To beat this in relaxed is impossible.
To beat this in realistic is realistic - I promise.
Get Parasite.
Sell every starting symptom, buy all resistances to 2 (heat cold moisture drug), then buy rodent transmission.
It will take like 10 minutes but you should get them all infected.
If not, restart.
Once you get all the countries infected, get vomiting and then save up so you can kill the entire population quickly.
Happy infecting! :D
 "Pandemic 2"){kind=icon}