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Basic mistakes
in the control of FMD UK2001
which must not be repeated
James Irvine
Teviot Scientific, Edinburgh and Perthshire,
Scotland
Filed 19 Jul 06
©www.land-care.org.uk
In a recent article on this website entitled
"My visit to the Royal Highland Show" (1)
I lamented the apparent lack of interest shown by government and
other influential bodies in updating their contingency plans for
the control of a future outbreak of Foot and Mouth Disease (FMD),
to which the UK remains vulnerable. In particular, I lamented the
apparent lack of interest in the application of available science
to provide highly relevant technology that could be applied to great
advantage, both in central laboratories and also locally on farms
that are under suspicion or at risk of being infected.
Application of modern technology
Much of that technology was available at the start
of the FMD UK2001, but was not used. Since then the technology has
advanced even further. It would be negligent for the authorities
not to make adequate provision for it in their contingency planning
in 2006. Description of relevant modern technology will be the subject
of future articles on Land-Care.
But to use modern technology in a logical
manner it is essential to have an overall strategy that pays attention
to the basic principles of infection control.
Neglect of a basic principle in the control of the spread of viral
diseases, such as FMD
In an excellent, authoritative, recent paper (2)
the authors - from Winnipeg in Canada, and from Edinburgh and Reading
in the UK - describe how in FMD UK2001 an important basic principle
in relation to the control of the spread of a viral infection, such
as FMD, was overlooked. What took preference, with damaging consequences,
was an inappropriate emphasis on epidemiological modelling based
on poor quality data.
Thus,
to control an epidemic of FMD it is essential
to break the transmission of the virus. Provided any persistently
infected animals ("carriers") are removed, the virus
will soon disappear for want of a host.
It could well be that today this axiom of infection
control might still not be receiving the attention it deserves.
But it is fundamental to the effective use of the new technologies
that should be widely available.
In 2001 at the outbreak of FMD in the UK the mistake
was made to be guided by epidemiological modelling, which led to
the pre-emptive culling of susceptible animals that the models themselves
predicted to have a higher probability of becoming infected than
others - even when that probability was not particularly high. There
was no requirement to assess the mechanisms and likelihood of transmission
in real, individual cases.
To control an epidemic of FMD it is essential
to understand the mechanism by which the FMD virus is being spread.
This provides the basis for attempting to break the line of viral
transmission. Once that is achieved the virus will die out for want
of a host, provided any persistently infected animals are removed.
Many scientists realised the truth of this
at the time of the outbreak of FMD UK2001, but their protests were
ignored. As a result far more animals were slaughtered than was
necessary.
This situation must not be allowed to happen again.
Yet, as I found as I did my rounds of the stands at the Royal Highland
Show 2006, this indeed seems to be the way we are heading - ironically
with a revised Animal Health and Welfare Act that ensures it would
be legal.
What is now urgently needed is a radical change
in outlook by the authorities particularly within the UK and by
some of the lobby groups, such as NFU, NFU Scotland, the National
Beef Association and certain of the veterinary bodies. The spread
of infection - be it FMD, Avian Influenza or any other such viral
disease - must surely be based on knowledge concerning the biology
of the specific infection and its mode of spread, coupled with the
up to date application of modern science to provide the maximum
level of science-based information as to where the infection is,
where it is going and where it is persisting.
Clearly vaccination is a powerful potential weapon
in breaking the line of transmission, rather than simply following
it. But to use vaccination effectively, speed in diagnosis and in
defining the virus's specific characteristics is essential. For
that we need the technology brought up to date and we need it fast.
©www.land-care.org.uk
References
1. Irvine, James (2006). My visit
to the Royal Highland Show 2006.
See SOCIAL/ECONOMIC/POLITICAL Homepage, filed 12 Jul 06,
www.land-care.org.uk Click
Here to view
2. Kitching, R.P., Thrusfield,
M.V. & Taylor, N.M. (2006). Use and abuse of mathematical models:
an illustration from the 2001 foot and mouth disease epidemic in
the United Kingdom.
Rev. sci. tech. Off. int. Epiz., 25:293-311.
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