Catchy little game, isn't it ?
I thought you'd like it ;)
First time I managed to wipe out the entire world on realistic in 69 days, starting in Madagascar :D
I *removed* all symptoms, switched to fever only, got the transmited by rodents and insects and level 1 resists, got lucky with a ship early on to Australia, the entire world got infected before anybody realized anything was going on, and then it was killin' time :)
Quick drug resistance and full spectrum of coughing/sneezing/etc meant infection rates bumped up suddendly, and before you knew it, everybody was infected and I had enough points for more deadly options.
The second time I managed to do it was a but slower, about 120 days or so, and it was with a parasite... removed all visible symptoms, added only cysts for a good while, with resists slowly building up and it went by unnoticed again until it infected everything.
The most rewarding however was the "zombie plague" bacteria... Insanity+Necrosis+Boils ftw.