An avian flu virus is any flu virus that spreads among birds, especially domestic chickens, and can result in substantial economic losses and outbreak concerns. Between 1918 and 1919, the Spanish flu virus, a mutated variant of the H1N1 avian flu virus, caused the death of between 50 and 100 million humans worldwide in a single year. A large outbreak of the H5N1 avian flu in southeast Asia in 2005 caused the destruction of millions of chickens and international concern about the possibility of the virus mutating into a human-transmissible form. This has not yet occurred, but there is a constant worry that it will, leading to a possible repeat of the 1918 disaster.
Avian flu is caused by Influenza A virus, the only species in the viral genus called Influenzavirus A. This genus is one of five that makes up the viral family Orthomyxoviridae, which includes all influenza viruses. Avian flu is technically what the virus is called only when it is infecting birds – when spread to other animals, it is alternatively known as Human Flu, Swine Flu, Horse Flu, Dog Flu, and so on.
The Influenza A virus, the organism behind avian flu, stores its genetic information in eight linear segments of RNA, which code for as many as eleven proteins. Its genetic information can recombine within infected host cells to produce new strains. Certain antiviral drugs can become obsolete within a mere decade as a result of this continuous mutation. During any given flu season or flu pandemic, a flu virus reproduces millions of trillions of times, leaving much room for variation and natural selection.
H5N1, the current strain of avian flu that is a threat, has spread from chickens to humans in about a hundred instances in southeast Asia since the virus emerged there. No human-to-human transmission has ever happened, and the only people infected are those who have had close exposure to many chickens and their viral manure. However, as many as half of those infected have died. When chicken meat is cooked thoroughly, it will not spread the disease, though this did not prevent the destruction of millions of chickens when the disease was suspected among them. In recent years, the avian flu has been a topic of political discussion in the United States and elsewhere, with several major governments stockpiling medicines for treating the disease and formulating strategies to confront a future outbreak.