This is a term used in the description of several well known diseases entities, one of which is herpes zoster, although it has very little to do with herpes virus infection, except for the lesions produced by zoster eruptions sometimes looks like those of herpes. The virus causing zoster is the varicella-zoster virus, the same virus responsible for chickenpox. Initially, patients feel pain and burning sensation along the areas of the body supplied by the same nerve. About 2 days later, vesicles appears at the same area and this lasts for about 1 week. In patients with compromised immune system (e.g. AIDS), zoster eruption may precede significant depression of immunity. People who has had chickenpox is a potential candidate for zoster infection due to the reactivation of the chickenpox virus in the nerve. The previous chickenpox infection gives them immunity from infection by another individual who is suffering from a zoster infection. Those who never had chickenpox can be infected by zoster, and have the clinical symptoms of chickenpox.