Editing Shingles (section)

==Diagnosis==
[[Image:Herpes zoster chest.png|right|thumb|Shingles on the chest]]
If the rash has appeared, identifying this disease (making a [[differential diagnosis]]) requires only a visual examination, since very few diseases produce a rash in a [[Dermatome (anatomy)|dermatomal pattern]] (sometimes called by doctors on TV "a dermatonal map").{{Citation needed|date=July 2024|reason=This statement is very vague and could benefit from specific examples.}} However, [[herpes simplex virus]] (HSV) can occasionally produce a rash in such a pattern (zosteriform herpes simplex).<ref name=Koh>{{cite journal| vauthors = Koh MJ, Seah PP, Teo RY |title=Zosteriform herpes simplex|journal=[[Singapore Med. J.]]|date=Feb 2008|volume=49|pages=e59–60|pmid=18301829|url=http://smj.sma.org.sg/4902/4902cr9.pdf|issue=2|url-status=live|archive-url=https://web.archive.org/web/20140602213312/http://smj.sma.org.sg/4902/4902cr9.pdf|archive-date=2 June 2014}}</ref><ref name=Kalman>{{cite journal| vauthors = Kalman CM, Laskin OL |title=Herpes zoster and zosteriform herpes simplex virus infections in immunocompetent adults|journal=[[Am. J. Med.]]|date=Nov 1986|volume=81 |pages=775–778|pmid=3022586|issue=5|doi=10.1016/0002-9343(86)90343-8}}</ref>

When the rash is absent (early or late in the disease, or in the case of {{lang|la|zoster sine herpete}}), shingles can be difficult to diagnose.<ref name=pmid15334402>{{cite journal|vauthors=Chan J, Bergstrom RT, Lanza DC, Oas JG | title=Lateral sinus thrombosis associated with zoster sine herpete| journal=Am. J. Otolaryngol.| volume=25| issue=5| pages=357–360| year=2004| pmid=15334402| doi=10.1016/j.amjoto.2004.03.007}}</ref> Apart from the rash, most symptoms can occur also in other conditions.

Laboratory tests are available to diagnose shingles. The most popular test detects VZV-specific [[IgM]] [[antibody]] in blood; this appears only during chickenpox or shingles and not while the virus is dormant.<ref name=pmid8809466>{{cite journal| author=Arvin AM| title=Varicella-zoster virus| journal=[[Clin. Microbiol. Rev.]]| volume=9| issue=3| pages=361–381| year=1996| pmid=8809466| url= http://cmr.asm.org/cgi/reprint/9/3/361.pdf| pmc=172899| url-status=live| archive-url=https://web.archive.org/web/20080625213222/http://cmr.asm.org/cgi/reprint/9/3/361.pdf| archive-date=25 June 2008| doi=10.1128/CMR.9.3.361}}</ref> In larger laboratories, [[lymph]] collected from a blister is tested by [[polymerase chain reaction]] (PCR) for VZV DNA, or examined with an electron microscope for virus particles.<ref name="pmid9515761">{{cite journal|vauthors=Beards G, Graham C, Pillay D | title=Investigation of vesicular rashes for HSV and VZV by PCR| journal=[[J. Med. Virol.]]| volume=54| issue=3| pages=155–157| year=1998| pmid=9515761 |doi=10.1002/(SICI)1096-9071(199803)54:3<155::AID-JMV1>3.0.CO;2-4| s2cid=24215093}}</ref> Molecular biology tests based on ''in vitro'' nucleic acid amplification (PCR tests) are currently considered the most reliable. [[Nested PCR]] test has high [[sensitivity and specificity|sensitivity]], but is susceptible to contamination leading to [[False positives and false negatives#False positive error|false positive results]]. The latest [[real-time polymerase chain reaction|real-time PCR]] tests are rapid, easy to perform, and as sensitive as nested PCR, and have a lower risk of contamination. They also have more sensitivity than [[viral culture]]s.<ref name=DePaschaleClerici2016>{{cite journal| vauthors=De Paschale M, Clerici P| title=Microbiology laboratory and the management of mother-child varicella-zoster virus infection. | journal=World J Virol | year= 2016 | volume= 5 | issue= 3 | pages= 97–124 | pmid=27563537 | doi=10.5501/wjv.v5.i3.97 | pmc=4981827 | type= Review | doi-access=free }}</ref>

=== Differential diagnosis ===
Shingles can be confused with [[herpes simplex]], [[dermatitis herpetiformis]] and [[impetigo]], and skin reactions caused by [[contact dermatitis]], [[candidiasis]], certain drugs and insect bites.<ref name=SampathkumarDrage2009>{{cite journal| vauthors=Sampathkumar P, Drage LA, Martin DP| title=Herpes zoster (shingles) and postherpetic neuralgia | journal=Mayo Clin Proc | year= 2009 | volume= 84 | issue= 3 | pages= 274–280 | pmid=19252116 | doi=10.4065/84.3.274 | pmc=2664599 | type= Review }}</ref>