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==Overview==
=== Overview ===
 
== Historical Perspective ==
 
== Classification ==
 
== Pathophysiology ==
 
== Causes ==
 
== Differentiating Influenza from other Diseases ==
 
== Epidemiology and Demographics ==
 
== Risk Factors ==
 
== Natural History, Complications and Prognosis ==
 
== Diagnosis ==
 
=== History and Symptoms ===
 
=== Physical Examination ===
 
=== Laboratory Findings ===
 
=== Chest X Ray ===
 
=== Other Diagnostic Studies ===
 
== Treatment ==
 
=== Medical Therapy ===
 
Primary Prevention
 
Cost-Effectiveness of Therapy
 
Future or Investigational Therapies
<!---
=== Overview ===
Influenza, commonly known as flu, is an [[infectious disease]] of birds and [[mammal]]s caused by  [[RNA virus]]es of the biological family [[Orthomyxoviridae]] (the influenza viruses). In humans, common symptoms of influenza infection are [[fever]], [[pharyngitis|sore throat]], [[myalgia|muscle pains]], severe [[headache]], [[cough]]ing, [[fatigue (medical)|weakness]] and [[malaise|general discomfort]].<ref name=Merck>{{cite web |author= Merck Manual Home Edition |title=Influenza: Viral Infections |url= http://www.merck.com/mmhe/sec17/ch198/ch198c.html?}}</ref> In more serious cases, influenza [[sequela|causes]] [[pneumonia]], which can be fatal, particularly in young children and the elderly. Sometimes confused with the [[common cold]], influenza is a much more severe disease and is caused by a different type of virus.<ref name=Eccles>{{cite journal | last = Eccles | first = R | title = Understanding the symptoms of the common cold and influenza | journal = Lancet Infect Dis | volume = 5 | issue = 11 | pages = 718–25 | year = 2005 | id = PMID 16253889}}</ref> Although [[nausea]] and [[vomiting]] can be produced, especially in children,<ref name=Merck/> these symptoms are more characteristic of the unrelated [[gastroenteritis]], which is sometimes called "stomach flu" or "24-hour flu."<ref> [http://coldflu.about.com/od/flumisconceptions/f/stomachflu.htm Seasonal Flu vs. Stomach Flu] by Kristina Duda, R.N.; accessed March 12, 2007 (Website: "About, Inc., A part of The New York Times Company")</ref>
Influenza, commonly known as flu, is an [[infectious disease]] of birds and [[mammal]]s caused by  [[RNA virus]]es of the biological family [[Orthomyxoviridae]] (the influenza viruses). In humans, common symptoms of influenza infection are [[fever]], [[pharyngitis|sore throat]], [[myalgia|muscle pains]], severe [[headache]], [[cough]]ing, [[fatigue (medical)|weakness]] and [[malaise|general discomfort]].<ref name=Merck>{{cite web |author= Merck Manual Home Edition |title=Influenza: Viral Infections |url= http://www.merck.com/mmhe/sec17/ch198/ch198c.html?}}</ref> In more serious cases, influenza [[sequela|causes]] [[pneumonia]], which can be fatal, particularly in young children and the elderly. Sometimes confused with the [[common cold]], influenza is a much more severe disease and is caused by a different type of virus.<ref name=Eccles>{{cite journal | last = Eccles | first = R | title = Understanding the symptoms of the common cold and influenza | journal = Lancet Infect Dis | volume = 5 | issue = 11 | pages = 718–25 | year = 2005 | id = PMID 16253889}}</ref> Although [[nausea]] and [[vomiting]] can be produced, especially in children,<ref name=Merck/> these symptoms are more characteristic of the unrelated [[gastroenteritis]], which is sometimes called "stomach flu" or "24-hour flu."<ref> [http://coldflu.about.com/od/flumisconceptions/f/stomachflu.htm Seasonal Flu vs. Stomach Flu] by Kristina Duda, R.N.; accessed March 12, 2007 (Website: "About, Inc., A part of The New York Times Company")</ref>
Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating particulates/aerosols containing the virus, and from infected birds through their [[feces|droppings]].  Influenza can also be transmitted by [[saliva]], [[mucus|nasal secretions]], [[feces]] and [[blood]].  Infections also occur through contact with these body fluids or with contaminated surfaces.  
Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating particulates/aerosols containing the virus, and from infected birds through their [[feces|droppings]].  Influenza can also be transmitted by [[saliva]], [[mucus|nasal secretions]], [[feces]] and [[blood]].  Infections also occur through contact with these body fluids or with contaminated surfaces.  
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[[Vaccination]]s against influenza are most commonly given to high-risk humans in industrialized countries<ref name=WHOvaccines>[http://www.who.int/wer/2005/wer8033.pdf WHO position paper: influenza vaccines] ''WHO weekly Epidemiological Record'' 19 August 2005, vol. 80, 33, pp. 277–288.</ref> and to farmed poultry.<ref>{{cite journal | last = Villegas | first = P | title = Viral diseases of the respiratory system | journal = Poult Sci | volume = 77 | issue = 8 | pages = 1143–5 | year = 1998 | id = PMID 9706079}}</ref> The most common human vaccine is the trivalent [[flu vaccine]] that contains purified and inactivated material from three viral strains. Typically this vaccine includes material from two [[influenzavirus A|influenza A virus]] subtypes and one [[Influenzavirus B|influenza B virus]] strain.<ref>{{cite journal | last = Horwood | first = F | coauthors = Macfarlane J | title = Pneumococcal and influenza vaccination: current situation and future prospects. | url= http://thorax.bmjjournals.com/cgi/reprint/57/suppl_2/ii24.pdf | journal = Thorax | volume = 57 Suppl 2 | issue = | pages = II24–II30 | year = | id = PMID 12364707}}</ref> A vaccine formulated for one year may be ineffective in the following year, since the influenza virus changes rapidly over time and different strains become dominant.  [[Antiviral drug]]s can be used to treat influenza, with [[neuraminidase inhibitor]]s being particularly effective.
[[Vaccination]]s against influenza are most commonly given to high-risk humans in industrialized countries<ref name=WHOvaccines>[http://www.who.int/wer/2005/wer8033.pdf WHO position paper: influenza vaccines] ''WHO weekly Epidemiological Record'' 19 August 2005, vol. 80, 33, pp. 277–288.</ref> and to farmed poultry.<ref>{{cite journal | last = Villegas | first = P | title = Viral diseases of the respiratory system | journal = Poult Sci | volume = 77 | issue = 8 | pages = 1143–5 | year = 1998 | id = PMID 9706079}}</ref> The most common human vaccine is the trivalent [[flu vaccine]] that contains purified and inactivated material from three viral strains. Typically this vaccine includes material from two [[influenzavirus A|influenza A virus]] subtypes and one [[Influenzavirus B|influenza B virus]] strain.<ref>{{cite journal | last = Horwood | first = F | coauthors = Macfarlane J | title = Pneumococcal and influenza vaccination: current situation and future prospects. | url= http://thorax.bmjjournals.com/cgi/reprint/57/suppl_2/ii24.pdf | journal = Thorax | volume = 57 Suppl 2 | issue = | pages = II24–II30 | year = | id = PMID 12364707}}</ref> A vaccine formulated for one year may be ineffective in the following year, since the influenza virus changes rapidly over time and different strains become dominant.  [[Antiviral drug]]s can be used to treat influenza, with [[neuraminidase inhibitor]]s being particularly effective.


==Diagnosis==
=== Diagnosis ===
===History and Symptoms===
==== History and Symptoms ====
In humans, influenza's effects are much more severe than those of the [[common cold]], and last longer. Recovery takes about one to two weeks. Influenza, however, can be deadly, especially for the weak, old or chronically ill.
In humans, influenza's effects are much more severe than those of the [[common cold]], and last longer. Recovery takes about one to two weeks. Influenza, however, can be deadly, especially for the weak, old or chronically ill.


==Treatment==
=== Treatment ===
===Future or Investigational Therapies===
==== Future or Investigational Therapies ====


Research on influenza includes studies on [[molecular virology]], how the virus produces disease ([[pathogenesis]]), host [[immune response]]s, [[genomics|viral genomics]], and how the virus spreads ([[epidemiology]]). These studies help in developing influenza countermeasures; for example, a better understanding of the body's immune response helps [[vaccine]] development, and a detailed picture of how influenza invades cells aids the development of antiviral drugs. One important basic research program is the [[Influenza Genome Sequencing Project]], which is creating a library of influenza sequences; this library should help clarify which factors make one strain more lethal than another, which genes most affect [[immunogenicity]], and how the virus [[evolution|evolves]] over time.<ref> [http://msc.tigr.org/infl_a_virus/index.shtml Influenza A Virus Genome Project] at The Institute of Genomic Research. Accessed 19 Oct 06</ref>
Research on influenza includes studies on [[molecular virology]], how the virus produces disease ([[pathogenesis]]), host [[immune response]]s, [[genomics|viral genomics]], and how the virus spreads ([[epidemiology]]). These studies help in developing influenza countermeasures; for example, a better understanding of the body's immune response helps [[vaccine]] development, and a detailed picture of how influenza invades cells aids the development of antiviral drugs. One important basic research program is the [[Influenza Genome Sequencing Project]], which is creating a library of influenza sequences; this library should help clarify which factors make one strain more lethal than another, which genes most affect [[immunogenicity]], and how the virus [[evolution|evolves]] over time.<ref> [http://msc.tigr.org/infl_a_virus/index.shtml Influenza A Virus Genome Project] at The Institute of Genomic Research. Accessed 19 Oct 06</ref>
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The [[Influenza Genome Sequencing Project]] is creating a library of influenza sequences that will help us understand what makes one strain more lethal than another, what genetic determinants most affect [[immunogenicity]], and how the virus evolves over time.
The [[Influenza Genome Sequencing Project]] is creating a library of influenza sequences that will help us understand what makes one strain more lethal than another, what genetic determinants most affect [[immunogenicity]], and how the virus evolves over time.


==References==
--->
 
=== References ===
{{Reflist|2}}
{{Reflist|2}}



Revision as of 00:31, 25 October 2014

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Influenza from other Diseases

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Chest X Ray

Other Diagnostic Studies

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Medical Therapy

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Future or Investigational Therapies

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