Kuru

Definition

Kuru is the name of a progressively disabling and ultimately fatal brain infection caused by a unique protein particle called a prion.

Description

Kuru was first described in a specific tribal group in Papua, New Guinea. The word "kuru" means "to shake or tremble" in this tribal group's language. Individuals in New Guinea are believed to have acquired the infection through a cannibalistic ritual involving the blood and brains of deceased tribal members.

Because infection with kuru may occur years or decades before the advent of actual symptoms of the disease, it belongs to a group of diseases originally known as slow virus infections. Currently, slow virus infections are classed together as transmissible spongiform encephalopathies (TSE). TSEs include kuru, Creutzfeldt-Jakob disease , Gerstmann-Sträussler-Scheinker syndrome, and fatal familial insomnia. The TSE new variant called Creutzfeldt-Jakob disease (also known colloquially as "Mad Cow Disease") has received a great deal of public attention. The TSEs, including kuru, involve abnormal clumps of protein that accumulate throughout the brain, destroying brain tissue and leaving spongy holes.

Demographics

Kuru reached epidemic proportions among tribal members in the 1950s. Since the practice of cannibalism was halted, the disease has essentially disappeared. Some sources suggest that as few as zero to 10 cases of kuru are diagnosed each year.

Causes and symptoms

Kuru is caused by an infectious protein particle called a prion, which stands for proteinaceous infectious particle. A prion is similar to a virus, except that it lacks any nucleic acid, which prevents it from reproducing. Prions are abnormal versions of proteins that are found in the membranes of normal cells. These abnormal proteins can be passed directly to individuals through the ingestion of prion-infected tissue or when open sores on the recipient's skin are exposed to prion-infected tissue. In addition to being transmissible (as are other infectious agents like viruses or bacteria), prions are unique because they can also be acquired through genetic inheritance.

Symptoms of kuru tend to begin in later middle age, years or decades after the prion was actually acquired. Early symptoms include lack of energy, intense fatigue , headache , weight loss, joint pain , difficulty walking, twitchy muscles, personality changes, mood swings, memory problems, and bizarre behavior. As the disease progresses, the individual experiences stiff muscles, involuntary movements, problems talking, hallucinations, increased confusion, blindness, and sometimes dementia . Death often occurs within three months to two years of the initial symptoms.

Diagnosis

Diagnosis is arrived at through characteristic abnormalities found on the electroencephalogram (EEG), a test of brain waves and electricity. Seventy-five percent of individuals with kuru will display these specific abnormalities on EEG. MRI studies and biopsies (tissue samples) from the brain may also show changes that are characteristic of slow virus infection.

Treatment team

Diagnosis of slow virus infection is usually made by a neurologist .

Treatment

There are no available treatments for kuru. It is relentlessly progressive, incurable, and fatal. Supportive care for the patient and his or her family is the only treatment.

Prognosis

Kuru is always fatal.

Resources

BOOKS

Berger, Joseph R., and Avindra Nath. "Slow virus infections." Cecil Textbook of Medicine, edited by Thomas E. Andreoli, et al. Philadelphia: W.B. Saunders Company, 2000.

Murray, T. Jock, and William Pryse-Phillips. "Infectious diseases of the nervous system." Noble: Textbook of Primary Care Medicine, edited by John Noble, et al. St. Louis: W.B. Saunders Company, 2001.

PERIODICALS

Sy, Man-Sun, Pierluigi Gambetti, and Wong Boon-Seng. "Human Prion Diseases" Medical Clinics of North America 86 (May 2002) 551–571.

WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). Kuru Fact Sheet. Bethesda, MD: NINDS, 2003.

Rosalyn Carson-DeWitt, MD

Kuru

Mystery in New Guinea

What Are the Symptoms?

Kuru is a disease of the nervous system that is extremely rare today, but that once was common among people in certain tribes in Papua, New Guinea, who practiced cannibalism.

KEYWORDS

for searching the Internet and other reference sources

Cannibalism

Neuromuscular system

Prions

Spongiform encephalopathies

Mystery in New Guinea

In the 1950s, a strange disease of the nervous system was killing people in certain tribes in the highlands of New Guinea, an island north of Australia in the Pacific Ocean. An American scientist named Daniel Carleton Gajdusek traveled to New Guinea to study the disease, which the people there called kuru. Eventually, he traced the problem to cannibalism, the eating of human flesh by another human. In this case, cannibalism took the form of a ritual in which people ate the uncooked brains of relatives who had died. Today, those New Guinea tribes no longer practice this ritual, and kuru has almost vanished.

Gajdusek thought that kuru was passed from a dead person’s brain to a living person by a slow virus, a virus that takes years to cause symptoms. Most scientists no longer believe this theory, however. Instead, most now think that kuru is caused by a prion, a type of protein that can cause infection. Kuru belongs to a group of human and animal diseases of the brain, known as transmissible spongiform (SPUN-ji-form) encephalopathies (en-sef-a-LOP-a-theez), that may be caused by prions. The word “spongiform” refers to the way infected brains become filled with holes until they look like sponges under a microscope. The most common such disease in humans is Creutzfeldt-Jakob disease.

What Are the Symptoms?

People with kuru have trouble controlling their movements, and this problem gets worse over time. Their arms and legs may appear stiff, or they may have rapid muscle spasms. Occasionally, their muscles may twitch or jerk uncontrollably, or their fingers, hands, toes, and feet may move in a slow, writhing motion. As the disease gets worse, people with kuru may start to lose their mental abilities, such as thought, memory, and concentration. Death usually occurs within 3 to 12 months. Kuru is extremely rare today, but it still fascinates scientists who are studying related diseases.

See also

Creutzfeldt-Jakob Disease

Kuru. One of the sixteen polities of ancient India lying to the north-west near modern Delhi, between the Yamunā and the Ganges, north of Mathurā. Though relatively unimportant during his lifetime, the country is said to have been visited on a few occasions by the Buddha Śākyamuni and a few discourses were given there.

kuru Or trembling disease; progressive degeneration of brain cells, associated with cannibalism in Papua‐New Guinea, and believed to be caused by a prion. More or less eradicated since ritual cannibalism was abolished.