Kuru

What is Kuru?

Kuru is a disease that was first identified by Dr. D. Carleton Gajdusek and Vincent Zigas in 1957. It was found among the Fore tribes in Papua New Guinea and its name “kuru” translates to trembling from fever or cold. Kuru is a non-inflammatory disease which means it doesn’t cause swelling or redness, but it does cause damage to the nerves in the brain. It is classified as a form of transmissible spongiform encephalopathy, meaning it is a disease that can be passed on and causes a sponge-like degeneration in the brain. Unusually, it was spread through cannibalism.

People with kuru show symptoms quickly and these symptoms can affect coordination (cerebellar) and movement (extrapyramidal). Sadly, those impacted usually die within one to two years of showing symptoms. Thankfully, this disease is now extinct. However, when it was first discovered in the 20th century, it was crucial to helping us understand other similar diseases, known as prion diseases. Some other prion diseases include Creutzfeldt-Jakob disease (CJD), fatal familial insomnia (FFI), variant CJD (vCJD), and Gerstmann-Straussler-Scheinker (GSS) disease.

What Causes Kuru?

Kuru is a type of infectious disease that you can get from the traditional practice of eating the bodies of deceased family members as a part of mourning, also known as endocannibalism. The disease is caused by something called prions, which are proteins that have been misshaped and don’t include instructional nucleic acids, the parts of the cell responsible for storing and transmitting genetic information.

Risk Factors and Frequency for Kuru

Kuru was a common disease in Eastern Highlands of Papua New Guinea in the early 1900s, specifically among the Fore tribe and their neighboring groups. The disease, caused by an infectious prion, is concentrated in the victim’s brain. The worst times for the disease were in the 1940s and 1950s, where the death rate in affected villages could reach 35 in every 1000 people. Children and women were usually more affected than men because they consumed the brain in contrast to men who preferred muscles. The number of cases dropped significantly after the practice of ritualistic cannibalism lessened. Between July 1996 to June 2004, only 11 new cases were identified in a survey in Papua New Guinea. Some of these cases had an incubation period- the time between catching the virus and showing symptoms- of more than 50 years. No new cases have been reported recently, with the last one reported in 2005.

Signs and Symptoms of Kuru

Kuru is a lethal brain disorder that progressively damages the nervous system. This disease has a more predictable timeline compared to other prion diseases, which are a group of rare, fatal brain disorders that affect humans and animals.

After getting infected, a person may experience a mostly undefined phase for a few months with symptoms like headaches and joint pain, especially in the knees, ankles, elbows, and wrists. Abdominal pain and weight loss could also occur. Though kuru is infectious, it doesn’t typically cause fever, convulsions, or coma, unlike common brain infections like meningitis or encephalitis.

Kuru disease generally passes through three distinguishable stages:

• Ambulatory phase: This stage is characterized by unsteadiness while walking due to damage to the cerebellum (part of the brain that controls balance). Symptoms may include unsteady gait, shivering, unusual body movements, foot curling, reflex abnormalities, and other signs of cerebellar damage. Emotional instability, including bursts of laughter, also known as the “laughing disease,” may be observed.
• Sedentary phase: This phase begins when the patient can no longer stand without assistance and ends when they can’t sit without help. Symptoms get worse in this phase, and the patient may experience exaggerated reflexes, erratic eye movements, and involuntary muscle contractions.
• Terminal stage: In the final stage, the patient becomes bedridden and might develop swallowing difficulties and incontinence. Although they remain conscious, they become unresponsive to their surroundings. Symptoms may include fixed abnormal postures, involuntary muscle movements, and features of dementia. Sadly, most patients in this phase die due to pneumonia or infections in the wounds that have become ulcers, typically 9 to 24 months after the onset of the disease.

The time from exposure to the disease to the appearance of symptoms can vary widely, anywhere from 4 to 40 years, and in rare cases, even up to 50 years.

Testing for Kuru

If you’re being checked for kuru, a rare, incurable brain disease, your doctor will rely mainly on your personal health history and a physical exam. They’ll be looking for a specific order in which your symptoms appear, especially if you’re in a vulnerable population group.

Unfortunately, there aren’t any lab or imaging tests that can definitely say whether you have kuru. The only way to be absolutely sure is by looking at the affected brain tissue under a microscope after a biopsy procedure. The damaged tissue will show some very specific abnormalities if you have the disease.

An electroencephalogram (EEG), a test that records electrical activity in the brain, is another tool that doctors use to check for kuru. The EEG record can show unusual patterns in brain waves which can help determine if the symptoms are due to kuru or another condition. Compared to other similar diseases, an EEG of a kuru patient doesn’t show any sudden bursts of electrical activity, which is thought to be a distinguishing feature.

Treatment Options for Kuru

Human prion diseases are extremely serious and currently, there is no cure available. The only way to manage this condition is through supportive treatments – these are intended to relieve symptoms and improve quality of life, rather than cure the disease itself.

What else can Kuru be?

It’s important to identify and eliminate other types of dementia, some of which can be treated and even reversed. Some forms of dementia might be tied to certain signs or symptoms related to the brain, which can help to distinguish them from kuru disease. Doctors will use tools such as brain scans, blood tests, genetic studies, and pathology evaluations to make a diagnosis. Conditions that might be considered include:

• Other diseases caused by prions (misfolded proteins)
  • Creutzfeldt-Jakob disease (CJD) is the most common prion disease and often includes symptoms such as muscle jerks and signs of damage to the motor neurons in the brain. Unlike kuru, dementia tends to appear early in the course of CJD.
  • Familial fatal insomnia is another prion disease and it typically comes with severe insomnia, autonomic dysfunctions, and muscle jerks, making it different from kuru.
• Gerstmann-Straussler-Scheinker syndrome, which can bring about a wide range of symptoms including coordination issues, spastic leg weakness, and cognitive difficulties similar to Alzheimer’s disease.
• Autoimmune disorders or disorders induced by antibodies.
• Diseases that involve dementia, like Alzheimer’s, frontal lobe dementia, and temporal dementia.
• Various unspecified forms of dementia, Lewy body dementia, and vascular dementia.
• Encephalitis, an inflammation of the brain
• Infections, such as those caused by herpes virus, syphilis, HIV, Lyme disease, and a type of fungal infection that affects the brain known as aspergillosis.
• Tumors and conditions that result from cancer (paraneoplastic syndromes).
• Metabolic disorders, toxins, or poisoning from substances like lithium or heavy metals.

What to expect with Kuru

Kuru is a disease that unfortunately always results in death, usually within 24 months after symptoms begin. This illness significantly reduces the quality of life. In the later stages of the disease, patients usually become incredibly dependent on their relatives for care and support.

Possible Complications When Diagnosed with Kuru

As the condition of patients suffering from kuru worsens, they display severe symptoms related to the cerebellum and extrapyramidal system parts of the brain. These symptoms lead to a state where the patients are extremely weak and bedbound.

Taking care of these patients falls primarily on the shoulders of their family members, especially once the illness enters its third stage. At this stage, the patients are generally undernourished, which can lead to the development of pressure ulcers that get infected, and aspiration pneumonia – a type of lung infection caused by inhaling food, drink, or saliva into the lungs. Any of these complications can potentially result in the patient’s death.

Common Symptoms and Complications:

• Severe symptoms related to the cerebellum and extrapyramidal system
• Extreme weakness
• Being bedridden
• Undernourishment
• Development of pressure ulcers with secondary infections
• Aspiration pneumonia
• Potential death

Preventing Kuru

The practice of cannibalism was once responsible for the spread of a disease called kuru. Since cannibalism practices stopped, the last recorded case of kuru was in 2005. Kuru was significant because it was the first disease we know of that was caused by abnormal proteins called prions, which helped researchers understand more about other similar diseases. Even though kuru isn’t around now, it was remarkable for being the largest outbreak ever of a prion disease that spread between humans through eating contaminated tissues, specifically in the Eastern Highlands of Papua New Guinea.