Shingles is, a painful and often debilitating condition involving the nerves and skin caused by the reactivation of the virus that causes chickenpox, [Varicella zoster] (formerly [Herpes zoster]). Everyone who has ever had chickenpox carries the virus for the rest of their lives. The virus itself remains dormant in nerve cells until it is reactivated. The result is a painful rash characterized by multiple blister-like bumps arranged in a belt-like pattern that reflects the distribution of the involved nerves. Most people with shingles have pain in the area of the rash. For some, the pain is only mild and temporary, but occasionally it can be severe and last for months or even years - a complication known as postherpetic neuralgia.
The varicella zoster virus that stays in the body after a case of chicken pox usually is kept inactive by the body's natural immune system. As people get older, their immune system naturally weakens to some germs, such as herpes zoster. Most people with shingles, therefore, are 65 years or older. Typically, but not always, shingles occurs in elderly people who are in some stressful situation.
Shingles affects more than 800,000 people in the United States annually. It is most common and most painful in people who are over 60, because immunity to the virus weakens with ageing.