In August/September 1999 these issues were debated in the EMPRES-Livestock-L electronic mailing list.
The debate was raised by Dr Michael Van-Ham (Epidemiology Department, Beit Dagan, Israel) who asked whether a country could be classified as free from Newcastle disease (ND) if it is visited by migratory wild birds originating from countries with ND. Two responses from the OIE stated that a country could be regarded free of a domestic animal disease despite its possible presence in wildlife, provided the country could demonstrate that the risk of transfer of this disease to domestic population and the consumers was negligible. In practice this involves a clear separation between wild and domestic animals (compartmentalization) and evidence of its freedom in the domestic population through intensive surveillance.
Dr Dennis J. Alexander (FAO/EU Reference Laboratory for Newcastle disease and avian influenza) replied that reports of ND transfer from wild to domesticated birds were rare, but that there is a need to address how ND in different avian species should be controlled, given a new OIE definition of ND. Professor Peter Spradbrow (Virus Laboratory, University of Queensland, Australia) elaborated on these definitions, pointing out that the official ND diagnosis was now linked to the presence of ND virus with certain characteristics rather than to the presence of clinical disease. Many countries lack the capabilities for such advanced diagnostics and he warned that this might lead to serious underreporting of the disease. Alexander indicated that the new OIE criteria included virus-excreting birds without clinical symptoms, which occur quite often in immunized birds. In support of Spradbrow's warning from a developing country field worker's point of view, Dr Nick Honhold of the EC/HMGN SVSLDC Project in Nepal suggested that the clinical signs combined with positive antibody results should be maintained in the OIE diagnostic criteria for unvaccinated birds.
EMPRES had received no conclusions to the issue on diagnostic criteria but learned that this would be addressed at the OIE Wildlife Disease Group Meeting, held in Paris in mid-October.
We regard this debate as continuing and contributions to the debate may still be sent to: EMPRES-Livestock-L@mailserv.fao.org.
The full discussion can be obtained under "Electronic Discussion Group" at our Web site: www.fao.org/empres.
Other issues regarding transboundary livestock diseases are also welcome. This mailing list is moderated, implying that we reserve the right to filter submitted contributions.
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