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Archivo: 1999 Session - Appendix 18

1999 Session of the Research Group of the Standing Technical Committee of EuFMD



Strategy for emergency vaccination against Foot-and-Mouth Disease: A report of a scientific committee of the European Commission


G.F. Panina, Scientific Committee íAnimal Health and Animal WelfareÎ. European Commission. Bruxelles


On March 10th 1999, the Scientific Committee on Animal Health and Animal Welfare, a Committee of the European Commission (DG XXIV), has adopted a report on the íStrategy for emergency vaccination against FMDÎ.

The report includes:
i) the criteria leading to a decision to implement emergency vaccination,
ii) the guidelines for a vaccination programme,
iii) the guidelines for the movement of animals and animal products within and out of the vaccination zone(s).

I don't believe that it is now the case to illustrate all the report. However, let me only remind you that the more controversial point was that concerning the ímovement of the vaccinated live animals out of the area which has been subjected to emergency vaccinationÎ.

According to the OIE International Zoo-sanitary Code (1997), free movement of vaccinated animals should be permitted 1 year after cessation of the vaccination or 3 months after slaughtering of the last vaccinated animal, with documented evidence that an effective system of surveillance is in operation. The OIE rules do not take into account the now available new tests, as the 'non structural proteins (NSP) test', that would allow discrimination between animals which have been vaccinated and those that have been infected.

On the basis of several recent papers published on this topic, indicating a sensitivity of the NSP test around 90-100%, the report:
- recognizes the validity of the NSP-test, for testing animals at the herd level rather than at the individual animal level,
- expresses the opinion that the application of a NSP-test may allow for an earlier lifting of the restrictions on the movement of vaccinated animals,
- recommends that not less than 30 days from the time of completion of vaccination, an adequate surveillance system, including a serological test for NSP in all vaccinated ruminants (the NSP test is considered not yet validated for use in pigs), should be established in the vaccination area, and
- states that restrictions for movement of vaccinated ruminants out of the vaccination zone, should be lifted when a surveillance system, including the NSP-test in all vaccinated animals, in addition to the clinical inspection, the virus isolation, the genome or antigen detection and the epidemiological analysis, has been completed with negative results.

If there is any indication that in the premises with vaccinated ruminants:
* 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 the holding, under controlled conditions;
- cleaning and disinfection of the holding.

Considering that the NSP test has not been yet validated for pigs, free movement of vaccinated swine can only take place out of the vaccination zone when clinical inspection, tests for virus isolation or genome or antigen detection (based on statistically valid number of samples) and epidemiological analysis have given negative results.

As stated before, the points related to the movement of vaccinated live animals out of the vaccination zone have been largely debated. According to a minority opinion, the proposed solutions could represent a significant decrease in the safety of FMD control, for two reasons:
i) Seropositive animals (but NSP negative) would be distributed from an area near an outbreak out to all areas of the EU. This would affect the status of the non-vaccinating countries and represent problems for the export of animals that react positive in the standard tecniques.
ii) At the current stage of knowledge, NSP techniques would be only promising and not enough data would be available to give any final recommendation. In addition, it still has to be shown how applicable the NSP test will be when used for screening a very large number of samples.

With regard to these considerations, it is necessary to bear in mind that:
i) The NSP test is not the only test applied. It should be integrated in a surveillace system including the clinical inspection, the virus isolation, the genome or antigen detection and the epidemiological surveillance.
ii) The NSP test should be used for testing animals at the herd level. It means that in case of positive animals in a herd, the free movement of all the animals of the herd will be prohibited. The positive animals will be killed and destroyed, the negative ones remaining on the holding will be slaughtered under controlled conditions.
iii) In any case, free movement of vaccinated animals will take place out of vaccination zone when all restrictions applied to protection and surveillance zones have been lifted, in accordance with the specific present regulation.

In addition, the report recognizes that NSP test should be optimized and further validated. The test has to be offered as a complete test kit which is easy to use and possibly compatible with pipetting robots. It should be available to the National FMD reference laboratories.

In conclusion, the report considers that emergency vaccination can be a useful tool in the control of FMD outbreaks with a risk or tendency towards uncontrolled spread.

In particular, the report 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 European Commission;
- 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 under review;
- 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.