Editing Measles (section)

==Diagnosis==
Typically, clinical [[diagnosis]] begins with the onset of [[fever]] and [[malaise]] about 10 days after exposure to the measles virus, followed by the emergence of [[cough]], [[coryza]], and [[conjunctivitis]] that worsen in severity over 4 days of appearing.<ref>{{Citation|last1=Rainwater-Lovett|first1=Kaitlin|title=Measles (Rubeola)|date=2018|url=https://accessmedicine.mhmedical.com/content.aspx?bookid=2129&sectionid=192025856|work=Harrison's Principles of Internal Medicine|editor-last=Jameson|editor-first=J. Larry|edition=20|place=New York, NY|publisher=McGraw-Hill Education|access-date=7 December 2020|last2=Moss|first2=William J.|editor2-last=Fauci|editor2-first=Anthony S.|editor3-last=Kasper|editor3-first=Dennis L.|editor4-last=Hauser|editor4-first=Stephen L.|archive-date=24 September 2020|archive-url=https://web.archive.org/web/20200924221558/http://accessmedicine.mhmedical.com/content.aspx?bookid=2129&sectionid=192025856|url-status=live}}</ref> Observation of Koplik's spots is also diagnostic.<ref name="baxby">{{cite journal |author-link=Derrick Baxby |vauthors=Baxby D |date=July 1997 |title=The diagnosis of the invasion of measles from a study of the exanthema as it appears on the buccal mucous membraneBy Henry Koplik, M.D. Reproduced from Arch. Paed. 13, 918-922 (1886) |journal=Reviews in Medical Virology |volume=7 |issue=2 |pages=71–74 |doi=10.1002/(SICI)1099-1654(199707)7:2<71::AID-RMV185>3.0.CO;2-S |pmid=10398471 |s2cid=42670134}}</ref> Other diseases that may appear similar to measles include [[dengue fever]], [[rubella]], [[Fifth disease|erythema infectiosum]] (also called fifth disease, caused by [[parvovirus B19]]), and [[roseola]] (also called exanthem subitum or sixth disease, caused by [[Human herpesvirus 6|HHV6]]).<ref name="Rot2016" /> Laboratory confirmation is therefore strongly recommended, especially in non-endemic areas.<ref name="Pink Book" />

===Laboratory testing===
Laboratory diagnosis of measles can be done with confirmation of positive measles [[IgM antibodies]] or detection of measles virus RNA from throat, nasal or urine specimen by using the [[reverse transcription polymerase chain reaction]] assay.<ref name=":6">{{cite web|url=https://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html|title=Surveillance Manual {{!}} Measles {{!}} Vaccine Preventable Diseases |date=23 May 2019|website=U.S. [[Centers for Disease Control and Prevention]] (CDC)|access-date=25 November 2019|archive-date=4 August 2020|archive-url=https://web.archive.org/web/20200804015227/https://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html|url-status=live}}</ref><ref name=":5"/> This method is particularly useful to confirm cases when the IgM antibodies results are inconclusive.<ref name=":6"/> For people unable to have their [[phlebotomy|blood drawn]], saliva can be collected for salivary measles-specific [[IgA]] testing.<ref name=":5">{{cite journal | vauthors = Friedman M, Hadari I, Goldstein V, Sarov I | title = Virus-specific secretory IgA antibodies as a means of rapid diagnosis of measles and mumps infection | journal = Israel Journal of Medical Sciences | volume = 19 | issue = 10 | pages = 881–4 | date = October 1983 | pmid = 6662670 }}</ref> Salivary tests used to diagnose measles involve collecting a saliva sample and testing for the presence of measles antibodies.<ref name=":3">{{Cite journal|last1=Dimech|first1=Wayne|last2=Mulders|first2=Mick N.|date=July 2016|title=A review of testing used in seroprevalence studies on measles and rubella|journal=Vaccine|volume=34|issue=35|pages=4119–4122|doi=10.1016/j.vaccine.2016.06.006|pmid=27340096}}</ref><ref name=":4">{{cite journal |last1=Simon |first1=Jakub K. |last2=Ramirez |first2=Karina |last3=Cuberos |first3=Lilian |last4=Campbell |first4=James D. |last5=Viret |first5=Jean F. |last6=Muñoz |first6=Alma |last7=Lagos |first7=Rosanna |last8=Levine |first8=Myron M. |last9=Pasetti |first9=Marcela F. |title=Mucosal IgA Responses in Healthy Adult Volunteers following Intranasal Spray Delivery of a Live Attenuated Measles Vaccine |journal=Clinical and Vaccine Immunology |date=March 2011 |volume=18 |issue=3 |pages=355–361 |doi=10.1128/CVI.00354-10 |pmid=21228137 |pmc=3067370 }}</ref> This method is not ideal, as saliva contains many other fluids and proteins which may make it difficult to collect samples and detect measles antibodies.<ref name=":3"/><ref name=":4"/> Saliva also contains 800 times fewer antibodies than blood samples do, which makes salivary testing additionally difficult. Positive contact with other people known to have measles adds evidence to the diagnosis.<ref name=":3"/>

Biopsies and [[Histopathology|histopathologic]] examinations are not typically used to diagnose measles, but [[Warthin–Finkeldey cell]]s, giant cells with multiple nuclei and eosinophilic inclusions, are frequently seen in affected [[Lymphatic system|lymphoid]] tissue but are not unique to measles.<ref name="Mil2015" /><ref name=":15">{{Cite web |last=Weisenberg |first=Elliot |date=9 August 2022 |title=Measles |url=https://www.pathologyoutlines.com/topic/lungnontumormeasles.html |access-date=9 April 2025 |website=PathologyOutlines.com |archive-date=30 June 2024 |archive-url=https://web.archive.org/web/20240630182204/https://www.pathologyoutlines.com/topic/lungnontumormeasles.html |url-status=live }}</ref> Affected [[epithelium]] may have giant cells with [[viral inclusion bodies]] or [[Cowdry bodies]].<ref name=":15" />