Tuesday, March 20, 2007

And so to Wales

The Wesh Assembly is contemplating action on wildlife reservoirs of bovineTB after digesting the contents of the recent Welsh 'found dead' survey, which indicated that over a quarter of the badger carcasses presented, were displaying - er, bovine TB. Further to that, the spoligotypes found in the badger carcasses were the same as in slaughtered cattle within the same area.

The number of candidate carcasses does not include those who died underground out of sight and thus out of 'survey', but we will not be picky over that.

FARMERS WEEKLY reports a 'Complete change' as Welsh Assembly ponders badger cull to combat Bovine TB - but after the May elections you understand.

"The Welsh Assembly has taken a major step towards ordering local badger culls to combat bovine tuberculosis ..." Why now, may one ask?

"Wales' chief vet Christianne Glossop said it could not be determined whether the disease had originated with the cattle or the badgers, but Dr Glossop said diseased badgers were raising as many as four disease-carrying litters before the dams eventually died underground".

Actually, in many instances, it can be determined 'whether the disease has originated in cattle or badgers'. If no cattle movements 50 days prior to the previous Tb test have been recorded by the CTS (Cattle Tracing System) then by default, infection from cattle it is not.

6 comments:

Anonymous said...

And so you go on

"Dr Glossop said diseased badgers were raising as many as four disease-carrying litters before the dams eventually died underground".

Nonesense! Unless she can expain where she gets the data>

"Actually, in many instances, it can be determined 'whether the disease has originated in cattle or badgers'. If no cattle movements 50 days prior to the previous Tb test have been recorded by the CTS (Cattle Tracing System) then by default, infection from cattle it is not.

Sorry - I don't follow this argument. Are you suggesting that there is some way of knowing 100% sure whether cattle are carrying TB?

Matthew said...

Anon 10.47.
As PQ's confirmed that a diseased badger can live, rear cubs (and thus perpetuate Tb within the social group) and maintain body weight, before being overwhelmed with the disease for up to eight years, you had better take up your 'Nonsense' comment with Dr. Glossop. It would seem to us, that she has erred on the side of caution.

If bTb is found and the previous test was clear then SVS trace all cattle movements 'On' to the farm, back to a couple of months prior to the last clear herd test.
On annual testing that would be about 14 / 15 months.

If no bought in cattle appear on CTS database during that time, an alternative hypothesis must be offered as to the source of infection. The skin test as a herd test is as good as it gets; up to 95 per cent sensitivety and 98 per cent specificity. On 60 day repeat tests, that rises to 100 percent, even on single animals where the sensitivety rating is lower.

Anonymous said...

Matthew said...

Anon 10.47.
As PQ's confirmed that a diseased badger can live, rear cubs (and thus perpetuate Tb within the social group) and maintain body weight, before being overwhelmed with the disease for up to eight years, you had better take up your 'Nonsense' comment with Dr. Glossop. It would seem to us, that she has erred on the side of caution.


Come on Matthew - this describes a possibility - "a diseased badger can live .......
Assuming this to be the case every time is not erring on the side of caution - it is speculation!

As for your favourite 100% test, it seems not to be so effective in Scotland - even given their wariness on importing cattle from 'south of the border'.
Seems Scotland is exporting bTB to Ireland.

Girvan TB outbreak 'no cause for alarm'
DAN BUGLASS

http://business.scotsman.com


THE Scottish Executive yesterday confirmed a significant outbreak of bovine tuberculosis (TB)on a farm near Girvan in Ayrshire, but joined forces with NFU Scotland in stating that there was no need for widespread concern for the overall health of Scotland's cattle herd.

On 25 January the Department of Agriculture and Rural Development in Northern Ireland informed the Scottish Executive's Environment and Rural Affairs Department that a cow that had been "exported" from Scotland had shown some symptoms of TB when slaughtered. The State Veterinary Service office in Ayr then traced the animal back to Enoch farm, near Girvan. Movement restrictions were imposed on 26 January and the suspect was confirmed TB positive on 23 February.

Further tests were carried out on the Ayrshire farm, resulting this week in the slaughter of 46 animals. The farmer will receive the full rate of compensation.

All cattle previously moved from the farm have been traced and are now subject to restrictions, isolation and further testing.

A spokesman for NFU Scotland said: "The incidence of cases of TB in Scotland remains extremely low. We had only 11 cases last year and 13 in 2005. That compares very favourably with the almost 2,000 in England and Wales in 2006, and even more the previous year.

"There has been a close working relationship between the Executive and the industry, and that explains why we have kept Scotland almost totally clear of TB."

The thrust of that policy is that any animals moved from so-called hot-spots south of the Border must be subject to pre- and post-movement testing. Most of the Scottish outbreaks have been traced back to restocking programmes undertaken by farmers in the wake of the foot-and-mouth crisis of 2001.

The NFU Scotland spokesman added: "We have to stress that there is absolutely no risk to human health, but farmers must remain vigilant."

Matthew said...

Anon. 8.44
Thanks for the Scottish bit. We've posted it.

Th intradermal skin test is not 'our' favourite test, it is the only recognised inter community test for Tb. Anything else is supplementary. It has successfully cleared tb from countries where a wildlife reservoir does not exist.

"All countries have either eradicated, or have a programme to control bTb use one or more forms of the skin test. ..[].. The government is not aware of any country that has replaced the skin test as the primary test for bovine tuberculosis"

8th Dec 2003; col 218W [141968]
30 Jan 2004; col 540W [150492]

PQ's re badger/badger transmission and the length of time it can rumble around within them, their setts and newborn cubs are below;

8 Dec 2003: Col 210W [141080]
10 Dec 2003; Col 522W [141394]
10 Dec 2003; Col 523W [142461]
29 Jan 2004; Col 483W [150567]
29 Jan 2004; col 483W [150578]
12 Feb 2004; col 1560W [153924]

"Typically, an infected badger may excrete M. bovis bacilli for 12 - 15 months before death, although there are recorded cases of animals with Tb living up to nine years."

17thMarch 2004; col 278W [158017]
18th march 2004; col 434W [159065]

Anonymous said...

Yes of course only the one test is internationally 'approved', and this has been used effectively as a herd test.

That's a herd test - detect bTB in a herd then 'remove' the whole herd - only then can you be sure. Otherwise you risk leaving infected animals undetected that then spread the infection - 80% of outbreaks due to cattle movements has been quoted. Presumably, no farmer would intentionally move infected animals?

You continue to quote PQ's this time regarding how long TB can be in badgers. Personally I don't hold much faith in politicians but prefer to try and read between the lines of the science.

Yep - TB can be around in an animal for some time - those animals include cattle.

The point here is that Dr Glossop is SPECULATING over specifics - there is no way of telling whether a live badgers has TB without a blood test (repeated several times over).

Matthew said...

Anon. 9.38

When a herd test identifies a 'reactor' then a further test is required at 60 days, or if lesions found 120 days as well. If that is clear, a 6 month short interval 'check test' is carried out to see if anything is lurking. If the area has had just one confirmed reactor, then the whole parish is on annual testing.

Our strains of m bovis in the UK have a latency to the skin test of 30 - 50 days prior to it and 221 days after exposure, hence this time frame for checks.

Only in very rare cases of overwhelming exposure, and multiple reactors, is whole herd slaughter considered.

No 'farmer' can move anything at all when he is under restriction, except for direct slaughter or by Defra license to an exempt finishing unit. Trading Standards monitor.

80 per cent of breakdowns in CUMBRIA only, were down to cattle movements in the few months post FMD. Often a single animal, and when that was slaughtered - end of story. The remaining cases in Cumbria are in fact the Cumbrian strain of Tb. A post movement test would have found these, and should have been used. That has now been covered - very belatedly - by Defra's 're formed' herds legislation.

Yes we do quote the PQ's. They were asked for a specific purpose, and have proved most useful. Often answered without a political skew, and most informative.

We agree re your comment about politicians.

At the moment, there is no 'validated' test to confirm bTb in badgers, or at what level that may be. But we also feel that 'validation' is a smokescreen for fluffy scientists to reach out their avaricious little paws to the taxpayers once more, and would push for PCR to be used. Personally I don't care if it's a machine made by Enigma, the Americans or the Chinese - as long as it works. Hospitals are using this amazing kit, the army is using it and Porton Down are trialling it.

Tb diagnosis (ahead of postmortem) of infectious badgers does seem to be the sticking point, and this technology would allow this to be done. Of course, the losers would be the myriad of 'beneficiaries' hanging around the edge of this dreadful disease, who would then have to find some other bandwagon on which to climb.