Which migratory pathway was implicated in introducing HPAI into North America in 2015?

• A. East Asia/Australia flyway
• B. Pacific Americas flyway
• C. Atlantic flyway
• D. Mississippi flyway

Answer: (A)

This question tests how migratory bird flyways can move pathogens across continents. In 2014–2015, highly pathogenic avian influenza (HPAI) was introduced into North America primarily via birds using the Pacific route that links East Asia with North America across the Bering Strait. Birds carrying the virus moved from East Asia to Alaska and then dispersed along the Pacific coast into western North America, with subsequent spread to domestic birds. Genetic analyses of the North American isolates showed closest relationships to East Asian lineages, supporting this route of introduction. The East Asia/Australia flyway involves movements between Asia and Australia, not North America, so it doesn’t explain the introduction into North America. The Atlantic and Mississippi flyways are internal North American routes and do not account for the initial cross-continental introduction from Asia.