Animate Object 3/r
Touch Range -1/r
Total Fade +1/r
Slow Fade for however long the zombies need to last. +x
Triggered (trigger on subject death) +1
Total: 4/r +x +1
Target infected, upon death, rises as an uncontrolled zombie. Anyone the zombie hits gets infected (on a failed save) and upon death rises as a zombie. And so on.
Does this work?