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{{Avian influenza}}
{{Avian influenza}}'''For more information about seasonal human influenza virus that is not associated with animal exposure, see [[Influenza]]'''<br><br>
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{{CMG}}


== Overview ==
== Overview ==
Following exposure to the [[avian influenza virus]], an incubation period of 2 to 3 days for [[H5N1]] and 2 to 8 days for H7N9 delays the onset of symptoms. The majority of patients present with with a high grade [[fever]], [[cough]], [[headache]], [[sore throat]], [[vomiting]], [[diarrhea]], and [[abdominal pain]]. Approximately 50% of patients with avian influenza develop severe complications such as [[acute respiratory distress syndrome]], [[renal failure]], [[sepsis]], and [[multiple organ dysfunction syndrome]]. Of the reported cases, about 60% of patients have died, particularly those who develop early complications. Patients without complicated disease usually recover within 3 to 5 days with no sequelae.


== Natural History ==
== Natural History ==
* Following initial exposure to the virus, the usual incubation period for the H5N1 avian influenza is approximately 2 to 3 days, but possibly as long as 17 days in some individuals. For the H7N9 avian influenza, the incubation period ranges from 2 to 8 days, with an average of 5 days.
* Following initial exposure to the [[virus]], the usual incubation period for the [[H5N1]] avian influenza is approximately 2 to 3 days, but possibly as long as 17 days in some individuals. For the H7N9 avian influenza, the [[incubation period]] ranges from 2 to 8 days, with an average of 5 days.<ref name=":0">Avian Influenza Factsheet. World Health Organization.&nbsp;http://www.who.int/mediacentre/factsheets/avian_influenza/en/ Accessed on April 22, 2015</ref>
* The majority of patients present with a high grade fever, cough, headache, sore throat, vomiting, diarrhea, abdominal pain.
* The majority of patients present with a high grade [[fever]], [[cough]], [[headache]], [[sore throat]], [[vomiting]], [[diarrhea]], [[abdominal pain]]. <ref name=":0" /><ref name=":1">Yuen KY, Chan PK, Peiris M, et al. Clinical features and rapid viral diagnosis of human disease associated with avian influenza A H5N1 virus. Lancet. 1998;351(9101):467-71. [http://www.ncbi.nlm.nih.gov/pubmed/9482437 PMID: 9482437]</ref>
* The illness is has an very aggressive clinical course, often with rapid deterioration.
* The illness is has an very aggressive clinical course, often with rapid deterioration.<ref name=":1" />
* Most patients develop significant lower respiratory tract involvement, with aggressive viral pneumonia, pleural effusions, and ARDS.
* Most patients develop significant [[lower respiratory tract]] involvement, with aggressive [[viral pneumonia]], [[pleural effusion]]<nowiki/>s, and [[ARDS]].<ref name=":1" />
* The rate of complications is very high with approximately 50% of patients suffering from life-threatening complications.
* The rate of complications is very high with approximately 50% of patients suffering from life-threatening complications.<ref name=":1" />


==Complications==
==Complications==
* [[Acute respiratory distress syndrome]]
Approximately 50% of patients with avian influenza develop one or more of the following complications:<ref name=":1" />
* [[Pneumonia]]
* Acute pulmonary hemorrhage
* Acute pulmonary hemorrhage
* [[Pneumonia]]
* [[Pleural effusion]]
* [[Pleural effusion]]
* [[Acute respiratory distress syndrome]]
* [[Acute renal failure]]
* [[Acute renal failure]]
* [[Multiple organ dysfunction syndrome]]
* [[Multiple organ dysfunction syndrome]]
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* [[Disseminated intravascular coagulopathy]]
* [[Disseminated intravascular coagulopathy]]
* [[Reye's syndrome]]
* [[Reye's syndrome]]
==Prognosis==
==Prognosis==
Of the human cases associated with the ongoing [[H5N1]] [[outbreak]]s in poultry and wild birds in Asia and parts of Europe, the Near East and Africa, more than half of those people reported [[infection|infected]] with the [[virus]] have died. Most cases have occurred in previously healthy children and young adults and have resulted from direct or close contact with [[H5N1]]-[[infection|infected]] poultry or [[H5N1]]-[[contamination|contaminated]] surfaces. In general, [[H5N1]] remains a very rare disease in people. The [[H5N1]] [[virus]] does not infect humans easily, and if a person is [[infection|infected]], it is very difficult for the [[virus]] to spread to another person.
Of the human cases associated with the [[H5N1]] outbreaks in [[poultry]] and wild birds in Asia and parts of Europe, the Near East, and Africa, about 60% of people reported to be [[infected]] with the virus have died. Most cases have occurred in previously healthy children and young adults.<ref name=":2">Key Facts About Avian Influenza (Bird Flu) and Highly Pathogenic Avian Influenza A (H5N1) Virus. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/avian/gen-info/facts.htm Accessed on April 22, 2015
</ref> Patients with early complications are at a much higher risk of death, often from [[multiple organ dysfunction syndrome]].<ref name=":1" /> Patients with no complications usually recover within 3 to 5 days with no [[sequelae]].<ref name=":2" />
==References==
==References==


{{Reflist|2}}
{{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:Microbiology]]
[[Category:Poultry diseases]]
[[Category:Emergency medicine]]
[[Category:Pulmonology]]
[[Category:Pulmonology]]
[[Category:Disease]]
[[Category:Occupational safety and health]]
[[Category:Needs overview]]
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Latest revision as of 20:22, 23 April 2015

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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]

Overview

Following exposure to the avian influenza virus, an incubation period of 2 to 3 days for H5N1 and 2 to 8 days for H7N9 delays the onset of symptoms. The majority of patients present with with a high grade fever, cough, headache, sore throat, vomiting, diarrhea, and abdominal pain. Approximately 50% of patients with avian influenza develop severe complications such as acute respiratory distress syndrome, renal failure, sepsis, and multiple organ dysfunction syndrome. Of the reported cases, about 60% of patients have died, particularly those who develop early complications. Patients without complicated disease usually recover within 3 to 5 days with no sequelae.

Natural History

Complications

Approximately 50% of patients with avian influenza develop one or more of the following complications:[2]

Prognosis

Of the human cases associated with the H5N1 outbreaks in poultry and wild birds in Asia and parts of Europe, the Near East, and Africa, about 60% of people reported to be infected with the virus have died. Most cases have occurred in previously healthy children and young adults.[3] Patients with early complications are at a much higher risk of death, often from multiple organ dysfunction syndrome.[2] Patients with no complications usually recover within 3 to 5 days with no sequelae.[3]

References

  1. 1.0 1.1 Avian Influenza Factsheet. World Health Organization. http://www.who.int/mediacentre/factsheets/avian_influenza/en/ Accessed on April 22, 2015
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Yuen KY, Chan PK, Peiris M, et al. Clinical features and rapid viral diagnosis of human disease associated with avian influenza A H5N1 virus. Lancet. 1998;351(9101):467-71. PMID: 9482437
  3. 3.0 3.1 Key Facts About Avian Influenza (Bird Flu) and Highly Pathogenic Avian Influenza A (H5N1) Virus. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/avian/gen-info/facts.htm Accessed on April 22, 2015

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