Avian influenza: Difference between revisions
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==Influenza pandemic== | ==Influenza pandemic== | ||
Revision as of 15:56, 25 September 2012
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Avian influenza Microchapters |
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Avian influenza On the Web |
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American Roentgen Ray Society Images of Avian influenza |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Influenza pandemic
Template:Details more Pandemic flu viruses have some avian flu virus genes and usually some human flu virus genes. Both the H2N2 and H3N2 pandemic strains contained genes from avian influenza viruses. The new subtypes arose in pigs coinfected with avian and human viruses and were soon transferred to humans. Swine were considered the original "intermediate host" for influenza, because they supported reassortment of divergent subtypes. However, other hosts appear capable of similar coinfection (e.g., many poultry species), and direct transmission of avian viruses to humans is possible.[1] The Spanish flu virus strain may have been transmitted directly from birds to humans.[2] In spite of their pandemic connection, avian influenza viruses are noninfectious for most species. When they are infectious they are usually asymptomatic, so the carrier does not have any disease from it. Thus while infected with an avian flu virus, the animal doesn't have a "flu". Typically, when illness (called "flu") from an avian flu virus does occur, it is the result of an avian flu virus strain adapted to one species spreading to another species (usually from one bird species to another bird species). So far as is known, the most common result of this is an illness so minor as to be not worth noticing (and thus little studied). But with the domestication of chickens and turkeys, humans have created species subtypes (domesticated poultry) that can catch an avian flu virus adapted to waterfowl and have it rapidly mutate into a form that kills in days over 90% of an entire flock and spread to other flocks and kill 90% of them and can only be stopped by killing every domestic bird in the area. Until H5N1 infected humans in the 1990s, this was the only reason avian flu was considered important. Since then, avian flu viruses have been intensively studied; resulting in changes in what is believed about flu pandemics, changes in poultry farming, changes in flu vaccination research, and changes in flu pandemic planning. H5N1 has evolved into a flu virus strain that infects more species than any previously known flu virus strain, is deadlier than any previously known flu virus strain, and continues to evolve becoming both more widespread and more deadly causing Robert Webster, a leading expert on avian flu, to publish an article titled "The world is teetering on the edge of a pandemic that could kill a large fraction of the human population" in American Scientist. He called for adequate resources to fight what he sees as a major world threat to possibly billions of lives.[3] Since the article was written, the world community has spent billions of dollars fighting this threat with limited success.
H5N1
Template:H5N1 Template:Details more The highly pathogenic Influenza A virus subtype H5N1 virus is an emerging avian influenza virus that has been causing global concern as a potential pandemic threat. It is often referred to simply as "bird flu" or "avian influenza" even though it is only one subtype of avian influenza causing virus.
H5N1 has killed millions of poultry in a growing number of countries throughout Asia, Europe and Africa. Health experts are concerned that the co-existence of human flu viruses and avian flu viruses (especially H5N1) will provide an opportunity for genetic material to be exchanged between species-specific viruses, possibly creating a new virulent influenza strain that is easily transmissible and lethal to humans.[4]
Since the first H5N1 outbreak occurred in 1997, there has been an increasing number of HPAI H5N1 bird-to-human transmissions leading to clinically severe and fatal human infections. However, because there is a significant species barrier that exists between birds and humans, the virus does not easily cross over to humans, though some cases of infection are being researched to discern whether human to human transmission is occurring.[1] More research is necessary to understand the pathogenesis and epidemiology of the H5N1 virus in humans. Exposure routes and other disease transmission characteristics such as genetic and immunological factors, that may increase the likelihood of infection, are not clearly understood. [5]
Although millions of birds have become infected with the virus since its discovery, 206 humans have died from the H5N1 in twelve countries according to WHO data as of November 2007. (View the most current WHO Data regarding Cumulative Number of Human Cases.)
The Avian Flu claimed at least 200 humans in Romania, Greece, Turkey and Russia. Epidemioloigists are afraid that the next time such a virus mutates, it could pass from human to human. If this form of transmission occurs, another big pandemic could result. However, disease-control centers around the world are making avian flu their top priority.
Related Chapters
- H5N1
- Global spread of H5N1
- Transmission and infection of H5N1
- Subtypes of Influenza A virus
- Influenzavirus A
- Influenza pandemic
- Influenza Genome Sequencing Project
- Influenza research
- Influenza vaccine
- OIE/FAO Network of Expertise on Avian Influenza
- International Partnership on Avian and Pandemic Influenza
- Pandemic Preparedness and Response Act
References
- ↑ 1.0 1.1 Blanchard, Ben. "China says son likely infected father with bird flu." Reuters 10 Jen 2008 10 Jen 2008 <http://www.reuters.com/article/healthNews/idUSPEK27288320080110>.
- ↑ Chapter Two : Avian Influenza by Timm C. Harder and Ortrud Werner
- ↑ Webster, R. G. and Walker, E. J. (2003). "The world is teetering on the edge of a pandemic that could kill a large fraction of the human population". American Scientist. 91 (2): 122. doi:10.1511/2003.2.122.
- ↑ Food Safety Research Information Office. "A Focus on Avian Influenza". Created May 2006, Updated November 2007.
- ↑ World Health Organization. (2006). Avian influenza (" bird flu") – The Disease in Humans. Retrieved April 6, 2006.
External links
- International
- World Health Organisation (WHO)
- Food and Agriculture Organization of the UN (FAO)
- FAO Avian Influenza portal Information resources, animations, videos, photos
- FAO Bird Flu disease card
- World Organisation for Animal Health (OIE)
- United States
- PandemicFlu.Gov U.S. Government avian and pandemic flu information
- US Avian Influenza Response U.S. Agency for International Development (USAID)
- Europe
- Avian Influenza: Prevention and Control Proceedings of the Frontis workshop on Avian Influenza: Prevention and Control, Wageningen, The Netherlands
- Other
- Flu Wiki
- Bird Flu Pandemic Alert and Breaking News
- The spread of avian flu with time; new maps exploiting Google Earth’s time series function updated Google Earth maps of bird flu spread by Nature reporter Declan Butler
- birdfluthreat.org information page