Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Shingles ?
    ### Response:
    Shingles is caused by a virus called the varicella-zoster virus -- the one that gave you chickenpox when you were a child. As you recovered from chickenpox, the sores and other symptoms healed, but the virus remained. It is with you for life. Researchers know that the varicella-zoster virus behaves differently from other viruses, such as the flu virus.
    