Epstein-Barr virus is close to that ideal, 90-95% of adults have it. Unfortunately, it's connected with cancers:
http://en.wikipedia.org/wiki/Epstein%E2%80%93Barr_virus
EBV latently persists in the individual's B cells for the rest of the individual's life [1]
[1]: http://www.ncbi.nlm.nih.gov/pubmed/15546128