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| __NOTOC__
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| {{Polio}}
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| {{CMG}}
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| ==Overview==
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| ==Causes==
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| [[Image:Polio EM PHIL 1875 lores.PNG|thumb|left|A [[Transmission electron microscopy|TEM]] [[micrograph]] of poliovirus]]
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| {{main|Poliovirus}}
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| Poliomyelitis is caused by infection with a member of the [[genus]] ''[[enterovirus]]'' known as [[poliovirus]] (PV). This group of [[RNA virus]]es prefers to inhabit the [[gastrointestinal tract]].<ref name=Harrison /> PV [[pathogen|infects and causes disease]] in humans alone.<ref name=Sherris /> Its [[Virus#Structure|structure]] is very simple, composed of a single [[sense (molecular biology)|(+) sense]] [[RNA]] [[genome]] enclosed in a protein shell called a [[capsid]].<ref name=Sherris /> In addition to protecting the virus’s genetic material, the capsid proteins enable poliovirus to infect certain types of cells. Three [[serovar|serotype]]s of poliovirus have been identified—poliovirus type 1 (PV1), type 2 (PV2), and type 3 (PV3)—each with a slightly different capsid protein.<ref>{{cite book |author=Katz, Samuel L.; Gershon, Anne A.; Krugman, Saul; Hotez, Peter J. |title=Krugman's infectious diseases of children |publisher=Mosby |location=St. Louis |year=2004 |pages=81–97 |isbn=0-323-01756-8 |oclc= |doi=}}</ref> All three are extremely [[virulence|virulent]] and produce the same disease symptoms.<ref name=Sherris /> PV1 is the most commonly encountered form, and the one most closely associated with paralysis.<ref name= Ohri/>
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| Individuals who are exposed to the virus, either through infection or by [[immunization]] with polio vaccine, develop [[immunity (medical)|immunity]]. In immune individuals, [[IgA]] [[antibodies]] against poliovirus are present in the [[tonsil]]s and gastrointestinal tract and are able to block virus replication; [[IgG]] and [[IgM]] antibodies against PV can prevent the spread of the virus to motor neurons of the [[central nervous system]].<ref name=Kew_2005/> Infection or vaccination with one serotype of poliovirus does not provide immunity against the other serotypes, and full immunity requires exposure to each serotype.<ref name=Kew_2005/>
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| ==References==
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| {{Reflist|2}}
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| [[Category:Disease]]
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| [[Category:Infectious disease]]
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