Movements of Birds and Avian Influenza from Asia into Alaska

Kevin Winker,Irina V Kulikova,David L Suarez,Yuri N Zhuravlev,Christin L Pruett,Rose Meier,David E Swayne,Erica Spackman,Michael Wege,Daniel D Gibson,Michael L Perdue,Kevin G Mccracken,Falk Huettmann

doi:10.3201/eid1304.061072

Abstract

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.

Highlights

Asian-origin avian influenza (AI) viruses are spread in part by migratory birds
To estimate the risk of Asian-origin AI viruses being delivered by migratory birds to North America through Alaska, we evaluated AI virus infection rates, bird movements, and the diversity and degree of intercontinental host overlap
To estimate a baseline delivery rate of Asian-origin AI viruses to Alaska through these overlapping migration systems, we considered movement rates (M) of individuals from Asia (i) to Alaska (j) in conjunction with infection rates (I) and the incidence of specific influenza virus strains (Vx) that we detected in this study

Summary

Introduction

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. To estimate the risk of Asian-origin AI viruses being delivered by migratory birds to North America through Alaska, we evaluated AI virus infection rates, bird movements, and the diversity and degree of intercontinental host overlap.

Results

Conclusion