Despite involvement of large numbers of birds, the delivery rate of Asian-origin viruses to North America through Alaska is apparently low. Asian-origin avian influenza (AI) viruses are spread in part by migratory birds. In Alaska, diverse avian hosts from Asia and the Americas overlap in a region of intercontinental avifaunal mixing. This region is hypothesized to be a zone of Asia-to-America virus transfer because birds there can mingle in waters contaminated by wild-bird–origin AI viruses. Our 7 years of AI virus surveillance among waterfowl and shorebirds in this region (1998–2004; 8,254 samples) showed remarkably low infection rates (0.06%). Our findings suggest an Arctic effect on viral ecology, caused perhaps by low ecosystem productivity and low host densities relative to available water. Combined with a synthesis of avian diversity and abundance, intercontinental host movements, and genetic analyses, our results suggest that the risk and probably the frequency of intercontinental virus transfer in this region are relatively low.
【저자키워드】 Asia, Research, Avian Influenza, North America, migratory birds, influenza in birds,