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 lead to the various symptoms of cold. | [[Rhinovirus]] (the most common cause of common cold) is usually [[Transmission (medicine)|transmitted]] via [[aerosol]] generated by [[coughing]] or [[sneezing]]. Following [[Transmission (medicine)|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== | ||
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The common cold virus is transmitted between people by one of two ways: | The common cold virus is [[Transmission (medicine)|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. | :* Contact with the [[saliva]] or nasal secretions of an infected person, either directly or from contaminated surfaces. | ||
* 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> | * [[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]] and rapidly multiplies. | * 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 [[Eye|eyes]] (through drainage of [[tears]] from the [[lacrimal ducts]] into the [[nasopharynx]]). | ||
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==Pathogenesis== | ==Pathogenesis== | ||
* Viruses undergo frequent changes in their [[Antigenic|antigenic coat]]. This helps the [[viruses]] to evade the [[immune system]] and enables them to cause recurrent infections. | * [[Viruses]] undergo frequent changes in their [[Antigenic|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 [[Cytokine|inflammatory cytokines]] but does not cause damage to [[epithelial cells]]. | * [[Rhinovirus]] binds to [[ICAM-1]] receptors on [[epithelial cells]]. Binding to [[ICAM-1]] receptors releases [[Cytokine|inflammatory cytokines]] but does not cause damage to [[epithelial cells]]. | ||
* [[Respiratory syncytial virus|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]].<ref name="pmid27251607">{{cite journal |vauthors=Blaas D, Fuchs R |title=Mechanism of human rhinovirus infections |journal=Mol Cell Pediatr |volume=3 |issue=1 |pages=21 |year=2016 |pmid=27251607 |pmc=4889530 |doi=10.1186/s40348-016-0049-3 |url=}}</ref> | * [[Respiratory syncytial virus|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]].<ref name="pmid27251607">{{cite journal |vauthors=Blaas D, Fuchs R |title=Mechanism of human rhinovirus infections |journal=Mol Cell Pediatr |volume=3 |issue=1 |pages=21 |year=2016 |pmid=27251607 |pmc=4889530 |doi=10.1186/s40348-016-0049-3 |url=}}</ref> | ||
* [[Human parainfluenza virus]] causes [[inflammation]] of the tract and subsequently, [[Parainfluenza virus|parainfluenza]] infection is much more severe than other viruses. | * [[Human parainfluenza virus]] causes [[inflammation]] of the tract and subsequently, [[Parainfluenza virus|parainfluenza]] infection is much more severe than other [[viruses]]. | ||
* The body responds using both [[humoral immunity]] ([[IgA]] in the [[epithelium]]) and [[Cell-mediated immunity|cell mediated immunity]] (different [[inflammatory cells]] in the [[adenoids]] and [[tonsils]]) to fight the offending [[virus]].<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> | * The body responds using both [[humoral immunity]] ([[IgA]] in the [[epithelium]]) and [[Cell-mediated immunity|cell mediated immunity]] (different [[inflammatory cells]] in the [[adenoids]] and [[tonsils]]) to fight the offending [[virus]].<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> | ||
* [[Normal flora]] inhabitants in the [[nasopharynx]] also play an important role in eliminating the infection. | * [[Normal flora]] inhabitants in the [[nasopharynx]] also play an important role in eliminating the infection. | ||
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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:
- 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.