Kuru is a rare and fatal nervous system disease that occurred mainly during the 1950s and 1960s among the Fore people in the highlands of New Guinea. The Fore people contracted the disease by performing cannibalism on corpses during funeral rituals.
The name kuru means “to shiver” or “trembling in fear.”
The symptoms of the disease include muscle twitching and loss of coordination. Other symptoms include difficulty walking, involuntary movements, behavioral and mood changes, dementia, and difficulty eating. The latter can cause malnutrition. Kuru has no known cure. It’s usually fatal within one year of contraction.
The identification and study of kuru helped scientific research in a number of ways. It was the first neurodegenerative disease resulting from an infectious agent. It led to the creation of a new class of diseases including Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease, and fatal familial insomnia.
Today, the study of kuru still impacts research on neurodegenerative diseases.
Symptoms of more common neurological disorders such as Parkinson’s disease or stroke may resemble kuru symptoms. These include:
- difficulty walking
- poor coordination
- difficulty swallowing
- slurred speech
- moodiness and behavioral changes
- dementia
- muscle twitching and tremors
- inability to grasp objects
- random, compulsive laughing or crying
Kuru occurs in three stages.
It’s usually preceded by headaches and joint pain. Since these are common symptoms, they are often missed as clues that a more serious disease is underway.
First stage: A person with kuru exhibits some loss of bodily control. They may have difficulty balancing and maintaining posture.
Second stage: Also called the sedentary stage, the person is unable to walk. Body tremors and significant involuntary jerks and movements begin to occur.
Third stage: the person is usually bedridden and incontinent. They lose the ability to speak. They may also exhibit dementia or behavior changes, causing them to seem unconcerned about their health.
Starvation and malnutrition usually set in at the third stage, due to the difficulty of eating and swallowing. These secondary symptoms can lead to death within a year. Most people end up dying from pneumonia.
Kuru belongs to a class of diseases called transmissible spongiform encephalopathies (TSEs), also called prion diseases. It primarily affects the cerebellum — the part of your brain responsible for coordination and balance.
Unlike most infections or infectious agents, kuru is not caused by bacteria, viruses, or fungi.
Infectious, abnormal proteins known as prions cause kuru. Prions are not living organisms and do not reproduce. They are inanimate, misshapen proteins that multiply in the brain and form clumps, hindering typical brain processes.
Creutzfeldt-Jakob, Gerstmann-Sträussler-Scheinker disease, and fatal familial insomnia are other degenerative diseases caused by prions. These spongiform diseases, as well as kuru, create sponge-like holes in your brain and are fatal.
You can contract the disease by eating an infected brain or coming into contact with open wounds or sores of someone living with it.
Kuru developed primarily in the Fore people of New Guinea when they ate the brains of dead relatives during funeral rites. Women and children were mainly infected because they were the primary participants in these rites.
The New Guinea government has discouraged the practice of cannibalism. Cases still appear, given the disease’s long incubation period, but they are rare.
Neurological exam
Your doctor will perform a neurological exam to diagnose kuru. This is a comprehensive medical exam including:
- medical history
- neurological function
- blood tests, such as thyroid, folic acid level, and liver and kidney function tests (to rule out other causes for symptoms).
Electrodiagnostic tests
Tests such as electroencephalogram (EEG) are used to examine the electrical activity in your brain. Brain scans such as an MRI may be performed, but they may not be helpful in making a definitive diagnosis.
There is no known successful treatment for kuru. Prions that cause kuru can’t be easily destroyed. Brains with prions remain infectious even when preserved in formaldehyde for years.
People with kuru require assistance to stand and move and eventually lose the ability to swallow and eat because of symptoms.
As there is no cure for it, people with it may lapse into a coma within six to 12 months after experiencing initial symptoms.
The disease is fatal and it’s best to prevent it by avoiding exposure.
Kuru is exceptionally rare. It’s only contracted by ingesting infected brain tissue or coming into contact with sores containing kuru prions. Governments and societies sought to prevent the disease in the mid-20th century by discouraging the social practice of cannibalism.
The incubation period of kuru — the time between initial infection and the appearance of symptoms — can be as long as 30 years. Cases have been reported long after the practice of cannibalism has ceased.
Today, kuru is rarely diagnosed. Symptoms similar to those of kuru are more likely to indicate another serious neurological disorder or spongiform disease.