The Anti-Varicella Zoster Virus (VZV) Antibody IgG CSF test detects VZV IgG antibodies in cerebrospinal fluid (CSF) to diagnose central nervous system (CNS) infections like meningitis or encephalitis caused by VZV (shingles/chickenpox virus). A positive result indicates active or past CNS involvement, though interpretation considers blood contamination/barrier transfer; it helps differentiate CNS infection from systemic disease, especially when PCR is negative