A highly infectious viral disease that affects poultry and other birds; often called avian influenza or popularly bird flu. It is spread by the movement of infected birds or contact with their secretions. There are about 100 strains of the disease. H5N1, the most deadly strain, which can be passed to humans, is a particular kind of H5 avian flu. Not all H5 viruses can infect human beings. H5N1 emerged in Hong Kong in 1997, killing or forcing the destruction of 1ยท5 million chickens, ducks and geese. It re-emerged in Korea in 2003, spread to other Asian countries and Russia, and in 2005 cases were confirmed in some European countries, initially Turkey, Romania, and Greece, then in Germany, Slovenia, France, and Poland in early 2006. The first cases of the virus in cats were reported in Germany and Austria in March that year. By that date, a total of 95 human deaths had been recorded in SE Asia from the H5N1 strain and three deaths in Turkey were the first outside SE Asia. In April 2006, a swan found dead in Scotland tested positive for the H5N1 strain, the first reported case in the UK. In October that year Indonesia confirmed its 55th human death, making it the worst affected country.
Flu| Flu Flu season Flu vaccine Flu treatment Avian flu H5N1 flu Flu research Genome sequencing |
Avian flu (also "bird flu", "avian influenza", "bird influenza"), means "flu from viruses adapted to birds", but is sometimes mistakenly used to refer to both other flu subsets (such as H5N1 flu) or the viruses that cause them (such as H5N1).
"Bird flu" is a phrase similar to "Pig flu", "Dog flu", "Horse flu", or "Human flu" in that it refers to an illness caused by any of many different strains of flu viruses such that the strain in question has adapted to the host. All subtypes (but not all strains of all subtypes) of Influenza A virus are adapted to birds, which is why for many purposes avian flu virus is the Influenza A virus (note that the "A" does not stand for "avian").
Genetic factors in distinguishing between "human flu viruses" and "avian flu viruses" include:
PB2: (RNA polymerase): Amino acid (or residue) position 627 in the PB2 protein encoded by the PB2 RNA gene. Until H5N1, all known avian influenza viruses had a Glu at position 627, while all human influenza viruses had a lysine. HA: (hemagglutinin): Avian influenza HA bind alpha 2-3 sialic acid receptors while human influenza HA bind alpha 2-6 sialic acid receptors.The HA changes have not yet occurred in any sequenced H5N1 virus - even ones from humans that died from it and the PB2 changes don't stop it from being a flu virus adapted to birds (the definition of "avian flu virus").
Pandemic flu viruses have some avian flu virus genes and usually some human flu virus genes. 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). 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. 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 inflects 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 the world's number one 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.
H5N1
As of 2006, "avian flu" is being commonly used to refer to infection from a particular subtype of Influenza A virus, H5N1, which can cause severe illness in humans who are infected.
Illustrative examples of correct usage
H5N1| Influenza A virus subtype H5N1 Genetic structure Infection Global spread in 2006 Social impact Pandemic |
|
WHO pandemic phases Low risk New virus Self limiting Person to person Epidemic exists Pandemic exists |
In technical contexts, correct usage of terms is necessary because precise distinctions are the essence of the communication.
"Avian influenza strains are those well adapted to birds" "An outbreak of influenza A (H5N1), also known as 'avian flu' or 'bird flu,' has been reported in several countries throughout Asia." "Avian influenza virus usually refers to influenza A viruses found chiefly in birds, but infections can occur in humans." "avian influenza HA bind alpha 2-3 sialic acid receptors while human influenza HA bind alpha 2-6 sialic acid receptors. "While the pandemic human influenza viruses of 1957 (H2N2) and 1968 (H3N2) clearly arose through reassortment between human and avian viruses, the influenza virus causing the 'Spanish flu' in 1918 appears to be entirely derived from an avian source (Belshe 2005)." Here "bird flu" is used to mean "Asian lineage HPAI A(H5N1) flu" (which is a bird flu) and contrasted with flu from an avian adapted strain of H7N3 (which is also a bird flu). ^ Full HTML text of Avian Influenza A (H5N1) Infection in Humans by The Writing Committee of the World Health Organization (WHO) Consultation on Human Influenza A/H5 in the September 29, 2005 New England Journal of Medicine ^ The Threat of Pandemic Influenza: Are We Ready? Workshop Summary (2005) Full text of online book by INSTITUTE OF MEDICINE OF THE NATIONAL ACADEMIES ^ Here is the tree showing evolution by antigenic drift since 2002 that created dozens of highly pathogenic varieties of the Z genotype of avian flu virus H5N1, some of which are increasingly adapted to mammals. ^ Evolutionary characterization of the six internal genes of H5N1 human influenza A virus ^ Chapter Two : Avian Influenza by Timm C. ^ OSHA ^ CDC Avian Influenza (Bird Flu) ^ WHO Avian influenza frequently asked questions ^ Greninger Paper (PDF) ^ News Avian flu quarantine zone lifted published May 1, 2006.Further reading
Official - international UN United Nations WHO World Health Organization The United Nation's World Health Organization's Avian Flu Facts Sheet for 2006 Epidemic and Pandemic Alert and Response Guide to WHO's H5N1 pages Avian Influenza Resources (updated) - tracks human cases and deaths National Influenza Pandemic Plans WHO Collaborating Centres and Reference Laboratories Centers, names, locations, and phone numbers FAO Avian Influenza portal Information resources, animations, videos, photos FAO Food and Agriculture Organisation - Bi-weekly Avian Influenza Maps - tracks animal cases and deaths FAO Bird Flu disease card FAO Socio-Economic impact of AI Projects, Information resources OIE World Organisation for Animal Health - tracks animal cases and deaths Official outbreak reports by country Official outbreak reports by week Chart of outbreaks by country Official - United States PandemicFlu.Gov U.S. Government's avian flu information site USAID U.S. Agency for International Development - Avian Influenza Response CDC Centers for Disease Control - responsible agency for avian influenza in humans in US - Facts About Avian Influenza (Bird Flu) and Avian Influenza A (H5N1) Virus USGS - NWHC National Wildlife Health Center - responsible agency for avian influenza in animals in US HHS U.S. Department of Health & Search for research publications about H5N1: Entez PubMed Latest publications on H5N1 Full HTML text of Avian Influenza A (H5N1) Infection in Humans by The Writing Committee of the World Health Organization (WHO) Consultation on Human Influenza A/H5 in the September 29, 2005 New England Journal of Medicine Evolutionary "Tree of Life" for H5N1: Here is the phylogenetic tree of the influenza virus hemagglutinin gene segment. Here is the tree showing evolution by antigenic drift since 2002 that created dozens of highly pathogenic varieties of the Z genotype of avian flu virus H5N1, some of which are increasingly adapted to mammals. WHO (PDF} contains latest Evolutionary "Tree of Life" for H5N1 article Antigenic and genetic characteristics of H5N1 viruses and candidate H5N1 vaccine viruses developed for potential use as pre-pandemic vaccines published August 18, 2006 Evolutionary characterization of the six internal genes of H5N1 human influenza A virus Genome database Page links to the complete sequence of the Influenza A virus (A/Goose/Guangdong/1/96(H5N1)) genome. General information Avian influenza disease and control strategies site sponsored by Intervet International CIDRAP-Avian Flu Nature Magazine focus on the global spread of H5N1 Bird Flu Fears: Is There a Better Way to Develop Drugs? (Center for Economic and Policy Research) October 2005 (PDF) Q&A: What is Bird Flu and Who's At Risk? Nature Magazine: Avian flu special: The flu pandemic: were we ready!? Workshop Summary (2005) - Online book by Board on Global Health (BGH) from the Institute of Medicine of The National Academies Flu Wiki Wikinews has news related to: Category:Avian Flu FAO's map of overlapping flyways for migratory waterfowl worldwide Google Earth updated maps of avian flu spread in poultry and humans Department of Health and Human Services Pandemic Planning Update A Report from Secretary Michael O. WHO Avian influenza resource (updated) CDC Facts About Avian Influenza (Bird Flu) and Avian Influenza A (H5N1) Virus FAO information on Avian Influenza - Latest news, Disease Card, Maps, Animations Avian Influenza (Bird Flu): Agricultural and Wildlife Considerations Woodrow Wilson International Center for Scholars (text and video) Emerging Pandemic: Costs and Consequences of an Avian Influenza Outbreak Critical Dialogues on Avian InfluenzaBringing Together the Public Health, Animal Health, and Wildlife Management Communities The Avian Flu Challenge in Southeast Asia: the Potential of Public-Private Partnerships News Blauer's Bird Flu and H5N1 News Overview using Reuters and Yahoo News Current status (Google news of "H5N1") Bird Flu news updates Bird Flu News Focus from SciDev.Net, regularly updated with the latest news stories
User Comments Add a comment…