I have to believe this is much more than simple food poisoning. Bacteria doesn't make you sick right after you eat it unless it's a poison like botulism.
Like almonds and peach or apricot pits, manioc root (casava) contains natural cyanide compounds that improper preparation doesn't remove. Shred; squeeze; soak; squeeze; (repeat? Not sure.) dry; powder, grind, or rice; then prepare.
The women may have obtained improperly prepared or contaminated flour.
And to think we had tapioca for desert tonight.
I read somewhere that this particular edible, when prepared improperly, produces cyanide as it's broken down. Two of the plants in question can apparently kill an adult. *shrug* Just relating what I read. I'll have to go back and see if I can find it.