Hm - easier then the first.
The first one I had extream difficulty beating it once they shut down the transit. this is far easier. all you need to do is spend the intal 5 points to get your infecticality to lvl 3; then end your turn (providing the guy with the virus dosn't die) infect the rest of your country, once you do that, infect boardering countrys and the airport. and from there repeat the "Infect fully ; travel " thing.
Don't upgrade your leathalcality untillyou have ever country infected. cuz you need your people infected, and alive. not dead and useless, and unless someone in greenland, or australia gets a cure before your luck allows you to fly there, you should wipe out humanity with a swift blow.
In closing ; Fun. The upgrading your virus does seem a little difficult.
-Pat