Foot and mouth disease has been eradicated from the
European Union (EU). The last outbreak occurred in Greece in 1996. However, the risk for
Member States remains extraordinarily high as a consequence of:
Footnote 1 from
infected areas which may carry infective fomites.
- the presence of countries where foot and mouth disease is endemic on the periphery of
- the possibility of illegal introduction into the EU, because of price differences, of
infected animals, especially sheep/goats, or meat, meat products, milk and milk products
contaminated with foot and mouth disease virus;
- the movement of tourists and migrants
Compulsory prophylactic vaccination of cattle against foot and mouth disease ceased in
the EU during 1990-91, in the framework of a policy laid down in Council Directive
85/511/EEC (W19.18Nov1985 -
http://europa.eu.int/eur-lex/en/lif/dat/1985/en_385L0511.html) as amended by Council Directive 90/423/EEC
(W19.26Jun1990 - http://europa.eu.int/eur-lex/en/lif/dat/1990/en_390L0423.html). The measures adopted to control possible outbreaks and
eliminate the virus should it gain entry are based on the strategy of killing infected
herds with appropriate disposal of potentially infective material (stamping out) and
controlling the movements of live animals, meat, meat products, milk, milk products,
animal by-products, persons, vehicles, farm fomites and any other substance liable to
transmit the virus. This strategy alone might not be sufficient to eradicate the virus and
therefore Council Directive 90/423 (see above) (art. 13.3) permits the use of emergency
vaccination, as an adjunct to the control and eradication measures.
In the past, emergency vaccination has been applied to protect ruminant and in
particular cattle populations against FMD when local outbreaks had occurred and when the
circumstances indicated that an exotic strain had been introduced, against
which protection by annual vaccination was not guaranteed. This was most frequently the
case when pigs had been infected through swill feeding, e.g. Germany 1976 (Boehm and
Kaaden, 1978). Emergency vaccination was also applied as a supplementary instrument to
reinforce protection in cattle or ruminants in general when a local outbreak of FMD
occurred which was elicited by a classical virus strain. The effectiveness of
such a measure, which was always accompanied by other control measures, was most often
assumed when there was no further spread of the disease and no development of an epidemic
(Roehrer and Olechnowitz, 1980).
More recently (Leforban, 1996), regional vaccination against FMD has been applied in
some countries on the Balkans area. This was based on recommendations from FAO (FAO,
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The Scientific Committee on Animal Health and
Animal Welfare has been requested to:
- establish the criteria leading to a decision to implement emergency vaccination against
foot and mouth disease;
- establish guidelines for a vaccination programme;
- prepare guidelines for the movement of animals and animal products within and out of the
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Rationale for the possible use of emergency vaccination
In 1990/91, the EU decided to cease routine
prophylactic vaccination. The control procedures are now total stamping out of the disease
in affected herds and movement control in the surrounding area. This policy was effective
in eradicating foot and mouth disease in Italy in 1993 and in Greece in 1994 and 1996.
However, in the future there may be certain circumstances when these measures may need to
be supplemented by the use of an emergency vaccination (Donaldson and Have, 1996; Amadori,
The rationale for using emergency vaccination for
foot and mouth disease is:
Fear that after the introduction of FMDV into a free region, it may
spread out of control;
In particular, outbreaks in areas containing high densities of susceptible animals and
inadequate resources of manpower or rendering plants for the slaughter and disposal of
animals or outbreaks involving a predicted risk of airborne virus spread beyond the
Availability of high potency vaccines.
It has been demonstrated (Salt et al., 1994 and 1996) that a high level of immunity
can be induced by potent vaccines within a few days in both cattle and pigs. These
experimental data were confirmed on several occasions under field conditions.
Availability of new tests that will differentiate between infected and
The availability of these tests allows the vaccine to be used in a similar fashion to
a marker vaccine.
Responding to public opposition to the implementation of total stamping
out and the demand for an alternative approach or the impossibility of carcass disposal
because of concerns about water (carcass burial) or urban air pollution by smoke of
The successful implementation of emergency vaccination will limit the
number of animals experiencing the symptoms and poor welfare associated with FMD
The objectives of emergency Footnote3 vaccination are:
to create a zone of vaccination outside the protection zone to protect
animals against airborne infection ('protective' emergency vaccination);
'protective' emergency vaccination is vaccination carried out on holdings in order to
create an immune zone and protect the animals within the area being vaccinated against
airborne infection from the infected area;
To reduce the quantity of virus spread within the suspected infected
area (='dampening down' emergency vaccination)
'dampening down' emergency vaccination is vaccination which should be used only in
conjunction with a pre-emptive slaughter policy in a known foot and mouth disease infected
area where it is considered that there is an urgent need to reduce the amount of virus
circulating and the risk of spread beyond the area. This may be indicated as a measure to
assist pre-emptive slaughter particularly in the following circumstances: a high density
of animals (especially pigs); an overwhelming of the capacity to kill and dispose of
carcasses within a short time period, poor infrastructure, inadequate manpower or delayed
stamping out. In the event that this emergency vaccination is applied, stamping out
procedures should continue and be applied to the animals, irrespective of the
implementation of vaccination.
to assist the completion of stamping out and disposal of carcasses and
materials from infected premises by minimising virus transmission while this is taking
to reduce the severity of 'direct' economic losses.Footnote4
It should be noted, however, that during the 14 days following the vaccination of
cattle and 7 days following the vaccination of pigs, virus transmission can occur from
those species to susceptible animals in contact with them (Donaldson and Kitching 1989;
Salt et al. 1998).
It is emphasised, however, that with effective surveillance, rapid reporting of
suspected cases, rapid diagnosis and the implementation of control measures without delay,
foot and mouth disease can be controlled and virus eradicated before outbreaks develop
into epidemics. On the other hand, should the circumstances be appropriate for the
implementation of emergency vaccination then the decision to do so must be made quickly.
Farmers whose herds/flocks are vaccinated and who suffer losses as a result of the
restrictions placed on them should be fully compensated. If not, they are unlikely to
co-operate with an emergency vaccination programme.
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4. Vaccines and Tests
The EU has recognised the need for the
provision of emergency vaccines in the national contingency plans of Member States and has
established a Community Vaccine Bank in which concentrated inactivated FMDV antigens are
stored at three sites, viz. Brescia, Lyon and Pirbright (Council Directive
85/511/EEC (W19.18Nov1985 -
http://europa.eu.int/eur-lex/en/lif/dat/1985/en_385L0511.html) as amended by Directive 90/423/EEC (W19.26Jun1990 - http://europa.eu.int/eur-lex/en/lif/dat/1990/en_390L0423.html); Commission Decision 93/590/EEC (W19.5Nov1993 - http://europa.eu.int/eur-lex/en/lif/dat/1993/en_393D0590.html) and Council Decision 91/666/EEC (W19.11Dec1991 - http://europa.eu.int/eur-lex/en/lif/dat/1991/en_391D0666.html)). In addition, some Member States have established
National Banks of antigens and/or vaccines, but these banks would not be accessible to
other Member States.
Currently, FMD vaccines are typically inactivated vaccines containing whole virus in a
semi-purified state. Vaccines may include one or several of the serotypes. The vaccine
strain used should be as homologous as possible with the field strain. In addition to
aluminium hydroxide adjuvanted vaccines, oil based vaccines have become available. These
are of comparable quality. However, oil-adjuvanted vaccines should be used whenever
possible since they can be expected to produce an acceptable immune response in all foot
and mouth disease susceptible species, whereas aluminium hydroxide formulated vaccines are
effective in ruminants but not in pigs. (Pay, 1984)
In the case of emergency vaccination, emphasis must be put on highly potent, safe
vaccines, capable of inducing early protection and dramatically reducing virus replication
in vaccinated livestock when exposed to infection (Amadori and Berneri 1996; Salt et al.,
1998). Formulated foot and mouth disease emergency vaccines (inactivated antigens being
stored as concentrates over liquid nitrogen) must have been validated as potent vaccines.
High potency is essential (at least 6 PD50 E.P.) to achieve rapid development of immunity
and a broad antibody response in vaccinated animals. Therefore, in circumstances when
there is a lack of homology between a field virus and the vaccine strain then the broader
response induced by a highly potent vaccine can compensate in part for the lack of
antigenic homology. (Barteling and Swam, 1996; Kitching et al., 1989)
Non structural proteins (e.g. 3ABC) should not be present in the vaccines because this
could interfere with differential diagnostic tests. Batches must be tested to verify this.
Diagnostic procedures on FMDV isolates should include the provision of information
about the degree of relationship to vaccine strains Footnote5 .
In this context, Council Decision 91/666/EEC (W19.11Dec1991 - http://europa.eu.int/eur-lex/en/lif/dat/1991/en_391D0666.html) listed 10 antigens to be stored in the EU Bank, but not
all of these have been purchased by the EU. Some strains now appear extinct, but other
antigenically distinct strains have appeared. Therefore, the suitability of the strains of
antigens held in the EU Bank should be continually kept under review.
The criteria for deployment of vaccine produced from the stored antigens for emergency
use have not been clearly defined. Delays are to be avoided at the time of an emergency
and it is therefore essential that the procedures governing the chain of events from
formulation of antigen into vaccine, through the bottling and labelling procedures, to
delivery to the region where it is to be used, are clearly specified and efficiently
implemented. At present, these issues are unresolved and so it is critical that they are
addressed as a matter of urgency.
4.2 Differentiating infection from vaccination
for Non Structural Protein (NSP)
The differentiation of herds or flocks which have
been infected from those which have been vaccinated is a critically important follow-up
activity to 'protective' emergency vaccination.
Antibodies to the capsid (structural) proteins of foot and mouth disease virus are
produced by animals following either vaccination or infection. It is not possible,
therefore, to use tests based on the detection of antibodies to structural proteins of
foot and mouth disease virus (OIE Manual of Standards 1996) to differentiate animals which
have been infected from those that have been vaccinated.
Viral replication during infection results in the production of a number of
non-structural proteins (NSP), some of which are antigenic. Sera from naive or vaccinated
animals are usually negative; in contrast, the majority of infected or vaccinated-infected
animals produce detectable antibodies to the 3ABC non-structural protein, irrespective of
the FMDV serotype causing the infection. Foot and mouth disease vaccines consist of
purified preparations of inactivated virions that induce antibodies almost exclusively to
the structural proteins of the virus. Differentiation of infection from vaccination by
detecting antibodies to NSP in infected ruminants has been described (Bergmann et al.,
1989; De Diego et al. 1997; Haas 1997; Meyer et al. 1997; Silberstein et al. 1997;
Sorensen et al. 1998b; Mackay et al. 1998a). To date, the detection by ELISA of an
antibody response to the non-structural polyprotein 3ABC seems to be the most reliable
indicator of a previous infection (Concerted action CT93 0909,1997). NSP ELISAs are simple
to perform and are suited to large scale application by a routine serological laboratory.
To date this test has been validated in cattle (refs. cited above). There is good data
available for sheep but further work needs to be done in pigs.
Recently developed 3ABC-ELISAs show relatively high sensitivity and specificity. For
infected animals at more than 8-15 days after infection the sensitivity is close to 100%.
However, in the "worst case" scenario, when vaccinated animals have been exposed
to virus and become infected without developing clinical signs, the sensitivity will be
lower, probably around 90% (Haas, 1997). As a consequence, the 3ABC-ELISA should then be
used for testing animals at the herd/flock level rather than the individual animal level.
Furthermore, although the 3ABC-ELISA has been validated in some laboratories, additional
technical improvements are required so that its use can be extended to
regional laboratories, whose involvement will be essential for large scale campaigns Footnote6 (De Diego et al., 1997; Sorensen et al., 1998a; Berlinzani et al.,1998;
Mackay et al., 1998a; Mackay et al., 1998b).
Further development of NSP tests
Additional work is necessary in order to complete
the development of the NSP tests:
The antigen used in NSP tests needs to be standardised.
A panel of positive and negative reference sera needs to be established
which NSP tests must correctly identify before use is permitted. This panel should include
sera from non infected animals vaccinated with highly potent vaccine and sera from animals
that have been vaccinated and afterwards infected with FMD virus.The specificity of the
tests in field situations needs to be determined accurately.
This is of crucial importance in defining a singleton (i.e. false
positive) reactor and differentiating the herd from an infected herd ( for example see
Report of Scientific Committee on Animal Health and Animal Welfare of 10 August 1998 on
Swine Vesicular disease Annex II). It should also be noted that there is a
possibility that the use of high potency vaccines could influence the performance of NSP
tests, in particular by reducing the specificity of the test. This aspect of the use of
these test needs further research to determine the extent, if any, of this effect.
Current developments in other diagnostic tests
A range of additional laboratory diagnostic tests
are currently under development:
- assays for isotype-specific viral antibody in secretions (Archetti et al. 1995; Salt et
al. 1996; Armstrong 1997);
- analysis of nasal swabs by RT-PCR (Marquardt et al. 1994);
- detection of PCR products by ELISA (Donini et al. 1992).
Further studies are necessary to validate these methods.
Silent foot and mouth disease infection and FMDV carriers
It is well known that vaccinated ruminants may
become subclinically infected with FMDV and may excrete the virus following exposure.
Therefore, it will be essential to consider vaccinated animals in the vaccination zone as
potentially infected because they have been at risk of exposure and hence a potential
source of FMDV. In exceptional cases some ruminants may become carriers (Wittmann, 1990).
However, the likelihood of carriers transmitting the infection under field conditions is
As an adjunct to serological monitoring of vaccinated animals for antibodies to the
non-structural proteins of FMD virus, it may be necessary to carry out tests for the
detection of FMDV antigen to determine if vaccinated herds/flocks are subclinically
infected. Tests can be carried on suitable samples (e.g. probang samples, blood, milk,
nasal swabs) to detect the presence of live virus or viral RNA. The culture of probang
samples on bovine thyroid cells is considered a sensitive method to detect FMDV in
non-vaccinated carrier ruminants. The sensitivity of virus detection tests, especially in
vaccinated animals, is not known and may be a problem. The probang test suffers from some
major constraints: (i) virus excretion in carrier animals is intermittent and (ii)
false-negative results can be obtained due to virus inactivation during sampling and
shipment to the laboratory. As a consequence, virus isolation from probang sampling cannot
be considered to have a sensitivity of 100% for carrier animals. A combination of probang
sampling with PCR may increase the sensitivity (Callens M and De Clercq C., 1997; Callens
et al., 1998; Reid et al., 1998; Marquardt .1998; Forsyth et al., 1998.)
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5. Criteria and factors
affecting the decision to implement emergency
The rapid and objective assessment of the
determining parameters is crucial to the decision to commence a vaccination programme.
If an analysis of parameters gives a result which supports a programme of protective
emergency vaccination then the programme must be implemented without delay. It is
emphasised that if decision-making and the required actions are delayed and as a
consequence the initiative is lost and the disease becomes widespread, then the only
remaining option may be a programme of either regional or national vaccination.
Several computer assisted models have been developed (De Jong and Diekmann 1992; Sanson
1995; Mackay 1997; Haydon and Woolhouse 1997; Donaldson et al. 1999), some of which are
useful for strategic purposes e.g. operational planning, allocation of resources, whereas
others are suitable for use in an epidemic e.g. to predict airborne spread of virus. These
models are useful tools to assist in decision making and planning but for further
development require the input of more data to refine their parameters and assumptions. It
is essential that the necessary data (e.g. farm locations, stocking density) be collected
and kept up to date in advance of an outbreak.
It is recommended that simulation models be further developed and used by Veterinary
Services and experts to test the effects of variations in the quantitative elements
referred to in Table 1. A list of criteria for or against the decision to implement a
'protective' emergency vaccination is presented in Table 1. When considering a decision to
use emergency vaccination, these criteria should be assessed on a case by case basis.
Table 1 - List of criteria for consideration in decision-making related to
'protective' emergency vaccination
|Population density of susceptible
|Clinically affected species
||Significant number of pigs
|Movement of potentially infected
animals or products out of the protection zone Footnote 8
|Predicted airborne spread of virus
from infected premises
||Low or absent
|Suitable vaccine Footnote 9
|Origin of outbreaks (traceability)
|Incidence slope of outbreaks Footnote 10
||Shallow or slow rise
|Distribution of outbreaks Footnote7
|Public reaction to total stamping out
|Acceptance of regionalisation after
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for the emergency vaccination programme
The National Contingency Plans of Member States
(Council Directive 90/423/EEC, FAO 1993) should include all the provisions for the
implementation of emergency foot and mouth disease vaccination.
The National Contingency Plans for emergency vaccination should provide an estimation
of the total number of doses of foot and mouth disease vaccine required for the emergency
vaccination (Commission Decision 91/42/EEC, Annex). This should be based on the most
likely scenario and include the daily rate at which vaccine could be administered and the
time over which the application of vaccination could be sustained.
The area of 'protective' emergency vaccination should be as
small as possible, and its shape should be related to the geographical and meteorological
situation. The inner boundary of the vaccination area should be clearly defined; on the
basis of the available epidemiological data, it may include a part of the surveillance
zone (i.e. an area 'at risk'), but not the protection zone. Provision of slaughter, milk
collection and insemination services for vaccination zones must be considered in
establishing the boundaries of restricted areas. Where such facilities are not contained
in the zones, special controls are necessary if authorising transport from such zones to
The usual disease control measures (including stamping out) as
laid down e.g. in Council Directive 85/511/EEC should be continued irrespective of when
Clinical inspections should always precede the administration
of vaccine. Suspect signs must be reported. If a case of foot and mouth disease is
encountered during the application of protective emergency vaccination , then vaccination
must be suspended and measures taken.
Vaccine. An emergency vaccine should be a vaccine of high
potency containing antigen of a strain which is antigenically appropriate. It should
provide a sufficient level of protection after the application of a single dose. However,
if the field strain is antigenically different from the available vaccine strain and there
is no alternative strain available it may be necessary to implement a second round of
Cold chain facilities must be available for the storage and
distribution of vaccine so that it is, at all times, kept under cool temperature
conditions, as specified in the European Pharmacopoeia
Vaccination teams and equipment. A sufficient number of well
trained vaccinators and the required equipment to ensure the rapid administration of
vaccine to the animals must be immediately available according to prior contingency
- In the case of 'protective' emergency vaccination the first animals to
be vaccinated should be those at the outer boundary of the zone. Vaccination should
proceed inwards from those holdings towards the inner boundary. Personnel involved in
vaccination should follow the zoo-sanitary measures specified in the National Contingency
Plan to prevent the spread of infection between holdings.
- In the case of 'dampening down' emergency vaccination within the
infected area, the holdings should be selected for vaccination according to risk ranking
with the highest priority being given to the vaccination of pigs, the species which has
the greatest potential for the dispersion of plumes of airborne virus and environmental
Identification and traceability of every vaccinated animal must
be guaranteed (e.g. ear tagging or notching).
A detailed report at the end of a vaccination campaign must
contain fundamental information about the number and the species of vaccinated animals,
the holdings, if clinical signs were detected on holdings, the actions taken, and the
number of doses of vaccine used.
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7. Guidelines for the movement of animals and
animal products within and out of an area which has been subjected to emergency
The concept of regionalisation in
these circumstances has already been incorporated in Community law e.g. Council Directive
90/423/EEC (art. 2.3) (W19.26Jun1990 - http://europa.eu.int/eur-lex/en/lif/dat/1990/en_390L0423.html) amending Council Directive 64/432/EEC (W19.26Jun1964 - http://europa.eu.int/eur-lex/en/lif/dat/1964/en_364L0432.html).
The Committee considers that there is no scientific reason to refuse a regionalisation
policy for Member States which have used emergency vaccination under the following
- the disease control measures laid down in Council Directive 85/511/EEC
(W19.18Nov1985 - http://europa.eu.int/eur-lex/en/lif/dat/1985/en_385L0511.html)
are fully implemented;
- a detailed report giving up to date epidemiological information and full details of
measures taken must be available;
- the region is submitted to rigorous controls;
- the control of movement of animals and animal products is effective.
Similar provisions should apply to third countries, according to OIE rules. In the
context of emergency vaccination, international acceptance of regionalisation is
7.2 Movement of vaccinated live animals within
and out of the vaccination zone
The Committee notes that when a foot and mouth
disease outbreak occurs in a free zone where prophylactic vaccination is not practised,
there are two possible scenarios, in relation to the policy adopted:
Policy 1: stamping out and surveillance.
Taking into consideration Council Directive 85/511/EEC (W19.18Nov1985 - http://europa.eu.int/eur-lex/en/lif/dat/1985/en_385L0511.html), free movement of live animals (ruminants and pigs ) out
of the restricted area (i.e. protection and surveillance zones) is permitted 30 days after
the completion of stamping out in the last outbreak, provided that adequate surveillance
of the protection zone and cleaning and disinfection of the contaminated holdings have
been carried out.
Policy 2: stamping out, surveillance and emergency vaccination
The OIE International Zoo-Sanitary Code (1997) [Text of Chapter 2.1.1 - Foot
and mouth Disease available in Wildpro: LCofC3 - International
Animal Health Code 2000 (Office International des Epizooties) - See "Special Section Reference"],
Chapter 2.1.1., states that a vaccinated area can be considered free
- 1 year after cessation of the vaccination (Article 18.104.22.168; page 87),with documented
evidence that an effective system of surveillance is in operation and that theregulatory
measures for the prevention and control of FMD have been implemented,
- 3 months after slaughtering of the last vaccinated animal (Article 22.214.171.124; page 91),
where stamping-out, serological surveillance and emergency vaccination are applied.
The OIE code does not state that free movement of vaccinated animals from free areas is
permitted but this would be a logical conclusion.
In addition, the OIE rules do not take into account the new serological tests for
FMDV-NSP, able to discriminate between vaccinated and infected herds. In spite of the
uncertainties with regard to vaccinated herds, the Committee is of the opinion that the
application of NSP-tests allows for an earlier lifting of the restrictions on the movement
of vaccinated animals.
The Committee recommends that not less than 30 days Footnote 11 from
the time of completion of vaccination, an adequate surveillance system (see 7.2.1 and 7.2.2 below) including serological tests for
NSP in ruminants must be established in the vaccination area.
Restrictions could be lifted when the surveillance described below (paragraphs 7.2.1 to 7.2.3) for ruminants and swine has been
completed with negative results. In the period from vaccination until lifting of
restrictions, animals shall only be moved to a slaughterhouse preferably within the
'protective' vaccination zone, under the conditions detailed in section 7.3 of this report.
7.2.1 Surveillance to allow movement of ruminants
Free movement of vaccinated ruminants can only
take place out of the vaccination zone when:
- clinical inspection in all herds of the vaccination zone have provided no indication of
FMD virus infection and;
- the NSP-ELISA performed in all vaccinated animals has given a negative result and;
- all the restrictions applied to protection and surveillance zones have been lifted in
accordance with the Council Directive 85/511/EEC.
Cattle herds and sheep and goat flocks positive to NSP-test (i.e. herds with more than
a singleton Footnote 12 reactor) Footnote 13 shall
be treated under the conditions detailed in the paragraph 7.2.3 of this report.
7.2.2 Surveillance to allow movement of swine
It is recognised that the NSP-tests are not yet
validated for use in pigs. Until this is done, it is recommended to use tests for virus
isolation in this species. Free movement of vaccinated swine can only take place out of
the vaccination zone when:
18Nov1985 - http://europa.eu.int/eur-lex/en/lif/dat/1985/en_385L0511.html).
clinical inspection in all herds of the vaccination zone has provided no
indication of FMD virus infection and;
the laboratory tests for virus isolation or genome or antigen detection,
based on a statistically valid number of samples, have given negative results and;
all the restrictions applied to protection and surveillance zones have
been lifted in accordance with the Council Directive 85/511/EEC (W19.
Swine herds are considered 'infected' when FMD virus has been isolated or when genome
or antigen has been detected in biological samples.
on positive results to surveillance
If there is any indication that in the premises
with vaccinated animals:
- virus is present (clinical disease or virus isolation or genome or antigen detection),
then the holding shall be treated as an outbreak (stamping out and restrictions);
- virus has been present (NSP-positive animals at numbers exceeding singleton levels) then
the minimum actions should be:
- - killing and destruction of the NSP-positive animals without delay;
- - slaughter of the residual animals of susceptible species remaining on theholding,
under controlled conditions; the products should be handled according to section 7.3 of this report;
- - cleaning and disinfection of the holding;
Movement of animals for slaughter and products thereof within and out of the
Movement of animals to slaughter in the 30
day period following the completion of vaccination should be limited to that absolutely
necessary on welfare grounds. This is to permit the observation of any cases of disease in
the zone. Following this 30 day period until the lifting of all restrictions, animals may
be moved to a slaughterhouse preferably within the 'protective' vaccination zone under the
Footnote 14 ,
without passing through a market and without contact to other animals;
the transport vehicles have been cleaned and disinfected before loading and after the
animals have been delivered;
animals have passed the ante-mortem health inspection at the slaughterhouse and have in
particular been subject to a thorough examination of mouth and feet and have not shown
signs of foot and mouth disease. Animals must be slaughtered without any delay on arrival
at the slaughterhouse. This is particularly important in the case of pigs which might have
encountered carrier cattle.
- animals are accompanied by an official document certifying that all cloven hoofed
animals in the holding of origin have been subjected to a clinical examination and have
shown no clinical signs of foot and mouth disease;
- animals have been transported directly from their holding of origin to an approved
slaughterhouse preferably within the vaccination zone
and beef products (also mutton)
Beef from the above animals may be commercialised
within and out of the vaccination zone provided that one of the following treatment has
been applied and certified by the competent veterinary authorities:
7.3.3 Pork and pork
- maturation of carcasses at a temperature of more than +2°C for at least 24 hours and
then the pH value in the middle of longissimus dorsi muscle has been recorded as less than
6.0, and deboning and removal of the main lymph nodes. Offal and heads should be destroyed
or heat treated (Savi et al., 1962b).
- heat treatment to an FC-value of 3.00 or higher, i.e. autoclaving in tins (Council
Directive 80/215/EEC), or alternative heat treatments such as those currently approved for
pork (Council Directive 80/215/EEC), if also validated for beef.
Pork from animals slaughtered may be
commercialised within and outside the vaccination zone as cured or heat-treated products.
The treatment must be certified by the competent veterinary authority.
- Heat treated products. Experiments have shown that adequate thermal processing
(time-temperature combination) of pork prepared from FMD-infected animals has produced
safe products (Savi et al. 1962 b). Council Directive 80/215/EEC prescribes thermal
processing to core temperature of 70°C for 30 min.
- Cured products. Pork products which are not heat treated owing to their
particular characteristics (hams, salami, etc.), are cured and preserved by procedures
such as salting, drying and smoking.
- Hams. In hams, FMD virus is normally inactivated within 24-48 hours in
the muscle, due to the drop of pH, but can persist longer in tissue such as bone marrow,
lymph nodes or lard. The survival of FMD virus in typical Italian and Spanish hams has
been studied by McKercher et al. (1987) and Mebus et al. (1993) respectively. The
products, which were not deboned, were free of viable virus by days 170 and 168
respectively. According to the Council Directive 80/215/EEC deboned ham should be not be
commercialised before 9 months have elapsed from the date of preparation.
- Salami. The risk posed by salami (minced, cased and cured pork meat)
can be considered negligible, provided these are manufactured industrially, according to
the criteria given by the Scientific Veterinary Committee-Section Animal Health in 1995.
In salami, FMD virus is normally inactivated in 24-48 hours in pig meat stored unfrozen
after slaughter. In addition, the specific formulations used for salami production are
able to eliminate any residual viral infectivity, mainly thanks to the low pH achieved in
the mixture as a consequence of the metabolism of the sugars by the starter microrganisms
and the typical flora of salami (Savi et al. 1962 a & b, McKercher et al. 1975,
Dhennin et al 1980 a & b, Panina et al. 1989).
and dairy products
In accordance with the OIE Sanitary Code 1997,
Appendix 126.96.36.199, page 541, milk produced within the vaccination zone in the period from
the beginning of vaccination until the removal of all restrictions may be commercialised
within or out of the vaccination zone provided that one of the following treatments has
been applied in a plant preferably located in the vaccination zone and certified by the
competent veterinary authorities:
- if for animal consumption, (a) double HTST pasteurisation (72°C for 15-17 sec),
or (b) single HTST combined with another physical treatment, such as lowering the pH <
6 for at least one hour or additional heating to 72°C or more, combined with desiccation,
or (c) single UHT pasteurisation (130°C for 2-3 sec) combined with another physical
treatment referred to in (b) (Sellers 1969, Cunliffe et al, 1979; Scientific Veterinary
Committee,1994; OIE International Zoo-Sanitary Code 1997).
- if for human consumption only , check the pH and (a) if 7.0 or over (abnormal),
treat by double HTST or single UHT; or (b) if less than 7.0 then treat by HTST or UHT.
(Scientific Veterinary Committee,1994; OIE International Zoo-Sanitary Code 1997).
No special ban should be enforced on dairy products produced during the period
from the beginning of vaccination until the removal of all restrictions, provided that the
raw milk has been previously treated as above.
Whey to be fed to pigs and produced from milk heat treated as above must be
collected at least 16 hours after milk clotting and its pH must be recorded as <6.0
before transport to swine holdings within or out of the vaccination zone. Following a
delivery to pig premises the vehicle must be cleaned and disinfected before it leaves.
Semen and Embryos
Production of semen and embryos in Artificial
Insemination centres within the vaccination zone should be stopped during the period from
the beginning of vaccination until all restrictions have been lifted. During that period,
personnel at AI centres within the vaccination zone should not visit farms. If they are to
be vaccinated, bulls or boars in AI centres must be checked for antibodies to FMDV before
administration of vaccine in order to exclude that these centres may lead to spread of the
disease (Amadori and Luini, 1995).
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Conclusion and recommendations
In conclusion, the Scientific Committee on Animal
Health and Animal Welfare having reviewed the scientific and technological progress made
in the field of FMD diagnosis and vaccine production considers that emergency vaccination
can be a useful tool in the control of FMD outbreaks with a risk or tendency towards
uncontrolled spread. The text of this report sets out criteria leading to a decision to
implement emergency vaccination against foot and mouth disease and establishes guidelines
both for a vaccination programme and for the movement of animals and animal products
within and out of the vaccination zone(s).
In particular, the Scientific Committee on Animal Health and Animal Welfare recommends:
- The Community Reference Laboratory for foot and mouth disease should be established as a
matter of urgency.
- The foot and mouth disease situation world-wide should be carefully monitored by the
- The antigens of recent highly contagious and significantly antigenically different FMD
virus strains, particularly from regions neighbouring Europe, should be produced and
stored in the EU or National antigen banks for production of emergency vaccines;
- The quality of the antigens stored in the banks should be monitored by an Institute
(Community Reference Laboratory) designated by the EU;
- The suitability of the strains of antigens held in the banks should be kept continually
- Non structural proteins (e.g. 3ABC) should not be present in vaccines;
- Computer assisted models should be further developed for strategic purposes (future
planning, allocation of resources, operational use in epidemics);
- The National Contingency Plans should consider the possibility of emergency vaccination
and provide an estimate of all logistical requirements such as the number of vaccination
teams required in different areas, in order to complete the task as rapidly as possible.
- NSP tests should be optimised and further validated. The antigen used in these tests
should be standardised. Regional laboratories should be trained in their practical use. An
ELISA test kit, validated by an Institute designated by the EU, should be available at the
national FMD laboratories.
- In particular the specificity of NSP tests needs to be determined more accurately,
especially when following the use of highly potent vaccine.
- A panel of positive and negative sera should be established. Inter-laboratory comparison
trials for diagnostic tests should be regularly carried out.
It is considered necessary for the Commission to pursue efforts to reach progress in
negotiations within the framework of the World Trade Organisation for recognition of a
regionalisation policy regarding trade restrictions for areas where FMD emergency
vaccination has been applied, based on the principle of an acceptable risk level.
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Minority opinion Professor, Dr. Soren Alexandersen
Summary: The draft report on "Strategy for Emergency Vaccination against
Foot-and-mouth disease (FMD)" have been discussed at two subcommittee meetings and I
have on two occasions submitted written comments to the draft.
Although the report has improved significantly, I still think it needs considerable
improvement. Especially, because the safety inherent in the procedures is yet, in my
opinion, not known in detail, and much more data is needed. So in conclusion, it is my
opinion, that there is not enough data on the new tests to make the statements with any
degree of precision. Therefore, it should be reworded to say, that earlier lifting of
restrictions may be envisioned, when the full capacity of the tests is known (or may not
be possible, if the tests have too many mistakes). Also, it still have to be shown, how
these tests will work when used for screening thousands or millions of samples, and
especially how precise they are when used as only diagnostic tool and on animals
vaccinated in the field during an outbreak.
Specific remarks: The major issues missing or not dealt with properly are:
- When and how can restrictions be lifted, and what will the level of assurance be
(compared to current regulations);
- Vaccinated animals should NOT be allowed to leave the area;
- Although almost no new information regarding potential importance of carrier animals in
spread of disease is available, the current report apparently totally excludes the
potential importance of carrier animals (state, that the sensitivity may in these
situations only be 90%, meaning, that up to 10% of carrier animals may be negative against
antibodies to NSP);
- Who decides to allow emergency vaccination in each case: PVC?;
- The details of post-vaccination surveillance is not detailed at all, this should be
defined in detail in the report (however, data are most likely not yet available to detail
this, because the prevalence of infection in vaccinated animals will be unknown);
- The sensitivity of the tests on animals vaccinated in the field and perhaps infected
at/before/after vaccination, is not known in detail and may be a problem;
- The singleton reactor phenomenon mentioned in the report is not at all characterised for
the NSP antibody test.
Regarding the period from vaccination to lifting of restrictions I do not agree with
the report. At the current stage of knowledge, the period is set too short (not enough is
known) and moreover, with the current knowledge, it would be necessary to sample ALL
vaccinated animals or at least to sample large numbers of animals and rely potential
lifting on a full epidemiological report. Thus, instead of a 30-day period after
vaccination before screening, I would suggest a period of at least 60 days (to be on the
safe side, when more data become available this period may be shortened). The opinion is
based on a 4-day period for the vaccine to work and a 14-day period for the potential
incubation period. However, in a biological system like this, these periods may work for
the majority of the animals, however, as a safety margin (because nothing is known under
field conditions) the period should, in my opinion, be doubled (and thus at least 60 days
after vaccination before start of NSP surveillance etc). It is mentioned in the report,
that immunity can be induced by potent vaccines in a few days in both cattle and pigs.
This may be true for most of the animals, however when many animals are vaccinated, some
animals will be slower than others and some animals may react poorly and infection will
thus depend on challenge dose. Secondly, piglets only respond when older than 2 weeks of
age and also, two rounds of vaccination may be necessary to induce full protection for
certain heterologous vaccines. Thus, the period before potential lifting of restrictions
should have a wide safety margin.
Vaccination should in my opinion only be allowed OUTSIDE both the protection and the
SURVEILLANCE zone. Otherwise, it will be impossible to estimate the potential infectious
load in the area (based on clinical surveillance). However, if it is accepted, that no
vaccinated animal can leave the zone except directly for slaughtering and processing, the
vaccination in the surveillance zone could be accepted from a safety point of view.
In my opinion, vaccinated animals should not be allowed to leave the vaccination zone,
except directly for slaughter and using the procedures described in section 7.3.2 and
7.3.3 of the report (after lifting of restrictions). All animals should go through this
In conclusion, there are several weaknesses in the current report on emergency
vaccination against FMD. The recommendations made will, with the current knowledge,
represent a significant, and in my opinion intolerable, decrease in the safety of FMD
control. The problems can be divided into two separate areas. The first area, which
everything considered is a smaller problem, is the fact that the recommendations will
result in vaccinated and thus seropositive (but NSP negative) animals being distributed
from an outbreak near zone and out to all areas of the EU. This may for sure affect our
status as non-vaccinating countries and furthermore, will present problems for
export/import samples (which will react positive in the standard techniques). Having
antibody positive animals in the region is in my opinion a scientific issue, because
presence of a significant population of antibody positive animals may hide a potential FMD
infection and may very well make clinical surveillance difficult and furthermore, put
pressure on national laboratories for only using, or at least also using, the NSP tests
instead of well known serological techniques.
The second problem is the major problem and can definitely not be ignored. It is a
fact, that there may be an increased risk when allowing movement of vaccinated,
potentially infected animals and products. It should be emphasised, that at the current
stage of knowledge concerning the NSP techniques, these techniques are promising, however,
not nearly enough is known to give any final recommendations. A potential scientific
"safety level" may be reached, when we have more data, and provided, that any
recommendation or decision involving potential lifting of restrictions on vaccinated
animals, should be based on a thorough, statistically highly significant, epidemiological
surveillance for NSP antibodies and FMD virus isolation or genome/antigen detection. Thus,
after vaccination in a zone (decided on the basis on thorough risk assessment) potential
lifting of restrictions on herds/flocks can only be allowed after epidemiological analysis
of the whole area and provided, that this analysis gives assurance for the absence of FMDV
infection based on a high number of samples (statistically valid). However, vaccinated
animals should not be removed from the zone except after lifting restrictions and then
only directly for slaughtering and processing to remove potential FMD virus.
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This report of the Scientific Committee on Animal
Health and Animal Welfare is substantially based on the work of a working group of the
The working group was chaired by Prof. G. Panina. The members of the group were as
follows; Prof. G. Panina, Dr. R. Ahl, Dr. M. Amadori, Dr. S. Barteling, Dr. K. De Clercq,
Dr. A.I. Donaldson, Dr. P. Have, Dr. S. Marangon.
- The Committee considered the possibility of foot and mouth disease being
a zoonosis and reviewed the literature. The Committee considers that there is no
convincing recent evidence that the disease can be a zoonosis. In any event, human
infection is unimportant in the epidemiology of the disease.
- The protection zone is a zone defined by the competent authority with a
minimum radius of 3km around the infected holding, itself contained in a surveillance zone
of minimum radius 10km. Zones should take account of geographical, administrative,
ecological and epizootiological factors e.g. Council Directive 92/119/EC (W19.17Dec1992 - http://europa.eu.int/eur-lex/en/lif/dat/1992/en_392L0119.html
- In this context the shape of the vaccination zone could vary depending on
the epidemiological and geographic situation.
- If a policy of emergency vaccination is
implemented the trade restrictions imposed on the vaccinated area (region) and/or country
will be in place for longer than if stamping out only, is used. Therefore emergency
vaccination will result in an increase of 'indirect' costs. For countries with a large
export trade in animals and animal products this economic consequence will be the
strongest argument against the implementation of emergency vaccination
- The Animal Health Institute, Pirbright
(UK) was designated as Community Reference Laboratory (Council Directive 85/511/EEC (W19.18Nov1985 - http://europa.eu.int/eur-lex/en/lif/dat/1985/en_385L0511.html) as amended by Directive 90/423/EEC (W19.26Jun1990 - http://europa.eu.int/eur-lex/en/lif/dat/1990/en_390L0423.html).
Contract ended March 1995. The OIE World Reference Laboratory will provide services
- The test has to be offered as a complete, validated test kit which is
easy to use and is compatible with pipetting robots. ELISA kits should be available to the
National FMD reference laboratories and in addition could be stored in the vaccine banks.
- See Report of the Scientific Veterinary Committee of 14 November 1996
"The feasibility of identifying densely populated livestock areas in the Community
that pose a particular high risk of major disease epidemics" doc ref VI/1986/96
- The presence of susceptible wildlife in the area should be taken into
- High potency for all species and containing appropriate type/strain
- An analytic expression (formula) which provides insight into the
contribution of different parameters to the effectiveness of the control measures has been
proposed (De Jong and Diekmann, 1992). The analysis is based on the 'basic reproduction
ratio', R 0 (the average number of animals/herds infected by one infectious animal/herd),
for which the following threshold condition holds: when R 0 >1, the infection can
spread trough the population; when R 0 <1, infection will eventually die out. 'Basic
reproduction ratios' typical of foot and mouth disease epidemics in UK have been reported
(Haydon et al. 1997).
- The 30 day period allows for 14 days needed for
the development of complete protection plus a further14 days as the maximum incubation
period reported in the literature. (Roeher and Olechnowitz, 1980).
- The precise definition of a singleton reactor needs to be addressed in
the context of an accurate estimation of the specificity of the test in cases where high
potency vaccines have been used.
- Singleton reactors should be removed from the herd and destroyed. Samples
should be taken from these animals for virus detection (isolation, PCR) and the NSP test
repeated on all remaining animals in the herd.
- Or as close as possible to the zone. Measures must be taken to avoid
spread of infection.