Thursday, May 11, 2006

Drop in Cattle Reactors - Good News?

A comment on the thread below gave us a wake up call to delve more deeply into the latest slaughter figures from Defra.

The comment we print in full:

"The latest bovine TB figures would appear to be good news!
According to the Provisional TB statistics for Great Britain released on 5 May 2006

TB TESTS CARRIED OUT (in the year to 31st March) increased from
1,649,543 in 2005 to
1,807,805 in 2006

Despite this the number of cows slaughtered as reactors decreased from 7731 to 5455.

I reckon that is about 29% DECREASE

However 6099 herds were under movement restriction on 31 March 2006 (due to a TB incident, overdue TB test, etc), almost half of these
(2994) restricted due to overdue TB tests!

More cattle tested, loads less reactors than last year, and half of the herds under movement restrictions due only to late testing.

Am I missing something, or is this very good news?"

Mmmmm. We really are not sure and for that reason had not explored this too deeply. That's not to say we were unaware of the figures, more listening hard to the many reasons flagged up.

Here are some:

*Defra will no doubt attribute the drop to pre movement testing, but as that only started at the end of March, any cattle involved will not have had a second 60 day test at the posting of these figures. In other words, it has not been around long enough.

*Cynical members of the farming community may have realised that when tabular valuations arrived on Feb 1st., both non pedigree and pedigree cattle values would be severely affected and up with that they would not put.

*Vets were telling us that the Dutch tuberculin, used as we exhausted UK supplies late last year, and mentioned in previous postings, was more sensitive. And in fact it contains 30,000 iu/ ml of bovine antigen compared with 25,000 iu/ml in the UK dose. (25,000 iu/ml of avian in both).

And now we have this amazing drop in cattle numbers. You ask us why. We don't believe in the tooth fairy, and think that the vets may have a point in their concern over the Dutch tuberculin.
The figures have been dropping (they say) since February. But that should have resulted in more reactors if the Dutch serum was more sensitive.

So we are asking some serious and pertinent questions of the specific antigen used and its concentration. Some serum doses are constructed on a broad base to cope at a low level with many strains, but others have a specific 'receptor site' antibody / antigen lock and only identify the strains they are set up to find. And if that were the case, not too many UK cattle wear clogs, or produce Edam cheese. But we return to the earlier veterinary concerns that the Dutch product was TOO sensitive. So if it has it changed, how has it changed from being 'more sensitive' to less? HAS it changed at all? Are they now saying it is not sensitive enough?
The label on the vials still say 25,000 iu/ml for Avian, and 30,000 ph.eur.u/ml for bovine)
Are other factors mentioned above all playing a part?

For the moment the Chancellor may be grateful for small mercies from the Department of the Environment, Food and rural Affairs. His Tb budget is dropping, but if this serum is failing for whatever reason to find reactors, then initially slaughterhouse cases will be seen to increase and eventually, the chickens will come home to roost with an explosion in undiagnosed cases. And that is the worst news.

Defra figures are here:

'Slaughterhouse' figures have almost doubled from 109 to 189, but the confirmed culture samples from these animals is stable at 68 / 71 respectively.


Anonymous said...

Thanks for taking this up.

With the 'standard' test apparently missing infected cattle routinely, it's pretty worrying if the test is now even less effective.
It will indeed be interesting to find out what is going on.

Are the overdue tests down to DEFRA, & why doesn't anyone seem to be shouting about it?

Matthew said...

With so many cattle coming up NVL (No visible Lesions) at slaughter, it is our understanding that pressure was being applied to get this number down. Even some vets who really should know better, were referring to these animals as 'false positives', which is to misunderstand what the skin test is looking for. That is, exposure to m.bovis, not necessarily full blown, riddled with lesions, tuberculosis. We think this was case of 'shooting the messanger', in fact Matt 5 has told us that only 2 of his nearly 50 reactors were found to be VL or culture positive. But the test was showing a pernicious drip feed of constant reinfection. And not from Matt's cattle. It was doing its job.

So the 'standard UK' intradermal spec. skin test actually 'missed' very few, in fact one could argue it was too successful.

But we are into a whole new ball game with these figures. The herds under restriction have increased, so do we assume from that that even there are less reactors, more IR's are being flagged up?

Overdue tests are up on last year, but this 'event' is activated now if a herd test is delayed by only a day. A farmer is given a date by SVS when the test may be carried out - a start date, and then about a week's grace to arrange it, beyond that window. Tests need a 3 day period for reading so are usually carried out Monday/Thursday and Tuesday/Friday and if a vet cannot accomodate that particular date, and delays by a few days, Bank holiday or anything at all, then the herd will invoke an automatic herd 'restriction' notice. The figures do not show the length of the delay that has flagged up this 'restriction'. A day? a week? a month? Some farmers may have accepted temporary voluntarily 'restriction' rather than go outside their prefered testing time. To gather up cows and young calves in the spring / summer months is no mean task.

You're right that no one is shouting about any of this, least of all a phenomenal drop in reactors. 40% in some areas we are told, with close to 30 % overall.
Given our minister's habit of leaping into print with spin, smoke and mirrors, we find this curious. Very curious.

Anonymous said...

Also curiously quiet-

another body not averse to 'spin, smoke and mirrors' -

the NFU!

Matthew said...

Wouldn't know about the NFU. None of us belong!
But the silence from all sides is deafening. From memeory the reactor figures for January were still rising, so this precipital drop is Feb / March. But you're right. No press releases. Nothing. We smell a rat, in fact buckets of 'em.

Anonymous said...

And rats get bovine TB too.

Anonymous said...

Unbelievable - a bit of apparent good news and farmers immediately think the worst. Is it any wonder the farming industry is in the mess that its in. You can only blame the government for so much. You couldn't make this up!

Matthew said...

To Sunday's Anonymous commentators:
We haven't (made it up) and we are not 'thinking the worst'. Merely viewing Defra's absolute non-reaction to this 'apparent' good news - with caution and a healthy dose of cynicism.
And rats may carry TB. But all farms have to prepare a 'vermin' control package as part of farm assurance. No unauthorised entry etc. and this includes worming the cat, especially if he is the 'organic' method of rat control. What is important is the amount of bacteria carried by any host that is capable of onward transmission to cattle and the opportunity to do so.

Anonymous said...

In January 2006 the number of cattle compulsorily slaughtered rose from 1,887 in December 2005 to 2,646 in January 2006.

The number of herds under movement restrictions rose month-on-month, from 2,605 in December 2005 to 2,724 in January 2006. This compares to 2,455 herds under movement restrictions in January 2005.

This figure of 2646 if subtracted from Defra's 3 month rolling figure of 5455 as at March 2006, gives an even clearer view of a bigger and more sudden drop in February / March.
2809 reactors slaughtered in the two months, or 1400 per month instead of in excess of 2500.

Anonymous said...

Herds 'under restriction for delaying a test' can be misleading.
A test becomes over due if the results are not logged into the system by the test date. A test is not taken off the list until all / any queries etc are completed- this can be 3 or more weeks after it has been carried out. The list also includes Brucellosis tests!

On my list of 38 overdue tests, 1 has no cattle, 9 are PBT (blood tests)and 12 have been done.
The rest (16) are overdue.

On reactors found at PM post testing - Most Vets use the pistol type syringes which are very bulky particularly in a crush. ( I still use the old fashion alot smaller dental ones) From the pressure I have to apply I know whether the tuberculin has gone intradermally ( where it should be) or subcut where it should not be; Here there will be minimal reaction. With the pistol type the trigger pressure is constant so whether you are injecting fresh air or muscle you cannot tell.
All the Vets I have 'watched' using the pistol type instead of carefully placing the needle at an angle of 45 degrees, just ram the needle in at right angles to the skin. The majority of the Tuberculin can only go subcut- NBG.
Since the majority of Vets testing are either juniors or foreign with little or no responsibility, it is hardly surprising that reactors by pass the system!

Anonymous said...

I have seen many vets carrying out TB tests, including junior and foreign. In my experience the junior/foreign testers follow the testing procedures to a very fine degree (including checking the skin for a "pea" of tuberculin when using McClintock syringes, which would prevent your supposedly abundant subcutaneous injections, instead of just relying on how it feels when you apply pressure to the syringe).

Suggesting that the number of slaughterhouse cases is due to junior and foreign testers' incompetance is ridiculous. Unprofessional comments like this will only make an already difficult job even harder for these people if any farmers were to actually give your statement credence.

Perhaps there was a sudden drop in the number of highly skilled, experienced vets, like yourself, and a rise in junior/foreign vets at the beginning of the year, which would account for the drop in reactors and rise in slaughterhouse cases!? I doubt it. I find the dutch tuberculin a far more likely culprit.

Matthew said...

The farming press has picked up on the Defra figures this week, and report that VLA are now running 'comparison' tests between the Dutch and UK tuberculin.
As it has been used for months with no visible problems, one could describe this a case of 'shutting the stable door'.
As we said at the beginning of the post, we are 'monitoring' the figures. Several things happened, including OTM cattle back into the food chain, which may have led to a backlog of reactors in some areas. Not that that is anything new, 4/5 weeks was the norm a couple of years ago. We understand in the far SW it is now 10 days.

We'll post these new angles over the weekend. But whatever happened to the 'reactors' slaughtered figures, it was not happening in January. It flagged up in the 3 month figure to March, and whatever it was, it caused one heck of a drop which Defra did not even acknowledge - until prodded.