With a disease that contagious, I cannot possibly believe that the entire world of the comic has not already been infected with lycanthropy or a full-blown Werewolf/Zombie Apocalypse that filled the world with werewolves long ago. Not to mention, it could also likely spread through fleas and other blood-sucking vermin.
It's the same argument with the Vampire/Zombie Apocalypse: if vampirism was a contagious disease, the world would have been filled with vampires long ago.
But since this is a comic, I will momentarily suspend my disbelief... disbelief suspended.