I think I understand what you are doing and, if I am right, I didn’t explain myself clearly enough — I apologize.
I’m looking for a way to spread random “dots” of infection over the earth… Doing your method will give me a slowly revealed solid color over the land masses. I’m looking more for like a google maps kind of “pushpins” look where there are multiple points (i.e. pushpins) around the world.
Does that make more sense?