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Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus, which causes the disease avian influenza (often referred to as "bird flu"). It is enzootic (maintained in the population) in many bird populations, and also panzootic (affecting animals of many species over a wide area). [ 1 ]
Avian influenza virus can survive for 100 days in distilled water at room temperature, and 200 days at 17 °C (63 °F). The avian virus is inactivated more quickly in manure, but can survive for up to two weeks in feces on cages. Avian influenza viruses can survive indefinitely when frozen. [57] Influenza viruses are susceptible to bleach, 70% ...
Avian influenza, also known as avian flu or bird flu, is a disease caused by the influenza A virus, which primarily affects birds but can sometimes affect mammals including humans. [1] Wild aquatic birds are the primary host of the influenza A virus, which is enzootic (continually present) in many bird populations.
Because of the impact of avian influenza on economically important chicken farms, a classification system was devised in 1981 which divided avian virus strains as either highly pathogenic (and therefore potentially requiring vigorous control measures) or low pathogenic. The test for this is based solely on the effect on chickens – a virus ...
The subtypes of influenza A virus are estimated to have diverged 2,000 years ago. Influenza viruses A and B are estimated to have diverged from a single ancestor around 4,000 years ago, while the ancestor of influenza viruses A and B and the ancestor of influenza virus C are estimated to have diverged from a common ancestor around 8,000 years ago.
Avian flu virus can last indefinitely at a temperature dozens of degrees below freezing, as is found in the northernmost areas that migratory birds frequent. [citation needed] Heat kills H5N1 (i.e. inactivates the virus). Influenza A viruses can survive: Over 30 days at 0 °C (32.0 °F) (over one month at freezing temperature)
[8] [10] In 2020, reassortment (genetic "swapping") between these H5-2.3.4.4b viruses and other strains of avian influenza led to the emergence of a H5N1 strain with a H5-2.3.4.4b gene. [8] The virus then spread across Europe, first detected there in the autumn of 2020, before spreading to Africa and Asia . [ 1 ]
While other H5N1 influenza strains are known, they are significantly different on a genetic level from a highly pathogenic, emergent strain of H5N1, which was able to achieve hitherto unprecedented global spread in 2008. [1] The H5N1 strain is a fast-mutating, highly pathogenic avian influenza virus (HPAI) found in multiple bird species. It is ...