I have finally managed to get hold of/assemble some details of the MAFF
official policy/procedures WRT serological testing and surveying prior to
lifting of restrictions which I believe to be accurate.

They are using a new test for this type of testing - a competitive ELISA
test (rather than the Blocking ELISA test used and still being used for
diagnostic testing) - which is easier to set up and standardise reagents
apparently so has higher throughput and should produce results more rapidly

They are calculating number of animals to be sampled based of being 95%
confident of identifying FMDV virus infection at 5% prevalence. There is a
table for use in the field to calculate the number of animals that should
be sampled. A maximum of 60 samples is required regardless of the size of
the flock.

The samples are NOT identified/tied-to individual animals on first round of

If all samples are negative to the Competitive ELISA the flock is
'labelled' as negative.

If there is a single positive sample - regardless of the no. of samples
taken - then it will be re-tested using a Virus Neutralisation Test (VNT) -
if it's still positive then the will do a second round of sampling but this
time sample EVERY animal and label the samples will be identified/tied-to
individual animals. If there is again only a single positive result then
just the animal yielding the positive result will be culled and the flock
then 'labelled' negative.

If there are two or more positive samples then there is no VNT carried out
and no second round of sampling/testing - the whole flock will be
'labelled' as positive and will be culled as a Dangerous Contact (DC). The
animals will be examined on slaughter for FMD lesions - if FMD lesions are
the premises will be 're-labelled' as an IP and Contiguous Cull (and
possibly 3Km cull procedures) will come into effect.

I understand that this policy was communicated from Page Street about 2
weeks ago to Control Centres and is to be a UK wide policy - ie. England,
Scotland and Wales. There is no known 'scope' for regional variations.

Because they are using a new test - Competitive ELISA - there remains some
debate about the issue of false positives, since this is a new test whose
performance characteristics may not yet be fully understood. . Some of
those who understand this 'stuff' believe that labelling a flock as
positive solely on the basis of two positive samples using this test -
without confirmation using VNT tests - risks 'over diagnosis'. Others - eg.
the French - it seems believe that the Competitive ELISA is more accurate
than VNT so no second-setp VNT tets are required. Overall it seems that
MAFF has accepted this risk - of possible occasional 'over diagnosis ' -
because doing confirmatory VNT tests is fiddling and time consuming of lab
resources and may not increase precision when lab.resources are still a
limiting factor in the rate at which flocks can be tested and hence would
delay lifting restrictions. So it appears MAFF have opted to err on the
'safe side' rather than either delay things and/or risk leaving an infected
flock alive longer.

Of course since we are still in the early stages of this serological
testing/survey phase we should expect that this policy may be subject to
some 'tuning' as results come in. I'm told that there is still 'great
uncertainty about serology' WRT this phase of the FMD control progamme, and
that one should bear in mind that those people who 'administer' the
policies at MAFF HQ are not themselves experts in this field.

However I am left with the impression that this serological testing/survey
policy has been drawn up with significantly more care and consultation with
the real experts than the discredited 12/48 hour and 3Km cull policies.