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.