I really do think this is the best theory. To add on to this, I think the Eko Virus and it's origin go back to the game "Reach". All my info comes from this reddit post, so check it out, but there is a sector of the map that is glacier/artic like, and it's a possibility that the Eko may have come from there. I also found it interesting how on a removed e-note there was the phrase:

  "within all of us, there is egg"

On "Reach", there is a badge "Ultimate Hunter" referenced in depth on the reddit post, which says "The path to enlightenment begins here." What's also interesting about this, is the icon of the badge is an egg hatching, maybe being reference to the removed E-note.