suspension from tb testing

Re: suspension from tb testing

Busybee — Thu, 24 Jul 2014 20:59:31 GMT

[quote user="Alan Tevendale"]

[quote user="Bob Russell"]

[quote user="Michael Woodhouse"]

[quote user="Neil Wheadon"]c) incorrectly stored tuberculin[/quote]

You mean when AHVLA send it through the normal post, unrefrigerated?

[/quote]

Do they still do this?

[/quote]

Yes they still do this. I have regularly opened our post on a Monday to find tuberculin sent by animal health the previous week. Wonderful!

[/quote]

I thought could be readily transported/stored at +2 to +37 degrees for up to 14 days without a problem??

Re: suspension from tb testing

Bob Russell — Thu, 24 Jul 2014 17:01:27 GMT

IMHO or IMO just means you think you are likely to be shot down in flames if you state something as a fact!

Re: suspension from tb testing

Alan Tevendale — Thu, 24 Jul 2014 15:32:49 GMT

[quote user="Neil Wheadon"]

[quote user="Malcolm Ness"]You can take the man out of the Ministry, but you can't take the ministry out of the man!![/quote]

Very funny, and very true, I've never quite been the same since my Animal Health experience. Made even funnier by I dislike the use of shortened language and still don't understand IMHO. SI = Short Interval test = Run all those cattle through the crush again, 60 days after the previous test and for a laugh do it all summer, all year, all decade as farms with loads of cows do, especially as you can't separate groups anymore. 6M = Lets do it all again, after you finally got clear and lets start the whole process all over again

Neil

[/quote]

A funny and truely accurate description of the VE-SI and 6M tests.

Re: suspension from tb testing

Neil Wheadon — Thu, 24 Jul 2014 14:23:22 GMT

[quote user="Malcolm Ness"]You can take the man out of the Ministry, but you can't take the ministry out of the man!![/quote]

Neil

Re: suspension from tb testing

Alan Tevendale — Thu, 24 Jul 2014 13:16:26 GMT

[quote user="Bob Russell"]

[quote user="Michael Woodhouse"]

[quote user="Neil Wheadon"]c) incorrectly stored tuberculin[/quote]

You mean when AHVLA send it through the normal post, unrefrigerated?

[/quote]

Do they still do this?

[/quote]

Yes they still do this. I have regularly opened our post on a Monday to find tuberculin sent by animal health the previous week. Wonderful!

Re: suspension from tb testing

vetbl.locum — Thu, 24 Jul 2014 12:51:44 GMT

it has to do refrigerated ?? oops :-p

Glad I stopped TB testing given the level of hassle now involved in doing tests these days

Re: suspension from tb testing

Bob Russell — Thu, 24 Jul 2014 12:51:18 GMT

[quote user="Michael Woodhouse"]

[quote user="Neil Wheadon"]c) incorrectly stored tuberculin[/quote]

You mean when AHVLA send it through the normal post, unrefrigerated?

[/quote]

Do they still do this?

Re: suspension from tb testing

Michael Woodhouse — Thu, 24 Jul 2014 11:14:21 GMT

[quote user="Neil Wheadon"]c) incorrectly stored tuberculin[/quote]

You mean when AHVLA send it through the normal post, unrefrigerated?

Re: suspension from tb testing

Malcolm Ness — Thu, 24 Jul 2014 10:35:54 GMT

[quote user="Neil Wheadon"]SI [/quote]

[quote user="Neil Wheadon"]VE-6M[/quote]

You can take the man out of the Ministry, but you can't take the ministry out of the man!!

Re: suspension from tb testing

Neil Wheadon — Thu, 24 Jul 2014 09:35:51 GMT

OK I'll try to explain how I would have looked at this

It's unusual that I/R's turn into reactors but it does happen, the sllightly odd thing here is that the Avian readings have increased as well, that said here goes

1) The I/R's were isolated in an area where there was still contact with an antigenic source, Consider it almost as a VE-SI test where the next test throws up more reactors. If we accept that TB is basically from 2 sources either other cattle or wildlife then look at a) Were they housed or popped in a field where there is wildlife activity. b) Other cattle. It's accepted that some cattle are riddled with TB but simply don't react to the TB test anymore as the body is overwhelmed with the bacteria, so reacting to 0.1ml of tuberculin is nothing in comparison. Now consider that one of the I/R's slaughtered (and you had 2) were one of these and potentially an open case. The regulations say that I/R's should be isolated. In reality the cattle are crammed intoa shed somewhere eating from the same hay rack and guess what there's an open case in there too, a recipe for spread and was always a concern of mine dealing with TB.

2) Operator error at the initial test, this has to be broached I'm afraid and does happen. In life does anyone get everything right every time?

a) Truly intradermal. I re-tested lots of I/R's and was truly obsessive in getting the tuberculin perfectly intradermal. This takes time, the cow has to be pretty still, the syringe set correctly etc. a ministry vet will do this and before any smart comments of 'we all do it properly' appear, remember that state vets are faced with maybe 3 cows not 300, a farmer who is watching their every move and the knowledge that if this test fails the farmer goes under restriction, so they'd better do it just right

b) Air in the tuberculin syringe, so not getting the correct dose

c) incorrectly stored tuberculin

In your case with a hatfull of these I think that scenario 1 is very very likely and would be interested to know if one of those I/R's was an open case (not easy information to find, believe me, it's buried in the paperwork at AHVLA) and also where they were isolated, though accept that lots of farmers don't isolate!!

Neil

Re: suspension from tb testing

macflea — Wed, 23 Jul 2014 20:59:56 GMT

actually based in the republic of ireland , here when you find inconclusives , they are retested at 42 days and if inconclusive again , deemed reactors.

but in this situation they werent inconclusive again at the 42 day test but reactors, usually in my experiance when you retest inconclusives ,they are still inconclusives . confused, was not allowed to question ministry vet about their testing regime .

Re: suspension from tb testing

karen jones — Wed, 23 Jul 2014 20:45:31 GMT

I thought you couldn't do another test for 60 days! Why were the ministry testing at 42? If you have paperwork with your readings don't let them bully you and get advice from vds . Good luck , my experience with many defra vets is they are pedantic!

Re: suspension from tb testing

Neil Wheadon — Wed, 23 Jul 2014 20:41:58 GMT

[quote user="Richard Carter"]You don't think this has more to do with the chance of exposure to real disease over those 6 months if you have a confirmed (i.e. lesions cultured and positive) herd as opposed to reactors.[/quote]

You're talking about VL as opposed to NVL herds here aren't you?

Yes I can see your point here, but NVL reactors have still be exposed to TB, it's just that the tests we use to confirm (chopping up a lymph node looking for abscesses and trying to grow a bacteria that doesn't culture that well) aren't 100%. Therefore you can argue that in both cases TB is in the area, just with VL reactors there's more of it about.

[quote user="Richard Carter"]When I used to teach the subject in South Africa we had to change the tuberculin type to the Dutch strain (if memory serves) and this messed up all the reactor charts severely with a much lower reaction having to be graded up so two different charts were developed - one for confirmed infected herds and another more lenient chart for unknown or disease free herds as you do get lots of reactors for all sorts of reasons other than the presence of bovine TB.[/quote]

The UK changed to the Dutch strain too and personally I thought it worked better. the reactions were larger and firmer and I got the impression it produced less NVL cows (though my memory after 3 years is dimming)

Neil

Re: suspension from tb testing

Richard Carter — Wed, 23 Jul 2014 19:54:54 GMT

You don't think this has more to do with the chance of exposure to real disease over those 6 months if you have a confirmed (i.e. lesions cultured and positive) herd as opposed to reactors.

When I used to teach the subject in South Africa we had to change the tuberculin type to the Dutch strain (if memory serves) and this messed up all the reactor charts severely with a much lower reaction having to be graded up so two different charts were developed - one for confirmed infected herds and another more lenient chart for unknown or disease free herds as you do get lots of reactors for all sorts of reasons other than the presence of bovine TB.

Re: suspension from tb testing

Neil Wheadon — Wed, 23 Jul 2014 19:33:37 GMT

[quote user="Richard Carter"]Could be the tuberculin has 'boosted' a response[/quote]

No, it does the opposite

This is why a herd that has survived rounds of SI (Short Interval ) testing and gone clear will often break down again at the VE-6M (6 month test) It's because the immune system reacts less and less to 0.1ml of tuberculin under the skin and by the time 6 months swings around it's had time to recover.

Neil

Re: suspension from tb testing

Richard Carter — Wed, 23 Jul 2014 19:27:34 GMT

Could be the tuberculin has 'boosted' a response. Any positive pm/abattoir lesions in the herd because this plays a massive role in deciding whether the herd is to be treated as tuberculin reactors or positives.

Re: suspension from tb testing

Neil Wheadon — Wed, 23 Jul 2014 19:23:01 GMT

[quote user="Braden Collins"]

I think the ministry vet is full of it. I've had cattle with no lumps at one test then HUGE lumps at the next test 6 weeks later. I certainly never expect the results to be the same or repeatable. If they were consistent we would very quickly clear TB from a heard with 1-2 tests, which I'm yet to see.

[/quote]

Just for once Braden you're wide of the mark here.

The cattle you are quoting here would only have been IR's not a herd test as the standard has always been 60 days.

The consistency of testing IR cattle is an interesting subject and occasionally one would react a lot greater than at the revealing test. I did a lot working for AHVLA and reckoned that if you started with 9 IR's you would end up with 1 taken as a reactor as would pass about a 1/3 each test. These days cattle get 2 chances not 3.

I also found that cattle kept indoors between tests also helped a lot in regards passing and surmised that they weren't getting the repeat antigenic stimulus of being outside, so the reactions were less.

Neil

Re: suspension from tb testing

Neil Wheadon — Wed, 23 Jul 2014 19:12:48 GMT

A 42 day retest is an odd interval

This used to be the norm 5 years ago but has now been phased out to be replaced by 60 days. (To do with withdrawl period of the tuberculin, nothing to do with the validity after 42 days)

Are you able to say why this decision was made by AHVLA?

It sounds like someone made the decision to test the cattle again as soon as they could.

Neil

Re: suspension from tb testing

Bob Russell — Wed, 23 Jul 2014 16:37:37 GMT

If you did things by the book then trust your readings. How anyone can say your readings were wrong, I don't know!

TB testing is not nor ever has been an exact science!

Re: suspension from tb testing

Hannah Wynne Richards — Wed, 23 Jul 2014 15:17:17 GMT

Any exposure to sewage sludge? I'd suspect cross-reaction with human strains - but, of course DEFRA says that can't happen - even though they still claim TB is a zoonosis!

Wynne

Re: suspension from tb testing

Braden Collins — Wed, 23 Jul 2014 15:13:33 GMT

Does the title mean you're suspended from TB testing because of the ministry vets opinion?

Re: suspension from tb testing

Braden Collins — Wed, 23 Jul 2014 15:12:43 GMT