The virus becomes latent in sensory nerve ganglia and may recur later in life. Transmission of VZV to a susceptible person occurs through contact with either a person with varicella or, less commonly, a person with zoster. Varicella is generally a mild disease in children but may result in secondary bacterial infections of skin lesions, pneumonia, cerebellar ataxia, and encephalitis.
Adults are at higher risk for complications than are children.
Occurrence Varicella is endemic in the United States and virtually all persons are infected by adulthood. Incidence is expected to decline as vaccine coverage levels increase. This age distribution is probably the result of earlier exposure to VZV in preschool and child care settings. Risk for Travelers Varicella and herpes zoster occur worldwide, and the vaccine is routinely used in very few countries. The risk of varicella to the traveler is as high in the United States as anywhere in the world.