The 1st person infected by a zombie plague starting the zombie apocalypse/end of times. reffering to a mass infection of a populace either by a secret operation or misshap. This "zombie plague" swamps normal military and law enforcement organizations, leading to the panicked collapse of civilian society until only isolated pockets of survivors remain, scavenging for food and supplies in a world reduced to a pre-industrial hostile wilderness also known as Z day.
becky was the first infected with the virus...she's patient zero. lets kill that bitch.
see:Night of the living dead, zombieland, left for dead, 28 days later
The most effective way to contain the rise of the undead is to hit hard and hit often.