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Monday, 19 March, 2001, 16:35 GMT
Head-to-head: Vaccination
Sheep on hilltop
Vaccinated sheep may still carry foot-and-mouth
The slaughter of 500,000 apparently healthy animals has prompted many farmers and veterinary experts to ask about alternatives.

Professor Julian Wimpenny from the Cardiff School of Biosciences puts the case for vaccination while Professor Joe Brownlie of the Royal Veterinary College argues that vaccination is not the solution.

Professor Julian Wimpenny, Cardiff School of Biosciences

We are in the middle of what is a devastating epidemic of foot-and-mouth disease (FMD) but the strategy of killing and burning many thousands of healthy animals strikes me quite simply as barbaric in this day and age.

FMD was eliminated from Europe by 1989 by a successful vaccination campaign.

The decision was then taken to designate Europe as an FMD-free zone, and hence no more vaccines were to be used.

This strategy will always be high risk since it is based on the maintenance of a permanently vulnerable population of animals necessitating dramatic action of the sort seen now to endeavour to control spread of the disease.

Vaccine held for 'an emergency'

Clearly once the epidemic gets out of control, as it has at the moment, we see the possibility of costs amounting to 9bn.

This is about 300m for every year since the last outbreak.

So why don't we vaccinate?

The UK, together with other European countries, holds some 30 million doses of vaccine of all the main types of virus that can be deployed in an emergency.

Several other countries have eliminated FMD precisely by vaccination

Professor Julian Wimpenny
In such a case the strategy is either to use mass vaccination or to 'ring fence' outbreaks, that is to vaccinate all the animals in the area surrounding an outbreak.

We have not used these, nor are there plans to do so.

I wonder what constitutes an emergency in the government's eyes?

At present we are 'ring fencing' by slaughtering what could be millions of animals with all the logistic problems of disposing of the animals once slaughtered.

There are good reasons why we should vaccinate in the future

  • rapid transport and communications mean that infection in one country could be quickly passed to another;
  • developments in immunology suggest that we will soon have vaccines that do not involve whole virus particles at all, but tailored systems effective against a wide range of FMD types;
  • one of the main arguments against vaccination, that it is impossible to distinguish between an infected animal and an immunised one, may soon be solved as new sophisticated diagnostic techniques are beginning to reveal;
  • several other countries have eliminated FMD precisely by vaccination;
  • vaccination can help in possible cases of agro-sabotage;
  • we would avoid the grotesque sight of huge funeral pyres of dead animals and the consequent cost to agriculture and all the ancillary industries like tourism, as well as the risk (due both to BSE and FMD) of becoming a pariah state in Europe.


Professor Joe Brownlie, Department for Pathology and Infectious Diseases, Royal Veterinary College


There is increasing pressure for a vaccination programme to control the current outbreak of foot-and-mouth disease.

Vaccines are used to control, if not eradicate, other viral diseases - for example, the global elimination of smallpox and possibly, in 2010, rinderpest.

So why not foot-and-mouth disease?

Vaccination can reduce the number of carriers of foot-and-mouth by reducing the general level of virus in the field.

Virus could still circulate

But vaccinated animals that have contact with the live virus are just as likely to become carriers as animals that have recovered from clinical disease.

So vaccination can reduce disease but does not prevent infection; this means that the virus can circulate.

It is reported from Saudi Arabia that in spite of probably the most vigorous vaccination schedule in the world, there have been two outbreaks in three years.

It is possible to distinguish antibodies from animals that have been infected from those that are vaccinated.

...foot-and-mouth, once endemic, would take a decade or longer to eliminate

Professor Joe Brownlie
However, when a vaccinated animal becomes infected, this distinction is usually lost.

This becomes a critical issue for epidemiological surveillance and for export.

Thus, any animal with antibodies must still be considered as having potentially been infected.

Such animals are not acceptable for importation into foot-and-mouth disease-free countries.

The internationally-agreed criteria clearly state that to achieve "foot-and-mouth disease-free country" status, we must await three months after the last clinical case where there is a stamping-out policy.

New proposals

'Stamping out' is the slaughter of all affected and in-contact susceptible animals on the premises, followed by the disposal of carcasses by burial, burning or rendering.

The premises are correctly disinfected and not re-stocked with susceptible animals for a defined period (usually six months).

However, new proposals currently being considered would extend the time period to two years if all vaccinated animals were not slaughtered.

In "countries where vaccination is regularly practised" (that is, not relevant to the UK), it could take two years to re-establish freedom.

Insufficient supplies

It would not be unreasonable to predict that foot-and-mouth, once endemic, would take a decade or longer to eliminate.

Vaccination may shorten this period but we would still have to return to stamping-out in order to achieve foot-and-mouth freedom.

Then there is the question of availability of vaccine.

The five million doses of suitable vaccine immediately available are insufficient for a general vaccination of all susceptible sheep, pigs and cattle - though there would be sufficient for strategic vaccination.

All that does is to provide an invaluable safety net if all else fails - but it should be seen very much as a last resort.







See also:

06 Mar 01 | Science/Nature
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