what causes zoster shingles
Shingles-Cause. Shingles is a reactivation of the varicella-zoster virus, a type of herpes virus that causes chickenpox. After you have had chickenpox, the virus lies inactive in your nerve roots and remains inactive until, in some people, it flares up again.hingles is a reactivation of the varicella-zoster virus, a type of herpes virus that causes chickenpox. After you have had chickenpox, the virus lies inactive in your nerve roots and remains inactive until, in some people, it flares up again.