yeah i did the same thing last night. i was on realistic and used a virus. i got it to be waterborn and took out as much visibility as i could while trying to keep some infectiousness. i put one in each of the cold/heat/water categories. from there i just let it sit. after a while more n more countries start to get infected, but because its such a low number and its not spreading fast, they dont notice. once countries start acting, i added airborn/rodent/insect and more water/heat/cold/drug. i stack up mad pts till countries start acting fast, and thats when i put the hammer down. add as many symptoms as i can towards infecting people. notice nothing on lethality yet. i will basically get the entire world infected before it starts killing people. it takes a while to get more pts, but just be patient/look on ns forums and when you get more pts add them to lethal things such as kidney failure, fever, and so on. read the descriptions/effects of the symptoms, they help a lot.
i tend to try change the disease a lot after they start making a cure so that hopefully it wont work. even if it does, the only country still alive is madagascar. adding more to the drug category makes it take them longer to get a vacine made, meaning more infected people. and after that just save up on more lethality things and everyone will soon die thats infected.
thats my strategy