Curriculum · Public Health and Communicable Diseases
Varicella (chickenpox)
What it is
Varicella (chickenpox) is one of the common childhood infections that carry an exanthem. The virus does not leave the body once the rash is gone: herpes zoster, or shingles, is an eruption of the latent varicella zoster virus (VZV), an acute, unilateral, painful blistering rash caused by its reactivation. Following the primary infection the virus remains dormant in sensory nerve root ganglia, written elsewhere as the dorsal root ganglion, and can be reactivated to cause a vesicular erythematous skin rash in a dermatomal distribution. Disseminated zoster or exposed zoster, ophthalmic for example, in any individual, and localized zoster in an immunosuppressed patient, are considered to be infectious, as viral shedding may be greater.
Causes and risk
Chickenpox comes first; zoster is the reactivation of the same virus, later, from where it lay latent. When the reactivation is in the geniculate ganglion the result is herpes zoster oticus, also called Ramsay Hunt syndrome, which is more common in the immunosuppressed and in the elderly. Primary infection in pregnancy is uncommon, estimated to complicate 3/1000 pregnancies. Women from tropical and subtropical areas are likely to be seronegative for VZV IgG and therefore more susceptible in pregnancy.