This op has failed every time I've tried to use it. The message says my spies were klutzes and accidentally poisoned my own food supply, yet none of my civs die. What's up with this?

It's a bug - its been happening for a few weeks at least, the bioterrorisms do actually work even when it says they've failed.

Hmmm

OK, then, that's a provable point, right there. If you've successfully plagued some country, that should show up on a standard spy report, however, I think you might need to wait for them to run a turn before it appears in that report.

This is the third post about it recently but can only find this one:

https://www.earthempires.com/...kfires-47808?t=1570519653

I've had it myself, it says you've poisoned your own water but you lose no civs. The target had zero spies and I had a lot of spies so very unlikely to have actually failed. Bioterrorism is working cause I've been poisoned I can only assume (though I've not proved it) that there's a bug causing the wrong message to display.

You will infect yourself not based on spal ratios but based on how many bios are active on the target.

So if you do 10 bioterrors with 1000 spal against a 0 spal country of your size you will probably reflect 1-4 on yourself, but fail none.