It's important to note that Zombie & Vampire are similar. Both need blood to survive... And according to the Word of GOD "There is Life in the Blood"
The infected humans would either drink actual blood to feel alive or suck life out of people through their words/deeds. There is a reason why a lot of people feel better when other humans are hurt by their hurtful Words.
Way back in the beginning of the Bible, Adam and Eve sinned by eating the fruit. Then they realized they were naked, and sewed fig leaves together to cover themselves. They hid from the Lord as He walked in the Garden in the cool of the day.
Personally, I think that Adam and Eve change physically as well as spiritually. After all, a husband and wife are almost required to be naked in front of each other, just so they can help the other through friendly, bodily examination. So, what's with A & E? They changed physically.
As their offspring, we're all zombies through them.