What Happened to Kuru (disease)?

Kuru is a transmissible spongiform encephalopathy (TSE), a class of invariably fatal neurodegenerative disorders caused by abnormally folded proteins called prions. The disease gained notoriety in the mid-20th century for its epidemic spread among the Fore people and neighboring linguistic groups in the Eastern Highlands of Papua New Guinea. The term 'kuru' means 'trembling' or 'shivering' in the Fore language, accurately describing a primary symptom of the disease, which also earned it the moniker 'laughing sickness' due to involuntary bursts of laughter.

The transmission of Kuru was directly linked to the Fore people's funerary practice of endocannibalism, where deceased relatives were ritually consumed as a mark of respect and mourning. Women and children were disproportionately affected because they typically consumed the brain, where infectious prions were most concentrated. The epidemic is believed to have originated from a single individual who developed sporadic Creutzfeldt-Jakob disease (CJD), another prion disorder, around the early 1900s, with the disease then spreading through the community via these mortuary feasts. At its peak in the 1950s, the mortality rate in some affected villages reached as high as 35 per 1,000 people.

A key turning point came in the late 1950s when the Australian administration of Papua New Guinea banned cannibalism, a practice that had already begun to decline due to missionary efforts. This cessation of the transmission route led to a dramatic decline in Kuru cases, although new cases continued to emerge for decades due to the disease's exceptionally long incubation period, which could extend to over 50 years. The pioneering research of D. Carleton Gajdusek and Vincent Zigas, beginning in 1957, established the infectious nature of Kuru and its classification as a transmissible spongiform encephalopathy, leading to Gajdusek's Nobel Prize in 1976. Later, Stanley Prusiner's work in 1982 identified prions as the causative agents, earning him a Nobel Prize in 1997, further solidifying Kuru's role in modern neuroscience.

As of 2026, Kuru has virtually disappeared, with the last known death reported in 2009. Despite its eradication, Kuru remains profoundly significant for scientific research. The study of the Fore population revealed a naturally occurring genetic variant (G127V) in the prion protein gene (PRNP) that confers strong resistance to Kuru, demonstrating a powerful example of recent human natural selection. This discovery, published in 2009, continues to inform research into genetic resistance to other prion diseases like CJD and neurodegenerative conditions such as Alzheimer's and Parkinson's. Recent developments include new genetic analyses in March 2024 shedding further light on the epidemic, and research published in April 2025 showing promising results in altering genes to reduce prion protein levels in mice, a potential step towards future treatments. The 'Prion 2025' congress, held in November 2025, further highlighted ongoing advancements in understanding and treating prion diseases, underscoring Kuru's enduring legacy in the field of neurobiology.