There are many different means of contagion for zombies. One can become a zombie in different ways based upon what sort of zombie plague is upon us. The vectors vary widely.
There Are Different Ways To Become A Zombie
Direct infection through transference of bodily fluids from a zombie, radiation or other mutagens, a virus – all are staple means of becoming a zombie in science-fiction and horror. Yet those means pale in effect and virulence as compared to the real world zombie infection – college.
Between their ongoing efforts to destroy the capacity for independent thought in favor of Liberal indoctrination and their focus on training through rote in order to churn out good little cogs in the various machines, all American colleges and universities are is zombie spawn points.
If you don’t believe me, just go to any campus and watch the drooling, shuffling hordes wander from class to class, or go look at the recent graduates and they shamble back home to feed off their parents. 😉