factors that affect the cause of chickenpox
Risk Factors. The varicella-zoster virus is responsible for both chickenpox and herpes zoster, but its method of infection is different in both diseases. 1  Both the active varicella and zoster form of the virus can cause chickenpox.2  The shingles virus in its latent (inactive) form is never contagious.eveloping Shingles. Shingles itself can develop only from a reactivation of the varicella-zoster virus in a person who has previously had chickenpox. In other words, shingles itself is never transmitted from one person to another either in the air or through direct exposure to the blisters.