I know several that had it or at least are convinced they had and never got tested. The only one I know of that tested positive was a 30 year-old that tested positive after emergency surgery for a bowel problem. He tested negative upon arrival at the hospital and then positive, no symptoms, 3 days later when discharged. This guy ended up getting it, along with many others that attended a wedding, a couple of months later.
I use the Chicken Pox virus as my example.
If it is a virus, the symptoms MUST act as a virus.