This game is fantastic. It actually was the game that made me finally sign up and write a review.
Its incredibly in depth and addictive. The only downfall is that even if you have zero visibility, eventually the countries will start closing borders and looking for a cure. It shuold be made so that if you take away all symptoms, the disease will spread through rodents, insects airborn and water, but cant be detected. This would make you able to get all countries infected before you start making it apparent.
Overall this game is fantastic and I look forward to a third installment.