The diagnosis is usually made clinically.
2nd order laboratory parameters – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.
- Direct virus detection using PCR (polymerase chain reaction) from vesicle contents, skin biopsies, cerebrospinal fluid* , or blood – for detection of varicella zoster virus infection [sensitivity and specificity of 95-100%]* when CNS involvement is suspected.
- Antigen detection using the immunofluorescence test [specificity (probability that actually healthy people who do not have the disease in question are also detected as healthy by the test) 76%; sensitivity (percentage of diseased patients in whom the disease is detected by the use of the test, i.e., a positive finding occurs) 82%].
- Viral culture [specificity 99%; sensitivity 20%).
- Antibody detection (= indirect virus detection) using serological methods such as ELISA (Enzyme Linked Immunosorbent Assay) from serum, dried blood or cerebrospinal fluid [positive predictive value about 90%; in the majority of cases IgA antibodies are present/IgM antibodies may be absent].
- HIV test – herpes zoster is considered an indicator disease for HIV.
