Varicella / Chicken pox is an acute viral disease caused by Varicella zoster virus (VZV) that belongs to the Herpes virus family. Reactivation of VZV usually manifests as Zoster (Shingles). The disease begins with fever, malaise and maculopapular rash that heals over a 3 week period.VZV IgG antibody usually appears within 5 days of the rash and persists for indeterminate time. A positive result indicates immunity or past exposure to VZV.