Objective: Varicella zoster virus (VZV) is a member of Herpesviridae family and is the responsible etiological agent in two clinical forms as varicella (chicken pox) and zona (herpes zoster). VZV which is the infectious agent of a treatable infection based on accurate diagnosis is susceptible to antivirals. Serologic VZV IgG avidity test is important as VZV Ig G test shows whether the patient has ever acquired this infectionVZV IgG avidity test helps to distinguish recent infection from the past; but is not standardized yet. The aim of this study is to evaluate the VZV IgM and IgG enzyme immunoassay (EIA) tests and VZV IgG avidity test which we have started to use routinely and to determine our routine laboratory diagnostic approach.

Material and Methods: A total of 5884 VZV IgG and 3570 VZV IgM test and VZV IgG avidity test were performed in the patients’ sera with the pre-diagnosis of VZV infection or request for viral screening tests.

Results: In this study, of the 3570 samples tested with VZV IgM; 7.6% (273 samples) were positive, 3.4% (120 samples) were borderline and 89% (3177) were negative. The number of VZV IgG positive, negative, and borderline results were 4251 (72.2%), 1363 (23.2%) and 270 (4.6%) respectively. VZV IgG avidity test was performed in a total of 24 samples including 15 samples clinically not thought to be associated with varicella yet repeated VZV IgM test result was positive for the disease, 2 samples of the patients with clinical manifestations of varicella, and 7 samples of the patients whose initial VZV IgM test gave borderline positivity, however when the test was repeated it yielded positive/borderline/ negative result. Lower avidity indices were not detected in any case, In only 4 cases borderline avidity index value was detected., while the remaining samples had high avidity indices.

Conclusion: In conclusion the VZV IgM enzyme immunoassay test is not considered to be a suitable test in the confirmation of the diagnosis of acute infection in the absence of clinical infection . Unexpected positivity in VZV IgM tests is related to the lack of standardization of EIA for the detection of these isotype antibodies. The VZV IgG avidity test has not helped for the diagnosis. The utility of VZV IgM and IgG avidity EIA tests were considered to be limited in diagnosing acute infection.