Since almost everyone gets chickenpox as a child, most of us are susceptible to developing shingles as adults. Each illness is caused by the same virus, which is called varicella in children and herpes zoster in adults. After the chickenpox ends, the virus goes into hibernation in the nerve cells along the spinal cord. Then, many years later, when the immune system is weakened in some way–by age, stress, certain drugs, illness (even the flu)–the virus awakens. At some point along the spine, it travels along a nerve, producing a painful rash along the band of skin served by that nerve. Herpes zoster means “belt of fire”–the name is apt.