Varicellazoster

Varicella-zoster virus (VZV) is a human herpesvirus (family Herpesviridae) with double-stranded DNA. It causes two clinically distinct diseases: varicella (chickenpox), typically the primary infection in children, and herpes zoster (shingles), the reactivation of latent virus later in life.

VZV spreads by respiratory droplets or direct contact with vesicular fluid and is highly contagious; most susceptible individuals develop primary varicella after exposure. After the primary infection, VZV becomes latent in dorsal root and cranial nerve ganglia and may reactivate years later.

Varicella presents after an incubation of about 10–21 days with fever, malaise, and a pruritic vesicular rash that evolves from macules to vesicles to crusts in successive crops; contagion persists until lesions crust over.

Shingles arises from reactivation, producing a unilateral, dermatomal vesicular eruption with pain that can be severe; fever may be present. Complications include postherpetic neuralgia, ophthalmic involvement, and in immunocompromised individuals, disseminated disease.

Treatment focuses on antiviral therapy (acyclovir, valacyclovir, or famciclovir) begun early in the course to shorten illness and reduce complications; analgesia and supportive care as needed. Severe disease or immunocompromise may require hospitalization and intravenous antiviral therapy.

Prevention relies on vaccination. Varicella vaccine (live attenuated) is given in childhood and to susceptible adults in a two-dose schedule. For shingles, the recombinant zoster vaccine Shingrix is recommended for adults 50 and older (and is preferred to the older live Zostavax vaccine where available), reducing risk and severity of zoster and postherpetic neuralgia.

Laboratory confirmation may use PCR from vesicular fluid, direct fluorescence, or serology when appropriate.