Avian influenza overview: Difference between revisions
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==Cause== | ==Cause== | ||
Avian influenza is caused by '''influenza A virus'''. Neither [[influenza B]] nor [[influenza C]] causes avian influenza. Influenza belongs to the ''[[Orthomyxoviridae]]'' family. Influenza is an [[enveloped]], [[pleomorphic]] ([[spherical]] and [[filamentous]] forms) virus that contains a [[linear]], [[segmented]] (8 segments), [[negative-sense]], [[single-stranded]] [[RNA]] genome. The genome is composed of 8 segmented genes that encode 11 proteins. | |||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
Avian influenza should be differentiated from the following diseases or pathogens that cause [[upper respiratory tract infection|upper]] or [[lower respiratory tract infection]] or [[flu-like illness]], such as other [[influenza virus]]es, such as [[human influenza|human]] or [[swine influenza]], other viral, bacterial, fungal, and parasitic agents that are typically associated with [[nasopharyngeal infection|nasopharyngeal]] and [[respiratory tract infection]]s, and non-infectious causes, such as [[asthma]], [[chronic obstructive pulmonary disease]] (COPD), [[drug adverse effects]], and [[cardiac]] causes. | Avian influenza should be differentiated from the following diseases or pathogens that cause [[upper respiratory tract infection|upper]] or [[lower respiratory tract infection]] or [[flu-like illness]], such as other [[influenza virus]]es, such as [[human influenza|human]] or [[swine influenza]], other viral, bacterial, fungal, and parasitic agents that are typically associated with [[nasopharyngeal infection|nasopharyngeal]] and [[respiratory tract infection]]s, and non-infectious causes, such as [[asthma]], [[chronic obstructive pulmonary disease]] (COPD), [[drug adverse effects]], and [[cardiac]] causes. | ||
Revision as of 17:45, 23 April 2015
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yazan Daaboul, M.D., Synonyms and keywords:, Gerald Chi, M.D.
Overview
Historical Perspective
Avian influenza was first described by Perroncito in 1878 in northern Italy following an outbreak of contagious disease of poultry. In 1918, the avian-descended influenza A H1N1 caused the first major human influenza pandemic. The first avian influenza A H5N1 virus infection in humans was described in 1997 in Hong Kong, where 18 cases were documented (including 6 deaths). The first human-to-human transmission of avian influenza infection was described in 2003 during the outbreaks in Southeast and Central Asia.
Pathophysiology
Classification
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).
Cause
Avian influenza is caused by influenza A virus. Neither influenza B nor influenza C causes avian influenza. Influenza belongs to the Orthomyxoviridae family. Influenza is an enveloped, pleomorphic (spherical and filamentous forms) virus that contains a linear, segmented (8 segments), negative-sense, single-stranded RNA genome. The genome is composed of 8 segmented genes that encode 11 proteins.
Differential Diagnosis
Avian influenza should be differentiated from the following diseases or pathogens that cause upper or lower respiratory tract infection or flu-like illness, such as other influenza viruses, such as human or swine influenza, other viral, bacterial, fungal, and parasitic agents that are typically associated with nasopharyngeal and respiratory tract infections, and non-infectious causes, such as asthma, chronic obstructive pulmonary disease (COPD), drug adverse effects, and cardiac causes.