I completely eradicated everyone.. mwahahah. Even Madagascar. The trick is to keep your visibility at zero and only have your virus/bacteria/parasite infect people. Once you get into every country, then turn on the killing symptoms. Of course they'll start a vaccine once you get so many countries, but just ignore it. Once you start killing, it will take them forever to make it because all of the hospitals will be down. Then its just a waiting game until everyone dies.
 "Fantastic Contraption"){kind=icon}
 "Pandemic 2"){kind=icon}