Kuru
Kuru is a rare and fatal neurological disease caused by prions, which are infectious proteins. It was primarily observed among the Fore people of Papua New Guinea, where the practice of consuming the brains of deceased relatives during cannibalistic rituals led to its spread. The term "kuru" means "shaking" in the Fore language, reflecting one of its key symptoms. Kuru gained attention in the mid-20th century, with over 200 deaths reported during its peak in the 1950s and 1960s, particularly affecting women and children who were more likely to consume brain tissue. Symptoms manifest in three stages: initial fatigue and unsteadiness, followed by severe tremors and emotional disturbances, and ultimately leading to profound physical incapacitation. No known cure exists for kuru, making supportive care the only available treatment. Prevention strategies include refraining from ingesting infected human tissue and promoting public health education to deter cannibalism. While kuru is no longer a public health crisis, continued research and cultural sensitivity are vital in preventing future outbreaks and understanding prion diseases.
Kuru
- ANATOMY OR SYSTEM AFFECTED: Brain, central nervous system
- ALSO KNOWN AS: Acquired prion disease, laughing death, transmissible human spongiform encephalopathy
Definition
Kuru is a rare, progressively degenerative, ultimately fatal, chronic, neurological ailment caused by an infectious protein (now called a prion). Scientists initially discovered kuru through studies of cannibalistic rituals of the Fore peoples of Papua New Guinea, who consumed the brains of dead tribal members. In the Fore language, the word kuru meant shaking, but it became associated with the disease because trembling was a characteristic symptom.
Although this brain infection is nonexistent or extremely rare in most countries, it reached epidemic proportions among the Fore in the 1950s and 1960s when more than two hundred deaths occurred (in a population of about 11,000 persons). Deaths increased in the 1970s and 1980s before dramatically declining in the 1990s and the first decade of the twenty-first century. Kuru is no longer the public health crisis it once was, as the last death from the disease occurred in 2009. However, it cannot be said that kuru has been wholly eradicated.
Causes
The cause of kuru was a riddle until researchers, including American physician Daniel Carleton Gajdusek, found that the disease was connected with the cannibalistic burial customs of the Fore and was transmissible to chimpanzees. These discoveries had significant implications for human disorders like Creutzfeldt-Jakob disease and animal illnesses such as bovine spongiform encephalopathy (so-called because of the large holes in infected brains). In 1976, Gajdusek received the Nobel Prize in Physiology or Medicine for his breakthrough discoveries.
In 1997, Stanley B. Prusiner won the Nobel Prize in Physiology or Medicine for his research on infectious proteins, which he called “prions” (derived from the terms “protein” and “infectious”). This research further deepened the understanding of the cause of kuru and other diseases by showing that prions caused them. Prions cannot reproduce but can be transmitted by ingesting prion-infected tissue, such as human brain tissue, which lacks nucleic acids. Another transmission route is genetic inheritance, thereby distinguishing prions from infectious agents such as viruses.
Risk Factors
The riskiest behavior is consuming prion-infected tissue. At the disease’s peak, kuru was about eight times more prevalent among women and children than among men, most likely because women were the primary consumers of dead brain tissue while men ate other body parts.
Symptoms
Because of kuru’s long incubation period, symptoms can take several months to several years to appear (some researchers extend the period to thirty or fifty years). The average incubation time for kuru is between ten and thirteen years. According to Gajdusek, kuru’s symptoms emerge in three main stages. The first or ambulant stage is characterized by excessive fatigue and unsteadiness of stance, speech, and limbs, which are prone to shivering; the second or sedentary stage is distinguished by more extreme tremors, lack of coordination, and deep depression, followed by fits of laughter (kuru is also known as “laughing death”); the third or terminal stage is marked by the person’s inability to sit or stand, by incontinence, and by difficulty swallowing (leading to malnutrition, which often factors into the ultimate cause of death). Individuals with kuru may also experience muscle weakness, headaches, joint pain, behavioral changes, and dementia.
Screening and Diagnosis
A doctor (generally a neurologist) will question an infected person and those who know them about the onset of symptoms, especially changes in the ability to walk and speech slurring. Other indications, such as head, trunk, and limb tremors, will also form part of the diagnosis. Brain imaging, such as Magnetic Resonance Imaging (MRI) and Electroencephalogram (EEG), may also help distinguish kuru from other neurological disorders. Laboratory tests for kuru include blood tests, cerebrospinal fluid analysis, and genetic testing. Finally, examining a patient’s brain during autopsy can determine if the patient had kuru. However, these tests must be available to the patient, and they are often not due to lack of healthcare access.
Treatment and Therapy
Because no treatment for kuru exists, and the prognosis is always fatal, the best treatment is supportive care and ameliorative medicines. Prusiner believes that a comprehensive understanding of the three-dimensional structure of infectious proteins will lead to anti-gene therapies for persons with prion diseases, which has yet to come to fruition. However, studies continue into repurposing existing drugs that show anti-prion properties, using immunotherapy to develop drugs or a vaccine, and using gene editing.
Prevention and Outcomes
Kuru can be prevented by not ingesting prion-infested brains. Other prevention methods include enacting public policies that ban cannibalism and helping to educate healthcare workers and the general population about proper methods of handling and disposing of infected tissues. Although kuru has not been a public health issue for over a decade, research into treatments and observing the communities in which it was once found remains vital. Finally, visiting with Indigenous communities and discussing changing cultural practices, though a sensitive topic, remains crucial to preventing future outbreaks of kuru.
Bibliography
Anderson, Warwick. The Collectors of Lost Souls: Turning Kuru Scientists into Whitemen. Baltimore: Johns Hopkins University Press, 2008.
Emfietzoglou, Maria. "Kuru: What Is It, Causes, Signs and Symptoms, and More." Osmosis, 30 Mar. 2023, www.osmosis.org/answers/kuru. Accessed 30 Sept. 2024.
Klitzman, Robert. The Trembling Mountain: A Personal Account of Kuru, Cannibals, and Disease. New York: Plenum Press, 2001.
"Kuru." MedlinePlus, 4 Dec. 2022, medlineplus.gov/ency/article/001379.htm. Accessed 30 Sept. 2024.
Piran, Pirouz, and Jahangir Moini. Functional and Clinical Neuroanatomy: A Guide for Health Care Professionals. Elsevier Science, 2020.
Prusiner, Stanley B., editor. Prion Biology and Diseases. 2d ed., Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory Press, 2004.
Zigas, Vincent. Laughing Death: The Untold Story of Kuru. Clifton, N.J.: Humana Press, 1990.