The article even says that the natives had no idea why they were getting sick! How did they connect the "can't use legs" to the cassava they ate?
Again, I realize that it must have been the way you describe, but it's still amazing.
The people getting sick are in eastern Africa, while cassava is native to South America. Stands to reason that the methods of cassava preparation weren't as ingrained to the people who were getting sick.
> How did they connect the "can't use legs" to the cassava they ate?
Keep in mind these people are in Africa cassava is native in South America. I am pretty sure people in south America will tell you that cassava is toxic if you don't do all the steps and not just "it's our culture".
The it's our culture response might be the case in places where it was introduced and people were told you have to do x,y,z to eat it.