Avian Influenza Active
Avian influenza is a viral disease caused by various strains of avian influenza viruses that can be classified as low pathogenic avian influenza (LPAI) or highly pathogenic avian influenza (HPAI). It remains a global disease with potential high consequence with the potential to threaten wildlife, agriculture, and human health.
The USGS National Wildlife Health Center (NWHC) in collaboration with multiple partners conducts research into the ecology of avian influenza virus and surveillance for highly pathogenic avian influenza (HPAI) viruses leading to several significant findings towards early detection and response to HPAI.
Avian Influenza (AI) is a global disease with potential high consequence. Wild birds, in particular certain species of waterfowl and shorebirds, are considered to be the natural reservoirs for avian influenza viruses. These subtypes that naturally occur in wild species usually cause little or no disease. In domestic birds, however, some AI viruses can be more pathogenic and mutation or recombination of a virus acquired from wild birds can increase disease potential. In recent years, spill-back has occurred negatively affecting wild birds.
Avian influenza viruses (AIV) are classified by a combination of two groups of proteins found on the surface of the virus: hemagglutinin proteins (H), of which there are 18 (H1-H18), and neuraminidase proteins (N), of which there are 11 (N1-N11). Additional information on avian influenza viruses are available in the Field Manual of Wildlife Diseases.
AI strains are divided into two groups based on the pathogenicity of the virus, or the ability of the virus to produce disease. Most AI strains are classified as low pathogenic avian influenza (LPAI) and cause few clinical signs in infected birds. LPAI generally does not pose a significant health threat to humans. However, LPAI is monitored because two strains of LPAI— the H5 and H7 strains–can mutate into highly pathogenic forms. On the other hand, highly pathogenic avian influenza (HPAI) strains frequently fatal to birds and easily transmissible between susceptible species.
Avian Influenza Movement in the Atlantic
Highly pathogenic avian influenza outbreaks in domestic poultry cause large economic losses to the U.S. economy. It has been thought that Eurasian strains of avian influenza viruses enter the United States through the Pacific Flyway (Alaska to Baja California) and that this route is the most likely avenue for emerging Eurasian AIV strains to enter North America. However, AIV also frequently infects domestic poultry and wild ducks in Europe and Africa and migrating wild birds that use the east Atlantic flyway may also risk introducing Eurasian strain viruses to North America via this route. With the on-going European outbreaks of HPAI there is a risk of moving these viruses to North America as well.
The USGS National Wildlife Health Center, in collaboration with the National Institutes of Health Centers of Excellence for Influenza Research and Surveillance (CEIRS), the University of Iceland, and other partners, has explored the ecology and movement of AI viruses in the North Atlantic region since 2010. This research has demonstrated the importance of the migratory bird flyways in this region to the intercontinental movement of viruses between Europe and North America. AI viruses from both continents, as well as recombinations of both strains, were isolated in Iceland, sometimes from within a single flock of birds, showing that this region is a hotspot of virus movement and genetic reassortment. These studies also demonstrated the longer-term persistence of portions of these viruses within the North Atlantic avian community.
Highly pathogenic AI viruses have been frequently found in wild and domestic European birds, significantly in 2006, and annually since then. This continued European epizootic increases the risk of HPAIV being transported from Europe to North America as bird populations migrate through the North Atlantic to breeding sites in Greenland and Canada, and highlights the importance of these studies. Stakeholders include federal and state agencies, North Atlantic and European countries, and commercial poultry businesses who have an interest in protecting wildlife and/or domestic animals by identifying the risks of HPAIV entering the United States through North Atlantic wild bird flyways. Significant findings from this research in the North Atlantic include:
- Gulls and marine birds are an integral component of AIV ecology in this region;
- Genetic sequence data revealed frequent mixing of North American and Eurasian AIV lineages in the North Atlantic;
- Icelandic viruses were discovered to have genetic relationships with viruses causing seal mortalities in Europe; and
- No HPAIV has been identified, however, viruses with genetic relationships to HPAIV H5N1 viruses have been detected in Iceland.
HPAI and other influenzas circulate in freshwater waterfowl. It is also possible that sea ducks, which regularly move between continents, could play a role in how HPAI moves and evolves around the world. In collaboration with CEIRS, State Wildlife Agencies, Ducks Unlimited, and hunting guides, the NWHC has conducted surveillance in wild sea ducks in the Northeastern United States, Alaska, Canada, and Iceland over the past 6 years. This research has shown that sea duck avian influenzas often differ from those carried by freshwater ducks. This research is currently defining environmental factors that affect AI transmission in marine environments.
Quantitative Applications in Disease Ecology
Human, agricultural, and wildlife health depend on each other. Therefore, risk assessment, prediction, and management of wildlife diseases are important for our nation’s health and economy. However, monitoring and evaluating wildlife health is difficult and expensive. This leads to incomplete and biased datasets that are difficult to analyze with traditional methods. A project is underway to develop new statistical and mathematical techniques and package them into user-friendly tools. Some examples of new tools in development are the ability to analyze and interpret complex data, assess risk of future or ongoing disease outbreaks, estimate the effects of disease on individuals, populations, and ecosystems, and evaluate potential management solutions. This project, performed in partnership with the Department of Statistics at the University of Wisconsin-Madison, is broadly applicable to a variety of wildlife diseases, but is currently working on new statistical methods for predicting virus isolation of avian influenzas.
Minor Spillover of Avian Influenza Between Wild and Domestic Birds
In another study, NWHC reserachers also analyzed the genomes of HPAIV that spread in the United States during 2014-2015 and resulted in over $3 billion in losses to the U.S. poultry industry. As infection and transmission of pathogens in wild birds are difficult to measure during a fast-moving outbreak, the NWHC used cutting-edge modeling techniques to analyze genetic similarity between HPAIVs infecting wild birds and poultry. Analyses indicated that even though the viruses likely evolved in Asia, they easily infected and spread among North American wild birds. The viruses were also able to spread between domestic and wild birds (i.e., spillover). However, the rate of spillover was minor, and the poultry outbreak persisted without need for ongoing transmission from wild birds. Techniques used in this study can also be used to examine transmission and adaptation of avian influenza within waterfowl populations and between waterfowl and poultry.
Avian Influenza Surveillance
The USGS National Wildlife Health Center is a member of the U.S. Interagency Steering Committee for Surveillance for Highly Pathogenic Avian Influenza in Wild Birds. The NWHC performs both passive and active surveillance for the detection and monitoring of avian influenza. Check out the Avian Influenza Surveillance page to learn more.
Below are multimedia items related to avian influenza.
Below are publications related to avian influenza.
Evolution of a reassortant North American gull influenza virus lineage: drift, shift and stability
Avian influenza in shorebirds: experimental infection of ruddy turnstones (Arenaria interpres) with avian influenza virus
Evidence that life history characteristics of wild birds influence infection rates and exposure to influenza A viruses
High seroprevalence of antibodies to avian influenza viruses among wild waterfowl in Alaska: implications for surveillance
Comparison of filters for concentrating microbial indicators and pathogens in lake-water samples
Estimating transmission of avian influenza in wild birds from incomplete epizootic data: implications for surveillance and disease spreac
Migratory flyway and geographical distance are barriers to the gene flow of influenza virus among North American birds
Emergence of fatal avian influenza in New England harbor seals
The effect of swab sample choice on the detection of avian influenza in apparently healthy wild ducks
Paired serologic and polymerase chain reaction analyses of avian influenza prevalence in Alaskan shorebirds
Presence of avian influenza viruses in waterfowl and wetlands during summer 2010 in California: Are resident birds a potential reservoir?
Evidence for limited exchange of avian influenza viruses between seaducks and dabbling ducks at Alaska Peninsula coastal lagoons
Below are news stories related to avian influenza.
Below are FAQs related to avian influenza.
What is Avian Influenza?
Avian influenza (AI) is caused by an influenza type A virus that can infect poultry such as chickens, turkeys, pheasants, quail, domestic ducks, geese, and guinea fowl. It is carried by wild waterfowl (ducks and geese) and shorebirds. Learn more: USGS Avian Influenza
Below are partners associated with avian influenza projects.
- Overview
Avian influenza is a viral disease caused by various strains of avian influenza viruses that can be classified as low pathogenic avian influenza (LPAI) or highly pathogenic avian influenza (HPAI). It remains a global disease with potential high consequence with the potential to threaten wildlife, agriculture, and human health.
The USGS National Wildlife Health Center (NWHC) in collaboration with multiple partners conducts research into the ecology of avian influenza virus and surveillance for highly pathogenic avian influenza (HPAI) viruses leading to several significant findings towards early detection and response to HPAI.
Avian Influenza (AI) is a global disease with potential high consequence. Wild birds, in particular certain species of waterfowl and shorebirds, are considered to be the natural reservoirs for avian influenza viruses. These subtypes that naturally occur in wild species usually cause little or no disease. In domestic birds, however, some AI viruses can be more pathogenic and mutation or recombination of a virus acquired from wild birds can increase disease potential. In recent years, spill-back has occurred negatively affecting wild birds.
Avian influenza viruses (AIV) are classified by a combination of two groups of proteins found on the surface of the virus: hemagglutinin proteins (H), of which there are 18 (H1-H18), and neuraminidase proteins (N), of which there are 11 (N1-N11). Additional information on avian influenza viruses are available in the Field Manual of Wildlife Diseases.
AI strains are divided into two groups based on the pathogenicity of the virus, or the ability of the virus to produce disease. Most AI strains are classified as low pathogenic avian influenza (LPAI) and cause few clinical signs in infected birds. LPAI generally does not pose a significant health threat to humans. However, LPAI is monitored because two strains of LPAI— the H5 and H7 strains–can mutate into highly pathogenic forms. On the other hand, highly pathogenic avian influenza (HPAI) strains frequently fatal to birds and easily transmissible between susceptible species.
Avian Influenza Movement in the Atlantic
Highly pathogenic avian influenza outbreaks in domestic poultry cause large economic losses to the U.S. economy. It has been thought that Eurasian strains of avian influenza viruses enter the United States through the Pacific Flyway (Alaska to Baja California) and that this route is the most likely avenue for emerging Eurasian AIV strains to enter North America. However, AIV also frequently infects domestic poultry and wild ducks in Europe and Africa and migrating wild birds that use the east Atlantic flyway may also risk introducing Eurasian strain viruses to North America via this route. With the on-going European outbreaks of HPAI there is a risk of moving these viruses to North America as well.
The USGS National Wildlife Health Center, in collaboration with the National Institutes of Health Centers of Excellence for Influenza Research and Surveillance (CEIRS), the University of Iceland, and other partners, has explored the ecology and movement of AI viruses in the North Atlantic region since 2010. This research has demonstrated the importance of the migratory bird flyways in this region to the intercontinental movement of viruses between Europe and North America. AI viruses from both continents, as well as recombinations of both strains, were isolated in Iceland, sometimes from within a single flock of birds, showing that this region is a hotspot of virus movement and genetic reassortment. These studies also demonstrated the longer-term persistence of portions of these viruses within the North Atlantic avian community.
Highly pathogenic AI viruses have been frequently found in wild and domestic European birds, significantly in 2006, and annually since then. This continued European epizootic increases the risk of HPAIV being transported from Europe to North America as bird populations migrate through the North Atlantic to breeding sites in Greenland and Canada, and highlights the importance of these studies. Stakeholders include federal and state agencies, North Atlantic and European countries, and commercial poultry businesses who have an interest in protecting wildlife and/or domestic animals by identifying the risks of HPAIV entering the United States through North Atlantic wild bird flyways. Significant findings from this research in the North Atlantic include:
- Gulls and marine birds are an integral component of AIV ecology in this region;
- Genetic sequence data revealed frequent mixing of North American and Eurasian AIV lineages in the North Atlantic;
- Icelandic viruses were discovered to have genetic relationships with viruses causing seal mortalities in Europe; and
- No HPAIV has been identified, however, viruses with genetic relationships to HPAIV H5N1 viruses have been detected in Iceland.
HPAI and other influenzas circulate in freshwater waterfowl. It is also possible that sea ducks, which regularly move between continents, could play a role in how HPAI moves and evolves around the world. In collaboration with CEIRS, State Wildlife Agencies, Ducks Unlimited, and hunting guides, the NWHC has conducted surveillance in wild sea ducks in the Northeastern United States, Alaska, Canada, and Iceland over the past 6 years. This research has shown that sea duck avian influenzas often differ from those carried by freshwater ducks. This research is currently defining environmental factors that affect AI transmission in marine environments.
Quantitative Applications in Disease Ecology
Human, agricultural, and wildlife health depend on each other. Therefore, risk assessment, prediction, and management of wildlife diseases are important for our nation’s health and economy. However, monitoring and evaluating wildlife health is difficult and expensive. This leads to incomplete and biased datasets that are difficult to analyze with traditional methods. A project is underway to develop new statistical and mathematical techniques and package them into user-friendly tools. Some examples of new tools in development are the ability to analyze and interpret complex data, assess risk of future or ongoing disease outbreaks, estimate the effects of disease on individuals, populations, and ecosystems, and evaluate potential management solutions. This project, performed in partnership with the Department of Statistics at the University of Wisconsin-Madison, is broadly applicable to a variety of wildlife diseases, but is currently working on new statistical methods for predicting virus isolation of avian influenzas.
Minor Spillover of Avian Influenza Between Wild and Domestic Birds
In another study, NWHC reserachers also analyzed the genomes of HPAIV that spread in the United States during 2014-2015 and resulted in over $3 billion in losses to the U.S. poultry industry. As infection and transmission of pathogens in wild birds are difficult to measure during a fast-moving outbreak, the NWHC used cutting-edge modeling techniques to analyze genetic similarity between HPAIVs infecting wild birds and poultry. Analyses indicated that even though the viruses likely evolved in Asia, they easily infected and spread among North American wild birds. The viruses were also able to spread between domestic and wild birds (i.e., spillover). However, the rate of spillover was minor, and the poultry outbreak persisted without need for ongoing transmission from wild birds. Techniques used in this study can also be used to examine transmission and adaptation of avian influenza within waterfowl populations and between waterfowl and poultry.
Avian Influenza Surveillance
The USGS National Wildlife Health Center is a member of the U.S. Interagency Steering Committee for Surveillance for Highly Pathogenic Avian Influenza in Wild Birds. The NWHC performs both passive and active surveillance for the detection and monitoring of avian influenza. Check out the Avian Influenza Surveillance page to learn more.
- Multimedia
Below are multimedia items related to avian influenza.
- Publications
Below are publications related to avian influenza.
Filter Total Items: 79Evolution of a reassortant North American gull influenza virus lineage: drift, shift and stability
Background: The role of gulls in the ecology of avian influenza (AI) is different than that of waterfowl. Different constellations of subtypes circulate within the two groups of birds and AI viruses isolated from North American gulls frequently possess reassortant genomes with genetic elements from both North America and Eurasian lineages. A 2008 isolate from a Newfoundland Great Black-backed GullAuthorsJeffrey S. Hall, Joshua L. TeSlaa, Sean W. Nashold, Rebecca A. Halpin, Timothy Stockwell, David E. Wentworth, Vivien Dugan, Hon S. IpAvian influenza in shorebirds: experimental infection of ruddy turnstones (Arenaria interpres) with avian influenza virus
Background: Low pathogenic avian influenza viruses (LPAIV) have been reported in shorebirds, especially at Delaware Bay, USA, during spring migration. However, data on patterns of virus excretion, minimal infectious doses, and clinical outcome are lacking. The ruddy turnstone (Arenaria interpres) is the shorebird species with the highest prevalence of influenza virus at Delaware Bay. Objectives:AuthorsJeffrey S. Hall, Scott Krauss, J. Christian Franson, Joshua L. TeSlaa, Sean W. Nashold, David E. Stallknecht, Richard J. Webby, Robert G. WebsterEvidence that life history characteristics of wild birds influence infection rates and exposure to influenza A viruses
We report on life history characteristics, temporal, and age-related effects influencing the frequency of occurrence of avian influenza (AI) viruses in four species of migratory geese breeding on the Yukon-Kuskokwim Delta, Alaska. Emperor geese (Chen canagica), cackling geese (Branta hutchinsii), greater white-fronted geese (Anser albifrons), and black brant (Branta bernicla), were all tested forAuthorsCraig R. Ely, Jeffrey S. Hall, Joel A. Schmutz, John M. Pearce, John Terenzi, James S. Sedinger, Hon S. IpHigh seroprevalence of antibodies to avian influenza viruses among wild waterfowl in Alaska: implications for surveillance
We examined seroprevalence (presence of detectable antibodies in serum) for avian influenza viruses (AIV) among 4,485 birds, from 11 species of wild waterfowl in Alaska (1998–2010), sampled during breeding/molting periods. Seroprevalence varied among species (highest in eiders (Somateria and Polysticta species), and emperor geese (Chen canagica)), ages (adults higher than juveniles), across geograAuthorsHeather M. Wilson, Jeffery S. Hall, Paul L. Flint, J. Christian Franson, Craig R. Ely, Joel A. Schmutz, Michael D. SamuelComparison of filters for concentrating microbial indicators and pathogens in lake-water samples
Bacterial indicators are used to indicate increased health risk from pathogens and to make beach closure and advisory decisions; however, beaches are seldom monitored for the pathogens themselves. Studies of sources and types of pathogens at beaches are needed to improve estimates of swimming-associated health risks. It would be advantageous and cost-effective, especially for studies conducted onAuthorsDonna S. Francy, Erin A. Stelzer, Amie M. G. Brady, Carrie Huitger, Rebecca N. Bushon, Hon S. Ip, Michael W. Ware, Eric N. Villegas, Vincent Gallardo, H.D. Alan LindquistEstimating transmission of avian influenza in wild birds from incomplete epizootic data: implications for surveillance and disease spreac
Estimating disease transmission in wildlife populations is critical to understand host–pathogen dynamics, predict disease risks and prioritize surveillance activities. However, obtaining reliable estimates for free-ranging populations is extremely challenging. In particular, disease surveillance programs may routinely miss the onset or end of epizootics and peak prevalence, limiting the ability tAuthorsViviane Henaux, Jane Parmley, Catherine Soos, Michael D. SamuelMigratory flyway and geographical distance are barriers to the gene flow of influenza virus among North American birds
Despite the importance of migratory birds in the ecology and evolution of avian influenza virus (AIV), there is a lack of information on the patterns of AIV spread at the intra‐continental scale. We applied a variety of statistical phylogeographic techniques to a plethora of viral genome sequence data to determine the strength, pattern and determinants of gene flow in AIV sampled from wild birds iAuthorsTommy Tsan-Yuk Lam, Hon S. Ip, E. Ghedin, David E. Wentworth, Rebecca A. Halpin, T. B. Stockwell, Robert J. Dusek, James B. Bortner, Jenny Hoskins, Bradley D. Bales, Daniel R. Yparraguirre, E. C. HolmesEmergence of fatal avian influenza in New England harbor seals
From September to December 2011, 162 New England harbor seals died in an outbreak of pneumonia. Sequence analysis of postmortem samples revealed the presence of an avian H3N8 influenza A virus, similar to a virus circulating in North American waterfowl since at least 2002 but with mutations that indicate recent adaption to mammalian hosts. These include a D701N mutation in the viral PB2 protein, pAuthorsS.J. Anthony, J. A. St. Leger, K. Pugliares, Hon S. Ip, J.M. Chan, Z.W. Carpenter, I. Navarrete-Macias, M. Sanchez-Leon, J.T. Saliki, J. Pedersen, W. Karesh, P. Daszak, R. Rabadan, T. Rowles, W.I. LipkinThe effect of swab sample choice on the detection of avian influenza in apparently healthy wild ducks
Historically, avian influenza viruses have been isolated from cloacal swab specimens, but recent data suggest that the highly pathogenic avian influenza (HPAI) H5N1 virus can be better detected from respiratory tract specimens. To better understand how swab sample type affects the detection ability of low pathogenic avian influenza (LPAI) viruses we collected and tested four swab types: oropharyngAuthorsHon S. Ip, Robert J. Dusek, Dennis M. HeiseyPaired serologic and polymerase chain reaction analyses of avian influenza prevalence in Alaskan shorebirds
Surveillance has revealed low prevalence of avian influenza viruses (AIV) in shorebirds except Ruddy Turnstones (Arenaria interpres) on the North American Atlantic coast. Similarly, of five species of shorebirds surveyed in Alaska in 2010, Ruddy Turnstones had the highest AIV antibody prevalence; prevalence of AIV RNA was low or zero.AuthorsJohn M. Pearce, Daniel R. Ruthrauff, Jeffrey S. HallPresence of avian influenza viruses in waterfowl and wetlands during summer 2010 in California: Are resident birds a potential reservoir?
Although wild waterfowl are the main reservoir for low pathogenic avian influenza viruses (LPAIv), the environment plays a critical role for the circulation and persistence of AIv. LPAIv may persist for extended periods in cold environments, suggesting that waterfowl breeding areas in the northern hemisphere may be an important reservoir for AIv in contrast to the warmer southern wintering areas.AuthorsV. Henaux, M. D. Samuel, Robert J. Dusek, J. P. Fleskes, Hon S. IpEvidence for limited exchange of avian influenza viruses between seaducks and dabbling ducks at Alaska Peninsula coastal lagoons
Avian influenza virus (AIV) prevalence and sequence data were analyzed for Steller's eiders (Polysticta stelleri) to assess the role of this species in transporting virus genes between continents and maintaining a regional viral reservoir with sympatric northern pintails (Anas acuta). AIV prevalence was 0.2% at Izembek Lagoon and 3.9% at Nelson Lagoon for Steller's eiders and 11.2% for northern piAuthorsAndrew M. Ramey, John M. Pearce, Andrew B. Reeves, J. Christian Franson, Margaret R. Petersen, Hon S. Ip - News
Below are news stories related to avian influenza.
- FAQ
Below are FAQs related to avian influenza.
What is Avian Influenza?
Avian influenza (AI) is caused by an influenza type A virus that can infect poultry such as chickens, turkeys, pheasants, quail, domestic ducks, geese, and guinea fowl. It is carried by wild waterfowl (ducks and geese) and shorebirds. Learn more: USGS Avian Influenza
- Partners
Below are partners associated with avian influenza projects.