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DRAFT MATERIAL[edit]

Compiled version of lead[edit]

H?N? is a subtype of the influenza A virus, which causes influenza (flu).

H5N2[edit]

H5 N2 is a subtype of the species Influenzavirus A (avian influenza virus or bird flu virus). The subtype infects a wide variety of birds, including chickens, ducks, turkeys, falcons, and ostriches. Affected birds usually do not appear ill, and the disease is often mild as avian influenza viral subtypes go. Some variants of the subtype are much more pathogenic than others, and outbreaks of "high-path" H5N2 result in the culling of thousands of birds in poultry farms from time to time. It appears that people who work with birds can be infected by the virus, but suffer hardly any noticeable health effects. Even people exposed to the highly pathogenic H5N2 variety that killed ostrich chicks in South Africa only seem to have developed conjunctivitis, or a perhaps a mild respiratory illness. There is no evidence of human-to-human spread of H5N2. On November 12, 2005 it was reported that a falcon was found to have H5N2.[1] On June 5, 2024, the first confirmed human case of H5N2 was reported in Mexico.[2]

H5N1[edit]

Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus, which causes influenza (flu), predominantly in birds. It is enzootic (maintained in the population) in many bird populations, and also panzootic (affecting animals of many species over a wide area).[3] A/H5N1 virus can also infect mammals (including humans) that have been exposed to infected birds; in these cases, symptoms are frequently severe or fatal.[4]

H1N1[edit]

In virology, influenza A virus subtype H1N1 (A/H1N1) is a subtype of influenza A virus. Major outbreaks of H1N1 strains in humans include the 1918 Spanish flu pandemic, the 1977 Russian flu pandemic and the 2009 swine flu pandemic. It is an orthomyxovirus that contains the glycoproteins hemagglutinin (H) and neuraminidase (N), antigens whose subtypes are used to classify the strains of the virus as H1N1, H1N2 etc. Hemagglutinin causes red blood cells to clump together and binds the virus to the infected cell. Neuraminidase is a type of glycoside hydrolase enzyme which helps to move the virus particles through the infected cell and assist in budding from the host cells.[5]

Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza, for instance in 2004–2005.[6] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza). Its size is 80 to 120 nm (3.1×10−6 to 4.7×10−6 in) in diameter.[7]

H9N2[edit]

Influenza A virus subtype H9N2 (A/H9N2) is a subtype of the species Influenza A virus (bird flu virus).[8][9] Since 1998 a total of 86 cases of human infection with H9N2 viruses have been reported.[10]

H3N2[edit]

Influenza A virus subtype H3N2 (A/H3N2) is a subtype of viruses that causes influenza (flu). H3N2 viruses can infect birds and mammals. In birds, humans, and pigs, the virus has mutated into many strains. In years in which H3N2 is the predominant strain, there are more hospitalizations.[11]

H2N2[edit]

Influenza A virus subtype H2N2 (A/H2N2) is a subtype of Influenza A virus. H2N2 has mutated into various strains including the "Asian flu" strain (now extinct in the wild), H3N2, and various strains found in birds. It is also suspected of causing a human pandemic in 1889.[12][13] The geographic spreading of the 1889 Russian flu has been studied and published.[14]

H7N9[edit]

Influenza A virus subtype H7N9 (A/H7N9) is a bird flu strain of the species Influenza virus A (avian influenza virus or bird flu virus). Avian influenza A H7 viruses normally circulate amongst avian populations with some variants known to occasionally infect humans. An H7N9 virus was first reported to have infected humans in March 2013, in China.[15] Cases continued to be reported throughout April and then dropped to only a few cases during the summer months. At the closing of the year, 144 cases had been reported of which 46 had died.[16][17][18] It is known that influenza tends to strike during the winter months, and the second wave, which began in October, was fanned by a surge in poultry production timed for Lunar New Year feasts that began at the end of January. January 2014 brought a spike in reports of illness with 96 confirmed reports of disease and 19 deaths.[19][20] As of April 11, 2014, the outbreak's overall total was 419, including 7 in Hong Kong, and the unofficial number of deaths was 127.[21][22][23]

H5N6[edit]

H5N6 is a subtype of the species Influenza A virus (sometimes called bird flu virus). Infected birds shed the virus in their saliva, mucous, and feces. The virus was first detected in poultry in 2013, since then spreading among wild bird populations and poultry around the world. Humans can be infected through unprotected contact with infected birds or contaminated surfaces. The virus transmits by getting into a person's eyes, nose, mouth, and through inhalation. Human infections are rare. Since 2014, at least 87 cases have occurred in humans.[24] 29 people have died. A spike in human cases was reported in 2021. There have been no confirmed cases of human-to-human transmission. Some infections have been identified where no direct contact with infected birds or contaminated surfaces has been known to had occurred. Only one infected woman has said that she never came into any contact with poultry.[25][26][27][28]

H5N8[edit]

H5N8 is a subtype of the influenza A virus (sometimes called bird flu) and is highly lethal to wild birds and poultry.[29] H5N8 is typically not associated with humans. However, seven people in Russia were found to be infected in 2021, becoming the first documented human cases.[30][31]

H1N2[edit]

Influenza A virus subtype H1N2 (A/H1N2) is a subtype of the species Influenza A virus (sometimes called bird flu or swine flu). It is currently endemic in pig populations and is occasionally seen in humans.[32] The virus does not cause more severe illness than other influenza viruses, and no unusual increases in influenza activity have been associated with it.

Keep for future reference[edit]

Hidden text & footnote[edit]

... and a footnote.[a]

H5N1 deaths (transcluded from Influenza A virus subtype H5N1[edit]

Between 2003 and May 2024, the World Health Organization has recorded 892 cases of confirmed H5N1 influenza, leading to 463 deaths.[33] The true fatality rate may be lower because some cases with mild symptoms may not have been identified as H5N1.[34]

Highly Pathogenic Avian Influenza (keep & copy as required)[edit]

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 strain is highly pathogenic avian influenza (HPAI) if 75% or more of chickens die after being deliberately infected with it. The alternative classification is low pathogenic avian influenza (LPAI).[35] This classification system has since been modified to take into account the structure of the virus' haemagglutinin protein.[36] Other species of birds, especially water birds, can become infected with HPAI virus without experiencing severe symptoms and can spread the infection over large distances; the exact symptoms depend on the species of bird and the strain of virus.[35] Classification of an avian virus strain as HPAI or LPAI does not predict how serious the disease might be if it infects humans or other mammals.[37][38]

Influenza virus nomenclature (keep & copy as required)[edit]

Diagram of influenza nomenclature

To unambiguously describe a specific isolate of virus, researchers use the internationally accepted Influenza virus nomenclature,[39] which describes, among other things, the species of animal from which the virus was isolated, and the place and year of collection. As an example - A/chicken/Nakorn-Patom/Thailand/CU-K2/04(H5N1):

  • A stands for the genus of influenza (A, B or C).
  • chicken is the animal species the isolate was found in (note: human isolates lack this component term and are thus identified as human isolates by default)
  • Nakorn-Patom/Thailand is the place this specific virus was isolated
  • CU-K2 is the laboratory reference number that identifies it from other influenza viruses isolated at the same place and year
  • 04 represents the year of isolation 2004
  • H5 stands for the fifth of several known types of the protein hemagglutinin.
  • N1 stands for the first of several known types of the protein neuraminidase.

Other examples include: A/duck/Hong Kong/308/78(H5N3), A/avian/NY/01(H5N2), A/chicken/Mexico/31381-3/94(H5N2), and A/shoveler/Egypt/03(H5N2).[40]

Research (keep & copy as required)[edit]

Influenza research includes efforts to understand how influenza viruses enter hosts, the relationship between influenza viruses and bacteria, how influenza symptoms progress, and why some influenza viruses are deadlier than others.[41] Past pandemics, and especially the 1918 pandemic, are the subject of much research to understand flu pandemics.[42][43]

The World Health Organization has published a Research Agenda with five streams:[44]

  • Stream 1. Reducing the risk of emergence of pandemic influenza. This stream is entirely focused on preventing and limiting pandemic influenza; this includes research into what characteristics make a strain either mild or deadly, worldwide surveillance of influenza A viruses with pandemic potential, and the prevention and management of potentially zoonotic influenza in domestic and farmed animals.[44]
  • Stream 2. Limiting the spread of pandemic, zoonotic and seasonal epidemic influenza. This is more broadly targeted at both pandemic and seasonal influenza, looking at the transmission of the virus between people and the ways in which it can spread globally, as well as the environmental and social factors which affect transmission.[44]
  • Stream 3. Minimizing the impact of pandemic, zoonotic, and seasonal epidemic influenza. This is principally concerned with vaccination - improving the effectiveness of vaccines, vaccine technology, as well as the speed with which an effective vaccine can be developed and ways in which vaccines can be manufactured and delivered worldwide.[44]
  • Stream 4. Optimizing the treatment of patients. This stream aims to reduce the impact of influenza by looking at methods of treatment, vulnerable groups, genetic predispositions, the interaction of influenza infection with other diseases, and influenza sequelae.[44]
  • Stream 5. Promoting the development and application of modern public health tools.[44] Aiming to improve the ways in which public policy can combat influenza; this includes the introduction of new technologies, epidemic and pandemic modelling, and the communication of accurate and trustworthy information to the public.[44]

References[edit]

  1. ^ [1] article Kuwait: Avian influenza H5N1 confirmed case in flamingo November 12, 2005
  2. ^ Dugar, Urvi (5 June 2024). "WHO confirms first human case of avian influenza A(H5N2) in Mexico". Reuters.
  3. ^ "Influenza (Avian and other zoonotic)". who.int. World Health Organization. 3 October 2023. Retrieved 2024-05-06.
  4. ^ Bourk, India (26 April 2024). "'Unprecedented': How bird flu became an animal pandemic". bbc.com. BBC. Retrieved 2024-05-08.
  5. ^ Lim, Boon H.; Mahmood, Tahir A. (23 September 2011). "Influenza A H1N1 2009 (Swine Flu) and Pregnancy". Journal of Obstetrics and Gynaecology. 61 (4): 386–93. doi:10.1007/s13224-011-0055-2. PMC 3295877. PMID 22851818.
  6. ^ "Influenza Summary Update 20, 2004–2005 Season". FluView: A Weekly Influenza Surveillance Report. Centers for Disease Control and Prevention. Archived from the original on 16 October 2020. Retrieved 9 September 2017.
  7. ^ Jilani TN, Jamil RT, Siddiqui AH (November 30, 2020). "H1N1 Influenza". H1N1 Influenza in StatPearls. StatPearls. PMID 30020613. Archived from the original on 12 March 2020. Retrieved 25 August 2020.
  8. ^ Guan Y, Shortridge KF, Krauss S, Webster RG (August 1999). "Molecular characterization of H9N2 influenza viruses: were they the donors of the "internal" genes of H5N1 viruses in Hong Kong?". Proc. Natl. Acad. Sci. U.S.A. 96 (16): 9363–7. Bibcode:1999PNAS...96.9363G. doi:10.1073/pnas.96.16.9363. PMC 17788. PMID 10430948.
  9. ^ NAID NIH Archived 2010-03-06 at the Wayback Machine
  10. ^ "COMMUNICABLE DISEASE THREATS REPORT Week 16, 18-24 April 2021" (PDF). European Centre for Disease Prevention and Control. 23 April 2021. Retrieved 23 April 2021.
  11. ^ "Pinkbook | Influenza | Epidemiology of Vaccine Preventable Diseases | CDC". CDC. 2019-03-29. Retrieved 6 June 2019. Greater number of hospitalizations during years that A(H3N2) is predominant
  12. ^ Hilleman, Maurice R. (2002). "Realities and enigmas of human viral influenza: pathogenesis, epidemiology and control". Vaccine. 20 (25–26): 3068–3087. CiteSeerX 10.1.1.523.7697. doi:10.1016/S0264-410X(02)00254-2. PMID 12163258.
  13. ^ "The Influenza H5N1 Report". Pliva.com. April 2, 1998. Archived from the original on 24 October 2004.{{cite web}}: CS1 maint: unfit URL (link)
  14. ^ Alexis Madrigal (April 26, 2010). "1889 Pandemic Didn't Need Planes to Circle Globe in 4 Months". Wired. Wired Science. Archived from the original on April 29, 2010. Retrieved April 28, 2010.
  15. ^ "The fight against bird flu". Nature. 496 (7446): 397. April 24, 2013. doi:10.1038/496397a. PMID 23627002.
  16. ^ "Hong Kong's first case of deadly H7N9 bird flu virus confirmed". SCMP. December 3, 2013. Archived from the original on December 3, 2013. Retrieved December 3, 2013.
  17. ^ "Hong Kong sees second case of H7N9 bird flu in a week". SCMP. December 6, 2013. Archived from the original on December 7, 2013. Retrieved December 7, 2013.
  18. ^ WHO: Global Alert and Response: Human infection with avian influenza A(H7N9) virus – update Archived April 28, 2014, at the Wayback Machine (accessed November 7, 2013)
  19. ^ "H7N9 bird flu resurges in China ahead of Lunar New Year - CNN.com". CNN. January 30, 2014. Archived from the original on January 31, 2014. Retrieved January 30, 2014.
  20. ^ "H7N9 Bird Flu Not Just a China Problem – TIME.com". Time. Archived from the original on January 31, 2014. Retrieved January 30, 2014.
  21. ^ "Study says Vietnam at H7N9 risk as two new cases noted". March 17, 2014. Archived from the original on December 28, 2016. Retrieved March 23, 2014.
  22. ^ Commonground (February 7, 2014). "Pandemic Information News: #H7N9 Human Cases 2014". Archived from the original on March 10, 2014. Retrieved February 7, 2014.
  23. ^ "WPRO|Human Infection with Avian Influenza A(H7N9)". Archived from the original on February 2, 2014. Retrieved February 18, 2014.
  24. ^ "CHP closely monitors human case of avian influenza A(H5N6) on Mainland". www.info.gov.hk. Retrieved 2023-09-27.
  25. ^ "Tracking human cases of H5N6 bird flu". BNO News. Retrieved 28 October 2021.
  26. ^ "WHO calls for surveillance to explain rise in human cases of H5N6 bird flu". BNO News. Retrieved 5 October 2021.
  27. ^ Avian Influenza Weekly Update Number 811
  28. ^ "CDC Update on A(H5N6) Bird Flu: How is the U.S. CDC Monitoring A(H5N6) Infections and Contributing to Global Pandemic Preparedness?". CDC. November 1, 2021. Archived from the original on 3 January 2022. Retrieved 15 January 2022.
  29. ^ "Avian influenza overview – update on 19 November 2020, EU/EEA and the UK" (PDF). European Centre for Disease Prevention and Control. 19 November 2020.
  30. ^ "Russia reports first human cases of H5N8 bird flu". BNO News. 2021-02-20. Retrieved 2021-02-20.
  31. ^ "Human infection with avian influenza A (H5N8) – the Russian Federation". World Health Organization. 26 February 2021. Archived from the original on 26 February 2021. Retrieved 26 February 2021.
  32. ^ "What is Influenza H1N2?". News-Medical.net. 2010-05-31. Retrieved 2023-12-01.
  33. ^ "Avian influenza A(H5N1) virus". www.who.int. Retrieved 2024-05-28.
  34. ^ Li FC, Choi BC, Sly T, Pak AW (June 2008). "Finding the real case-fatality rate of H5N1 avian influenza". J Epidemiol Community Health. 62 (6): 555–9. doi:10.1136/jech.2007.064030. PMID 18477756. S2CID 34200426.
  35. ^ a b Alexander, D. J.; Brown, I. H. (2009). "History of high pathogenic avian influenza". Rev. Sci. Tech. 28 (1): 19–38. doi:10.20506/rst.28.1.1856. PMID 19618616.
  36. ^ "Factsheet on A(H5N1)". European Centre for Disease Control. 2017-06-15. Retrieved 2024-05-21.
  37. ^ CDC (30 May 2024). "Avian Influenza Type A Viruses". Centers for Disease Control and Prevention. Retrieved 2024-07-07.
  38. ^ CDC (2024-04-05). "Current U.S. Bird Flu Situation in Humans". Centers for Disease Control and Prevention. Retrieved 2024-05-22.
  39. ^ "A revision of the system of nomenclature for influenza viruses: a WHO Memorandum". Bull World Health Organ. 1980; : (58(4)): 585–591. 1980. PMC 2395936. PMID 6969132 – via National Library of Medicine. This Memorandum was drafted by the signatories listed on page 590 on the occasion of a meeting held in Geneva in February 1980.{{cite journal}}: CS1 maint: extra punctuation (link)
  40. ^ Payungporn S, Chutinimitkul S, Chaisingh A, Damrongwantanapokin S, Nuansrichay B, Pinyochon W, Amonsin A, Donis RO, Theamboonlers A, Poovorawan T (2006). "Discrimination between Highly Pathogenic and Low Pathogenic H5 Avian Influenza A Viruses". Emerging Infectious Diseases. 12 (4): 700–701. doi:10.3201/eid1204.051427. PMC 3294708. PMID 16715581.
  41. ^ "Influenza Basic Research". National Institute of Allergy and Infectious Diseases. 13 March 2017. Archived from the original on 10 June 2024. Retrieved 24 March 2021.
  42. ^ Potter CW (October 2001). "A history of influenza". Journal of Applied Microbiology. 91 (4): 572–579. doi:10.1046/j.1365-2672.2001.01492.x. PMID 11576290. S2CID 26392163.
  43. ^ Taubenberger JK, Baltimore D, Doherty PC, Markel H, Morens DM, Webster RG, Wilson IA (November 2012). "Reconstruction of the 1918 influenza virus: unexpected rewards from the past". mBio. 3 (5). doi:10.1128/mBio.00201-12. PMC 3448162. PMID 22967978.
  44. ^ a b c d e f g "WHO public health research agenda for influenza: 2017 update". World Health Organization;. Geneva. 2017. Retrieved 2024-06-28.{{cite web}}: CS1 maint: extra punctuation (link)


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