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United States Department of Agriculture

Agricultural Research Service

Avian Influenza (1)
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Avian Influenza Virus


Bird flu (avian influenza virus)

"Bird flu" is the general term for Type A influenza virus strains which infect poultry and other avian species.  The term is synonymous with "avian influenza."  The natural reservoir species for bird flu are ducks, shorebirds and gulls.  The virus does not cause disease in these species, except in extremely rare cases.  Poultry including chickens and turkeys may become infected with the virus.  Most strains of avian influenza cause only mild disease, but rare strains can cause devastating disease.  Based on the severity of disease a particular bird flu strain causes in chickens and turkeys, it is classified as either low pathogenicity avian influenza (LPAI) or highly pathogenic avian influenza (HPAI).  Because avian influenza virus has important animal health and trade implications, poultry throughout the US is closely monitored for the presence of the virus.   


Historically, sporadic cases of low pathogenic strains of avian influenza virus have been detected in poultry in the US.  Although the disease caused by low pathogenic avian influenza virus is relatively mild, outbreaks can be very costly due to production losses, control measures and loss of export markets.  Highly pathogenic avian influenza virus was last seen in the US in 1983 in Pennsylvania. Control and eradication of this 1983 outbreak cost over $63 million in Federal funds and an additional $350 million in increased consumer costs.


The Asian H5N1 Bird Flu- An executive summary produced by the Respiratory Diseases Committee of the American Association of Avian Pathologists.


SEPRL and avian influenza virus (AIV) research

Avian Influenza research has focused on four major objectives:

  1. To determine how AIV causes disease in poultry and why some strains are more virulent than others
  2. To evaluate the genetics of the virus for epidemiological studies, which trace the origin of viruses during outbreaks.  Related to this, SEPRL is involved in surveillance of wild birds in North America for AIV.
  3. To develop control measures for the AIV, including vaccines and optimizing vaccine strategies.
  4. To develop diagnostic and detection tests for AIV.

SEPRL works with numerous academic researchers and institutions, other government agencies and industry to accomplish these goals and to provide practical solutions to scientific questions regarding AIV.


Some recent research accomplishments include:

••  The development of a rapid, sensitive and specific diagnostic for AIV called real-time RT-PCR, which has been utilized during outbreaks of AIV in the U.S. and numerous countries world-wide. 

••  The development and evaluation of novel vaccine types and formulations and developing the strategies for applying these vaccines, including determining which vaccine virus strains provide the best protection.

••  Demonstrating that during improper vaccine use AIV can undergo genetic changes that will decrease the protection provided by a vaccine, similar to what is seen with human influenza vaccine.

••  Determining that the risk of exposure to AIV through the food supply is negligible or minimal, and that AIV is rapidly inactivated by normal cooking and in the case of egg products, pasteurization.

••  Maintaining surveillance of free-flying birds throughout the U.S. for avian influenza virus, including Alaska, in collaboration with several universities.  This includes testing of over 12,000 samples since 1997. 

••  Characterizing AIV strains for numerous outbreaks in the U.S. and around the world.


Lead Scientist: David Suarez

Scientists: David Swayne

                Erica Spackman

                Mary Pantin-Jackwood

SEPRL and the Asian Bird Flu

SEPRL has been engaged in research focusing on the Asian H5N1 bird flu since 1997 when the virus first appeared.  Research performed by SEPRL has involved; evaluating the virulence of the virus for domestic poultry and numerous other bird species, identification of risk factors which could affect international trade, evaluating poultry health issues, developing diagnostic tests, developing and evaluating vaccines and assessing the food safety risk of the Asian bird flu. 

Last Modified: 8/13/2016
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