What is the cause of the zombie outbreak?


In the first episode from the anime Zombie's already exist. And after
finishing the anime there's still no explanation about their origins. Is the
outbreak cause already revealed in the manga?




With the current information given we **do not know** the reason of the
outbreak.

This might be a potential plot point later on in the story as they do hint to
trying to find out the cause, but we wont know till the manga is updated once
more. Which might some while as it been on hiatus for quite some time. [Is
Highschool of the Dead on hiatus
again?](https://anime.stackexchange.com/questions/7292/is-hotd-on-hiatus-
again)




With the current information given we **do not know** the reason of the
outbreak.

This might be a potential plot point later on in the story as they do hint to
trying to find out the cause, but we wont know till the manga is updated once
more. Which might some while as it been on hiatus for quite some time. [Is
Highschool of the Dead on hiatus
again?](https://anime.stackexchange.com/questions/7292/is-hotd-on-hiatus-
again)

