What is kuru?

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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.
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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 1950’s and 1960’s when more than one thousand deaths occurred (in a population of about eight thousand persons). Deaths increased in the 1970’s and 1980’s before dramatically declining in the 1990’s and the first decade of the twenty-first century.

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 important implications for such human maladies as Creutzfeldt-Jakob disease and for 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 understanding of the cause of kuru and other diseases by showing that they were caused by prions. Lacking nucleic acids, prions are unable to reproduce, but they can be transmitted through the ingestion of prion-infected tissue, such as human brain tissue. Another route of transmission is genetic inheritance, thereby distinguishing prions from such infectious agents 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 major consumers of dead brain tissue.

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). 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).

Screening and Diagnosis

A doctor (generally a neurologist) will question an infected person and those who know him or her about the onset of symptoms, especially changes in the ability to walk and the slurring of speech. Other indications, such as tremors of the head, trunk, and limbs, will also form part of the diagnosis.

Treatment and Therapy

Because no treatment for kuru exists and the prognosis is always fatal, the best treatment is supportive care and ameliorative medicines. However, scientist 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.

Prevention and Outcomes

Kuru can be prevented by not ingesting prion-infested brains.

Bibliography

Anderson, Warwick. The Collectors of Lost Souls: Turning Kuru Scientists into Whitemen. Baltimore: Johns Hopkins University Press, 2008.

Klitzman, Robert. The Trembling Mountain: A Personal Account of Kuru, Cannibals, and Disease. New York: Plenum Press, 2001.

Prusiner, Stanley B., ed. 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.