Controlling bovine TB in the UK

The chart on the right hand side logs the number of cattle slaughtered in GB from 1978 – 2008 but more importantly, aligns these figures with the various badger culling strategies operating – or not – at the time. It is correct to say that GB had a TB eradication program through the 1950s and 1960s, but the assumption that ‘not one badger was culled’ during it, is incorrect. Prior to 1972 Protection of Badgers Act, farmers and gamekeepers controlled numbers. And in a few cases, vets failing to clear cattle herds with continuous testing suggested removing any indigenous badgers. This cleared the cattle, and they remained clear.

Apart from a change in turberculin antigen in the mid 1970s, cattle testing did not change over this time, in fact it increased as more herds went under restriction, needing six tests annually instead of one. More contiguous parishes came under the annual testing net. England has always had a strict ‘lock down’ of herds revealing reactors. But Dr. May, following the lead from the Badger Trust argues that ‘history shows badger culling does not work as a method for controlling bTB’.

We would say that the chart, together with explanations for ongoing  progressive ‘badger friendly’ exceptions to culling, shows that it did. From the early 1970s, when stringent cattle only measures in Glos and Cornwall (under William Tait) were failing, badger setts close to persistently affected farms were gassed. No exceptions. No ‘closed season’ so that a sow could infect her cubs, and no waiting around for permission from various focus groups. And the CVO reports from the mid 70’s finally recorded a drop in cattle slaughterings in these two hotspots.

The number of cattle slaughtered in GB during 1982 was 605.

The Clean Ring strategy (1982 - 86) gassed badgers in rough circle up to 7km from a confirmed TB outbreak, until postmortems were clear of TB. The change to cage traps during this period showed a slight increase in cattle TB but was still workable - although fraught with opportunities for interference such as the RBCT suffered.

In 1987, the number of cattle slaughtered in GB was 1183.

But in that year (1987) the most significant sanitisation of badger policy occurred when the Interim Strategy reduced the land available to the WLUs for trapping to just 1km, and then only on land grazed by cattle. So if the sett was in an arable field, fenced woodland or on a neighbouring farm, the WLU couldn’t touch it. Finally after £1 million bung from the PAL in 1997, government introduced the moratorium on Section 10 of the Protection of Badgers Act and MAFF / Defra refused to issue licenses to control disease.

In 1997 GB slaughtered 3760 cattle and one year after the moratorium 6083.

Dr. May is mistaken if he genuinely believes that cattle testing and movement restrictions over this time were in any way loosened. They have progressively tightened as hotspots expanded.

[see parish testing maps on the right]

And of course his (and the Badger Trust’s) wide generalisations fall apart when the same TB testing of cattle in other countries which either do not support a wildlife reservoir of disease, or take parallel measures to control it, have cleared their cattle herds completely. The number of cattle found with TB by slaughterhouse inspections do not support this assumption of a huge hidden reservoir either.

Then there are Defra’s carefully crafted spoligotype maps showing a consistent strain in one area. Not a hotchpotch which there would be, if cattle continually and over the decades this data has been collected, had moved TB around the country.

Dr. May is quoted in FG article as “citing the Independent Scientific Group’s (ISG) 2008 report and subsequent updates based on continuing monitoring of the cull areas as the scientific proof.” That badger culling does not work.

In the centre of the proactive zones, even their occasional, short, cage trap cull achieved a 50 percent drop in cattle TB.  But this week we hear from the lead ex ISG mathematical modeller that although her data is showing sustained reductions in TB across all the proactively culled areas of the RBCT, it would be too expensive. In fact Christl Donnelly went so far as to say it would take “12 years to recoup the cost”. 

And with that we would agree. Culling badgers as done in the RBCT showed us exactly how not to do it. Launching into a highly infectious population for just 8 nights, using cage traps just once a year - if you were lucky. Ridiculous - as key bits of this EFRAcom submission from a trial manager explain:

 5. Krebs had too many anomalies and weaknesses in the strategy for it to be successful. It took us four years to steer away from trapping setts that had been interfered with by Animal Rights Activists, to be able to trap badgers anywhere, in order to eliminate them. That was only one of a raft of operational problems we faced and had to endure.

6. Limited trapping - eight days per year with Krebbs - has little effect if carried out late in the year. The effect being that areas went almost two years without an effective cull.

7. The costs for a future culling policy must NOT be based on Krebs costings. [ snipped ]

Krebs was ridiculously expensive for what it delivered.

The original Krebs protocol had no ‘closed season’ or exclusions  and wanted all the social group taken as quickly as possible. Compared to his ‘political science’ which Prof. John Bourne was so proud to explain to the EFRA committee, this most expensive charade was ‘designed to fail.’

At its outset, both vets and trial managers say they were told by Professor Bourne “this is a cattle disease, and will be treated as such”. The models were weighted with 2 parts badger to 1 part cattle, as a ‘ simple rough assumption’.

But a change to the RBCT came in 2004, with a new trial manager appointed, protocol loosened (as explained above), traps laid on badger trails and more diseased ones caught.

Thus the 2008 update report from Jenkins <em>et al</em>, after cattle tests caught up with this change, saw a reversal of Bourne’s unique ‘halo’ effect - his reason for dismissing badger culling in his 2007 report - and that improvement in cattle TB both within all the proactive areas and around them was intensified and sustained in Donnelly’s publication of 2010.

 Thus the change of emphasis onto cost – and as carried out by the RBCT, the cost per badger was outrageous. Hansard confirms that 59 per cent of the cage traps cited up to October 2003 were ‘interfered with’ and 12 percent disappeared. The cost of replacing traps to that time was £400,000 and each operative was said to have spent 4 hours daily travelling to trap sites.

Cattle slaughterings have dropped a little late last year and  in the first couple of months of this year, compared with 2009’s figure of 36,322. And inevitably this is used as an excuse to say ‘cattle measures must be working’. But the only ‘cattle measure’ which is reasonably new, preMT, was introduced in 2006, and that would (should?) find more reactors, not less. So what is happening?

1. Across all ten RBCT proactive badger cull areas, incidence of cattle TB has dropped. And much to the chagrin of the ISG team, that drop is continuing, the benefit now overflowing beyond the zones.

2. We’ve had a lot of UV sunlight this spring, which is death for  m.bovis deposited on pasture (in badger urine) in a short period of time. Dull, wet weather extends its survival.

3. Imported Dutch tuberculin antigen was introduced for testing in June/July 2009. And the last time this happened, in 2006, cattle slaughterings similarly dropped, with the CVO’s report of that year explaining:

“The sensitivity of the combined Dutch PPDs is less, because of failing to pick up NVLs (animals which could be in the early stages of disease) which may or may not be confirmed with culture, to the same extent as Weybridge PPDs. This would result in under detection of cases, resulting in a transient decline in cases reported, despite there being no true decline in cases.”

Thus the incidence of bTb may not be dropping significantly, but the incidence of its detection, especially in the early pre VL stages, was.

If this is the case again, then we will see a greater number of lesioned reactors and cattle presenting at slaughter this summer and later.

4. Areas of the country with deeply, entrenched TB problems are said to be exploring a badger ‘management’ plan .

5. Vets say that Defra tweaked the test interpretation chart on January 1st this year,  leading to less severe interpretation IRs slaughtered.

All will have had an impact on numbers of reactors.

Despite Dr. May’s and the Badger Trusts’ outraged howls that bTB is all about cattle, Defra (and others) have spent an inordinate amount of effort printing guidelines of how to protect cattle from …. badgers. Much is as useful as a wet paper bag, and is contradicted by taxpayer funded research.

The big one is trough height. Still the figure of 30 inches is quoted. Why? Defra know full well from Dr. Tim Roper’s work that badgers can easily access cattle feed in troughs over 4 feet high. And at that height, Hansard confirms, ‘cattle cannot reach to eat’. Quite.

Hansard also confirms that while cattle will often avoid faeces on their grazing ground, they cannot avoid the yard long trails of urine voided by incontinent wandering badgers, whose 30ml squirts can contain up to 300,000 units of bacteria in each 1ml.

Just 70ml is enough to provoke ‘slow TB infection’ in cattle.

And then there is electric fencing.  But in their evidence to EFRAcom, the Wildlife Trusts explained that badgers are the main predator of bees’ and wasps’ nests. So, if thousands of angry bees stinging their nose didn’t put them off - what chance electric fences?

And all offering these gems of wisdom would do well to remember the words of the retired director of Woodchester Park, Dr. Chris Cheeseman, who, when asked how to keep badgers and cattle apart, replied “You can’t, you get rid of your cattle”.

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