Diagnostic usefulness of varicella-zoster virus real-time polymerase chain reaction analysis of DNA in saliva and plasma specimens from patients with herpes zoster

Background. We evaluated the diagnostic usefulness of polymerase chain reaction (PCR) analysis for detecting varicella-zoster virus (VZV) infection and reactivation of VZV, using DNA extracted from saliva and plasma specimens obtained from subjects with suspected herpes zoster and from healthy volunteers during stressful and nonstressful conditions. Methods. Tere were 52 patients with a diagnosis of herpes zoster (group 1), 30 with a diagnosis of zoster-mimicking disease (group 2), and 27 healthy volunteers (group 3). Saliva and plasma samples were evaluated for VZV DNA by real-time PCR analysis. Results. Among patients with suspected herpes zoster (ie, patients in groups 1 and 2), the sensitivity of PCR analysis of salivary DNA for detecting VZV (88%; 95% confdence interval [CI], 74%-95%) was signifcantly higher than that of PCR analysis of plasma DNA (28%; 95% CI, 16%-44%; P <.001), whereas the specifcity of PCR analysis of salivary DNA (100%; 95% CI, 88%-100%) was similar to that of PCR analysis of plasma DNA (100%; 95% CI, 78%-100%; P >.99). VZV DNA was not detected in saliva and plasma samples from group 3 (0%; 95% CI, 0%-14%). Conclusions. Real-time PCR analysis of salivary DNA is more sensitive than that of plasma DNA for detecting VZV among patients with suspected herpes zoster. We found no subclinical reactivation of VZV in group 3 following exposure to common stressful conditions.