TB. A change in policy?

[steveR]

A little bemused when I had a letter from the APHA last week to tell us that we were now moving back to 12 month testing, after telling us last October, we were now 6 monthly... Quite happy at that, but why?

Then, I heard about a neighbour who has had a breakdown and APHA have apparently pulled the 2nd clear test requirement in a fortnights time, and moved him to 6 monthly testing. Not sure if he is now off restrictions, but I assume so.

What is happening? Change in policy?? @matthew

 

[borderterribles]

Interesting! What part of God's own County are you-ish? The high bit or the flat bit? We've been testing today. Clear ,but re-test in 60 days after a reactor at annual test at end of October. We also are supposed to be on six monthly, now anyway .

 

[steveR]

The civilised flat bit, N of the Wrekin....

 

[borderterribles]

The civilised flat bit, N of the Wrekin....

OK, thanks. Wonder if its County wide then? I arranged our next test, provisionally, as soon as the Vet left, but there was no mention of a policy change.

 

[Muddyroads]

We had 2 reactors in April and 2 more 60 days later. No lesions in any of them.
After another 60 days we had a clear test, with another test required after another 60 days, or so I thought.
Thanks to an eagle eye at the vets, it turned out that we only needed 1 clear test because no lesions had been found. The final test was only needed if I hadn’t sent the cleaning form back, although this wasn’t stated on the letter.
Never heard of this before.

 

[borderterribles]

Hmm, even more interesting! No lesions here either, and no previous history of Tb here either

 

[Muddyroads]

Hmm, even more interesting! No lesions here either, and no previous history of Tb here either

We went down in each of the previous 2 springs.

 

[steveR]

We had 2 reactors in April and 2 more 60 days later. No lesions in any of them.
After another 60 days we had a clear test, with another test required after another 60 days, or so I thought.
Thanks to an eagle eye at the vets, it turned out that we only needed 1 clear test because no lesions had been found. The final test was only needed if I hadn’t sent the cleaning form back, although this wasn’t stated on the letter.
Never heard of this before.

Interesting outcome....

I will try and find out more.

 

[Sid]

We had 2 reactors in April and 2 more 60 days later. No lesions in any of them.
After another 60 days we had a clear test, with another test required after another 60 days, or so I thought.
Thanks to an eagle eye at the vets, it turned out that we only needed 1 clear test because no lesions had been found. The final test was only needed if I hadn’t sent the cleaning form back, although this wasn’t stated on the letter.
Never heard of this before.

Had this conversation with APHA.

If NVL are found and nothing on culture your herd is deemed not to have "tb".
Therefore after your 2 test at severe you need one clear test at standard.

If VL or tb found at culture you "obviously "have tb.
Therefore after 2 tests at severe you need two clear tests at severe.


I need one clear test at standard in 60 days


There was also supposed to be PCR test on reactors instead of culture as of 1st Jan.
NFU are chasing information for me but we came to the conclusion that possibly due to Avian influenza lab space could be the issue and its on hold.

 

[Muddyroads]

Had this conversation with APHA.

If NVL are found and nothing on culture your herd is deemed not to have "tb".
Therefore after your 2 test at severe you need one clear test at standard.

If VL or tb found at culture you "obviously "have tb.
Therefore after 2 tests at severe you need two clear tests at severe.


I need one clear test at standard in 60 days


There was also supposed to be PCR test on reactors instead of culture as of 1st Jan.
NFU are chasing information for me but we came to the conclusion that possibly due to Avian influenza lab space could be the issue and its on hold.

That sums up our situation. Unfortunately the 2 letters contradicted each other, and we lost 4 cattle including a new to us breeding bull for no reason.
The only thing I don’t really understand now is why our 12 month routine whole herd test will be just 6 months after the last test which saw us go clear.

 

[Sid]

That sums up our situation. Unfortunately the 2 letters contradicted each other, and we lost 4 cattle including a new to us breeding bull for no reason.
The only thing I don’t really understand now is why our 12 month routine whole herd test will be just 6 months after the last test which saw us go clear.

6 month Check test.
Always after a breakdown now.
Then I think, 12 monthly but not sure if rules have changed.
Then of course there's the chance of contiguous test.


Last set of figures I saw herds and numbers were still dropping

 

[Muddyroads]

6 month Check test.
Always after a breakdown now.
Then I think, 12 monthly but not sure if rules have changed.
Then of course there's the chance of contiguous test.


Last set of figures I saw herds and numbers were still dropping

That’s a coincidence, Badger numbers have reduced too.

 

[twizzel]

That sums up our situation. Unfortunately the 2 letters contradicted each other, and we lost 4 cattle including a new to us breeding bull for no reason.
The only thing I don’t really understand now is why our 12 month routine whole herd test will be just 6 months after the last test which saw us go clear.

A proportion of herds will fail the 6month test after going clear twice 6months previously. We were 1 of them... 1 reactor last November NVL, no further reactors and 2 clear tests got us out of restriction in May. Went down on the 6 month test- 4 reactors- 2 had lesions I think it’s something to do with the incubation period after exposure to Tb.

 

[Sid]

A proportion of herds will fail the 6month test after going clear twice 6months previously. We were 1 of them... 1 reactor last November NVL, no further reactors and 2 clear tests got us out of restriction in May. Went down on the 6 month test- 4 reactors- 2 had lesions I think it’s something to do with the incubation period after exposure to Tb.

And here lies the problem.
Skin test false negatives
Blood test false positives

 

[matthew]

A little bemused when I had a letter from the APHA last week to tell us that we were now moving back to 12 month testing, after telling us last October, we were now 6 monthly... Quite happy at that, but why?

Then, I heard about a neighbour who has had a breakdown and APHA have apparently pulled the 2nd clear test requirement in a fortnights time, and moved him to 6 monthly testing. Not sure if he is now off restrictions, but I assume so.

What is happening? Change in policy?? @matthew

Maybe a shortage of vets??

We had 2 reactors in April and 2 more 60 days later. No lesions in any of them.
After another 60 days we had a clear test, with another test required after another 60 days, or so I thought.
Thanks to an eagle eye at the vets, it turned out that we only needed 1 clear test because no lesions had been found. The final test was only needed if I hadn’t sent the cleaning form back, although this wasn’t stated on the letter.
Never heard of this before.

That's normal. TB wasn't 'confirmed' by lesions or culture.
It hadn't had time to develop. The skin test shows exposure, not disease and is often ahead of confirmation.

That sums up our situation. Unfortunately the 2 letters contradicted each other, and we lost 4 cattle including a new to us breeding bull for no reason.
The only thing I don’t really understand now is why our 12 month routine whole herd test will be just 6 months after the last test which saw us go clear.

Check test after a period of restriction.
The skin test will not show an immune response if exposure to possible infection has been 30 - 42 days prior to the test, so 60 days between tests. And it may take up to 220 days to manifest itself in lesions / culture after exposure. Hence the 6 months check.
Ref: Answers to our PQs in 2004.

 

[Sid]

It hadn't had time to develop. The skin test shows exposure, not disease and is often ahead of confirmation.

This is when we should be catching them.

With an easier test.

 

[matthew]

This is when we should be catching them.

With an easier test.

OIE is the approved skin test, used world wide, so other tests have to match that for sensitivety / specificity, especially on severe interpretation and repeated regularly.

As you say, gamma gives a shed load of false positives. In Germany although gamma is licensed, it is NOT used as a slaughter test. A skin test has to confirm. Other blood tests have a very high level of specificity, but leave up to 50 per cent of infected animals behind. (Enferplex)

But it's all a hiding to nowhere if a wildlife reservoir is left untouched.