How is avian influenza spread?

State and federal government experts continue to evaluate how Highly Pathogenic Avian Influenza (HPAI) viruses can spread and impact wild and domestic birds.

The global spread of HPAI subtype H5N8 has been driven in large part by migratory waterfowl. Knowledge about migratory patterns and intercontinental associations of waterfowl, as well as genetic analyses of viral strains support the hypothesis that HPAI H5N8 entered North America from Asia via migratory birds.

Wild waterfowl and other species shed the virus into the environment through their oral and nasal secretions and feces.

Learn more at the USGS Avian Influenza website.

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Can people get avian influenza?

While rare, human infections with avian influenza viruses have occurred. The Centers for Disease Control and Prevention considers the risk to the general public from HPAI H5 infections in wild birds, backyard flocks, and commercial poultry, to be low. To date, no humans or other mammals have shown signs of disease from the HPAI viruses found in...

Can wild birds spread avian influenza to domestic poultry?

Although it is possible for domestic poultry to become infected with avian influenza from direct contact with wild birds, it is more likely that avian influenza viruses are spread indirectly to poultry on contaminated feed, clothing, and equipment. Agricultural agencies encourage producers to prevent wild birds and other wildlife from coming into...

How do scientists study avian influenza in wild birds?

To learn more about the impacts of avian influenza on wild birds and the role wild birds may play in the spread of the virus, experts from government agencies have gathered samples from hundreds of thousands of live-captured, apparently healthy wild birds; hunter-harvested birds; and dead wild birds of all species. Testing methods include analyses...

What is the meaning of the numbers next to the “H” and “N” in avian influenza designations?

Avian influenza (AI) viruses are classified by a combination of two groups of proteins: hemagglutinin or “H” proteins, of which there are 16 (H1 to H16), and neuraminidase or “N” proteins, of which there are nine (N1 to N9). Many different combinations of “H” and “N” proteins are possible. Each combination is considered a different subtype and can...

What are the different types of avian influenza?

Avian Influenza (AI) type A viruses are divided into subtypes based on two proteins on the surface of the virus: Hemagglutinin (HA), of which there are 16 subtypes (H1-H16) Neuraminidase (NA), of which there are 9 subtypes (N1-N9) Many combinations of HA and NA proteins are possible (i.e., H5N1, H5N2, H7N2, H7N8, etc). AI viruses are also...

What is chronic wasting disease?

Chronic wasting disease (CWD) is a fatal, neurological illness occurring in North American cervids (members of the deer family), including white-tailed deer, mule deer, elk, and moose. Since its discovery in 1967, CWD has spread geographically and increased in prevalence locally. CWD is contagious; it can be transmitted freely within and among...

What is White-nose Syndrome?

White-nose syndrome is an emergent disease of hibernating bats that has spread from the northeastern to the central United States at an alarming rate. Since the winter of 2007-2008, millions of insect-eating bats in at least 29 states and five Canadian provinces have died from this devastating disease. The disease is named for the white fungus,...
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Date published: December 4, 2017

Avian Flu From Abroad Can Spread in North American Poultry, Wild Birds

Some avian influenza, or bird flu, viruses that are able to enter North America from other continents through migrating birds can be deadly to poultry and can infect waterfowl populations, according to a recently published U.S. Geological Survey study.

Date published: July 18, 2017

Unusual Suspects: Diving Ducks and Avian influenza

Due to the global threat to health and human safety posed by avian influenza monitoring has been conducted in the United States to determine the prevalence of such viruses in our wild waterfowl.

Date published: April 5, 2016

Alaska Still a Likely Portal for Avian Influenza

ANCHORAGE, Alaska — The U.S. Geological Survey released additional evidence that western Alaska remains a hot spot for avian influenza to enter North America. 

Date published: January 23, 2015

USGS Statement Regarding Avian Flu Found in Washington State Green-Winged Teal

Some media are reporting that the Asian H5N1 strain of highly pathogenic avian influenza has now entered the United States. This is incorrect.

Date published: September 3, 2014

Avian Flu in Seals Could Infect People

The avian flu virus that caused widespread harbor seal deaths in 2011 can easily spread to and infect other mammals and potentially humans.

Date published: March 19, 2014

North Atlantic May Be a New Route for Spread of Avian Flu to North America

The North Atlantic region is a newly discovered important pathway for avian influenza to move between Europe and North America, according to a U.S. Geological Survey report published today.

Date published: October 30, 2009

North American Raptors Susceptible to Avian Influenza

American kestrels are extremely susceptible to highly pathogenic avian influenza, indicating that other endangered and threatened raptors may also be at risk if the virus reaches North America.
In a new U.S. Geological Survey (USGS) study, all kestrels inoculated with highly pathogenic avian influenza virus H5N1 died within seven days of inoculation, regardless of the virus dose.

Date published: October 27, 2008

Genetics Provide Evidence for the Movement of Avian Influenza Viruses from Asia to North America via Migratory Birds

Wild migratory birds may be more important carriers of avian influenza viruses from continent to continent than previously thought, according to new scientific research that has important implications for highly pathogenic avian influenza virus surveillance in North America.

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Avian influenza sample
July 26, 2017

Collecting a sample to test for Avian Influenza

Avian influenza among wild waterfowl is a concern among resource managers and owners of domestic fowl. The scientists take a sample to process at the lab.

August 3, 2016

Avian Influenza Transmission Risk Model Web Application Virtual Tour

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 full web application

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Blue-winged teal in Texas with an inset that shows the avian influenza virus
March 29, 2013

Blue-winged teal in Texas. Inset shows avian influenza virus

Blue-winged teal in Texas. Inset shows avian influenza virus

Brandt Meixell is holding two pintail ducks that he just retrieved from a net pen
July 1, 2010

Brandt Meixell holding pintail ducks

Brandt Meixell holding pintail ducks that will be banded and sampled for avian influenza

Image: Sampling Forster’s Tern Chicks for Avian Influenza Study
January 1, 2010

Sampling Forster’s Tern Chicks for Avian Influenza Study

Scientists sampling Forster's Tern chicks for avain influenza during salt pond restoration work in south San Francisco Bay salt ponds.

Image: Sampling Forster’s Tern Chicks for Avian Influenza Study
January 1, 2010

Sampling Forster’s Tern Chicks for Avian Influenza Study

Scientists sampling Forster's Tern chicks for avain influenza during salt pond restoration work in south San Francisco Bay salt ponds.

Testing for Avian Influenza
December 31, 2008

Testing for Avian Influenza

A USGS scientist takes a sample from a northern pintail duck (Anas acuta) to be tested for avian influenza. 

Avian Influenza Sampling

Avian Influenza Sampling

Oral-pharyngeal sample being taken on an American black duck (cloacal samples are also taken from each bird)