Herpes zoster laboratory tests: Difference between revisions
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{{CMG}}, L. Katie Morrison, MD; {{AE}} {{CZ}} | {{CMG}}, L. Katie Morrison, MD; {{AE}} {{CZ}} | ||
==Overview== | |||
Laboratory testing may be useful in cases with less typical clinical presentations, such as in immunosuppressed persons who may have disseminated HZ (defined as appearance of lesions outside the primary or adjacent dermatomes). | |||
==Laboratory Findings== | ==Laboratory Findings== | ||
===Direct Fluorescent Antibody Test=== | |||
Direct fluorescent antibody staining of VZV-infected cells in a scraping of cells from the base of a lesion is rapid, specific, and sensitive, but it is substantially less sensitive than polymerase chain reaction (PCR). This method can also be used on biopsy material and on eosinophilic nuclear inclusions. | |||
===Polymerase Chain Reaction=== | |||
PCR can be used to detect VZV DNA rapidly and sensitively in properly collected skin lesion specimens; however, PCR testing for VZV is not available in all settings. It is also possible to use PCR to distinguish between wild-type and vaccine strains of VZV. In larger laboratories, [[lymph]] collected from a blister is tested by the [[polymerase chain reaction]] for VZV DNA, or examined with an [[electron microscope]] for virus particles.<ref name="pmid9515761">{{cite journal|author=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=155–7| year=1998| pmid=9515761}}</ref> | |||
In a recent study, samples of lesions on the skin, eyes, and lung from 182 patients with presumed herpes simplex or herpes zoster were tested with [[real-time PCR]] or with [[viral culture]]. <ref name="pmid15072752">{{cite journal | author = Stránská R, Schuurman R, de Vos M, van Loon AM. | title = Routine use of a highly automated and internally controlled real-time PCR assay for the diagnosis of herpes simplex and varicella-zoster virus infections. | journal = J Clin Virol. | volume=30 | issue=1| pages=39-44 | year=2003 | pmid=15072752}}</ref>. In this comparison, viral culture detected VZV with only a 14.3% [[sensitivity]], although the test was highly specific ([[specificity]]=100%). By comparison, real-time PCR resulted in 100% sensitivity and specificity. Overall testing for herpes simplex and herpes zoster using PCR showed a 60.4% improvement over viral culture. | |||
===Tzanck Smear=== | |||
If the rash has appeared, identifying this disease (making a [[differential diagnosis]]) only requires a visual examination, since very few diseases produce a rash in a [[dermatomic area|dermatomal pattern]]. However, [[herpes simplex virus]] (HSV) can occasionally produce a rash in such a pattern. The [[Tzanck test|Tzanck smear]] is helpful for diagnosing acute infection with a herpes virus, but does not distinguish between HSV and VZV.<ref name="pmid2842739">{{cite journal | author = Oranje AP, Folkers E | title = The Tzanck smear: old, but still of inestimable value. | journal = Pediatr Dermatol | volume = 5 | issue = 2 | pages = 127–9 | year = 1988 | pmid = 2842739}}</ref> | |||
When the rash is absent (early or late in the disease, or in the case of zoster sine herpete), herpes zoster can be difficult to diagnose.<ref name="pmid15334402">{{cite journal| author=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=357–60| year=2004| pmid=15334402}}</ref> Apart from the rash, most symptoms can occur also in other conditions. | |||
===Serological Methods=== | |||
Serologic methods may also be used for laboratory diagnosis of HZ, although there are challenges to interpreting the results. HZ patients may mount an IgM response and would be expected to mount a memory IgG response. However, a positive IgM ELISA result could be an indication of primary VZV infection, re-infection, or re-activation. This only appears during chickenpox or herpes zoster 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=361–81| year=1996| pmid=8809466| url=http://cmr.asm.org/cgi/reprint/9/3/361.pdf| format=PDF}}</ref> It is also difficult to detect an increase in IgG for laboratory diagnosis of HZ since patients may have a high baseline antibody titer from prior varicella disease. | |||
In immunocompromised persons, even when VZV infection is diagnosed by use of laboratory methods, it may be difficult to distinguish between chickenpox and disseminated HZ by physical examination or serological testing.(1) In these instances, a history of VZV exposure or of a rash that began with a dermatomal pattern, along with results of VZV antibody testing at or before the time of rash onset may help guide the diagnosis. | |||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], L. Katie Morrison, MD; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Overview
Laboratory testing may be useful in cases with less typical clinical presentations, such as in immunosuppressed persons who may have disseminated HZ (defined as appearance of lesions outside the primary or adjacent dermatomes).
Laboratory Findings
Direct Fluorescent Antibody Test
Direct fluorescent antibody staining of VZV-infected cells in a scraping of cells from the base of a lesion is rapid, specific, and sensitive, but it is substantially less sensitive than polymerase chain reaction (PCR). This method can also be used on biopsy material and on eosinophilic nuclear inclusions.
Polymerase Chain Reaction
PCR can be used to detect VZV DNA rapidly and sensitively in properly collected skin lesion specimens; however, PCR testing for VZV is not available in all settings. It is also possible to use PCR to distinguish between wild-type and vaccine strains of VZV. In larger laboratories, lymph collected from a blister is tested by the polymerase chain reaction for VZV DNA, or examined with an electron microscope for virus particles.[1]
In a recent study, samples of lesions on the skin, eyes, and lung from 182 patients with presumed herpes simplex or herpes zoster were tested with real-time PCR or with viral culture. [2]. In this comparison, viral culture detected VZV with only a 14.3% sensitivity, although the test was highly specific (specificity=100%). By comparison, real-time PCR resulted in 100% sensitivity and specificity. Overall testing for herpes simplex and herpes zoster using PCR showed a 60.4% improvement over viral culture.
Tzanck Smear
If the rash has appeared, identifying this disease (making a differential diagnosis) only requires a visual examination, since very few diseases produce a rash in a dermatomal pattern. However, herpes simplex virus (HSV) can occasionally produce a rash in such a pattern. The Tzanck smear is helpful for diagnosing acute infection with a herpes virus, but does not distinguish between HSV and VZV.[3]
When the rash is absent (early or late in the disease, or in the case of zoster sine herpete), herpes zoster can be difficult to diagnose.[4] Apart from the rash, most symptoms can occur also in other conditions.
Serological Methods
Serologic methods may also be used for laboratory diagnosis of HZ, although there are challenges to interpreting the results. HZ patients may mount an IgM response and would be expected to mount a memory IgG response. However, a positive IgM ELISA result could be an indication of primary VZV infection, re-infection, or re-activation. This only appears during chickenpox or herpes zoster and not while the virus is dormant.[5] It is also difficult to detect an increase in IgG for laboratory diagnosis of HZ since patients may have a high baseline antibody titer from prior varicella disease.
In immunocompromised persons, even when VZV infection is diagnosed by use of laboratory methods, it may be difficult to distinguish between chickenpox and disseminated HZ by physical examination or serological testing.(1) In these instances, a history of VZV exposure or of a rash that began with a dermatomal pattern, along with results of VZV antibody testing at or before the time of rash onset may help guide the diagnosis.
References
- ↑ Beards G, Graham C, Pillay D (1998). "Investigation of vesicular rashes for HSV and VZV by PCR". J. Med. Virol. 54 (3): 155–7. PMID 9515761.
- ↑ Stránská R, Schuurman R, de Vos M, van Loon AM. (2003). "Routine use of a highly automated and internally controlled real-time PCR assay for the diagnosis of herpes simplex and varicella-zoster virus infections". J Clin Virol. 30 (1): 39–44. PMID 15072752.
- ↑ Oranje AP, Folkers E (1988). "The Tzanck smear: old, but still of inestimable value". Pediatr Dermatol. 5 (2): 127–9. PMID 2842739.
- ↑ Chan J, Bergstrom RT, Lanza DC, Oas JG (2004). "Lateral sinus thrombosis associated with zoster sine herpete". Am J Otolaryngol. 25 (5): 357–60. PMID 15334402.
- ↑ Arvin AM (1996). "Varicella-zoster virus" (PDF). Clin. Microbiol. Rev. 9 (3): 361–81. PMID 8809466.