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Potential dispersal range and rate of H5N1 HPAI virus by wild waterfowl: estimation from satellite-tracked bird movements

Cappelle J., Gaidet N., Newman S., Takekawa J.Y., Prosser D.J., Iverson S., Dodman T.. 2009. In : Eds by Verena Keller, John O'Halloran. 7th Conference of the European Ornithologists Union 21-26 August 2009, Zurich, Switzerland : abstracts. Sempach : Swiss Ornithological Institute, p. 25-25. European Ornithologists Union Conference. 7, 2009-08-21/2009-08-26, Zurich (Suisse).

The rapid spread of highly pathogenic avian influenza (H5N1) viruses over Asia, Europe and Africa, contemporary to outbreaks in migratory waterfowl, has questioned the potential for wild waterfowl to spread H5N1 viruses. While these viruses are still circulating over these regions, a number of recent experimental infection surveys have revealed that some wild waterfowl can excrete H5N1 virus for several days before or without exhibiting clinical signs. We here present the application of a large-scale satellite telemetry program to epidemiology. We evaluated the dispersive potential of H5N1 viruses by wild waterfowl through the analysis of the movement range and rate of satellite-tracked birds, in relation to the duration of potential asymptomatic viral shedding (DPAVS). Our review of all available inoculation surveys (120 birds from 15 wild waterfowl species) indicates that almost all infected birds show a period of asymptomatic viral shedding, ranging from 1 to 8 days. We compiled location data of more than 100 birds from more than 10 species of Anatidae we had equipped with PTTs in Africa and Asia. We then measured the magnitude, speed and frequency of bird movements during time frames corresponding to values of DPAVS. Our analysis confirms that wild waterfowl have the potential of being long-distance vectors of H5N1 viruses. Satellite-tracked birds were able to perform long-distance movements (up to 3000 km) during short periods compatible with DPAVS. However, their general dispersive potential was low. Long-distance dispersals (>100 km) were only occasional, with magnitudes no more than 1000 km for most ranging or migration movements, extensive distances being covered only when birds crossed large natural barriers. In addition, time between separate long-distance dispersals was generally longer than DPAVS, preventing birds from spreading viruses through successive long-distance flights. (Texte intégral)

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