Chickenpox
is caused by infection with varicella zoster virus that is quite contagious one. The illness starts with a skin rash that takes place primarily on the body and head and then starts to itch. These open sores heal almost without leaving any scares. The illness causes death quite seldom, though it is more severe in adults then in children. Once person has had chickenpox he or she acquires immunity against this infection for the rest of the life.