When a zombie bites a victim, the victim contracts a deadly illness, ultimately resulting in the victim's death and reanimation. Zombie scratches can also infect a victim with a deadly illness. Zombie bites are not how the "infection" is spread. Instead, zombie bites and saliva cause infections that are 100% fatal.
Symptoms of infection:
- Pale skin
- Dialated eyes
- Soreness (e.g. Jim in the TV Series episode, "Wildfire")
- Fluid discharge
The only way a victim can survive a zombie bite/scratch is to quickly amputate the part of the body that has been affected. The length of time that an amputation must be performed in to successfully save a victim from the illness taking hold is unknown, and seems to vary based on the circumstances of the situation. In the comic book, Dale is the only character known to have survived this process while both Morgan Jones and Allen died of either blood loss, bacterial infection or clots (unknown due to a constant lack of professional opinion). In the TV series, Hershel Greene is bitten on the leg by a zombie in the first episode of season three. Attempting to save Hershel's life, Rick amputates Hershel's leg, and it is later revealed that Hershel survives the event.