I can't wrap my head around how it became wide-spread relatively quickly. I imagine it will become a case study to track down how it proliferated (propagated?)
Basketball, Tom Hanks, soon our neighbors?
I looked at John Hopkins site and it has a nice interactive map for tracking. One case in Las Vegas: a woman from new your feeling ill went to some woman group get together, lots of interpersonal contact.
An old fable makes parallels how a virus replicates: a wise man entertained the emperor of china whom loved the performance so much he granted the old man his wish. The old man produced a checker board and stated he would be most pleased if he could fill the board with rice thus: in the first square place a single grain, the second place 2, then 4, and doubling so forth until all the squares have rice on them. The emperor felt the request modest and granted the old man's wish. Once done, the wise man had all the emperors rice and the emperors kingdom went without.