Going back over the past few pages, I see a lot of good ideas about the cause of the ZA disease.
Could it have something to do with viral load ? Everyone has a low intensity background level of infection, which has no noticeable symptoms.
Bites give a sudden massive viral spike overwhelming the subject and leading to death, after which...
...but the "what" of it all remains a mystery. There's a specific "bug" previously unknown to human history, so how was it introduced? It has to be
created, as all generations before died from usual causes, yet did not reanimate as cannibals. If one operates from the belief that the ZA has its origins in a lab, then anything created has elements that can be detected, and understood.
Obviously, Jenner's team did not have enough time to grasp the full picture of what they were dealing with. The horror of it all probably prodded them to (largely) operate in reverse (from effect to cause, instead of the other way around), which seems to be the thought process other survivors use.
Few (other than Hershel back on the farm) seem to wonder if the dead are only "half dead" (or "sick," as in Hershel's theory), as something is keeping the brain functioning--with a purpose, while the flesh decomposes. Clearly, that is not death as the world has come to accept the natural process (no matter the cause), so someone (in-series) has to stop thinking it is some random plague.
