Editing Common cold (section)

==Causes==
===Viruses===
[[File:Coronaviruses 004 lores.jpg|thumb|upright=1|[[Coronavirus]]es are a group of viruses known for causing the common cold. They have a halo or crown-like (corona) appearance when viewed under an electron microscope.]]
The common cold is an infection of the upper [[respiratory tract]] which can be caused by many different viruses. The most commonly implicated is a [[rhinovirus]] (30–80%), a type of [[picornavirus]] with 99 known [[serotype]]s.<ref>{{cite journal |vauthors=Palmenberg AC, Spiro D, Kuzmickas R, Wang S, Djikeng A, Rathe JA, Fraser-Liggett CM, Liggett SB |display-authors=6 |title=Sequencing and analyses of all known human rhinovirus genomes reveal structure and evolution |journal=Science |volume=324 |issue=5923 |pages=55–9 |date=April 2009 |pmid=19213880 |pmc=3923423 |doi=10.1126/science.1165557 |bibcode=2009Sci...324...55P}}</ref> Other commonly implicated viruses include [[coronavirus]]es, [[adenovirus]]es, [[enterovirus]]es, [[parainfluenza]] and [[Respiratory syncytial virus|RSV]].<ref name=ebm>{{cite book |chapter=Common Cold: Cause |vauthors=Janicki-Deverts D, Crittenden CN|title=Encyclopedia of Behavioral Medicine |page=504 |publisher=Springer |doi=10.1007/978-3-030-39903-0_795 |veditors=Gellman MD |year=2020 |edition=2nd|isbn=978-3-030-39901-6 |s2cid=242944824 }}</ref> Frequently more than one virus is present.<ref>Eccles p. 107</ref> In total, more than 200 viral types are associated with colds.<ref name=Eccles2005 /> The viral cause of some common colds (20–30%) is unknown.<ref name=ebm/>

===Transmission===
The common cold virus is typically transmitted via airborne droplets, direct contact with infected nasal secretions, or [[fomites]] (contaminated objects).<ref name=CE11/><ref name=Cold197>{{cite book |vauthors=Eccles R, Weber O |title=Common cold |year=2009 |publisher=Birkhäuser |location=Basel |isbn=978-3-7643-9894-1 |page=197 |url=https://books.google.com/books?id=rRIdiGE42IEC&pg=PA197 |edition=Online-Ausg. |url-status=live |archive-url=https://web.archive.org/web/20160502212944/https://books.google.com/books?id=rRIdiGE42IEC&pg=PA197 |archive-date=2 May 2016}}</ref>  Which of these routes is of primary importance has not been determined.<ref name=E211>Eccles pp. 211, 215</ref> As with all respiratory pathogens once presumed to transmit via respiratory droplets, it is highly likely to be carried by the aerosols generated during routine breathing, talking, and singing.<ref name="prather_jimenez_marr_1">{{cite journal|last1=Wang|first1=Chia C.|last2=Prather|first2=Kimberly A| last3=Sznitman|first3=Josué|last4=Jimenez|first4=Jose L|last5=Lakdawala|first5=Seema S.|last6=Tufekci|first6=Zeynep|last7=Marr|first7=Linsey C.|date=27 Aug 2021|title=Airborne transmission of respiratory viruses|journal=Science|volume=373|issue=6558 |doi=10.1126/science.abd9149|pmid=34446582 |pmc=8721651 }}</ref>  The viruses may survive for prolonged periods in the environment (over 18 hours for rhinoviruses) and can be picked up by people's hands and subsequently carried to their eyes or noses where infection occurs.<ref name=Cold197/> Transmission from animals is considered highly unlikely; an outbreak documented at a British scientific base on [[Adelaide Island]] after seventeen weeks of isolation was thought to have been caused by transmission from a contaminated object or an asymptomatic human carrier, rather than from the [[Siberian Husky|husky dogs]] which were also present at the base.<ref name=Allen1973>{{cite journal |vauthors=Allen TR, Bradburne AF, Stott EJ, Goodwin CS, Tyrrell DA |title=An outbreak of common colds at an Antarctic base after seventeen weeks of complete isolation |journal=The Journal of Hygiene |volume=71 |issue=4 |pages=657–67 |date=December 1973 |pmid=4520509 |pmc=2130424 |doi=10.1017/s0022172400022920 |author-link5=David Tyrrell (physician)}}</ref>

Transmission is common in daycare and schools due to the proximity of many children with little immunity and poor hygiene.<ref name=Text2007/> These infections are then brought home to other members of the family.<ref name=Text2007>{{cite book |vauthors=Papadopoulos NG, Xatzipsaltis M, Johnston SL |veditors=Zuckerman AJ |display-editors=etal |title=Principles and Practice of Clinical Virology |chapter-url=https://books.google.com/books?id=4il2mF7JG1sC&pg=PR3 |year=2009 |publisher=John Wiley & Sons |isbn=978-0-470-74139-9 |page=496 |chapter=Rhinoviruses |edition=6th |url-status=live |archive-url=https://web.archive.org/web/20160603221154/https://books.google.com/books?id=OgbcUWpUCXsC&pg=PA496 |archive-date=3 June 2016}}</ref> There is no evidence that recirculated air during commercial flight is a method of transmission.<ref name=Cold197/> People sitting close to each other appear to be at greater risk of infection.<ref name=E211/>

===Other===
[[Herd immunity]], generated from previous exposure to cold viruses, plays an important role in limiting viral spread, as seen with younger populations that have greater rates of respiratory infections.<ref name=E78/> Poor immune function is a risk factor for disease.<ref name=E78/><ref>Eccles p. 166</ref> [[Sleep deprivation|Insufficient sleep]] and [[malnutrition]] have been associated with a greater risk of developing infection following rhinovirus exposure; this is believed to be due to their effects on immune function.<ref>{{cite journal |vauthors=Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB |title=Sleep habits and susceptibility to the common cold |journal=Archives of Internal Medicine |volume=169 |issue=1 |pages=62–7 |date=January 2009 |pmid=19139325 |pmc=2629403 |doi=10.1001/archinternmed.2008.505}}</ref><ref>Eccles pp. 160–65</ref> [[Breast feeding]] decreases the risk of [[acute otitis media]] and [[lower respiratory tract infections]] among other diseases,<ref>{{cite journal |vauthors=McNiel ME, Labbok MH, Abrahams SW |title=What are the risks associated with formula feeding? A re-analysis and review |journal=Breastfeeding Review |volume=18 |issue=2 |pages=25–32 |date=July 2010 |pmid=20879657}}</ref> and it is recommended that breast feeding be continued when an infant has a cold.<ref>{{cite book |vauthors=Lawrence RA, Lawrence RM |title=Breastfeeding: A guide for the medical profession |publisher=Mosby/Elsevier |location=Maryland Heights, Mo. |isbn=978-1-4377-3590-1 |page=478 |url=https://books.google.com/books?id=c4BnozBW3EMC&pg=PA478 |edition=7th |year=2010 |url-status=live |archive-url=https://web.archive.org/web/20160617002059/https://books.google.com/books?id=c4BnozBW3EMC&pg=PA478 |archive-date=17 June 2016}}</ref> In the developed world breast feeding may not be protective against the common cold in and of itself.<ref name="NelsonWilliams2007">{{citation |vauthors=Nelson KE, Williams CM |title=Infectious Disease Epidemiology: Theory and Practice |url=https://books.google.com/books?id=o_j-G4zJ4cQC&pg=PA724 |year=2007 |publisher=Jones & Bartlett Learning |isbn=978-0-7637-2879-3 |pages=724– |edition=2nd |url-status=live |archive-url=https://web.archive.org/web/20160520134003/https://books.google.com/books?id=o_j-G4zJ4cQC&pg=PA724 |archive-date=20 May 2016}}</ref>