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Bird Flu

(Avian Flu; Avian Influenza)


Brenda L. Tesini

, MD, University of Rochester School of Medicine and Dentistry

Reviewed/Revised Apr 2022 | Modified Sep 2022
  • The bird flu virus rarely spreads from animals to people (spread to people may occur if the genetic material of the virus mutates).

  • Nearly all people who have been infected with bird flu have had close contact with an infected bird (it almost never spreads from one person to another).

  • People may have extreme difficulty breathing and flu-like symptoms.

  • To diagnose bird flu, doctors test a sample of secretions from the nose or throat.

  • Bird flu is treated with antiviral drugs.

Bird flu is caused by several strains of influenza A virus that normally infect wild birds. The infection can spread to domestic birds. However, it rarely spreads from animals to people. It may spread from birds to people if the genetic material of the virus changes (mutates), enabling the virus to attach to cells in the human respiratory tract. Nearly all people who have been infected with bird flu have had close contact with an infected bird. Bird flu almost never spreads from person to person.

Human infection with the avian influenza strain H5N1 (see influenza types and strains Influenza types and strains Influenza (flu) is a viral infection of the lungs and airways with one of the influenza viruses. It causes a fever, runny nose, sore throat, cough, headache, muscle aches (myalgias), and a general... read more ) first occurred in Hong Kong in 1997 and then spread to other nations. Over 800 human infections and over 400 deaths have been confirmed since 2003. One human infection was confirmed in 2021 in India.

In 2013, an outbreak of the avian flu strain H7N9 began in southeastern China. Another wave of infection in humans in China peaked in 2016–2017 with nearly 800 cases, and only sporadic cases have been reported since that time. Worldwide, over 1500 human cases and at least 615 deaths have been reported to the World Health Organization since 2013. The infection has occurred mainly in communities that consume poultry from live poultry markets.

Other strains of the avian flu virus have also caused sporadic outbreaks of infection in people.

Symptoms of Bird Flu

H5N1 and H7N9, which cause most cases of bird flu in people, have similar effects.

Diagnosis of Bird Flu

  • Testing of a sample taken the nose or throat

People should contact a doctor to be tested for bird flu if they have flu-like symptoms plus one of the following:

  • They have had contact with birds in an area where birds are known to carry the infection.

  • They have had contact with a person infected with bird flu.

The doctor can send a sample taken by swabbing the nose or throat to be tested.

Prevention of Bird Flu

China is vaccinating poultry with a vaccine to prevent H5 and H7 flu viruses. This vaccination program can help prevent the bird flu virus from spreading from wild birds to domestic birds. Domestic birds are more likely to come in contact with people and spread the virus to them.

Spread is contained by identifying and destroying infected flocks of domestic birds.

A vaccine for H5N1 bird flu has been created; in the United States it would be available through the government in case of an epidemic. The standard vaccine for influenza does not prevent bird flu.

Treatment of Bird Flu

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