What is kuru?

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.