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. Currently, this strain is transmitted by contact with infected birds, and has been transmitted from one person to another only in a few cases. H5N1 flu is therefore not pandemic now and is not currently capable of causing a pandemic. Only if H5N1 mutates into a form that can be readily transmitted from one person to another could it cause a pandemic.
Illustrative examples of correct usage
In technical contexts, correct usage of terms is necessary because precise distinctions are the essence of the communication.
- Low risk
- New virus
- Self limiting
- Person to person
- Epidemic exists
- Pandemic exists
- Influenza A virus subtype H5N1
- Genetic structure
- Infection
- Global spread
- "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."
- "Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of cases of severe disease and death in humans. Unlike normal seasonal influenza, where infection causes only mild respiratory symptoms in most people, the disease caused by H5N1 follows an unusually aggressive clinical course, with rapid deterioration and high fatality." Seasonal influenza is human flu.
- "avian influenza HA bind alpha 2-3 sialic acid receptors while human influenza HA bind alpha 2-6 sialic acid receptors. Swine influenza viruses have the ability to bind both types of sialic acid receptors."
- Sometimes a virus contains both avian adapted genes and human adapted genes. Both the H2N2 and H3N2 pandemic strains contained avian flu virus RNA segments. "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)."
Illustrative examples of imprecise usage
In nontechnical contexts, imprecise usage of terms is typical when discussing complex things.
- "A 1,000 square mile quarantine zone to combat an outbreak of bird flu was lifted in Scotland today - despite the spread of a similar disease south of the border." 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).
- H1N1
- H1N2
- H2N2
- H3N2
- H3N8
- H5N1
- H5N2
- H5N3
- H5N8
- H5N9
- H7N1
- H7N2
- H7N3
- H7N4
- H7N7
- H9N2
- H10N7
- Center for Biologics Evaluation and Research
- OIE/FAO Network of Expertise on Avian Influenza
- Flu research
- Flu vaccine
- H5N1 genetic structure
- ICEID
- Influenza Genome Sequencing Project
- Influenza pandemic
- Cytokine storm
- International Partnership on Avian and Pandemic Influenza
- National Influenza Centers
- Pandemic Preparedness and Response Act
- Reporting disease cases
- Transmission and infection of H5N1
Further reading
Influenza: research - vaccine - pandemic - Spanish flu - Avian influenza
Influenzaviruses: Influenzavirus A - Influenzavirus B - Influenzavirus C
Subtypes of type A flu: H1N1 - H1N2 - H2N2 - H3N2 - H3N8 - H5N1 - H5N2 - H5N3 - H5N8 - H5N9 - H7N1 - H7N2 - H7N3 - H7N4 - H7N7 - H9N2 - H10N7
- 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 & Human Services - Pandemic Influenza Plan
- Influenza Report 2006 Online book. Research level quality information. Highly recommended.
- Large-scale sequencing of human influenza reveals the dynamic nature of viral genome evolution Nature magazine presents a summary of what has been discovered in the Influenza Genome Sequencing Project.
- Links and descriptions to abstracts and full texts This bibliography of avian influenza publications was complied through the cooperative effort of the USGS National Wildlife Health Center and the Wildlife Disease Information Node.
- 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. Amino acid changes in three lineages (bird, pig, human) of the influenza virus hemagglutinin protein segment HA1.
- Here is the tree showing the evolution by reassortment of H5N1 from 1999 to 2004 that created the Z genotype in 2002.
- 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