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 IgM antibody usually appears within 5 days of the rash and disappears in 2-4 weeks time.