Bird Flu (Avian Influenza, Avian Flu): Symptoms & Signs

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Medically Reviewed on 7/13/2017

Bird flu (avian flu or avian influenza) is type of influenza virus that mainly affects wild or domesticated birds. Bird flu spreads easily among birds, although transmission to humans is not common. Most human infections occur after exposure to infected birds or their droppings. The H5N1 strain of avian influenza virus arose in the late 1990s and proved to be highly pathogenic (causing severe illness and death) in birds. Since then, other strains of bird flu have been identified that also have the ability to cause severe disease and death. Human infections with a new avian influenza A (H7N9) virus were first reported in China in March 2013.

Bird flu symptoms and signs resemble those of influenza infection and include

Other symptoms can occur, like

As in birds, bird flu can lead to complications, including pneumonia and multiorgan failure, and has a high mortality (death) rate in infected humans.

Causes of bird flu (avian influenza)

Bird flu is caused by strains of the influenza virus that are able to infect avian (bird) cells. The virus that causes bird flu is an influenza A type virus. Bird flu viruses include influenza H5N1, H7N9, H7N7, H5N8, H5N2, and H9N2.


United States. Centers for Disease Control and Prevention. "Avian Influenza A (H7N9) Virus." May 23, 2017. <>.

Medically Reviewed by a Doctor on 7/13/2017

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