Chickenpox, also known as varicella, is a highly contagious, vaccine-preventable disease caused by the initial infection with varicella zoster virus, a member of the herpesvirus family. The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. It usually starts on the chest, back, and face. It then spreads to the rest of the body. The rash and ... Wikipedia