I think Raydon is the cause of all this. If you step back and think...ground zero is a huge clue. If they were dumping this material that was found when the zombie dropped it after being chased by Michael on this past episode; this could have been making its way into the oceans for a very long and some how found its way into the worlds water supply. Hawaii is evidence to that. I noticed all the soldiers at the end of the last episode all seemed to know the gentlemen's name on the office door where the papers where found. So in my mind im thinking that's why saul is resistant is because he has already been exposed during his military career. Raydon could have been experimenting with some sort of mind control or super soldier serum. If you think about that, then Ink comes to mind( The man in the pinned stripped suit) he was in the insane asylum and a lot government black experiments use those people who have lost there damn minds(ie CIA mind control tests using LSD in the 70s) for those experiments. Another clue is...why would the zombies go thru that much to go back unless Ink already knew what we used on him and he wants it for his own misdeeds. Please chime in