How I believe it can start
i think there are several ways something similar to a zombie apocalypse could begin. Here are a few...
here is a link to some actual scientific ways a zombie apocalypse could start
http://www.cracked.com/article_15643_5-scientific-reasons-zombie-apocalypse-could-actually-happen.html
- a mutated disease such as mad cow disease or rabies, possibly both mutating together causing a crazy rampaging person biting people and spreading the disease. person is not dead but displaying manarisims of a zombie
- some sort of radiation blast that turns people crazy
- some scientist fuck's up some stem cell research experiment.
here is a link to some actual scientific ways a zombie apocalypse could start
http://www.cracked.com/article_15643_5-scientific-reasons-zombie-apocalypse-could-actually-happen.html