Open session of the standing technical committee of the EUFMD- 2004

Dr Helen Hondrokouki presented preliminary results of serosurveillance conducted in the Evros prefecture of North-West Greece for both FMD and Peste des petits ruminants (PPR) (Appendix 74).

Dr Ingrid Bergmann gave an overview of the occurrence of FMD in South America, presented data on the genetic and antigenic characterisation of recent isolates including a type C virus from Brazil and discussed the approach of the PANAFTOSA laboratory to diagnosis and serosurveillance (Appendix 75).

Conclusions 1. The ability of NSP tests to detect FMDV infection in vaccinated cattle under field conditions allows prevalence rates in vaccinated populations to be estimated.

2. NSP tests can be used in the serodiagnosis of SAT 1 and SAT 2-type FMD infections, such that they can be considered as serotype-independent serodiagnostic tests; SPCE tests also readily detected antibodies to these viruses.

3. The sensitivity of NSP tests for detection of SAT serotype FMDV carriers (75-90%) was very similar to estimates obtained with experimental sera during the NSP workshop in Brescia in May 2004.

4. Optimised RT-PCR was found to be more sensitive than virus isolation for detecting virus in probang samples; virus was detected rarely in nasopharyngeal swabs.

5. Serotype O and A FMD viruses isolated in South America between 2000 and 2004 represent strains that are indigenous to the region. Strains circulating in the Andean region are clearly separate from those that have occurred in the Southern Cone region.

Recommendations 1. Age stratification should be used as part of the assessment of potential virus circulation in a population following FMD outbreaks or in the determination of the absence of virus circulation.

2. To further evaluate the use of NSP tests for DIVA purposes they should be applied in different epidemiological situations and in different susceptible species.

3. Follow-up epidemiological investigations and additional laboratory tests are indicated where NSP seropositive animals are identified.

4. Sampling strategies which require the use of appropriate validated tests, should be developed that would assist countries in regaining the disease free status after an FMD outbreak and where vaccination has been used.

5. NSP serosurveillance (and follow-up investigation) should be conducted at least on an annual basis, and more frequently where risk indicates, in the Thrace region of Turkey and in neighbouring regions of Greece and Bulgaria.

6. Careful consideration should be given to the statistical validity of the sampling regime for the surveillance purpose intended and to subsequent interpretation of the data.

7. The work presented should be continued, with further analysis and sequencing of strains from epidemiologically important regions of S. America.

Item 14 - Regulatory compliance Dr David Paton reviewed progress on the development of serosurveillance strategies that could be used by European countries adopting a vaccinate-to-live policy for controlling future FMD outbreaks (Appendix 76). Information is now available on the sensitivity and specificity of diagnostic tests for use in cattle. However, uncertainty remains over: (i) the level of certainty with which freedom from infection must be demonstrated; (ii) how to interpret results from herd-based tests when herds comprise small numbers of animals and (iii) details of how to resolve test specificity problems by retesting and resampling.

Conclusions 1. Many of the problems associated with false positive results may be overcome by retesting and resampling/retesting.

2. It is impossible to prove complete absence of infection.

3. The issues of confidence in the status of a group of animals is is greatest in small herds.

Recommendations 1. Further work is needed to define sensitivity and specificity parameters for use of DIVA tests with susceptible species other than cattle.

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