They called the disease kuru, which means "shivering" or "trembling."
They'd also lose control over their emotions, which is why people called it the "laughing death." Within a year, they couldn't get up off the floor, feed themselves or control their bodily functions.
But it wasn't a virus — or a bacterium, fungus, or parasite. It was an entirely new infectious agent, one that had no genetic material, could survive being boiled, and wasn't even alive.
https://www.npr.org/sections/thesalt/2016/09/06/482952588/when-people-ate-people-a-strange-disease-emerged