That particular prion disorder comes from eating affected brain and/or spinal cord. Not from general cannibalism. If you ate the arm or leg of a person affected by the disease you wouldn't get the disease. If you ate the brain/spinal cord you would. Same goes for eating an affected cow, etc.
shareTrue.
In the film, when the doc is flipping through his medical books, he leaps from Parkinson's disease to Alzeimer's to Prion Disease to Kuru, where he comes across: 'Known Causes. Cannibalism. ...consumption of human brain tissue'. Note, it doesn't say, 'infected' brain tissue. He later suggests that prion disease comes from the eating of human flesh.
Kuru is contracted by eating infected brains of dead people, but why spoil a good story?
...it's just another dumb film, get over it.
I thought it was clear in the movie - if you ate the brains, you got the disorder.
They obviously ate the brains.