A fairly standard zombie, walkers from The Walking Dead universe are different from romeros in that they'll eat all of you. For the sake of simplicity and not infecting everyone who comes into contact with them with the Wildfire virus (the dormant version of the virus that all Walking Dead characters carry), we'll say that they are only able to infect by biting or (assumed in canon but never proven) scratching, or, if you are very unlucky, if a weapon contaminated with walker blood breaks your skin. The direct infection kills the victim in under a day with some undefined type of sepsis, and then the Wildfire virus takes over from there.

I am also working on a post for Daryl that details his own dormant infection and the possibility of him infecting other characters by sharing bodily fluids or drinks, just breathing closely together, etc. after reading up on how Wildfire has been managed in other game settings. It is very easy to transfer the dormant version of the virus as everyone in the canon is infected, no matter how isolated they've been, so this means that if your character has had any close contact with Daryl, especially when he was bleeding during his arrival, it is up to you if you'd like to opt into being a carrier! This would mean absolutely nothing at first, except that no matter how your character dies, if the brain is not destroyed, they will reanimate as a conscious-less walker in anywhere from 3 minutes to 8 hours.