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Avian influenza (AI) type A viruses are divided into subtypes based on two proteins on the surface of the virus:
Many combinations of HA and NA proteins are possible, for example H5N1, H5N2, H7N2, and H7N8.
AI viruses are also classified into two groups based on their ability to produce disease in chickens: highly pathogenic avian influenza (HPAI) or low pathogenic avian influenza (LPAI).
H5 and H7 LPAI viruses have the potential to change into HPAI viruses and are closely monitored by animal and public health officials. The first HPAI outbreak in the U.S. occurred in 2015 and the second outbreak started in 2022. The U.S. Department of Agriculture is the lead federal agency for avian influenza in animals, but they work closely with many partner agencies, including the USGS.
Learn more:
Distribution of Highly Pathogenic Avian Influenza H5 and H5N1 in North America, in Relation to U.S. Fish & Wildlife Service Refuges and National Park Service Lands, 2021/2022. Updated November 27, 2022.
Distribution of Highly Pathogenic Avian Influenza H5 and H5N1 in North America, in Relation to U.S. Fish & Wildlife Service Refuges and National Park Service Lands, 2021/2022. Updated November 27, 2022.
Hydrologist Laura Hubbard filters wetland water for infectious avian influenza in Izembek National Wildlife Refuge, Alaska.
Hydrologist Laura Hubbard filters wetland water for infectious avian influenza in Izembek National Wildlife Refuge, Alaska.
Erin Stelzer collected and transported over 1100 liters of wetland water to the Michigan Bacteriological Research Laboratory (MI-BaRL; Lansing, MI) as part of work to finalize laboratory methods to detect infectious avian influenza virus (AIV) in freshwater. The methods will test how biotic factors and water chemistry influenced the recovery of a known con
Erin Stelzer collected and transported over 1100 liters of wetland water to the Michigan Bacteriological Research Laboratory (MI-BaRL; Lansing, MI) as part of work to finalize laboratory methods to detect infectious avian influenza virus (AIV) in freshwater. The methods will test how biotic factors and water chemistry influenced the recovery of a known con
The Avian Influenza Transmission Risk Model web application depicts the intricate connections between 16 layers of administrative, environmental, and economic data in an application that runs inside a web browser. To view and manipulate the full web application, please visit http://www.pwrc.usgs.gov/ai.
The Avian Influenza Transmission Risk Model web application depicts the intricate connections between 16 layers of administrative, environmental, and economic data in an application that runs inside a web browser. To view and manipulate the full web application, please visit http://www.pwrc.usgs.gov/ai.
USGS scientist sampling water at Horicon National Wildlife Refuge for analysis of avian influenza to determine if wild bird habitat is a reservoir of the virus.
USGS scientist sampling water at Horicon National Wildlife Refuge for analysis of avian influenza to determine if wild bird habitat is a reservoir of the virus.
Blue-winged teal in Texas. Inset shows avian influenza virus
Blue-winged teal in Texas. Inset shows avian influenza virus
USGS National Wildlife Health Center laboratory technician preparing avian samples for avian influenza testing.
USGS National Wildlife Health Center laboratory technician preparing avian samples for avian influenza testing.
Scientists sampling Forster's Tern chicks for avain influenza during salt pond restoration work in south San Francisco Bay salt ponds.
Scientists sampling Forster's Tern chicks for avain influenza during salt pond restoration work in south San Francisco Bay salt ponds.
Listen to hear the answer.
A USGS scientist takes a sample from a northern pintail duck (Anas acuta) to be tested for avian influenza.
A USGS scientist takes a sample from a northern pintail duck (Anas acuta) to be tested for avian influenza.
USGS biologists swab a hen mallard duck for avian influenza in Rio Grande County, Colorado.
USGS biologists swab a hen mallard duck for avian influenza in Rio Grande County, Colorado.
Distribution of Highly Pathogenic Avian Influenza H5 and H5N1 in North America, in Relation to U.S. Fish & Wildlife Service Refuges and National Park Service Lands, 2021/2022. Updated November 27, 2022.
Distribution of Highly Pathogenic Avian Influenza H5 and H5N1 in North America, in Relation to U.S. Fish & Wildlife Service Refuges and National Park Service Lands, 2021/2022. Updated November 27, 2022.
Hydrologist Laura Hubbard filters wetland water for infectious avian influenza in Izembek National Wildlife Refuge, Alaska.
Hydrologist Laura Hubbard filters wetland water for infectious avian influenza in Izembek National Wildlife Refuge, Alaska.
Erin Stelzer collected and transported over 1100 liters of wetland water to the Michigan Bacteriological Research Laboratory (MI-BaRL; Lansing, MI) as part of work to finalize laboratory methods to detect infectious avian influenza virus (AIV) in freshwater. The methods will test how biotic factors and water chemistry influenced the recovery of a known con
Erin Stelzer collected and transported over 1100 liters of wetland water to the Michigan Bacteriological Research Laboratory (MI-BaRL; Lansing, MI) as part of work to finalize laboratory methods to detect infectious avian influenza virus (AIV) in freshwater. The methods will test how biotic factors and water chemistry influenced the recovery of a known con
The Avian Influenza Transmission Risk Model web application depicts the intricate connections between 16 layers of administrative, environmental, and economic data in an application that runs inside a web browser. To view and manipulate the full web application, please visit http://www.pwrc.usgs.gov/ai.
The Avian Influenza Transmission Risk Model web application depicts the intricate connections between 16 layers of administrative, environmental, and economic data in an application that runs inside a web browser. To view and manipulate the full web application, please visit http://www.pwrc.usgs.gov/ai.
USGS scientist sampling water at Horicon National Wildlife Refuge for analysis of avian influenza to determine if wild bird habitat is a reservoir of the virus.
USGS scientist sampling water at Horicon National Wildlife Refuge for analysis of avian influenza to determine if wild bird habitat is a reservoir of the virus.
Blue-winged teal in Texas. Inset shows avian influenza virus
Blue-winged teal in Texas. Inset shows avian influenza virus
USGS National Wildlife Health Center laboratory technician preparing avian samples for avian influenza testing.
USGS National Wildlife Health Center laboratory technician preparing avian samples for avian influenza testing.
Scientists sampling Forster's Tern chicks for avain influenza during salt pond restoration work in south San Francisco Bay salt ponds.
Scientists sampling Forster's Tern chicks for avain influenza during salt pond restoration work in south San Francisco Bay salt ponds.
Listen to hear the answer.
A USGS scientist takes a sample from a northern pintail duck (Anas acuta) to be tested for avian influenza.
A USGS scientist takes a sample from a northern pintail duck (Anas acuta) to be tested for avian influenza.
USGS biologists swab a hen mallard duck for avian influenza in Rio Grande County, Colorado.
USGS biologists swab a hen mallard duck for avian influenza in Rio Grande County, Colorado.
