In Zombie Fiction, it is classic for the majority of zombies to become zombies because they were biten by zombies. It is a classic exponential pattern of disease spreading. But, the onset of disease affects the plot of the story.
1) Fast: We're alive and "rage-class". Once the disease has erupts to critical mass, it is pretty much unstoppable. But, it essentially burns itself out. It is like Ebola. Easily spread, fast onset of symptoms followed by quick death in the 90% of the people. The natives were aware of Ebola and they would lock-down their village and the outbreak would be snuffed out. If people get sick and die too quickly, it is not very good at spreading past the point source if the population density is low.
** FT. Irwin has a 50 mile passive area-denial weapon of low density. The disease cannot get to the fort quickly so there is a lot of time to prepare. Not a lot of the zombies are going to be smart enough to hitch-hike and even fewer have the self control to not eat the driver. Even TOWTM chowed-down on
Paul the moment the door opened.
---------------------------------------------------
That "buffer" zone is the critical area. The infected have to walk there. The Ft would have had a few troops/dependents coming on to base and turning because they were in town when "IT" hit, but even 50 miles driving is longer than it takes them to turn. Tommy went from zero to sixty in about ten minutes, maybe less. ---------------------------------------------------------------------------------------------------------
2) Slow. The classic stuff. Although it spreads very slowly, it is awesome at infiltration. Too many people try to hide the bite and slip through the defensive measures. Then it can raise hell. The story has classic horror features and Lovecraftian paranoia to boot. Early in the outbreak an infected can use societies transportation system to be anywhere igniting another brushfire anywhere in the world in 24 hours.
-----------------------------------------------------------------------------------------------------------------------
The classic zombie case would give the base tons of preparation time. Sun Tzu says prepare the battlefield. Well, they'd have crazy advantage with their familiarity with the terrain. Chopper some artillary up to the hills, dig trenches or build dunes (plenty of sand). 50 miles for a walker is a lifetime.
-----------------------------------------------------------------------------------------------------------------------3) Hybrid: In Ex-heroes Peter Clines' virus is more like the AIDS virus. It does not kill, the secondary infections do. So, one person might get the virus and have the flu. He bites someone and passes on the Flu and the zombie-thing. The new person might have hepatitis.... So, the outbreak evolves slowly and people have the belief that it can be contained, but the acceleration obliterates best laid plans.
---------------------------------------------------------------------------------
Loved "Ex Heroes" by the way. I have the sequel in my kindle, but haven't started it yet.--------------------------------------------------------------------------------
We know that the disease is spread by a bite and takes over really really fast. We do not know anything about patient zero(s). I use plural because it errupts in many large cities at once. Did it just hit the first 100 top population centers or did it spark everywhere? This does not fit the fast model with a single point source model. Were a few zombies confined in multiple
places and something let them all out at once? Are multiple people infected all over the world with a latent virus that is simultaneously triggered?
Do not know.
But, if we find out that it was an alien invasion were the abductees of the past are taken to the mothership and the rest of humanity subjected to the virus at the same time, to complicate things, the alien invasion happens on the same day as the Rapture so a whole bunch of other people are pulled out on the same day we get whacked with a solar flare that knocks out the satelights, I will be pretty pissed.
