zombies are usually nuclear infections through air or living things or non living things. the infection can move and do what ever the host could when it was alive,(ex) if the person was a good runner then the infection could move just as fast.

the way the infection works, is that when it enters the body it makes it's way through the blood stream, and wherever the infection is in the body you will be paralyzed until you find some sort of vaccine then once you can't even breath it will make its way to the brain, you will be able to move again but you will forget every thing that just happened. in 1-2 months you will feel major migraines, 2 more weeks you will feel to sick to eat, 3 days after that you will experience seizures and stomach pains, 5 weeks after that you will be prone to excessive bleeding and lose skin color no matter how much you tan, the next day oh wait... uh never mind there is no next day you'll pretty much be a walking corpes with but you will be able to see and think but you won't control your actions your virus will.