Infectious Diseases 2022

Infectious Diseases 2022

The Intercontinental spread HPAI H5N1 Clade 2.3.4.4 virus to the United States, 2021

26 March, 2022

In a new study published in the United States Centers for Disease Control and Prevention (CDC) Emerging Infectious Diseases, researchers detected Eurasian-origin highly pathogenic avian influenza A(H5N1) virus belonging to the Gs/GD lineage, clade 2.3.4.4b, in wild waterfowl in 2 Atlantic coastal states in the United States. Bird banding data showed widespread movement of waterfowl within the Atlantic Flyway and between neighboring flyways and northern breeding grounds.
Data reported in the study, in combination with the recent highly pathogenic AIV findings in Newfoundland, Canada, suggest that wild bird surveillance captured the introduction of a Eurasian-origin highly pathogenic AIV into wild birds by the Atlantic Flyway of the United States. The potential introduction pathway probably includes wild bird migratory routes from northern Europe that overlap Arctic regions of North America and then dispersal farther south into Canada and the United States. In addition, the genetic analyses showed that all virus segments were of Eurasian origin and had a high degree of similarity with viruses found in Western Europe during spring of 2021. In addition, these findings demonstrate that targeted AIV surveillance in wild bird populations can detect newly introduced or emergent AIVs before spillover to domestic poultry. Advanced warnings from wild bird surveillance enable poultry producers to consider altering biosecurity in the face of increased AIV risk and also help inform zoonotic disease potential.


Bevins SN, Shriner SA, Cumbee Jr JC, Dilione KE, Douglass KE, Ellis JW, Killian ML, Torchetti MK, Lenoch JB. Intercontinental Movement of Highly Pathogenic Avian Influenza A (H5N1) Clade 2.3. 4.4 Virus to the United States, 2021. Emerging Infectious Diseases. 2022 Mar 18;28(5).