This page shows the progression of Foot and Mouth disease in the 2001 UK outbreak in Cumbria. Initially farms are small green dots, then when they are notified as infected become large red dots for a few days, and then become small red dots after that to show where the disease has been.
The animation may take a minute to load, then you can use the controls at the bottom to play. The images are all frames captured from Google Earth. Its timeline control is shown at the top, but is not usable on this web page. When viewed from Google Earth, this slider can be used to select data and do animations in a full 3-d environment.