TOPIC – Rare Disease
KURU DISEASE – The Omen of Death
Malda Medical College and Hospital (West Bengal, India)
Introduction:- Out of thousands of rarest diseases known so far on earth Kuru is one of them. It is an incurable and fatal neurodegenerative disorder caused due to the transmission of highly infectious Prion proteins. It is a transmissible spongiform Encephalopathy.
Distribution:- It is seen in the Cannibalistic Fore tribe of Papua New Guinea . Dead family members were cooked and eaten by the living members and it was done in superstition to help free the spirit of the dead. Women and children usually consumed the brain where Prion proteins were most concentrated thus allowing the transmission of Kuru. The disease was therefore more prevalent among women and children.
Etymology:- Kuru comes from the Fore word ‘Kuria’ which means trembling (a classic symptom of the disease). Also known as Laughing Sickness due to sudden bursts of laughter which is also a symptom.
History:- Previously it was linked with witchcraft and sorcery but later studies and extensive researches during Kuru Epidemic in the islands of Papua New Guinea during 1957 ; it was found that Endo-Cannibalism was the route and cause of transmission. Daniel Carleton Gajdusek and Vincent Zigas were the major pioneers in this field. Gajdusek got Nobel Prize for Medicine for this work in 1976. E.J Field spent a large time studying the disease and gave the ‘Prion Hypothesis’.
Cause:- Localised to Fore tribe and transmitted through Ritualistic Cannibalism . Responsible Prion is PrP(SC) which is abnormally folded due to mutation. It differs from normal prion not due to amino acid residues but due to configuration. In PrP(SC) there is extensive Beta pleated sheets whereas in normal there is extensive Alpha Helices. This configurational change allows PrP(SC) to aggregate and be extremely resistant to protein degradation by enzymes or by other chemical and physical means.
Signs and Symptoms:- The disease causes total breakdown of the nervous system. Progressive cerebellar ataxia follows.
STAGES OF KURU:-
1) Preclinical /Asymptomatic/ Incubation Stage
It is averagely between 10-13 years but can be even 5 years or 50 years after initial exposure. No sign or symptoms appear.
2) Clinical Stage: Usually lasts for 12 months. Death follows after that.
It has 3 phases :-
- a) Ambulant Stage :-
- Unsteady state and gait
- Decreased muscle control, Tremor
- Dysarthria, Titubation (Tremor of Head)
- b) Sedentary Stage:-
- Incapable of walking, tremors
- Shows signs of emotional instability and depression yet exhibits uncontrolled and sporadic laughter
- c) Terminal Stage :-
- Even sitting becomes problematic
- Dysphagia leading to malnutrition
- Loses the ability or will to speak and become unresponsive to environment.
- Chronic ulcerated wounds are seen that get easily infected
- Dies usually of Infection or Pneumonia
Help from Government:- It was largely due to Government interference that Cannibalism was banned and law of Death sentence was imposed that out of fear this practice has got limited to some extent but it still continues. The last sufferer of Kuru was somewhat between 2005 or 2009.
- Checking Neurological Functions
- Blood tests such as thyroid, folic acid level and liver and kidney function tests.
- Brain MRI can be done
Treatment:- It’s absolutely fatal. No known successful treatment . Supportive care to prevent other infections and opportunistic diseases can be done to extend life. Symptomatic treatment is needed. Awareness is required and bringing those tribal people to main stream is the only way.