Editing Infectious mononucleosis (section)

==Cause==

===Epstein–Barr virus===
{{Main|Epstein–Barr virus}}
About 90% of cases of infectious mononucleosis are caused by the [[Epstein–Barr virus]], a member of the [[Herpesviridae]] family of [[DNA viruses]]. It is one of the most commonly found [[viruses]] throughout the world. Contrary to common belief, the Epstein–Barr virus is not highly contagious. It can only be contracted through direct contact with an infected person's [[saliva]], such as through kissing or sharing toothbrushes.<ref>[http://www.mayoclinic.com/health/mononucleosis/AN00661 Mononucleosis and Epstein-Barr: What's the connection?] {{webarchive|url=https://web.archive.org/web/20130606232054/http://www.mayoclinic.com/health/mononucleosis/AN00661 |date=2013-06-06 }}. MayoClinic.com (2011-11-22). Retrieved on 2013-08-03.</ref> About 95% of the population has been exposed to this virus by the age of 40, but only 15–20% of teenagers and about 40% of exposed adults actually develop infectious mononucleosis.<ref>Schonbeck, John and Frey, Rebecca. ''The Gale Encyclopedia of Medicine.'' Vol. 2. 4th ed.  Detroit: Gale, 2011. Online.</ref>

===Cytomegalovirus===
{{Main|Human betaherpesvirus 5}}
About 5–7% of cases of infectious mononucleosis is caused by [[human cytomegalovirus]] (CMV), another type of [[Herpesviridae|herpes virus]].<ref name="pmid27933614">{{cite journal | vauthors=De Paor M, O'Brien K, Smith SM | title=Antiviral agents for infectious mononucleosis (glandular fever) | journal=[[Cochrane Library#The Cochrane Database of Systematic Reviews|The Cochrane Database of Systematic Reviews]] | volume=2016 | issue=12 | pages=CD011487 | year=2016 | doi = 10.1002/14651858.CD011487.pub2 | pmc=6463965 | pmid=27933614}}</ref> This virus is found in body fluids including [[saliva]], [[urine]], [[blood]], [[tears]],<ref name="STD Sourcebook">Larsen, Laura. ''Sexually Transmitted Diseases Sourcebook. Health Reference Series Detroit'': Omnigraphics, Inc., 2009. Online.</ref> [[breast milk]] and genital secretions.<ref name=frontiersCMV2006/> A person becomes infected with this [[virus]] by direct contact with infected body fluids. Cytomegalovirus is most commonly transmitted through kissing and sexual intercourse. It can also be transferred from an infected mother to her unborn child. This virus is often "silent" because the signs and symptoms cannot be felt by the person infected.<ref name="STD Sourcebook"/> However, it can cause life-threatening illness in infants, people with [[HIV]], [[Organ transplant|transplant]] recipients, and those with weak [[immune systems]]. For those with weak immune systems, cytomegalovirus can cause more serious illnesses such as [[pneumonia]] and inflammations of the [[retina]], [[esophagus]], [[liver]], [[large intestine]], and [[brain]]. Approximately 90% of the human population has been infected with cytomegalovirus by the time they reach adulthood, but most are unaware of the infection.<ref>Carson-DeWitt and Teresa G. ''The Gale Encyclopedia of Medicine.'' Vol. 2. 3rd ed. Detroit: Gale, 2006.</ref> Once a person becomes infected with cytomegalovirus, the virus stays in their body throughout the person's lifetime. During this latent phase, the virus can be detected only in [[monocytes]].<ref name=frontiersCMV2006>{{cite journal |last1=Forte |first1=Eleonora |last2=Zhang |first2=Zheng |last3=Thorp |first3=Edward B. |last4=Hummel |first4=Mary |title=Cytomegalovirus Latency and Reactivation: An Intricate Interplay With the Host Immune Response |journal=Frontiers in Cellular and Infection Microbiology |date=31 March 2020 |volume=10 |page=130 |doi=10.3389/fcimb.2020.00130|doi-access=free|pmid=32296651 |pmc=7136410 }}</ref>

===Other causes===
[[Toxoplasma gondii]], a parasitic [[protozoon]], is responsible for less than 1% of the infectious mononucleosis cases.  [[Viral hepatitis]], [[adenovirus]], [[rubella]], and [[herpes simplex]] viruses have also been reported as rare causes of infectious mononucleosis.<ref name=jms1978>{{cite journal |last1=Evans |first1=AS |title=Infectious mononucleosis and related syndromes. |journal=The American Journal of the Medical Sciences |date=November 1978 |volume=276 |issue=3 |pages=325–39 |doi=10.1097/00000441-197811000-00010 |pmid=217270|s2cid=22970983 }}</ref>

===Transmission===
[[Epstein–Barr virus]] infection is spread via [[saliva]], and has an [[incubation period]] of four to seven weeks.<ref name="pmid8710247">{{cite journal |author=Cozad J |title=Infectious mononucleosis |journal=The Nurse Practitioner |volume=21 |issue=3 |pages=14–6, 23, 27–8 |date=March 1996 |pmid=8710247 |doi=10.1097/00006205-199603000-00002 |s2cid=11827600 }}</ref> The length of time that an individual remains [[Contagious disease|contagious]] is unclear, but the chances of passing the illness to someone else may be the highest during the first six weeks following infection. Some studies indicate that a person can spread the infection for many months, possibly up to a year and a half.<ref>{{cite web |url=http://kidshealth.org/WillisKnighton/en/teens/mono-long.html |title=How Long Is Mono Contagious? |publisher=Kidshealth.org |access-date=2016-11-19 |author=Elana Pearl Ben-Joseph |url-status=live |archive-url=https://web.archive.org/web/20161119181853/http://kidshealth.org/WillisKnighton/en/teens/mono-long.html |archive-date=2016-11-19 }} Date reviewed: January 2013</ref>