Some Letters from the latest - 19 May - edition of the Vet Record.

A few biographical details:

Archie Hunter is a Senior Lecturer at the CTVM, Edinburgh.

Prof Bob Michell is a past President of the RCVS, and held senior positions
at the Royal Veterinary College and the Animal Health Trust.

Dr Alex Donaldson heads the Pirbright FMD World Reference Lab, Dr Paul
Kitching has very recently left Pirbright to take up a new appointment in

FMD control strategies
SIR,  Recent correspondence in The Veterinary Record from Bob Ward and from
David Wardope and Roger Windsor (VR, April 28, pp 546, 547) has indicated
growing disquiet within the profession concerning the politicisation of the
current foot-and-mouth disease (FMD) crisis. I can only support the
misgivings stated in these letters. This is my eighth week as a temporary
veterinary inspector (tvi) at the Carlisle centre, and since the beginning
of April, I have specifically been involved in training TVIs on FMD
procedures. We have trained over 150 TVIs and the most difficult training
topics have been the conflicting policies concerning livestock culls. The
cull of sheep in the conjoined 3 km zones surrounding infected premises in
the Cumbria focus has been switched from compulsory to voluntary to the
present voluntary/compulsory scheme, in which farmers have been invited to
surrender their sheep for removal to a central place for slaughter. Farmers
can appeal, but if their appeals are turned down or if they fail to accept
the invitation to surrender their livestock, then the cull will go ahead
though possibly on the farm. The Voluntary' aspect, therefore, has a strong
'compulsory' veneer. Within both the farming and veterinary communities,
these switches in policy have caused great confusion as to which policy was
in place at any one time. Adding to this confusion was the recent and much
publicised Downing Street policy switch concerning the cull of livestock on
premises contiguous to infected premises. This turned out to be no more
than a modification of the policy concerning cattle which can now be
excluded from the cull, subject to an assessment of the disease biosecurity
The crisis combined with insufficient resources within the State Veterinary
Service (svs) has resulted in political intervention at the highest level.
At times it has felt that the leadership has come, not from MAFF and the
Chief Veterinary Officer, but directly from Downing Street and the Chief
Scientific Adviser, resulting in the types of confusion mentioned above.
This is to say nothing of the scale of the cull that many of us feel has
been excessive. Targets beloved by politicians have been forced upon the
vets working in the field, despite the fact that there is not a single vet
worth his/her salt who does not appreciate the necessity of rapid detection
and slaughter of clinical cases combined with prompt but judicious culling
of susceptible livestock considered as dangerous contacts. We knew this
long before the 1967/68 epidemic, and certainly know it now.
What this epidemic has exposed in the cruellest way imaginable is that the
SVS is seriously under-resourced. After BSE and the outbreak of classical
swine fever, it would be nice to think that the Government will now realise
that the country needs a fully resourced SVS with the authority to
implement whatever disease control measures are appropriate and necessary
at the time. Politicians seem to be greatly influenced by the predictions
that mathematical disease models can provide, and in this day and age of
political correctness, if we need a model to work to, then lets give our
whole-hearted support to Bob Ward's LIVE model.
Archie Hunter, Centre for Tropical Veterinary Medicine, Royal (Dick) School
of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian
KH25 9RG

SIR, - Much of the current public perception of the controversies
surrounding the foot-and-mouth (FMD) outbreak is derived from instant
experts with country cottages. There is no doubt that in controlling an
outbreak of such a highly infectious disease, there is a real need to cull
healthy animals; not least because, in farm animal medicine, an individual
showing signs represents a much larger group at risk and that group
constitutes the focus for action. Moreover, unless clinical diagnosis is
100 per cent reliable, it is essential to have a high index of suspicion
and expect a number of clinical suspects to subsequently test negative.
This is not, as the media imply, some sort of defective diagnostic
competence, but the use of a screening test (clinical examination) at high
sensitivity, that is, maximising the likelihood that all positives are
detected, minimising false negatives. But in the confirmatory test,
specificity becomes at least as important, that is, minimisation of false
positives. Clearly, the appropriate use of a high index of suspicion
implies an obligation to await confirmatory tests unless the circumstances
are extremely exceptional; not least because it otherwise places a terrible
responsibility on veterinary surgeons dutifully erring of the side of
caution, and especially if the consequences extend well beyond the group
immediately at genuine risk.
Those with undiminished enthusiasm for the contiguous cull claim that it
brought the outbreak under control, a claim which requires rigorous
impartial statistical scrutiny. The predictive graph 'C (see VR, May 12, p
582) is compatible with the claim but in no way proves it. The rate of
decline also looks remarkably similar to that for the 1967 outbreak.
Granted that the decline began in the last week of March, the question is
whether, allowing for incubation and regional variation, contiguous culling
was the key factor; it almost seems to require a psychic effect to have
such instantaneous impact. It is also hard to understand the significance
of'the number of new cases arising from each outbreak falling to less than
one', when, unlike a human epidemic, many of the potential new cases have
been pre-emptively added to the death toll: in terms of cost and misery
they might as well have got it (and, in some instances, they may have had
it). If the Geological Museum fell victim to an uncontrollable fire, would
it be a reasonable precaution to pull down all contiguous museums?
A huge number of animals have been killed compared with 1967, many without
contact with infected premises. The exact reasons require independent
scrutiny, and particularly whether minimisation of animals culled, and
therefore of cost, was the primary objective or whether it was speed, and
if so why? A powerful independent inquiry is therefore essential, once the
outbreak is genuinely over.
A. R. Michell, The Mill Barn, Mill Lane, Exning, Suffolk CBS 7JW

FMD diagnosis
SIR,  We share the concern expressed by K. M. Wood (VR, May 12, p 607)
about the large discrepancy between the field and laboratory diagnosis of
foot-and-mouth disease (FMD), particularly, but not exclusively, in sheep.
FMD in sheep is frequently difficult to diagnose clinically as the signs in
adult animals are often very mild and transient or even absent. The death
of lambs maybe an indication of the underlying condition, as is a rapidly
spreading lameness accompanied by pyrexia. Not surprisingly, the rate of
spread of lameness is likely to be faster in sheep under intensive
conditions where the opportunity for contact will be greater than under
extensive conditions.
There are many causes for lameness and mouth lesions in sheep and so, in
the absence of vesicular lesions and the signs mentioned above, suspected
cases of FMD can only be definitively confirmed by laboratory
investigation. The reliability of those will depend on correct samples
being submitted under appropriate conditions.
Some of the discrepancy may have been due to poor samples, particularly as
it is difficult to collect sufficient epithelium from the small lesions
usually encountered in sheep. However, blood samples have been submitted
from many of the suspect sheep, and together with any epithelium, they
provide good diagnostic material. On epithelial samples we carry out an
ELISA and virus isolation using sensitive tissue culture, while in blood
samples we look for viraemia and antibody. The viraemia starts before
clinical signs and is replaced around three to four days later by high
antibody litres, so animals with FMD have either virus or antibody or both
in their blood. We are also comparing the sensitivity of virus isolation
with direct PCR on the epithelium
samples, and so far we have a very strong correlation in the results -
close to 100 per cent.
Pirbright has more than 70 years' experience with FMD diagnosis, providing,
as we do, a diagnostic service for countries around the world. We regularly
receive samples from cases of FMD in sheep from parts of the world where it
is prevalent, for example, Turkey, the Middle East and North Africa.
Samples submitted include epithelium, heart tissue and sera. No particular
difficulties or problems have been encountered with the laboratory
investigations. While it is never the intention that laboratory diagnosis
would replace clinical diagnosis, we believe that laboratory support for a
diagnosis of FMD in sheep, in particular, is essential. For samples
collected in the UK and submitted as recommended, we would expect a very
high success rate and certainly above 90 per cent.
The extreme difficulty of making a clinical diagnosis of FMD in sheep is,
in our opinion, the explanation for the discrepancy between the field and
laboratory diagnoses.
Staff here, both those normally involved in FMD diagnosis and those
redeployed from other parts of the Institute for Animal Health at Pirbright
and Compton, along with volunteers who have come to our assistance from
other laboratories in the UK and overseas, are currently fully occupied
with the processing of FMD specimens, in some cases working around the
clock. We regret that we do not have the spare capacity to investigate the
aetiology of the range of conditions which are possibly being confused with
Alex I. Donaldson, Paul Kitching,
Institute for Animal Health, Pirbright, Waking, Surrey GU24 ONF

.   Letters on all topics relating to the science, practice and politics of
veterinary medicine and surgery will be considered for publication. They
should be typed, double-spaced and addressed to the Editor, The Veterinary
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may be shortened for publication

The Veterinary Record, May 19, 2001 Copyright 2001 British Veterinary