Definition

A highly contagious disease marked by an itchy, blister-like rash caused by the varicella-zoster virus (a type of herpesvirus). The virus is easily spread from person to person through contact with mucus, saliva, or fluid from the blisters of an infected person or through droplets released when an infected person coughs or sneezes. The rash usually appears first on the face, chest, and back and then spreads to the rest of the body. Other symptoms may include fever, headache, fatigue, and loss of appetite. Chickenpox can sometimes cause serious health problems, especially in infants, teenagers, adults, pregnant women, and those who have a weakened immune system. Widespread use of the chickenpox vaccine since the early 1990s has prevented most cases of chickenpox in the United States. Also called varicella.