Pop Culture and Microorganisms: Viruses
With all the zombie movies that have come out in the past few years, one of the underlying causes of zombification is a virus. So far, we don't know of any viruses that actually make people zombies; however, many of the viruses mentioned in zombie movies are related to real viruses. Rabies virus infects individuals and causes manic aggressive behavior, including biting individuals, which increases the likelihood of the virus spreading to another host.
The "rage" virus mentioned in 28 Days Later exhibits properties similar to rabies virus. In I Am Legend, a mutant version of measles virus causes people to become zombies, which would be unlikely as measles virus is spread through the air, and generally does not infect the brain (which is what would make a virus zombie-inducing, presumably). The movie Zombieland claims that a variant of the prion mad cow disease is responsible for causing zombification. This is far more plausible than the I Am Legend virus, as prion disease is spread through consuming brain tissue. So, if the disease were to somehow cause individuals to desire brain tissue, then they could become zombies.
The movie Contagion also talks about how an epidemic flu-like disease would spread throughout the human population. It discusses issues of control of virus spread, including quarantine, how viruses can recombine between species (the virus in the movie is a combination of a pig and a bat virus that can infect humans). Ironically, the virus in this movie is also a paramyxovirus (like measles virus), but it also infects the brain. Either the people behind Contagion are trying to validate the possibility of the I Am Legend virus existing, or they just want to do as well in the box office as I Am Legend. We think they should just shoot for Ratatouille.