DISEASE CONTROL STRATEGIES: FOOT AND MOUTH
A CONSULTATION PAPER
1. This paper outlines the measures that may be taken to slaughter or
vaccinate animals in the event of an outbreak of foot-and-mouth disease
(FMD). It sets out the factors the Government will take into account in
deciding which strategy to adopt in order to control and eradicate the disease
in the future.
2. The EU Council Directive on FMD, 85/511 as amended, requires
slaughter of all susceptible animals on infected premises, and provides for
culling of susceptible animals on epidemiologically linked holdings (known as
dangerous contacts). This reflects the EU's policy of adopting "FMD free
without vaccination" status for all Member States, and is provided for in
Defra's FMD Contingency plan. The EU Commission is about to bring forward
revisions to the FMD Directive and the revised FMD Directive will be
discussed with stakeholders.
3. Beyond this basic strategy, which will apply in all cases, there are a
range of additional options and strategies potentially available depending on
the circumstances of a particular outbreak and on the scientific and veterinary
advice. These include: -
emergency vaccination (either to live or to kill; within an area or in a
ring around an area);
culling of other livestock exposed to the disease (e.g. premises under
virus plumes, contiguous premises); and,
subject to passage of the Animal Health Bill, pre-emptive or firebreak
culling of animals not on infected premises or dangerous contacts or
necessarily exposed to the disease, in order to prevent the wider spread of
the disease outwith an area.
4. Since each disease outbreak is different and each has to be tackled at
speed and inevitably with imperfect information it is not possible to
prescribe in detail which strategy will be followed in advance of knowing the
circumstances of a particular outbreak. This calls for a flexible approach,
which recognises that different approaches may be needed in different
geographical areas or to deal with different species. Nevertheless, there is
clear advantage in reaching a view on the likely options for response in
advance. Accordingly, this paper and the enclosed "decision tree" seeks to
set out:The factors that would be taken into account in deciding what kind of
slaughter policy will be adopted.
The factors that would be taken into account in deciding whether to use
vaccination and if so whether to vaccinate to live or kill.
5. The Governments objective in tackling any fresh outbreaks of FMD will
be to eradicate the disease as quickly as possible and to maintain the UKs
disease-free status. In doing so, the Government will seek to select a control
strategy which:minimises the number of animals which need to be slaughtered, either to
control the disease or on welfare grounds, and which keeps animal welfare
problems to a minimum;
causes the least possible disruption to the food, farming and tourism
industries, to visitors to the countryside, and to rural communities and the
minimises damage to the environment and protects public health;
minimises the burden on taxpayers and the public at large.
6. In responding to the FMD Inquiries the Government has made clear
that emergency vaccination will now be considered as part of the control
strategy from the start of any outbreak of FMD where measures additional to
the culling of infected animals and dangerous contacts are needed. The
Government also accepts that if emergency vaccination is used it should be
on the basis of vaccinate-to-live wherever possible.
7. EU legislation allows for the use of emergency vaccination in
circumstances where an outbreak of FMD threatens to become extensive in
the Member State concerned. In order for a vaccination strategy to be fully
effective there would need to be a concerted EU approach and a new
legislative framework at EU level. The Government will actively pursue with
the Commission the need for a new framework for the use of vaccination.
8. The decision to introduce vaccination is normally taken by the
European Commission in consultation with Member States, although Member
States can vaccinate and then seek the EUs agreement later. Two types of
vaccination strategy are envisaged:
(i) "Protective Vaccination" (Vaccination to live)
(ii) "Suppressive Vaccination" (Vaccination to kill)
9. The Inquiries investigated in detail the issues involved in employing
emergency vaccination. Between them they highlighted a range of significant
questions that would need to be addressed, particularly as regards
vaccination to live, but concluded that once these were resolved, the option of
emergency vaccination to live should be the preferred approach. The
Government is committed to tackling these issues in consultation with all
interested parties so that it is in a position to trigger an emergency vaccination
campaign should the need arise. As part of this process it is essential to have
stakeholder support and the Government will engage in dialogue with a wide
range of stakeholders in order to achieve, so far as possible, a shared
understanding in advance of an outbreak of the factors which influence the
choice of control options. The Decision Tree is intended to assist this
Protective Vaccination (Vaccination to live)
10. This strategy would be considered:-where veterinary and scientific advice is that an outbreak could not be
contained by stamping out of Infected Premises and Dangerous
where a defined category of animals could be identified for protection,
either in geographical or species terms;
to protect zoo animals and rare breeds collections as recommended by
the Royal Society;
11. More generally, this option is likely to carry advantages where the
population density of susceptible animals is high; where pigs are the main
species involved; where there is a high risk of airborne spread; where the
origin of the outbreak is unknown; where incidence is rising rapidly, and
where the distribution of outbreaks is widespread.
Suppressive Vaccination (Vaccinate to kill)
12. This strategy could be considered where the number of animals to be
culled is likely to exceed the available disposal capacity. In those instances,
animals in defined areas would be vaccinated first and slaughtered only as
disposal capacity became available. It could also be used where there is an
urgent need to reduce the amount of virus circulating in an area and reduce
the risk of spread beyond that area.
STAMPING OUT POLICY
13. EU Directive 85/511 lays down the minimum measures Member States
must take against FMD. The Directive requires slaughter of all susceptible
animals on infected premises, and provides for culling of susceptible animals
on epidemiologically linked holdings, as well as depopulation of holdings
where FMD is suspected.
14. UK legislation allows for slaughter of:Animals affected or suspected of being affected with FMD.
Animals which are believed to have been exposed to FMD infection.
Animals affected or suspected of being affected
15. When the State Veterinary Service (SVS) is made aware of suspicion
of foot and mouth disease in animals they will arrange for a veterinary
investigation to be undertaken.
16. The decision to slaughter will be based either on the results of
laboratory tests carried out on samples arising from animals suspected of
being affected with disease, or on convincing clinical evidence of disease. In
an area considered to be free of disease, except in exceptional
circumstances, it is likely that disease will be confirmed on laboratory results.
However, once disease has become established in an area it is likely that
cases will be confirmed on clinical grounds alone in order to ensure animals
are slaughtered quickly.
Animals which are believed to have been exposed to infection17. Animals may be slaughtered if they are believed to have been exposed
to infection. In these cases, animals will be subject to a veterinary inquiry to
determine if, in the opinion of the Veterinary Inspector, they have been
18. Animals that are believed to have been exposed to infection are known
as Dangerous Contacts. This can include animals on contiguous premises. As
virus can be excreted by such animals prior to the development of obvious
and identifiable clinical signs, it is important that they are culled as soon as
possible to stop virus production and hence spread of disease. A decision to
slaughter will be taken by the veterinary inspector based on information
gathered during the inquiry and account will be taken of levels of biosecurity.
The action that we take will depend on a risk assessment. Where it is
believed that the likelihood is that exposed animals are at an high risk of
becoming diseased they will be slaughtered. Where that risk is lower and
there are the resources to observe the animals, they will be restricted and
observed. So our action depends not only on the degree of risk but our ability
to mitigate the risk by having available the necessary resources to observe
animals regularly and our ability to detect early disease in exposed animals
and take immediate action should disease occur.
19. Animals can be exposed to infection by many routes. The following list
is not exhaustive and the relative importance of each will depend on a number
a. Direct contact with infected animals
b. Airborne Spread
c. Movement of a live animal
d. Movement of a person
e. Movement of vehicles
f. Movement of equipment or other materials
g. Movement of animal products
h. Movement of feedstuffs or bedding
i. Movement by wildlife or non-susceptible vector
To prevent the spread of disease
20. A third type of slaughter policy is proposed in the Animal Health Bill.
This is culling "to prevent the spread of disease", e.g. to create a firebreak.
Such a cull might be required in order to protect areas of high livestock
density, either as an addition to emergency vaccination or, in some cases,
instead of it. The species and geographical area of the cull would have to be
21. If the Bill becomes law, the Government is committed to using the new
slaughter powers only where this is justified by the circumstances and on the
basis of sound veterinary, epidemiological and scientific advice. That means
in particular that a risk assessment will be made of the possibility of disease
spreading. It will include those animals that are judged to be at lesser risk of
infection but which, should they become affected, would present a very
significant risk to the farming and livestock community more generally. It is in
these cases that effective preventative action may be necessary to safeguard
the wider public interest. The steps that would be undertaken before the
decision is reached include:
a) identify a group of animals that could contribute to spread of disease.
This would be based on
consideration of local factors
determination of which species involved
determine geographical area involved;
b) consider if any exemptions could be allowed based on husbandry or
other criteria, e.g. genetic value
c) determine the rules for inclusion of animals at the boundaries of that
d) analysis of risks, cost and benefits
e) publish an outline of the reasons why such a cull is needed.
22. Any decision to use the wider powers of slaughter provided in the
Animal Health Bill would be taken in the light of an overall assessment of the
risks, costs and benefits in a given situation. This could include not only risks
of transmission but also social and economic risks that would arise if effective
and timely action were not taken. The Government would justify its decision to
use the slaughter powers, explaining the veterinary, epidemiological and other
relevant factors that had been taken into account.
UK DECISION TREE FOR CONTROL STRATEGIES
FMD DECISION TREE - FACTORS TO BE CONSIDERED
(Warmwell cannot reproduce the diagram. It can be seen on DEFRA's site here: http://www.defra.gov.uk/footandmouth/contingency/tree.pdf
Each decision on the tree is taken on the basis of a number of factors. The
decision matrix has been based on a USDA paper but has been adapted to
take account of the fact that any disease control strategy in the UK must take
account of the relevant EU framework.
In using the decision tree, the following factors should be taken into account
at each decision point. Modelling economic & epidemiological will be
used to assist in identifying trigger points.
At decision box 1: can disease be eradicated by stamping out (of
Infected Premises and Dangerous Contacts)?
All outbreak and mitigation factors need to be considered at this point in
deciding whether stamping out will eradicate the disease. However at the
start of an outbreak information on many of these factors will be incomplete
and this may not be available until well into the outbreak. Decisions may
need to be revisited as more information becomes available.
Outbreak factorsTime from introduction of infection to detection (epidemiology);
Contact rate: type of farms; direct and indirect movement and distance
of movement; efficacy of movement controls;
Host or species affected the species affected and species at risk
(manifestation of clinical signs leading to early recognition): domestic
livestock only whether disease is in pigs, cattle or sheep; game
farms/zoos how effective would isolation methods be; wildlife.
Status of outbreak estimation of the extent of the geographical
distribution of FMD and duration of epidemic: number of affected
herds; number of foci of infection; rate of spread. Use of
Environmental: livestock density and distribution; livestock
management; casual access network of roads, etc; physical barriers;
climate does it favour airborne spread?.
Mitigation factors:Physical resources: slaughter capacity; transportation capacity;
disposal capacity. Incineration - max 1000 tonnes per week (2000
bovines or 20,000 sheep or 10,000 pigs approx.) Rendering - max
15,000 tonnes per week
Human resources: emergency response system ie are there sufficiently
trained staff for stamping out and to maintain movement controls; what
are the epidemic projections.
Socio-political factors: EU Directive 85/511 requires slaughter of all
susceptible animalson Infected Premises and provides for culling of
susceptible animals on epidemiologically linked holdings (known as
Dangerous Contacts); public opinion; industry acceptance; other
affected sectors eg. tourism.
Economic considerations: compensation; value of exports and value of
other affected sectors eg tourism a cost benefit analysis of loss of FMD
free status versus stamping out (cost-benefit analysis of different
scenarios to be commissioned)
Decision Box 2: is vaccination permissible and possible?
2.Physical resources to be considered:Vaccine strain availability there are 7 strains of FMD antigen kept by
the International Vaccine Bank to which the UK has drawing rights of
500,000 doses for each. In addition we have purchased 15.4M doses
of 01 Manisa antigen from Merial. The UK is currently taking steps to
procure a range of vaccines for the strains which IAH, Pirbright advise
as presenting the greatest risk to the UK at the moment. In addition,
the EU Vaccine Bank holds a range of antigens for emergency use.
Vaccine doses available there is currently enough 01 Manisa antigen
to vaccinate cattle in the England & Wales. The 500,000 doses of
each of the other main FMD strains would be sufficient to complete
vaccination within a defined area.
Vaccination strategy including position of rare breeds/zoos, etc.
Vaccination logistics this will be covered by the revised Viper
Chapter. A 1-dose strategy is more likely to be used where the policy
is vaccinate-to-slaughter as it saves on resources (human and vaccine)
but results in vaccine being used off-label. A 2-dose strategy (followed
by a booster at 6 months) would be necessary for a vaccinate-to-live
Vaccine distribution vaccine would be procured centrally and
distributed via vaccination centres (see revised Viper chapter).
Laboratory capacity/ability to distinguish vaccinates from infected
Laboratory capacity exists to do testing but there are currently no
internationally recognised standards for NSP testing. The Government
accepts that the validation of NSP (non-structural protein) tests is a key
area. There are a variety of NSP tests at differing levels of validation.
There are currently a number of research projects in the UK, Europe and
America and many of the European groups are partners in a European
Union Concerted Action project on FMD diagnosis. The main limiting
factor for the validation of such tests is the availability of suitable panels of
sera, especially from vaccinated and then challenged animals. Defra is
supporting research into this area. In addition, the Government also
accepts that there is a need to develop accepted strategies for
surveillance after vaccination. Indeed, this is something that the OIE has
Time Whether there would be enough time for vaccination to
completed before spread of infection would depend on the
epidemiological projections during the outbreak. Need for modelling
3. Human resources to be considered:Emergency response system need to have sufficient numbers of
vaccinators available. The revised Viper Chapter 3A will deal with
recruitment and training of vaccinators.
Movement controls are a recognised part of any UK control strategy.
Specific restrictions will apply on movement of vaccinated animals and
products from vaccinated animals within the vaccination zone as laid
down by EU. There will be welfare considerations in establishing a
vaccination zone. Need sufficient staff to monitor movement controls.
NSP tests are only reliable on a herd basis so herd integrity will need to
be maintained pending testing.
Epidemic projections different for each outbreak.
4.Socio-political factors to be considered:Available legislation Powers to vaccinate exist. Any decision to
vaccinate would have to be agreed by the EU (last year there was a
Decision allowing the UK to vaccinate in Cumbria and Devon).
Public opinion there needs to be a communications plan that should
be communicated to stakeholders in advance. Need active
engagement with stakeholders especially on FSA advice on safety and
to clarify any labelling issues.
Industry opinion Stakeholders to be kept involved in developments
connected with the issue of vaccination ie FMD Directive, changes to
the OIE Code. Stakeholder involvement (should be all inclusive) and
agreement would be important in any decision to vaccinate.
5.Economic considerations to be considered:Cost of vaccination the cost of purchasing 15.4M doses of 01 Manisa
antigen was £3.5 million (including VAT). There are also costs of
storage and formulation to be taken into account. There is also a cost
of the UK continuing to be a member of the International Vaccine Bank.
The cost of vaccination equipment, training and employing staff as part
of a vaccination campaign also needs to be costed into the equation.
Value of exports versus benefit to wider rural economy and tourism.
Regionalisation whether there would be regionalisation within the UK
would depend on the outbreak. EU legislation requires vaccination zones
to be clearly defined.
Decision Box 3: is the exit strategy "vaccinate to live"?
6.Physical resources to be considered:Slaughter capacity vaccinate to live is likely to reduce pressure on
slaughter capacity whereas as vaccinate to slaughter would lead to
higher numbers for slaughter than a stamping out policy (the Dutch
experience). Capacity would need to be able to cope with slaughter of
vaccinates and slaughter of infected livestock in a vaccinate-toslaughter
Disposal capacity The higher numbers generated by a vaccinate to
slaughter policy may result in disposal becoming a limiting factor. A
vaccinate to live policy would not cause disposal problems but there
would be implications for products from vaccinated animals entering
the food chain. And movement controls imposed on vaccinates
Controls on products from vaccinated animals - Under EU rules,
products from vaccinates would need to be kept separate from nonvaccinates.
This may raise practical problems for the processing
industry. The post vaccination controls that would have been required
had vaccination gone ahead are set out in Commission Decision
2001/257/EC of 30 March 2001. Meat from vaccinated animals would
have had to be heat treated during the first 30 days following
vaccination and then deboned and matured for 24 hours for a period of
12 months from vaccination or from the last confirmed case of the
disease in the vaccination zone. For a period of 12 months milk from
vaccinated animals would have had to be pasteurised; in the first 30
days following vaccination pasteurisation would be required within the
vaccination zone unless otherwise authorised in exceptional
circumstances. There are practical problems in meeting these
standards for pig and sheep meat. The taking of semen, ova and
embryos from vaccinated animals would have been forbidden.
Vaccinated cattle would not have been permitted to move out of the
vaccination zone for 12 months, except under licence to slaughter.
May create an internal dual market for livestock and products
Time If a vaccinate to slaughter policy was followed it would be more
cost-effective to cull after the first dose of a 2-dose strategy. Vaccinate
to live would probably require a 2 dose strategy followed by a booster
at 6 months.
Identification: individual identification of livestock is important so that
either one can ensure that all vaccinates are killed or products from
vaccinates are correctly treated. Currently very difficult for anything
other than cattle.
7.Human resources to be considered:Emergency response system we would need to consider whether we
had the necessary staff to complete a vaccinate to live policy eg
vaccinators for 2 dose strategy. For a vaccinate to slaughter policy,
we would need to consider whether we had the necessary staff ie.
Epidemic projections. As above.
8.Socio-political factors to be considered:Available legislation The AHA allows for emergency vaccination as
does EC 85/511. The AH Bill will allow for slaughter of vaccinates and
for payment of compensation for slaughter of vaccinates.
Public opinion Public are likely to support a vaccinate to live policy
and this would be in line with Follett and Anderson Inquiry
recommendations. Labelling for vaccinated products is an issue which
needs to be resolved through discussion with stakeholders.
Industry acceptance possible pressure from trade, and other Member
States, to slaughter vaccinates to regain FMD free status. Need to
engage industry stakeholders.
9.Economic considerations to be considered:Cost of vaccinate to slaughter include the costs of vaccination (Box
4) plus the cost of slaughter and disposal of all vaccinates.
Compensation Cost of compensation for slaughtered vaccinates
would substantially increase overall costs of epidemic.
Value of exports versus benefit to wider rural economy.
Regionalisation As for Box 2.
At decision box 4: are there additional culling strategies that are
permissible and possible?
In some circumstances culling additional to DCs and IPs maybe the optimal
solution based on a risk assessment. This culling could take a number of
forms contiguous premises (where these are judged to have been exposed
to infection) or preventive culling where scientific and veterinary advice is that
this will prevent further spread of disease outwith the area. In choosing
between these and other additional forms of culling a number of factors will
need to be taken into account:
10.Socio-political factors to be considered:Available legislation control options are provided for under existing
legislation. Others notably pre-emptive (or preventive) culling of
animals not exposed to FMD infection in order to get ahead of the
disease and stop it spreading are proposed in the Government's
Animal Health Bill and are not yet law. Better powers of entry to
vaccinate are also included.
public opinion - contiguous and 3km culls were controversial aspects of
industry opinion there was some resistance to the contiguous cull.
11.Economic considerations to be considered:compensation additional culling may significantly increase the
amount paid in compensation.
value of exports & other economic costs particularly in the wider
countryside and for tourism cost-benefit analysis (see Decision Box
1). There are extra costs involved in additional culling.
Regionalisation would regionalisation of the UK or England be
At decision box 5: are resources available for additional culling
The prime concern is whether adequate resources exist to accommodate the
anticipated number of additional livestock in addition to those slaughtered
under stamping out.
12.Physical resources to be considered:slaughter capacity does the capacity exist to slaughter animals under
the stamping out policy and additional culling;
transportation capacity does the transport capacity exist to remove
animals from farm for disposal under an additional culling scenario;
disposal capacity - does the capacity exist to dispose of animals under
the stamping out policy and additional culling in environmentally
time ie are there sufficient resources to permit additional culling before
such livestock develop FMD; identification of all premises included in
an additional cull.
13.Human resources to be considered:emergency response system ie are there sufficiently trained staff to
carry out an additional culling policy without adversely impacting on
other key control policies i.e. enforcing movement controls, etc;
what are the epidemic projections epidemiological modelling of high