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.
Avian influenza shedding patterns in waterfowl: implications for surveillance, environmental transmission, and disease spread
Experimental challenge and pathology of highly pathogenic avian influenza virus H5N1 in dunlin (Calidris alpina), an intercontinental migrant shorebird species
Influence of body condition on influenza A virus infection in mallard ducks: Experimental infection data
Evaluation of Nobuto filter paper strips for the detection of avian influenza virus antibody in waterfowl
Intercontinental reassortment and genomic variation of low pathogenic avian influenza viruses isolated from northern pintails (Anas acuta) in Alaska: examining the evidence through space and time
Prevalence of antibodies to type A influenza virus in wild avian species using two serologic assays
Transmission and reassortment of avian influenza viruses at the Asian-North American interface
Limited evidence of trans-hemispheric movement of avian influenza viruses among contemporary North American shorebird isolates
Characterization of recombinant Raccoonpox Vaccine Vectors in Chickens
Model-based evaluation of highly and low pathogenic avian influenza dynamics in wild birds
Validation of a real-time reverse transcriptase-PCR assay for the detection of H7 avian influenza virus
Surveillance plan for the early detection of H5N1 highly pathogenic avian influenza virus in migratory birds in the United States: surveillance year 2009
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: 79Avian influenza shedding patterns in waterfowl: implications for surveillance, environmental transmission, and disease spread
Despite the recognized importance of fecal/oral transmission of low pathogenic avian influenza (LPAI) via contaminated wetlands, little is known about the length, quantity, or route of AI virus shed by wild waterfowl. We used published laboratory challenge studies to evaluate the length and quantity of low pathogenic (LP) and highly pathogenic (HP) virus shed via oral and cloacal routes by AI-infeAuthorsViviane Henaux, Michael D. SamuelExperimental challenge and pathology of highly pathogenic avian influenza virus H5N1 in dunlin (Calidris alpina), an intercontinental migrant shorebird species
Background Shorebirds (Charadriiformes) are considered one of the primary reservoirs of avian influenza. Because these species are highly migratory, there is concern that infected shorebirds may be a mechanism by which highly pathogenic avian influenza virus (HPAIV) H5N1 could be introduced into North America from Asia. Large numbers of dunlin (Calidris alpina) migrate from wintering areas in centAuthorsJeffrey S. Hall, J. Christian Franson, Robert E. Gill, Carol U. Meteyer, Joshua L. TeSlaa, Sean W. Nashold, Robert J. Dusek, Hon S. IpInfluence of body condition on influenza A virus infection in mallard ducks: Experimental infection data
Migrating waterfowl are implicated in the global spread of influenza A viruses (IAVs), and mallards (Anas platyrhynchos) are considered a particularly important IAV reservoir. Prevalence of IAV infection in waterfowl peaks during autumn pre-migration staging and then declines as birds reach wintering areas. Migration is energetically costly and birds often experience declines in body condition thaAuthorsDustin M. Arsnoe, Hon S. Ip, Jennifer C. OwenEvaluation of Nobuto filter paper strips for the detection of avian influenza virus antibody in waterfowl
The utility of using Nobuto paper strips for the detection of avian influenza antibodies was examined in mallards (Anas platyrhynchos) experimentally infected with low pathogenic avian influenza viruses. Blood was collected 2 wk after infection and was preserved either as serum or whole blood absorbed onto Nobuto strips. Analysis of samples using a commercially available blocking enzyme-linked immAuthorsRobert J. Dusek, Jeffrey S. Hall, Sean W. Nashold, Joshua L. Teslaa, Hon S. IpIntercontinental reassortment and genomic variation of low pathogenic avian influenza viruses isolated from northern pintails (Anas acuta) in Alaska: examining the evidence through space and time
Migration and population genetic data for northern pintails (Anas acuta) and phylogenetic analysis of low pathogenic avian influenza (LPAI) viruses from this host in Alaska suggest that northern pintails are involved in ongoing intercontinental transmission of avian influenza. Here, we further refine this conclusion through phylogenetic analyses which demonstrate that detection of foreign lineageAuthorsAndrew M. Ramey, John M. Pearce, Paul L. Flint, Hon S. Ip, Dirk V. Derksen, J. Christian Franson, Michael J. Petrula, Bradley D. Scotton, Kristine M. Sowl, Michael L. Wege, Kimberly A. TrustPrevalence of antibodies to type A influenza virus in wild avian species using two serologic assays
Serologic testing to detect antibodies to avian influenza (AI) virus has been an underused tool for the study of these viruses in wild bird populations, which traditionally has relied on virus isolation and reverse transcriptase-polymerase chain reaction (RT-PCR). In a preliminary study, a recently developed commercial blocking enzyme-linked immunosorbent assay (bELISA) had sensitivity and specifiAuthorsJustin D. Brown, M. Page Luttrell, Roy D. Berghaus, Whitney Kistler, Shamus P. Keeler, Andrea Howey, Benjamin Wilcox, Jeffrey S. Hall, Larry Niles, Amanda Dey, Gregory Knutsen, Kristen Fritz, David E. StallknechtTransmission and reassortment of avian influenza viruses at the Asian-North American interface
Twenty avian influenza viruses were isolated from seven wild migratory bird species sampled at St. Lawrence Island, Alaska. We tested predictions based on previous phylogenetic analyses of avian influenza viruses that support spatially dependent trans-hemispheric gene flow and frequent interspecies transmission at a location situated at the Asian–North American interface. Through the application oAuthorsAndrew M. Ramey, John M. Pearce, Craig R. Ely, Lisa M. Sheffield Guy, David B. Irons, Dirk V. Derksen, Hon S. IpLimited evidence of trans-hemispheric movement of avian influenza viruses among contemporary North American shorebird isolates
Migratory routes of gulls, terns, and shorebirds (Charadriiformes) are known to cross hemispheric boundaries and intersect with outbreak areas of highly pathogenic avian influenza (HPAI). Prior assessments of low pathogenic avian influenza (LPAI) among species of this taxonomic order found some evidence for trans-hemispheric movement of virus genes. To specifically clarify the role of shorebird spAuthorsJohn M. Pearce, Andrew M. Ramey, Hon S. Ip, Robert E. GillCharacterization of recombinant Raccoonpox Vaccine Vectors in Chickens
Raccoonpox virus (RCN) has been used as a recombinant vector against several mammalian pathogens but has not been tested in birds. The replication of RCN in chick embryo fibroblasts (CEFs) and chickens was studied with the use of highly pathogenic avian influenza virus H5N1 hemagglutinin (HA) as a model antigen and luciferase (luc) as a reporter gene. Although RCN replicated to low levels in CEFs,AuthorsS.-H. Hwa, Keith P. Iams, Jeffrey S. Hall, B.A. Kingstad, Jorge E. OsorioModel-based evaluation of highly and low pathogenic avian influenza dynamics in wild birds
There is growing interest in avian influenza (AI) epidemiology to predict disease risk in wild and domestic birds, and prevent transmission to humans. However, understanding the epidemic dynamics of highly pathogenic (HPAI) viruses remains challenging because they have rarely been detected in wild birds. We used modeling to integrate available scientific information from laboratory and field studiAuthorsViviane Hénaux, Michael D. Samuel, Christine M. BunckValidation of a real-time reverse transcriptase-PCR assay for the detection of H7 avian influenza virus
This report describes the validation of an avian influenza virus (AIV) H7 subtype-specific real-time reverse transcriptasePCR (rRT-PCR) assay developed at the Southeast Poultry Research Laboratory (SEPRL) for the detection of H7 AI in North and South American wild aquatic birds and poultry. The validation was a collaborative effort by the SEPRL and the National Veterinary Services Laboratories. ThAuthorsJ. Pedersen, M.L. Killian, N. Hines, D. Senne, B. Panigrahy, Hon S. Ip, Erica SpackmanSurveillance plan for the early detection of H5N1 highly pathogenic avian influenza virus in migratory birds in the United States: surveillance year 2009
Executive Summary: This Surveillance Plan (Plan) describes plans for conducting surveillance of wild birds in the United States and its Territories and Freely-Associated States to provide for early detection of the introduction of the H5N1 Highly Pathogenic Avian Influenza (HPAI) subtype of the influenza A virus by migratory birds during the 2009 surveillance year, spanning the period of April 1,AuthorsChristopher J. Brand - 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.