I consider this movie to be a more realistic example of an unknown epidemic outbreak

So many movies that have been made in the genre have been overly-dramatic, skirted around the real science of epidemiology and had a neat conclusion where all things went back to normal. Outbreak is a good example.
Contagion is altogether more balanced, really uses the science of epidemiology and explores the politics of the CDC in dealing with local/state officials. The characters are not over-the-top, save the online/radio personality played by Jude Law. Contagion is a smart, believable movie, not a disguised action movie like Outbreak.