[quote=@ManoftheNorth]
That is true, to a degree. New Guinea is the most infamous for the Kuru Disease, but Kuru is a Prion disease, and the contraction of it can occur from a corpse being devoured. The biggest cause is devouring old brains, bone marrow, and other highly protein-heavy nutrient rich parts of the human body. Kuru is not the only issue though, Kuru is just the most well know. 

Prion disease in general are a problem in cannibalism. This is evident in a few cases in which cannibals have been noted having unstable hands, shaky arms, a jerking leg. These are early signs of a Prion Disease setting in with their muscle spasms.
[/quote]

Ah, I forgot that Kuru is a Prion disease. 

But anyway, Kuru is usually transmitted through eating human brain matter. 
There are a couple of reasons why Kaden might have contracted some form of Kuru, mainly that he's scavenging (therefore, what remains he's been feeding off of might not be particularly fresh), and that he's had no formal education and probably doesn't know about Kuru. But at the same time, most people who aren't trained hunters don't know that brains are edible. He's not likely to be eating organs that aren't typically consumed. Besides, since he can't save food easily, he tends to stick to smaller animals when he can find them.