More recently, Chipotle has suffered from publicity associated with a significant, western states e. coli outbreak, a Boston area norovirus outbreak, and finally a different strain of e. coli outbreak in Oklahoma/Kansas/etc. area.
I have a theory, and I bet you can predict what it is. But on the off chance it has not occurred to you yet, allow me to remind you of this earlier example of domestic terorism:
Until members of the cult came forward with confessions, despite quite a lot of suspicion, public health officials in Oregon persisted in treating this as a hygiene issue, rather than as a bio-terror attack.
The disparate nature of the incidents at Chipotle, and their persistence in the face of the chain engaging at all levels with the problem, suggests to me that this isn't a process problem. Well, _it is_ a process problem, but it's more in the nature of the "process problem" that was exposed by this attack:
We never did figure out who did that, altho we made a bunch of changes (caplets vs capsules, foil and similar tamper resistant and tamper evident packaging) to make it harder for that to recur. (I had no idea until I read that that the FBI was thinking it might have been the Unabomber.)
I'm poking around to see if there's any media speculation on this topic and not finding any. If you can find some, please shoot me a link either via email or in the comments.
ETA: You don't need to tell me _why_ there might be media silence on this theory. I can imagine those reasons all by myself.