The real breakthrough for understanding Creutzfeldt-Jakob disease occurred in 1957 with the discovery of a curious degenerative brain disease of cannibals. Certain Fore tribes of Papua, New Guinea were inflicted with a disease called Kuru - the trembling with fear. This disease manifested itself as a fatal disease with an onset and duration that lasted usually 1 year. To date there have been 2500+ cases reported in these relatively small villages with an occurrence of at least 1% of the population. It was prevalent in women and children but rarely affected adult males. The terminal stage of this brain disease was marked by total dementia, muteness, inability to move, ataxia (jerkiness of the muscles), dysarthria, dysphagia and death.

Kuru was determined to be linked to the ritual cannibalism that was practiced by these tribes. The brains of the elders were ritually prepared and eaten by the women and children, but seldom by the men. This endocannibalism was outlawed by the authorities of New Guinea and now the disease is slowly disappearing. There are still cases appearing due to the extreme incubation periods of the disease -exceeding 30 years in some instances. Kuru was successfully passed to chimpanzees in 1966 by intracerebral injection of brain specimens. This disease however, was not passed maternally or by mother's milk which was determined by very careful epidemiological studies.