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FMD_IMPROCON Résumé de rapport

Project ID: 503603
Financé au titre de: FP6-POLICIES
Pays: Belgium

Final Report Summary - FMD_IMPROCON (Improvement of Foot and Mouth disease control by ehtically acceptable methods based on scientifically validated assays and new knowledge on FMD vaccines ...)

There is a strong desire to reduce reliance on large-scale culling of animals to control future outbreaks of Foot-and-mouth disease (FMD) in European Union (EU) Member States. Consequently, the European Commission (EC) amended its policy and has changed its directive on FMD control (Council Directive 2003/85/EC), making the use of emergency vaccination easier when combined with screening for residual infection using tests for antibodies to Non-structural proteins (NSPs). In reality, this means that current contingencies must be based on the use of existing vaccines. Therefore, this project addressed the specific gaps in our knowledge and technological ability with respect to the implementation of a vaccinate-to-live policy.

The availability of adequate discriminatory diagnostic tests is the keystone of the new EU FMD control policy. The FMD_IMPROCON project focused on the validation of NSP-based tests to discriminate unequivocally between infected and vaccinated animals, in order to allow the implementation of the new policy in the immediate term. Validation of existing and new NSP-tests as confirmatory tests were a major output of this project.

The experimental design provided expected outputs in the field of the impact of vaccination on the carrier state and on virus dissemination, the onset of vaccinal protection, vaccine potency in relation to emergency use, vaccine strain selection and new marker vaccines. This project focused on marker vaccines to induce durable protection against FMD. Conventional and marker vaccines were targeted to dendritic cells with particular attention to promote dendritic cell mucosal homing (from parental immunisation), since mucosal immunity could prevent FMD virus establishing local infection and the carrier status.

Following the availability of the sensitivity and specificity estimates, it was recognised that none of the assays combine 100 % sensitivity with 100 % specificity which has consequences for their applicability in outbreak situations. Hence, a study was initiated to examine the ways in which serological testing with NSP ELISAs can be used and interpreted and the effect that this will have on the confidence with which freedom can be demonstrated within the guidelines specified by the OIE and the EC.
It was concluded that:
i) the vaccination-to-live policy in conjunction with NSP-serosurveillance is a realistic and achievable option to substantiate, not prove, freedom from infection if combined with cluster analysis;
ii) stamping-out should also remain part of the control policy, but is not always the best approach;
iii) where all vaccinated ruminants are tested, greater confidence in eliminating carriers can be achieved by using a testing algorithm to maintain a high sensitivity and then slaughtering individual reactor animals, rather than using a higher specificity and lower sensitivity combined with slaughter of reactor herds;
iv) where multiple reactors are found then herd-based slaughter would be appropriate;
v) testing all vaccinated animals is not achievable in areas of dense pig populations and therefore a sample scheme based on 5 % prevalence and 95 % confidence should be considered;
vi) vaccination of small herds remains controversial and should be discussed further.

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