Kuru is a human prion disease that was endemic among the Fore and related peoples of Papua New Guinea in the mid‑twentieth century. It is caused by ingestion of misfolded prion proteins from human brains during endocannibalistic funeral rites, leading to progressive cerebellar ataxia, tremors and death.
Pathogenesis and Clinical Features
Kuru is acquired rather than hereditary: infectious PrPSc isoforms enter the body through consumption of contaminated neural tissue and traverse the gastrointestinal mucosa to replicate in lymphoreticular tissues. From there they spread along peripheral nerves to the central nervous system, where PrPSc propagates by converting endogenous prion protein and accumulates in the cerebellum, thalamus and cortex. Histopathology shows spongiform vacuolation, neuronal loss and marked astrocytosis with scant inflammatory response. The incubation period can vary from a few years to more than two decades depending on the exposure dose and host PRNP genotype. Once symptomatic, kuru progresses through three recognizable stages. In the ambulant stage patients display unsteady gait, limb pain and tremor but can still walk. The sedentary stage is marked by severe ataxia, dysarthria, emotional lability and loss of coordination. The terminal stage involves inability to sit without support, dysphagia, urinary and faecal incontinence and susceptibility to secondary infections. Cognitive impairment is mild relative to motor dysfunction. There is no cure; supportive care can only mitigate symptoms, and death usually occurs within 12–18 months of onset.
Historical Outbreak and Decline
Kuru was first documented by Australian patrol officers in the 1950s, and investigations by Michael Alpers and Carleton Gajdusek demonstrated that the disease was transmitted through mortuary cannibalism practiced by the Fore people. At its peak in the early 1960s, kuru caused hundreds of deaths per year and was especially common among women and children who consumed the most brain tissue. When the colonial administration and local leaders discouraged cannibalistic rites, the incidence declined precipitously. Because of the long incubation period, isolated cases continued to appear for decades; the youngest patient born after the ban died in 2005 and the last recognized case occurred in 2009. Genetic studies have identified a valine-to-glycine substitution at PRNP codon 127 in some survivors that confers resistance to kuru and possibly other prion diseases. Research on kuru provided critical insight into human transmissible spongiform encephalopathies, supporting the concept that prions are proteinaceous infectious agents. The cessation of cannibalism remains the only effective prevention.
Kuru offers a historical example of how cultural practices can influence disease transmission and demonstrates the resilience of prions in causing neurodegeneration after prolonged incubation. Continued monitoring ensures that no secondary outbreaks arise and honours those whose suffering led to important scientific discoveries.
Related Terms: Creutzfeldt–Jakob disease, variant CJD, scrapie, chronic wasting disease, prion