"influenza caused by viruses adapted to birds."
The National Institute of Allergy and Infectious Diseases (NIAID) awarded H5N1 vaccine contracts to Aventis Pasteur (now Sanofi Pasteur) of Swiftwater, Pennsylvania, and to Chiron Corporation of Emeryville, California.
All known viruses that cause influenza in birds belong to the species influenza A virus.
Adaptation is not exclusive. Being adapted towards a particular species does not preclude adaptations, or partial adaptations, towards infecting different species
While its most highly pathogenic strain (H5N1) had been spreading throughout Asia since 2003, avian influenza reached Europe in 2005, and the Middle East, as well as Africa, the following year. On January 22, 2012, China reported its second human death due to bird flu in a month following other fatalities in Vietnam and Cambodia.
There are many subtypes of avian influenza viruses, but only some strains of four subtypes have been highly pathogenic in humans. These are types H5N1, H7N3, H7N7, and H9N2.
once domesticated birds such as chickens or turkeys are infected, it could become much more deadly because the birds are often within close contact of one another. There is currently a large threat of this in Asia with infected poultry due to low hygiene conditions and close quarters . Although it is easy for humans to become infected from birds, it's much more difficult to do so from human to human without close and lasting contact.
Spreading of H5N1 from Asia to Europe is much more likely caused by both legal and illegal poultry trades than dispersing through wild bird migrations, being that in recent studies, there were no secondary rises in infection in Asia when wild birds migrate south again from their breeding grounds.
Influenza A/H5N1 has evolved into a flu virus strain that infects more species than any previously known strain, is deadlier than any previously known strain, and continues to evolve, becoming both more...
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