Item 4 Virus characterisation

independent vaccine control were started in the Bornova Veterinary Control and Research Institute in Izmir.

Dr. Naci Bulut summarised the serosurvey performed after FMD vaccination in Thrace during autumn 2001 (Appendix 9). In total 4061 sera taken on day 0, 28, 60 and 120 pv, were examined by LPB ELISA. The protection level indicated by the test was acceptable after 28 and 60 days but insufficient after 120 days.

He then reported on a sero-survey for NSP antibodies by 3ABC ELISA conducted on the same sera (Appendix 10). In total, 1310 sera were tested of which 16 (1.22%) were found positive all of them from different herds. This gave no significant indication of circulating virus in the region.

Dr. Sinan Aktas presented a paper on the genetic characterisation of FMD type O and A viruses in Turkey (Appendix 11). The results showed that type A viruses isolated from Turkey between 2000-2002 were closely related to A Iran 96. Regarding the O type although slightly different type O viruses were isolated in Turkey, these were antigenically found to be related to the vaccine strain O Manisa.

The last paper presented by Dr. Hagai Yadin reviewed the policy of FMD control for prevention and emergency situations in an FMD endemic region (Appendix 12). This policy consists mainly of annual vaccination of all livestock including sheep, goats and pigs. The imported vaccine is checked upon arrival for serological response. An annual serological surveillance is performed to check the annual vaccination campaign. In case of an FMD outbreak, animals are vaccinated and risk animals are placed under quarantine.

Conclusions

• Due to the lack of clinical signs, the laboratory diagnosis of SVD is based on examining faeces samples instead of epithelial tissues. The VI test is affected by the possible loss of virus infectivity and the presence of entero-viruses other than SVDV that may grow more quickly than SVDV. The Immune PCR assay developed at the Brescia Reference Centre circumvents these difficulties.

• Serosurveillance in Thrace indicated that the duration of protection following FMD vaccination was shorter then 120 days which indicates that booster vaccination is required at least 3 times the first year and twice a year thereafter.

• The test used for the detection of NSP antibodies revealed that the probability of active virus circulation in Thrace is very low.

• FMD viruses circulating in Turkey seem to be covered by current vaccine strains.

• The policy of FMD control in an endemic area should consist of strict surveillance and vaccination, including vaccine control and sero-surveillance. In case of an outbreak, quarantine and emergency vaccination is carried out.

Recommendations

• SVD control should be based on serological survey and on the detection of virus in faeces by immune-PCR.

• For the future a more potent FMD vaccine should be applied in the Thrace region with a longer protection period. A training programme for the organisation and execution of a serosurvey should be organised to improve future serosurveys.

• Surveys for the detection of antibodies against NSPs and confirmatory tests should be continued to detect possible incursions into the Thrace region.

• Turkey should continue to characterise FMD viruses from new outbreaks and also continue to send samples to WRL, Pirbright.

• The policy of FMD control as adapted in Israel can form a model for endemic areas.

Item 2b: FMD control: epidemiology, surveillance and control measures: focus on epidemic incursions

The first paper under this heading was presented by Dr Michelle Remond on behalf of Dr Francois Moutou who was unable to attend. The paper describes the different models which have been used to help decision-making during FMD epidemics (Appendix 13). Prior to the UK 2001 epidemic a few models had been used for operational purposes during epidemics, however, the majority had been used as training tools. The UK 2001 epidemic stimulated the development of new models, including deterministic differential equation models, detailed microsimulation models and stochastic/deterministic models. In the paper these were compared using information from publications and their strengths and weaknesses as decision support tools were reviewed. Models had a major influence on the introduction of novel disease control strategies in the UK during the early stages of the 2001 epidemic even though the parameters on which they were based were collected during the 1967-68 UK epidemic when farming conditions were very different. During the course of the 2001 UK epidemic when contemporary data became available the models were refined and improved.

Following this presentation, Dr Michael Thrusfield reviewed the history of the development of models in the field of biology. He informed the audience that the polarisation of views between the quantifiers and non-quantifiers about the appropriateness of models seen during the UK 2001 epidemic was not new as a similar debate occurred when models were first introduced several centuries ago. He described the different types of models and the approaches, deductive or inductive, used for their development. Models can be used for retrospective or present-time analysis or for future prediction. Clearly, the value of models is dependent on the accuracy of the input data. Satisfying that requirement is most challenging for predictive models. In the context of the application of models to FMD, Dr Thrusfield underlined the difficulty of modelling the evolution of the epidemic due to the complexity of farm management systems and differences between livestock species in respect to their susceptibility and amplification of virus.