There are many rare diseases in the world that many people have never even heard of. One such rare and fatal disease is called kuru. Kuru is a nervous system disease that was highly prevalent during the 1950s and 1960s amongst the Fore tribe in New Guinea. It was believed that the disease originated due to the Fore people performing cannibalism on corpses during their funeral rituals. The term kuru means ‘trembling in fear or ‘shivering.’ Symptoms of kuru include loss of muscle coordination and muscle twitching. There is no known cure for the disease, and if a person contracts the disease, they usually succumb to it within a year of getting disease. Read on to find out everything you need to know about kuru.
What is Kuru?
Kuru is a rare type of nervous system disease that has a high rate of fatality. The disease was most commonly observed in the 1950s and 1960s in the Fore tribe of New Guinea, who contracted it due to cannibalism on corpses while performing funeral rituals.(1, 2)
The most common symptoms of kuru include loss of coordination and muscle twitching. Some other symptoms of kuru may include:
- Involuntary movements
- Mood and behavioral changes
- Difficulty eating
- Difficulty walking
Experiencing difficulty in eating can lead to malnutrition, which tends to worsen as the disease progresses. There is no known cure for kuru, and the disease tends to be fatal within one year.
Over the years, there has been a lot of research that has been done on kuru. In fact, kuru was identified as the first neurodegenerative disease caused by an infectious agent. This led to the formation of a new class of diseases which included fatal familial insomnia, Gerstmann-Sträussler-Scheinker disease, and Creutzfeldt-Jakob disease. Even today, the research and study of this disease continue to affect the field of neurodegenerative diseases.(3, 4, 5)
What are the Symptoms & Causes of Kuru?
Many of the symptoms of neurological conditions like Parkinson’s disease or stroke tend to mimic the symptoms of kuru. These similar symptoms may include:
- Poor coordination
- Difficulty walking
- Slurred speech
- Mood and behavioral changes
- Difficulty swallowing
- Muscle twitching
- Random and compulsive crying or laughing
- Inability to hold or grasp objects
Kuru tends to occur in three main stages. However, the disease is typically preceded by joint pain and headaches. Since these are also the common symptoms of many diseases, they are usually missed or ignored as clues that there is a much more severe disease underlying the symptoms.(6, 7)
Here are the three stages of kuru:(8)
- Stage one: A person who has contracted kuru starts to exhibit some level of loss of bodily control. They start experiencing difficulty in maintaining posture and balancing.
- Stage two: Commonly known as the sedentary stage, during the second stage of kuru, a person is left unable to walk. Body tremors combined with significant involuntary movements and jerks also start to develop.
- Stage three: In the last stage of kuru, the patient generally becomes incontinent and bedridden. The person loses the ability to speak and may also start to show symptoms of dementia or serious changes in their behavior or moods. This causes them to appear unconcerned about their health and condition.
Malnutrition and starvation also tend to set in at stage three because of the difficulty in eating and swallowing. These are the secondary symptoms of kuru that cause the death of the person within one year. Most people who have contracted kuru end up dying from complications like pneumonia.(9)
When kuru was first diagnosed, it was found that it was spreading amongst the Fore people due to cannibalism that they performed during their funeral rituals. Kuru is classified to belong to a class of diseases known as transmissible spongiform encephalopathies (TSEs), also known as prion diseases. This class of diseases affects the cerebellum part of the brain, which helps regulate balance and coordination in people. Unlike most of the common infections or infectious agents, kuru is neither caused by bacteria, fungi, or viruses. The disease is caused by infectious and abnormal proteins known as prions.(10, 11, 12)
Prions are not considered to be living organisms, and they do not reproduce. Prions are misshapen and inanimate proteins that tend to multiply rapidly in the brain, quickly forming clumps. This disrupts your usual brain processes.
Some of the other degenerative diseases that are caused by prions include fatal familial insomnia, Gerstmann-Sträussler-Scheinker disease, and Creutzfeldt-Jakob. These are all spongiform diseases, just like kuru, and they end up forming sponge-like holes in your brain. All these diseases have a high fatality rate.(13, 14, 15)
You can get kuru by coming into contact with open sores or wounds of a person who has the disease or by eating the infected brain of someone with kuru. In the initial days of kuru, women and children were the main people affected because they were usually the primary participants in the funeral rituals of the Fore people in New Guinea. Even though the government of New Guinea strictly discouraged the practice of cannibalism, even today, some cases of kuru keep appearing from time to time, especially given the long incubation period of the disease. However, the disease still remains a rare occurrence.(16)
Diagnosis and Treatment of Kuru
The first step in diagnosing kuru is a neurological exam. Your doctor will perform a thorough neurological examination, which will include the following:
- A complete medical history
- Testing of your neurological function
- Blood tests, including thyroid tests, folic acid levels, as well as kidney and liver function tests, help rule out other underlying causes of the symptoms.
- After the neurological examination, electrodiagnostic tests are prescribed. These tests can include an electroencephalogram (EEG) to look at the electrical activity in the brain.
- Brain scans like an MRI may also be ordered though they are not too helpful in reaching a confirmed diagnosis.
As mentioned above, there is no known cure for kuru even today. Similarly, there is no known successful treatment for the disease. It is not possible to easily destroy the prions that are responsible for causing the disease. Brains that are infected with these prions continue to remain infected even after being preserved in formaldehyde for several years.(17, 18)
Is It Possible To Prevent Kuru?
Cases of kuru are exceptionally rare. The disease can only be contracted if you eat the infected brain tissue or come into direct contact with someone who has sores that contain the kuru-causing prions. Societies and governments have been working together to prevent the spread of this disease since the mid-20th century by actively discouraging the practice of cannibalism, especially in tribal areas. According to the National Institute of Neurological Disorders and Stroke (NINDS), kuru has been almost entirely wiped out. However, some cases still do emerge from time to time in very remote areas.(19)
The incubation period of kuru, which is the time period between the initial infection and the actual development of symptoms, is extremely long, sometimes taking as long as 30 years even. Cases of kuru have even been reported today, long after the practice of cannibalism has been wiped off the world.
Today, the disease is rarely diagnosed, and if a person exhibits symptoms similar to those experienced in kuru, it is more likely to be due to other serious neurological disorders or spongiform diseases.
You can only contract kuru if you eat the infected brain of someone who has kuru or if you come in contact with someone who has sores or wounds that contain the prions that cause kuru. People with kuru need help even to stand up or move around, eventually losing the ability to eat and swallow because of symptoms. Since there is no cure for the disease, people with kuru may go into a coma within six months to a year after the development of the initial symptoms.
Kuru is a fatal disease, and you can prevent contracting the disease by avoiding exposure and consuming an infected brain.
- Gajdusek, D.C., 1963. Kuru. Transactions of the Royal Society of Tropical Medicine and Hygiene, 57(3), pp.151-66.
- Mathews, J., Glasse, R. and Lindenbaum, S., 1968. Kuru and cannibalism. The Lancet, 292(7565), pp.449-452.
- Hadlow, W.J., 1959. Scrapie and kuru. Scrapie and Kuru., pp.289-90.
- Gajdusek, D.C., 1977. Unconventional viruses and the origin and disappearance of kuru. Science, 197(4307), pp.943-960.
- Hornabrook, R.W., 1975. Kuru. Contemporary Neurology Series, 12, pp.71-90.
- Liberski, P.P., Sikorska, B., Lindenbaum, S., Goldfarb, L.G., McLean, C., Hainfellner, J.A. and Brown, P., 2012. Kuru: genes, cannibals and neuropathology. Journal of Neuropathology & Experimental Neurology, 71(2), pp.92-103.
- Lindenbaum, S., 2015. Kuru sorcery: disease and danger in the New Guinea highlands. Routledge.
- Collinge, J., Whitfield, J., McKintosh, E., Beck, J., Mead, S., Thomas, D.J. and Alpers, M.P., 2006. Kuru in the 21st century—an acquired human prion disease with very long incubation periods. The Lancet, 367(9528), pp.2068-2074.
- Kuru, T. and Lynch III, J.P., 1999. Nonresolving or slowly resolving pneumonia. Clinics in chest medicine, 20(3), pp.623-651.
- Collins, S.J., Lawson, V.A. and Masters, C.L., 2004. Transmissible spongiform encephalopathies. The Lancet, 363(9402), pp.51-61.
- Belay, E.D., 1999. Transmissible spongiform encephalopathies in humans. Annual review of microbiology, 53(1), pp.283-314.
- Haywood, A.M., 1997. Transmissible spongiform encephalopathies. New England Journal of Medicine, 337(25), pp.1821-1828.
- Johnson, R.T. and Gibbs Jr, C.J., 1998. Creutzfeldt–Jakob disease and related transmissible spongiform encephalopathies. New England Journal of Medicine, 339(27), pp.1994-2004.
- Chesebro, B., 2003. Introduction to the transmissible spongiform encephalopathies or prion diseases. British medical bulletin, 66(1), pp.1-20.
- Weissmann, C., 1999. Molecular genetics of transmissible spongiform encephalopathies. Journal of Biological Chemistry, 274(1), pp.3-6.
- Wilson, A., 2010. Kuru and the Fore.
- Nelson, H., 1996. Kuru: the pursuit of the prize and the cure. The Journal of Pacific History, 31(2), pp.178-201.
- Lindenbaum, S., 2001. Kuru, prions, and human affairs: Thinking about epidemics. Annual review of anthropology, pp.363-385.
- Kuru (no date) National Institute of Neurological Disorders and Stroke. U.S. Department of Health and Human Services. Available at: https://www.ninds.nih.gov/health-information/disorders/kuru (Accessed: November 27, 2022).