(See also Overview of Prion Diseases Overview of Prion Diseases Prion diseases are rare progressive, fatal, and currently untreatable degenerative disorders of the brain (and rarely of other organs) that result when a protein changes into an abnormal form... read more .)
Scientists have been interested in kuru mainly because it shows how prion diseases can be transmitted from person to person.
Until the early 1960s, kuru was fairly common in Papua New Guinea. Prions were probably acquired during a burial ritual, which involved eating tissues of a dead relative as a sign of respect (called ritual cannibalism). Kuru probably started when prion-contaminated tissues from a person with Creutzfeldt-Jakob disease Creutzfeldt-Jakob Disease (CJD) Creutzfeldt-Jakob disease is a prion disease characterized by progressive deterioration of mental function, leading to dementia, involuntary jerking of muscles (myoclonus), and staggering when... read more were eaten. Kuru was more common among women and children because they were given the brains, which were more infectious. These rituals have been prohibited since the 1950s, and kuru has been virtually eliminated. Few, if any, people develop kuru anymore. However, 11 cases of kuru were reported between 1996 and 2004. These cases suggest that after a person is infected, symptoms may not develop until more than 50 years later.
The first symptoms of kuru include loss of coordination ( ataxia Coordination Disorders ), difficulty walking, and shaking ( tremors Tremor A tremor is an involuntary, rhythmic, shaking movement of part of the body, such as the hands, head, vocal cords, trunk, or legs. Tremors occur when muscles repeatedly contract and relax. (See... read more ) that resembles shivering (kuru means to shake).
Later, abnormal involuntary movements, such as repetitive, slow writhing or rapid jerking of the limbs and body (called choreoathetosis Chorea, Athetosis, and Hemiballismus ), may develop. The limbs become stiff, and muscles jerk (called myoclonus Myoclonus Myoclonus refers to quick, lightning-like jerks (contractions) of a muscle or a group of muscles. Myoclonus may occur normally (for example, jerking of a leg when a person is falling asleep)... read more ). Emotions may switch suddenly from sadness to happiness with sudden outbursts of laughter. People with kuru become demented and eventually placid, unable to speak, and unresponsive to their surroundings.
Most people with kuru die within 24 months after symptoms appear, usually as a result of pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more or infection due to bedsores ( pressure sores Pressure Sores Pressure sores are areas of skin damage resulting from a lack of blood flow due to prolonged pressure. Pressure sores often result from pressure combined with pulling on the skin, friction,... read more ).
No effective treatment is available. Treatment of kuru focuses on relieving symptoms.