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Latest revision as of 15:56, 17 February 2017

For more information about seasonal human influenza virus that is not associated with animal exposure, see Influenza

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.

Overview

To date, only influenza type A has been associated with avian influenza. Neither influenza B nor influenza C is associated with avian influenza. Classification of avian influenza may be based on either the pathogenicity of the virus (low pathogenicity vs. high pathogenicity) or the viral genetic subtypes (H5 vs. H7 vs. H9).

Classification

Classification of avian influenza may be based on either the pathogenicity of the virus or the viral genetic subtypes. To date, only influenza type A has been associated with avian influenza.

Classification Based on Pathogenecity of the Virus

Avian influenza may be classified based on the pathogenicity of the virus:

Low pathogenic avian influenza (LPAI)

Mild/no clinical manifestations among humans

May convert to highly pathogenic avian influenza

Highly pathogenic avian influenza (HPAI)

Moderate/severe clinical manifestations among humans

Viral subtypes H5 and H7 are associated with HPAI

Classification Based on Viral Genetic Subtypes

To date, only influenza type A has been associated with avian influenza. Neither influenza B nor influenza C is associated with avian influenza.
Although avian influenza has many subtypes of haemagglutinin (HA) and neuraminidase (NA), only 3 subtypes have been associated with human infections.
The table below lists the subtypes of influenza A that have been associated with avian influenza in humans:^[1]^[2]^[3]


Influenza Subtype	Number of Subtypes	Pathogenicity	Clinical Manifestations
Influenza A H5	At least 9	May be either HPAI or LPAI	May cause either mild or severe/fatal clinical manifestations
Influenza A H7	At least 9	May be either HPAI or LPAI	May cause either mild or severe/fatal clinical manifestations
Influenza A H9	At least 9	Only reported as LPAI	Mild clinical manifestations in humans

References

↑ Gao R, Cao B, Hu Y, Feng Z, Wang D, Hu W, Chen J, Jie Z, Qiu H, Xu K, Xu X, Lu H, Zhu W, Gao Z, Xiang N, Shen Y, He Z, Gu Y, Zhang Z, Yang Y, Zhao X, Zhou L, Li X, Zou S, Zhang Y, Li X, Yang L, Guo J, Dong J, Li Q, Dong L, Zhu Y, Bai T, Wang S, Hao P, Yang W, Zhang Y, Han J, Yu H, Li D, Gao GF, Wu G, Wang Y, Yuan Z, Shu Y (2013). "Human infection with a novel avian-origin influenza A (H7N9) virus". N. Engl. J. Med. 368 (20): 1888–97. doi:10.1056/NEJMoa1304459. PMID 23577628.
↑ Liu D, Shi W, Shi Y, Wang D, Xiao H, Li W, Bi Y, Wu Y, Li X, Yan J, Liu W, Zhao G, Yang W, Wang Y, Ma J, Shu Y, Lei F, Gao GF (2013). "Origin and diversity of novel avian influenza A H7N9 viruses causing human infection: phylogenetic, structural, and coalescent analyses". Lancet. 381 (9881): 1926–32. doi:10.1016/S0140-6736(13)60938-1. PMID 23643111.
↑ Xiong C, Zhang Z, Jiang Q, Chen Y (2013). "Evolutionary characteristics of A/Hangzhou/1/2013 and source of avian influenza virus H7N9 subtype in China". Clin. Infect. Dis. 57 (4): 622–4. doi:10.1093/cid/cit294. PMID 23650290.

Template:WH Template:WS

[pmid23577628-1] Gao R, Cao B, Hu Y, Feng Z, Wang D, Hu W, Chen J, Jie Z, Qiu H, Xu K, Xu X, Lu H, Zhu W, Gao Z, Xiang N, Shen Y, He Z, Gu Y, Zhang Z, Yang Y, Zhao X, Zhou L, Li X, Zou S, Zhang Y, Li X, Yang L, Guo J, Dong J, Li Q, Dong L, Zhu Y, Bai T, Wang S, Hao P, Yang W, Zhang Y, Han J, Yu H, Li D, Gao GF, Wu G, Wang Y, Yuan Z, Shu Y (2013). "Human infection with a novel avian-origin influenza A (H7N9) virus". N. Engl. J. Med. 368 (20): 1888–97. doi:10.1056/NEJMoa1304459. PMID 23577628.

[pmid23643111-2] Liu D, Shi W, Shi Y, Wang D, Xiao H, Li W, Bi Y, Wu Y, Li X, Yan J, Liu W, Zhao G, Yang W, Wang Y, Ma J, Shu Y, Lei F, Gao GF (2013). "Origin and diversity of novel avian influenza A H7N9 viruses causing human infection: phylogenetic, structural, and coalescent analyses". Lancet. 381 (9881): 1926–32. doi:10.1016/S0140-6736(13)60938-1. PMID 23643111.

[pmid23650290-3] Xiong C, Zhang Z, Jiang Q, Chen Y (2013). "Evolutionary characteristics of A/Hangzhou/1/2013 and source of avian influenza virus H7N9 subtype in China". Clin. Infect. Dis. 57 (4): 622–4. doi:10.1093/cid/cit294. PMID 23650290.

[1]

[2]

[3]

@@ Line 1: / Line 1: @@
 __NOTOC__
-{{Avian influenza}}
+{{Avian influenza}}'''For more information about seasonal human influenza virus that is not associated with animal exposure, see [[Influenza]]'''<br><br>
-{{CMG}}
+{{CMG}}; {{AE}} {{YD}}
+==Overview==
+To date, only influenza type A has been associated with avian influenza. Neither [[influenza B]] nor [[influenza C]] is associated with avian influenza. Classification of avian influenza may be based on either the [[pathogenicity]] of the virus (low pathogenicity vs. high pathogenicity) or the viral genetic subtypes (H5 vs. H7 vs. H9).
-Please help WikiDoc by adding more content here.  It's easy!  Click  [[Help:How_to_Edit_a_Page|here]]  to learn about editing.
+==Classification==
+Classification of avian influenza may be based on either the pathogenicity of the virus or the viral genetic subtypes. To date, only influenza type A has been associated with avian influenza.
-==Overview==
+===Classification Based on Pathogenecity of the Virus===
-==Classification==
+Avian influenza may be classified based on the pathogenicity of the virus:
-===H5N1 Subtype===
+*Low pathogenic avian influenza (LPAI)
-{{H5N1}}
+::Mild/no [[Avian influenza history and symptoms|clinical manifestation]]s among humans
-{{details more|H5N1|Transmission and infection of H5N1}}
+::May convert to highly pathogenic avian influenza
-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.
+*Highly pathogenic avian influenza (HPAI)
+::Moderate/severe [[Avian influenza history and symptoms|clinical manifestation]]s among humans
+::Viral subtypes H5 and H7 are associated with HPAI
+===Classification Based on Viral Genetic Subtypes===
+*To date, only influenza type A has been associated with avian influenza. Neither influenza B nor influenza C is associated with avian influenza.
+*Although avian influenza has many subtypes of [[haemagglutinin]] (HA) and [[neuraminidase]] (NA), only 3 subtypes have been associated with human infections.
+*The table below lists the subtypes of influenza A that have been associated with avian influenza in humans:<ref name="pmid23577628">{{cite journal |vauthors=Gao R, Cao B, Hu Y, Feng Z, Wang D, Hu W, Chen J, Jie Z, Qiu H, Xu K, Xu X, Lu H, Zhu W, Gao Z, Xiang N, Shen Y, He Z, Gu Y, Zhang Z, Yang Y, Zhao X, Zhou L, Li X, Zou S, Zhang Y, Li X, Yang L, Guo J, Dong J, Li Q, Dong L, Zhu Y, Bai T, Wang S, Hao P, Yang W, Zhang Y, Han J, Yu H, Li D, Gao GF, Wu G, Wang Y, Yuan Z, Shu Y |title=Human infection with a novel avian-origin influenza A (H7N9) virus |journal=N. Engl. J. Med. |volume=368 |issue=20 |pages=1888–97 |year=2013 |pmid=23577628 |doi=10.1056/NEJMoa1304459 |url=}}</ref><ref name="pmid23643111">{{cite journal |vauthors=Liu D, Shi W, Shi Y, Wang D, Xiao H, Li W, Bi Y, Wu Y, Li X, Yan J, Liu W, Zhao G, Yang W, Wang Y, Ma J, Shu Y, Lei F, Gao GF |title=Origin and diversity of novel avian influenza A H7N9 viruses causing human infection: phylogenetic, structural, and coalescent analyses |journal=Lancet |volume=381 |issue=9881 |pages=1926–32 |year=2013 |pmid=23643111 |doi=10.1016/S0140-6736(13)60938-1 |url=}}</ref><ref name="pmid23650290">{{cite journal |vauthors=Xiong C, Zhang Z, Jiang Q, Chen Y |title=Evolutionary characteristics of A/Hangzhou/1/2013 and source of avian influenza virus H7N9 subtype in China |journal=Clin. Infect. Dis. |volume=57 |issue=4 |pages=622–4 |year=2013 |pmid=23650290 |doi=10.1093/cid/cit294 |url=}}</ref>
+{| style="border: 0px; font-size: 90%; margin: 3px;" align=center
+|+
+! style="background: #4479BA; width: 120px;" | {{fontcolor|#FFF|Influenza Subtype}}
+! style="background: #4479BA; width: 120px;" | {{fontcolor|#FFF|Number of Subtypes}}
+! style="background: #4479BA; width: 200px;" | {{fontcolor|#FFF|Pathogenicity}}
+! style="background: #4479BA; width: 150px;" | {{fontcolor|#FFF|Clinical Manifestations}}
+|-
+| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Influenza A H5]]'''
+| style="padding: 5px 5px; background: #F5F5F5;" | At least 9
+| style="padding: 5px 5px; background: #F5F5F5;" | May be either HPAI or LPAI
-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.<ref name=FSRIO>Food Safety Research Information Office. [http://fsrio.nal.usda.gov/document_fsheet.php?product_id=207 "A Focus on Avian Influenza"]. Created May 2006, Updated November 2007.</ref>
+| style="padding: 5px 5px; background: #F5F5F5;" | May cause either mild or severe/fatal clinical manifestations
+|-
+| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Influenza A H7]]'''
+| style="padding: 5px 5px; background: #F5F5F5;" | At least 9
-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. 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. <ref name=WHO>World Health Organization. (2006). [http://www.who.int/mediacentre/factsheets/avian_influenza/en/#humans Avian influenza (" bird flu") – The Disease in Humans.] Retrieved April 6, 2006.</ref>
+| style="padding: 5px 5px; background: #F5F5F5;" | May be either HPAI or LPAI
-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.
+| style="padding: 5px 5px; background: #F5F5F5;" | May cause either mild or severe/fatal clinical manifestations
-(View the most current WHO Data regarding [http://www.who.int/csr/disease/avian_influenza/country/en/ 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.
+|-
+| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Influenza A H9]]'''
+| style="padding: 5px 5px; background: #F5F5F5;" | At least 9
+| style="padding: 5px 5px; background: #F5F5F5;" | Only reported as LPAI
-'''Bird flu''' may refer to:
+| style="padding: 5px 5px; background: #F5F5F5;" | Mild clinical manifestations in humans
-* [[Avian influenza]] - another name for bird flu or avian influenza
+|-
-* [[H5N1]] - the current type of bird flu virus that is the worst pandemic threat
+|}
-* [[Influenzavirus A|Influenza A virus]] - the species of virus that causes all bird flu.
 ==References==
 {{Reflist|2}}
-[[Category:Needs content]]
+[[Category:Pandemics]]
-[[Category:Occupational safety and health]]
+[[Category:Influenza]]
-[[Category:Bird diseases]]
+[[Category:Infectious diseases]]
-[[Category:Avian influenza]]
+[[Category:Medicine]]
-[[Category:Infectious disease]]
+[[Category:Virology]]
-[[Category:Animal virology]]
 [[Category:Microbiology]]
-[[Category:Poultry diseases]]
-[[Category:Emergency medicine]]
 [[Category:Pulmonology]]
-[[Category:Disease]]
+[[Category:Occupational safety and health]]
 {{WH}}
 {{WS}}