Varicella-Zoster Virus

Varicella-zoster virus (VZV) is one of the eight herpesviruses that infects humans. The virus causes two diseases, varicella (chickenpox) and zoster (shingles) (1). Varicella is primarily an illness of children, although as many as 5% of adults in the United States may be susceptible. Zoster is caused by reactivation of latent VZV infection in sensory ganglia, which resulted during the attack of varicella, usually years to decades previously. VZV is able to cause a persistent infection in sensory ganglia without harm, expressing only 5 of its 70 gene products (2). In the setting of a low cell-mediated immune response to VZV, however, full gene expression can occur, and infectious virus may be formed within ganglia and transferred down the axon to the skin (1). Zoster occurs in about 15% of people over their lifetime. It characteristically occurs despite the presence of high titers of antibodies to VZV. Little more is understood about reactivation of VZV; it occurs most commonly in elderly and immunocompromised populations. Reasons for its development in otherwise healthy young persons are not fully understood, but fortunately it is a rather uncommon occurrence.