This may have been asked before, so I apologize if it has. If everyone is infected with the virus, and will change regardless of the cause of death, why does a non lethal scratch or bite cause one to turn into a zombie?

Maybe I'm misunderstanding what you're stating. Everyone is infected already, so of course any kind of death will result in reanimation. However, if someone gets bit one the arm, or scratched, by a walker then that person turns into a walker due to the transmission of the virus... but everyone is already infected with the virus, so.... I don't understand why everyone wouldn't already be a walker since the virus itself kills people and reanimates them.

Only the open wound but you do have a point they're.... Hmm I wonder.... We'll wait for Z-Day to find out :3 Then ask the scientist want now Biatch I killed 50 of the things and I- *Turns* Doc finds no source of injury or illness* Great question and answer I honestly don't have a clue.... :P