Varizella

Varizella is a contagious disease caused by the varicella-zoster virus (VZV). The illness is most commonly called varicella or chickenpox; Varizella is an alternate spelling encountered in some sources. It occurs worldwide and is preventable through vaccination.

Typical illness begins with fever, malaise, and loss of appetite, followed by a pruritic vesicular rash. The rash starts as red spots that quickly become fluid-filled blisters, which crust over as they heal. It often concentrates on the trunk and face and can be accompanied by fatigue and swollen lymph nodes. In children it is usually mild, while adults and people with weakened immune systems face higher risk of severe disease and complications such as pneumonia, meningitis, or encephalitis.

Varicella spreads mainly through respiratory droplets and contact with vesicular fluid from skin lesions. The incubation period is generally 10 to 21 days. People are contagious from about one to two days before the rash appears until all lesions have crusted.

Diagnosis is typically clinical, supported by the appearance of the rash and patient history; laboratory tests are used in uncertain cases. Most cases are managed with supportive care, including fever control, antipruritic measures, and adequate fluids. Antiviral therapy (for example, acyclovir) is considered for adults, pregnant women, newborns, and immunocompromised individuals when started early in the illness. Prevention relies on vaccination, with the varicella vaccine given in childhood and recommended for susceptible adults. Post-exposure prophylaxis may involve vaccination within a short window or immune globulin for certain high-risk exposed individuals.