Migrating wild birds play a key role in transporting highly pathogenic avian influenza

Jun 5 2006

Migrating wild birds have played and will likely continue to play a role in transporting highly pathogenic avian influenza (HPAI) virus, or bird flu, over long distances.

This was among the main conclusions of a two-day international scientific conference called by the UN Food and Agriculture Organization and the World Organisation for Animal Health (OIE).

But the conference, attended by over 300 scientists from more than 100 countries also recognized that the virus was mainly spread through poultry trade, both legal and illegal.

"Several presentations at the Conference, some supported by recent publications in peer-reviewed scientific journals, implicated wild birds in the introduction of HPAI H5N1 virus at considerable geographical distance from known H5N1 outbreaks in poultry," the meeting said in a concluding document.

But the participants admitted they could not resolve another of the key issues at the conference, which was the role of wild birds in the spread of HPAI to more than 50 countries on three continents, and whether wild birds should now be considered a permanent reservoir of the virus.

If they are such a reservoir, there is a strong likelihood they will carry the virus with them in subsequent migrations. Alternately H5N1 may subside naturally as infected animals die off, or it may mutate to a less aggressive form.

"This was one of the main gaps identified in our present scientific knowledge," said Joseph Domenech, FAO's chief veterinary officer. "We must therefore intensify our investigations."

The conference noted that the current outbreaks of H5N1 virus in eight African countries appeared to be poultry-related and chiefly based on trade in poultry for human consumption, including illegal trade. However, it called for further analysis for a more complete understanding of how the virus was introduced.

"There is a need to mobilize the international donor community to invest in the improvement of veterinary services in developing countries, especially in Africa and Asia," Dr Gideon K. Bruckner, Head of OIE's Scientific and Technical Department, said.

Wise investments here will promote early detection in wild birds and rapid response to disease outbreaks, Dr Bruckner added.

H5N1 disease management would need to be based on improved biosecurity and hygiene at the production level, and in all poultry sectors, including minimizing the possibility of contact between domestic and wild birds, the conference advocated.

It called for the establishment of a global tracking and monitoring facility involving all relevant institutions across the world, including scientific centers and farmers' organizations, hunters, bird watchers, and wetland and wildlife conservation societies.

The participants rejected any suggestion of trying to stop the spread of HPAI by killing wild birds. "Destruction of wild bird habitats or indiscriminate hunting of wildlife is scientifically and ethically unjustified as a response," one of the conference recommendations said.

It urged continuing research to adopt an inter-disciplinary approach, and called for investment to incorporate telemetry/satellite technology to improve understanding of wild bird migration patterns (see related article "Free as a bird -- or under surveillance").