Avian influenza, also known as bird flu, is an infectious disease that primarily affects birds. First identified in Europe, in Italy, over a century ago, avian influenza is an infection caused by influenza A viruses. Among these viruses, the H5, H7 and H9 subtypes are most commonly found.
Now widespread throughout the world, avian influenza can affect all species of wild and domestic birds. It poses a threat in industrial poultry farms, due to its contagiousness and high mortality (also known as "avian plague"). Avian influenza also poses a danger to humans due to the transmission of avian influenza from birds to humans (bird-to-mammal transmission).
How is bird flu and Avian influenza transmitted to humans?
In 1997, scientists reported the first case of human infection with the H5N1 strain or virus in Hong Kong, coinciding with a major outbreak of avian influenza in the region. To date, transmission of avian influenza to humans involves close contact between humans and infected birds. There is currently no direct human-to-human transmission of avian influenza, except in very rare cases. However, the spread of the avian influenza virus among birds increases the risk of developing a new virus that could lead to a human-to-human avian influenza, and cause a human avian influenza pandemic.
What causes a bird flu epidemic?
Exposure to infected live poultry is the main cause of Avian influenza in humans. In birds, the virus is transmitted through direct contact with a bird infected with the virus. Very often, it is the contact of a wild bird infected with the avian virus with a domestic bird that is the starting point for an avian influenza epidemic.
What are the signs and symptoms of bird flu in humans?
Symptoms of bird flu in humans appear, on average, between one and five days after exposure to the disease. They include:
a cough ;
shortness of breath;
a rise in fever ;
the appearance of muscle pain;
headaches.
In rarer cases, diarrhea , sore throat, fatigue or conjunctivitis can also be considered symptoms of bird flu. Note that it is possible for humans to be infected with bird flu without developing any symptoms.
In the most severe cases, bird flu can cause multiple organ failure and lead to death. Since 1997, one in two confirmed cases of bird flu has resulted in the death of the infected person.