Chickenpox is a contagious disease which causes fever and a very itchy, blister-like rash. It is caused by the varicella-zoster virus (VZV). It is serious problem especially in babies, children, adults and people with the weak immune system. Rarely, it causes pneumonia or inflammation in the brain. It is easily spread to others who haven’t had chickenpox or haven’t taken the chickenpox vaccine. When an infected person coughs or sneezes, the virus is spread through the air by respiratory droplets. Once someone has chickenpox, the virus remains dormant in the body and it can reactivate later in life as shingles.