Overview
Chickenpox (varicella) is an infectious disease caused by the varicella-zoster virus that goes away on its own. Infection spreads among humans through fluids from the airways, such as from coughing and sneezing, with non-infected household members at high risk of becoming infected as well. The development (incubation) period is 14–16 days, and the first sign of disease is a rash. People are considered contagious for 2–5 days before the onset of skin lesions and for 6 days after the last series of rashes have appeared.
The most common complication is infection of lesions with bacteria. Rare complications include lung infection (pneumonia) or brain infection (encephalitis). Children who have weak immune systems, eczema, or recent sunburns have more severe symptoms. Because the virus remains resting (latent) in the parts of nerves that are near the spinal cord (nerve roots) for life, about 1 in 10 adults will get shingles (zoster) when the virus reappears, usually under conditions of stress to the body.
After having chickenpox, a person is usually immune for life, although reinfection is possible.
