Editing Conjunctivitis (section)

== Causes ==
Infective conjunctivitis is most commonly caused by a virus.<ref name=Az2013/> Bacterial infections, allergies, other irritants, and dryness are also common causes. Both bacterial and viral infections are contagious, passing from person to person or spread through contaminated objects or water. Contact with contaminated fingers is a common cause of conjunctivitis. Bacteria may also reach the conjunctiva from the edges of the eyelids and the surrounding skin, from the nasopharynx, from infected eye drops or contact lenses, from the genitals or the bloodstream.<ref name=":1" /> Infection by human adenovirus accounts for 65% to 90% of cases of viral conjunctivitis.<ref>{{cite journal | vauthors = Singh MP, Ram J, Kumar A, Rungta T, Gupta A, Khurana J, Ratho RK | title = Molecular epidemiology of circulating human adenovirus types in acute conjunctivitis cases in Chandigarh, North India | journal = Indian Journal of Medical Microbiology | volume = 36 | issue = 1 | pages = 113–115 | date = 2018 | pmid = 29735838 | doi = 10.4103/ijmm.ijmm_17_258 | doi-access = free }}</ref>

=== Viral ===
[[Adenoviruses]] are the most common cause of viral conjunctivitis ([[adenoviral keratoconjunctivitis]]).<ref name=Yanoff/> [[Herpetic keratoconjunctivitis]], caused by [[herpes simplex]] viruses, can be serious and requires treatment with [[aciclovir]]. Acute hemorrhagic conjunctivitis is a highly contagious disease caused by one of two [[enterovirus]]es, enterovirus 70 and [[coxsackievirus]] A24. These were first identified in an outbreak in Ghana in 1969, and have spread worldwide since then, causing several epidemics.<ref>{{cite journal | vauthors = Lévêque N, Huguet P, Norder H, Chomel JJ | title = [Enteroviruses responsible for acute hemorrhagic conjunctivitis] | language = fr | journal = Médecine et Maladies Infectieuses | volume = 40 | issue = 4 | pages = 212–218 | date = April 2010 | pmid = 19836177 | doi = 10.1016/j.medmal.2009.09.006 }}</ref>

=== Bacterial ===
The most common causes of acute bacterial conjunctivitis are ''[[Staphylococcus aureus]]'', ''[[Streptococcus pneumoniae]]'', and ''[[Haemophilus influenzae]]''.<ref name="Yanoff">{{Cite book | vauthors = Yanoff M, Duker JS |title=Ophthalmology |publisher=Mosby |year=2008 |isbn=978-0-323-05751-6 |edition=3rd |location=Edinburgh |pages=227–236}}</ref><ref>{{Cite web |date=2017-10-02 |title=Protect Yourself From Pink Eye |url=https://www.cdc.gov/conjunctivitis/about/causes.html |access-date=2018-12-07 |website=Centers for Disease Control and Prevention (CDC) |language=en-us}}</ref> Though very rare, hyperacute cases are usually caused by ''[[Neisseria gonorrhoeae]]'' or ''[[Neisseria meningitidis]]''.  Chronic cases of bacterial conjunctivitis are those lasting longer than 3 weeks, and are typically caused by ''S. aureus'', ''[[Morax-Axenfeld diplobacilli|Moraxella lacunata]]'', or Gram-negative enteric flora.{{citation needed|date=September 2022}}

=== Allergic ===
Conjunctivitis may also be caused by allergens such as pollen, perfumes, cosmetics, smoke,<ref name="FD">{{Cite web |title=Allergic Conjunctivitis |url=http://familydoctor.org/familydoctor/en/diseases-conditions/allergic-conjunctivitis/causes-risk-factors.html |url-status=live |archive-url=https://web.archive.org/web/20150906031026/http://familydoctor.org/familydoctor/en/diseases-conditions/allergic-conjunctivitis/causes-risk-factors.html |archive-date=6 September 2015 |access-date=18 September 2015 |publisher=familydoctor.org |df=dmy-all}}</ref>{{Unreliable medical source|date=September 2015}} dust mites, [[Balsam of Peru]],<ref name="google1">{{Cite book | vauthors = Brooks P |url=https://books.google.com/books?id=eReGG6UtxbcC&pg=PT413 |title=The Daily Telegraph: Complete Guide to Allergies |date=25 October 2012 |publisher=Little, Brown Book |isbn=978-1-4721-0394-9 |access-date=15 April 2014}}{{Dead link|date=September 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> or eye drops.<ref name="MedNews">{{Cite web |title=What Is Allergic Conjunctivitis? What Causes Allergic Conjunctivitis? |url=http://www.medicalnewstoday.com/articles/157692.php |url-status=live |archive-url=https://web.archive.org/web/20100316174827/http://www.medicalnewstoday.com/articles/157692.php |archive-date=16 March 2010 |access-date=6 April 2010 |publisher=medicalnewstoday.com |df=dmy-all}}</ref> The most frequent cause of conjunctivitis is allergic conjunctivitis and it affects 15% to 40% of the population.<ref name=":0" /> Allergic conjunctivitis accounts for 15% of eye related primary care consultations; most including seasonal exposures in the spring and summer or perpetual conditions.<ref>{{cite journal | vauthors = Perkin MR, Bader T, Rudnicka AR, Strachan DP, Owen CG | title = Inter-Relationship between Rhinitis and Conjunctivitis in Allergic Rhinoconjunctivitis and Associated Risk Factors in Rural UK Children | journal = PLOS ONE | volume = 10 | issue = 11 | pages = e0143651 | date = 2015-11-24 | pmid = 26600465 | pmc = 4658044 | doi = 10.1371/journal.pone.0143651 | bibcode = 2015PLoSO..1043651P | doi-access = free }}</ref>

=== Other ===
* [[Computer vision syndrome]]
* [[Dry eye syndrome]]
* [[Reactive arthritis]]: Conjunctivitis is part of the triad of [[reactive arthritis]], which is thought to be caused by [[autoimmune]] cross-reactivity following certain bacterial infections. Reactive arthritis is highly associated with [[HLA-B27]]. Conjunctivitis is associated with the autoimmune disease [[relapsing polychondritis]].<ref name="Puechal 2014">{{cite journal | vauthors = Puéchal X, Terrier B, Mouthon L, Costedoat-Chalumeau N, Guillevin L, Le Jeunne C | title = Relapsing polychondritis | journal = Joint Bone Spine | volume = 81 | issue = 2 | pages = 118–124 | date = March 2014 | pmid = 24556284 | doi = 10.1016/j.jbspin.2014.01.001 | s2cid = 205754989 }}</ref><ref name="Cantarini 2014">{{cite journal | vauthors = Cantarini L, Vitale A, Brizi MG, Caso F, Frediani B, Punzi L, Galeazzi M, Rigante D | title = Diagnosis and classification of relapsing polychondritis | journal = Journal of Autoimmunity | volume = 48-49 | pages = 53–59 | year = 2014 | pmid = 24461536 | doi = 10.1016/j.jaut.2014.01.026 }}</ref>