Some kind of WW3/resource war event happens. The majority of human beings (definately over 90%, so billions) are killed by a series of bioweapon diseases used by both sides or die in the ensuing collapse (starvation, breakdown of infrastructure and medical care, general chaos, suicide from despair). There may be a limited nuclear exchange that destroys major targets, but not on the level of making the entire planet a radioactive wasteland, and it is not what kills most human beings. Obviously, the global economy as we know it and virtually all government ceases to exist.
Most survivors live in pockets of countryside backwater enough to avoid the worst of the collapse. They typically live by small scale agriculture and craftsmanship (roughly around the level off the Amish, maybe a little less. My point is, they don't go all the way back down to caveman-level). Some of these communities were founded by survivalists/homesteaders who believed that the world as they knew it was heading towards some kind of collapse. Some of these communities attempt to integrate surviving refugees from modern society, others leave them to die.
The survivors of the setting, especially the refugees from the not-backwater regions of the world, have seen a level of death and destruction unprecedented in human history. Billions dead, cities full of corpses, the entire modern way of life gone. I was thinking about the psychological and cultural effects of this. Obviously, many people would be traumatized and there would be a peculiar stress of knowing that the world you once counted on is now gone. I had the idea that something like a mass psychogenic illness or a culture bound syndrome might develop where people hallucinate that they are seeing the dead, or hearing dead people talk to them (if you are a survivor, it can be taken for granted that almost everyone you have encountered- from old classmates and coworkers to people in the checkout line of the grocery store, are now dead). How plausible is this?
This is my first question. I hope it was properly formatted and tagged.