Very few farmers have these.

One of our contributers does and thus is able to explain in more detail the lecensing procedure.

If the people who may operate this cull merely go out and knock off a few badgers, with no direction of where disease is entrenched, then early results will be as bad as the RBCT. That is what happened there.

Specific social groups CAN be identified using bait marking and the areas which have thrown up reactor cattle, alpacas, sheep, pigs etc. And a tightly targeted cull worked well in the past. The so-called Reactive areas of the RBCT were a joke. Believe me we were in one. They were so overwhelmed by the Pro active area problems, the Reactive slipped further and further behind. One area never started at all.
Three years, to arrive at all? That's not a reaction, it's a joke. Parliamentary questions 'regretted the delay'. Too right. So did we.

When they finally did come, the badgers caught here proved to be of the same spoligotype as our just 3, out almost 50 home bred pedigree closed herd cattle, which were shown to have Visible lesions or be capable of culture. Two of the badgers were in a dire state. One an emaciated wreck, the other a huge old sow with open abscesses from bite wounds in her back.

When these animals were removed, finally after almost 5 years, we went clear and on the whole have remained clear ever since.

Another contributer obtained detailed pm reports of an earlier clearance on his farm. The first 'ring' of badgers trapped showed over 80% lesioned and diseased. The second, further out about 40% and the last cull was all clear. The reported average thus became diluted and our contributer would have been more than happy to identify the last 'clean ring' and leave them.

This site prefers a management strategy linked to the presence of disease, to an indiscriminate area population reduction, based on a mathematical model.
And we will continue to push for that, together with the total involvement of Animal Health.

AH vets and WLO are on record as offering their experience that smaller targeted culls, provided they are complete and linked to the presence of disease, worked in the past and will work again.

No farmer contributing to this site wants a wipe out of badgers, But the RBCT's mathematical models, over simplifications and 'rough assumptions' (their descriptions, not ours) will haunt the process for some time yet..

Anonymous said...

Thanks for reminding us of this:

"This site prefers a management strategy linked to the presence of disease, to an indiscriminate area population reduction, based on a mathematical model.
And we will continue to push for that, together with the total involvement of Animal Health."

The discussions get confused at times and we should remember that this blog does not support the NFU's ideas on badgers.

Good luck with your campaign - you must have strong heads to withstand the banging against the wall!

If you succeed, one farmer at least should be rich - Brian Hill.

Unfortunately even if the processes proposed were agreed to be effective, I suspect the costs would be too high especially with the total involvement of Animal Health.

Presumably you mean the work would be financed by the taxpayer rather than the industry.

Anonymous said...

Please could you provide the link to the scientific evidence to support the theory that certain farmers will become rich?

Never will be able to and therefore never will be able to used, so lets use whats being offered.

Anonymous said...

“I’m off darling! – to Far Midden Meadow – then to Ten Acre Field - shooting sick badgers!

Like I’ve done every night since we were licensed – and like I’ll do every night ‘til the sickness abates.

Cheers darling!”

Matthew said...

Anons x 3.
You've been busy this morning!
And we have missed out a NOT on the previous answer.
Sorry, that should be " NOT to an indiscriminate area..."

Bryan may not become a 'rich man'. He is a very caring man, passionate about the countryside and all its inhabitants, and he will also need heart surgery some time soon. Our best wishes to him.

Last Anon. Yes our aching heads, from banging increasingly high brick walls, have revived with a long laugh.
Thanks.