Earlier quoted context omitted.
90-95% of adults had it at some point . Most people develop immunity to it and so it doesn't survive in them. I'd say the most successful virus in humans would be the common cold, given how frequently we seem to get it, although it's more of a massive family of virii.
No actually once you have it, you have it forever. 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
jbogp, I'd be interested to chat with you about your experience interviewing with DeepMind (found that searching HN for DeepMind info). My contact info is on my user profile page. Sorry about the thread-jack.