That’s something my grandmother used to say to me if I went outside with my hair wet: “You’ll catch your death!”. Or at least, someone’s grandmother used to say that. Television has made my memory of real-life events slightly hazy at times. I’m sure of at least one occasion in which she yelled at me for slicking my hair back though. My mother consoled me that it was probably nothing, but that my uncle or great-uncle or someone used to do this, and they went bald. We agreed that these things were probably not related.
The pre-zombification illness shown in The Walking Dead (and most other zombie movies) bears a striking resemblance to the Flu, probably because it is a painful and familiar condition to most people. It would be like catching your death, except that the Flu is incredibly non-lethal to anyone who is not a Big Damn Hero or a Big Dumb Crazy Person; unable to rest for a day or two and drink fluids as most living things must from time to time.
The general state of illness in the modern world makes zombie movies with infectious viruses seem silly. Humans don’t generally lay down and die from illness like we used to. In the old days there was the Bubonic Plague, which knocked out entire continents worth of people. And people died of Hepatitis, and Tuberculosis and other big words. Now people get vaccinations and take Penicillin, and they get STDs and take more Penicillin. And they get an STD that exists only to make them vulnerable to those diseases they got vaccination against again.
Humans have become so good at combating infectious disease, that I don’t think a Zombie Apocalypse is truly possible. The military probably would just carpet bomb Atlanta anyway.