Acute viral infection in a sensory nerve associated with fever and painful, itchy blisters, occurring particularly in older people with reduced resistance. It is caused by the chickenpox virus (Herpes zoster), which responds to certain, imperfectly understood stimuli with renewed activity in one or more sensory nerves and in the skin areas served by those nerves. Thus the condition affects one side of the body, usually the abdomen. The disorder begins with fatigue and fever, followed by itching in the affected area associated with slight pain which later becomes stabbing and severe. After 2 to 3 days the affected area becomes blistered; the blistering dries up in 2 weeks. Shingles in the eye can cause blindness, because the cornea becomes blistered. The disorder clears up in a few weaks, with slight loss of feeling or painful oversensitivity of the affected area. In severe cases neuralgic pain persists in the skin. There is no specific treatment, but measures can be taken against itching and pain.