Shingles is caused by a virus that is named after the two diseases it causes (chickenpox and herpes zoster), varicella-zoster virus. Most of the people who are first infected with the virus are children and, to a lesser extent, young people. Chickenpox occurs in 70% of people who are infected and 30% of people who are asymptomatic are called recessive infections. Both groups of people have a small amount of virus latent in the body that can cause herpes zoster to occur in your later years when your immunity is weakened. When the immune system is depressed, the small amount of virus that is latent in the body starts to replicate in large quantities and causes inflammation of a peripheral nerve, so the patient first experiences pain or numbness, itching, heaviness, and the virus reaches the skin along the branches of this nerve that innervate the skin before blisters appear on the skin. Therefore, herpes zoster usually starts with pain and other self-induced symptoms, and the rash appears only a few days later.