(The Best Years in Life) It is estimated that at some point in their lives 1 in every 3 Americans will be best by shingles - a viral infection caused by the varicella-zoster virus, the same virus that causes chickenpox. The medical term for shingles is ‘herpes zoster’. After you have had chickenpox, the virus becomes dormant in your nerve tissue, but it can be reactivated years later as shingles. It is more common in adults between the ages of 60 and 80 and those with weakened immune systems. Read More.