Acute viral nasopharyngitis pathophysiology: Difference between revisions
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==Overview== | ==Overview== | ||
[[Rhinovirus]] (the most common cause of common cold) is usually transmitted via aerosol generated by coughing or sneezing. Following transmission, the [[virus]] invades the [[epithelial cells]] and causes the release of [[Cytokines|inflammatory cytokines]] that | [[Rhinovirus]] (the most common cause of common cold) is usually transmitted via aerosol generated by coughing or sneezing. Following transmission, the [[virus]] invades the [[epithelial cells]] and causes the release of [[Cytokines|inflammatory cytokines]] that lead to the various symptoms of cold. | ||
==Pathophysiology== | ==Pathophysiology== | ||
===Virus=== | ===Virus=== | ||
Common colds are most often caused | Common colds are most often caused via infection by one of the more than 100 [[serovar|serotypes]] of [[rhinovirus]], a type of [[picornavirus]]. Other viruses causing colds are [[coronavirus]], [[human parainfluenza viruses]], [[human respiratory syncytial virus]], [[Adenoviridae|adenoviruses]], [[enterovirus]]es, or [[metapneumovirus]].<ref name="Merck">{{cite web | title = Common Cold (Upper Respiratory Infection) | work = The Merck Manual Online | publisher = [[Merck & Co.]] | date = November 2005 | url = http://www.merck.com/mmpe/sec14/ch188/ch188c.html}}</ref><ref name="CKS">{{cite web | author = CKS | year = 2007 | title = Common Cold (Topic Review) | publisher = Clinical Knowledge Summaries Service | url = http://www.cks.library.nhs.uk/common_cold/view_whole_topic_review}}</ref><ref name="pmid10567986">{{cite journal |vauthors=van Kempen M, Bachert C, Van Cauwenberge P |title=An update on the pathophysiology of rhinovirus upper respiratory tract infections |journal=Rhinology |volume=37 |issue=3 |pages=97–103 |year=1999 |pmid=10567986 |doi= |url=}}</ref> | ||
===Transmission=== | ===Transmission=== | ||
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The common cold virus is transmitted between people by one of two ways: | The common cold virus is transmitted between people by one of two ways: | ||
:* In aerosol form generated by coughing, sneezing | :* In aerosol form generated by coughing, sneezing. | ||
:* | :* Contact with the [[saliva]] or nasal secretions of an infected person, either directly or from contaminated surfaces. | ||
* Asymptomatic patients can | * Asymptomatic patients can transmit the infection.<ref name="gsacc">{{cite web | url=http://dh.sa.gov.au/pehs/Youve-got-what/ygw-common-cold.pdf |type = pdf | title=Common Cold | publisher=Department of Health, Government of South Australia | year=2005}}</ref> | ||
* The infectious period (time during which an infected person can infect others) begins about one day before symptoms begin, and continues for the first five days of the illness. | * The infectious period (time during which an infected person can infect others) begins about one day before symptoms begin, and continues for the first five days of the illness. | ||
* The virus enters the [[cell (biology)|cells]] of the lining of the [[nasopharynx]] | * The virus enters the [[cell (biology)|cells]] of the lining of the [[nasopharynx]] and rapidly multiplies. | ||
* The virus enters the body mainly through the nose. Other entry points include the eyes (through drainage of tears from the [[lacrimal ducts]] into the [[nasopharynx]]). | * The virus enters the body mainly through the nose. Other entry points include the eyes (through drainage of tears from the [[lacrimal ducts]] into the [[nasopharynx]]). | ||
<br clear="left" /> | <br clear="left" /> | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Ahmed Younes M.B.B.CH [2]
Overview
Rhinovirus (the most common cause of common cold) is usually transmitted via aerosol generated by coughing or sneezing. Following transmission, the virus invades the epithelial cells and causes the release of inflammatory cytokines that lead to the various symptoms of cold.
Pathophysiology
Virus
Common colds are most often caused via infection by one of the more than 100 serotypes of rhinovirus, a type of picornavirus. Other viruses causing colds are coronavirus, human parainfluenza viruses, human respiratory syncytial virus, adenoviruses, enteroviruses, or metapneumovirus.[1][2][3]
Transmission
 |
The common cold virus is transmitted between people by one of two ways:
- In aerosol form generated by coughing, sneezing.
- Contact with the saliva or nasal secretions of an infected person, either directly or from contaminated surfaces.
- Asymptomatic patients can transmit the infection.[4]
- The infectious period (time during which an infected person can infect others) begins about one day before symptoms begin, and continues for the first five days of the illness.
- The virus enters the cells of the lining of the nasopharynx and rapidly multiplies.
- The virus enters the body mainly through the nose. Other entry points include the eyes (through drainage of tears from the lacrimal ducts into the nasopharynx).
{{#ev:youtube|GoRhRJXp0j8}}
Pathogenesis
- Viruses undergo frequent changes in their antigenic coat. This helps the viruses to evade the immune system and enables them to cause recurrent infections.
- Rhinovirus binds to ICAM-1 receptors on epithelial cells. Binding to ICAM-1 receptors releases inflammatory cytokines but does not cause damage to epithelial cells.
- Respiratory syncytial virus (RSV) does not cause any release of cytokines. Instead, it replicates in the nose and pharynx. In many occasions, it can spread to the lower respiratory tract.[5]
- Human parainfluenza virus causes inflammation of the tract and subsequently, parainfluenza infection is much more severe than other viruses.
- The body responds using both humoral immunity (IgA in the epithelium) and cell mediated immunity (different inflammatory cells in the adenoids and tonsils) to fight the offending virus.[3]
- Normal flora inhabitants in the nasopharynx also play an important role in eliminating the infection.
References
- ↑ "Common Cold (Upper Respiratory Infection)". The Merck Manual Online. Merck & Co. November 2005.
- ↑ CKS (2007). "Common Cold (Topic Review)". Clinical Knowledge Summaries Service.
- ↑ 3.0 3.1 van Kempen M, Bachert C, Van Cauwenberge P (1999). "An update on the pathophysiology of rhinovirus upper respiratory tract infections". Rhinology. 37 (3): 97–103. PMID 10567986.
- ↑ "Common Cold" (PDF) (pdf). Department of Health, Government of South Australia. 2005.
- ↑ Blaas D, Fuchs R (2016). "Mechanism of human rhinovirus infections". Mol Cell Pediatr. 3 (1): 21. doi:10.1186/s40348-016-0049-3. PMC 4889530. PMID 27251607.