Funny that you mention Vegas: I actually think I got it there (in the airport) on the 21st of February. I went to California for a meeting on that week, and took a flight back to Mexico City, with a 6 hour airport scale in Las Vegas.

My flight was delayed, so I was in the airpot for about 8 hours. I decided to walk a lot during my time at the airport (I do that when I have long flights), so I walked about 20,000 steps in total back and forth in the waiting hall.

About one week later (beginning of March), I started with symptoms and since then it has been a nightmare from which I still haven't completely recovered.