Detection of cutaneous varicella zoster virus infections by immunofluorescence versus PCR

Detection of localized, clinically atypical cutaneous infections with varicella zoster virus (VZV) has proven difficult, as serum antibody tests sometimes are not sensitive and specific enough for that purpose. Therefore immunofluorescence and an internally controlled PCR for VZV are compared for sensitivity. Detection of PCR products was done by ELISA, and if positive, additionally by agarose gel electrophoresis. Of 60 samples 44 were PCR-positive by ELISA (44 = 100%), of which 37 (84%) were also positive on the agarose gel. Thirty-four samples (77%) were positive by immunofluorescence. No sample was positive by immunofluorescence and negative by PCR. A combination of immunofluorescence and PCR with agarose gel analysis detected 42 samples out of 44 positive by PCR ELISA (95%). These results demonstrate that immunofluorescence is a suitable, fast and inexpensive method for routine diagnostics. Additional sensitivity can be achieved by screening immunofluorescence-negative samples by PCR, which is extremely sensitive but time-consuming and labor-intensive.