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Kuru


Presentation

The disease Kuru grossly affects the cerebellum causing progressive loss of neurological functions. It primarily starts with the onset of headache and arthralgia followed by the below clinical signs and symptoms:

All these symptoms cause the individuals to develop malnutrition and recurrent bouts of pneumonia. Death is the ultimate result of this disease that usually occurs within a year of experiencing the first signs and symptoms.

Inflammation
  • Most notable were neuronal degeneration and intense astrocytosis with little, if any, inflammation. Especially eye-catching in kuru were the vacuolated neurons--the histologic hall-mark of scrapie that drew me to the human disease from the start.[ncbi.nlm.nih.gov]
Urinary Incontinence
  • The clinical symptoms were characterized by progressive dementia, gait ataxia, rigidity and urinary incontinence. The disease duration was 6 weeks. MRI did not show prominent atrophy or hyperintensities in cortical areas, striatum or thalamus.[ncbi.nlm.nih.gov]
Poor Coordination
  • These help to identify the poor coordination and can also assess the walking ability of the affected individuals. Treatment So far, there is no known treatment for kuru. The disease gradually disrupts the neurological functioning and causes death.[symptoma.com]
  • 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[healthline.com]
Resting Tremor
  • Parkinsonian symptomatology, other than resting tremor is frequent among the filmed subjects especially in the second stage of the disease.[ncbi.nlm.nih.gov]
Polyneuropathy
  • Thus, the behavior of the transmissible brain amyloidosis parallels completely that of the transthyretin amyloidoses causing familial amyloidotic polyneuropathy, in which there are 19 different point mutations, each one of which increases enormously the[ncbi.nlm.nih.gov]

Workup

No laboratory workup or imaging studies are sufficient to diagnose kuru. However, a postmortem evaluation of the tissues of the central nervous system with predominance of PrP plaques can help to detect infections in the brain [8].

In addition, neurological examinations can help detect changes in the coordination and walking abilities of the affected individuals.

Electrodiagnostic tests that include electromyography or nerve conduction velocity are carried out to determine the electrical activity in the brain.

MRI scans can also help derive appropriate conclusions. Cerebrospinal markers like neuronal specific enolase, protein 14-3-3, and S-100 although non-specific can help in the diagnosis of prion diseases in man [9].

Slowing
  • Repeated EEGs showed symmetrical slowing in one case and periodic generalised bursts of triphasic waves at 1 cps superimposed upon a slow (3-4 cps) background activity in the other.[ncbi.nlm.nih.gov]
  • Kuru, the first human neurodegenerative disease classified as a transmissible spongiform encephalopathy, prion disease or, in the past, slow unconventional virus disease, was first reported to Western medicine in 1957 by D.[ncbi.nlm.nih.gov]
  • Electroencephalography showed slow activity, and 14-3-3 protein detection was negative. Finally, the patient developed akinetic mutism and died 7 months after the onset of ataxia.[ncbi.nlm.nih.gov]
  • Kuru was the first human neurodegenerative disease in the group of transmissible spongiform encephalopathies, prion diseases or, in the past, slow unconventional virus diseases. It was reported to Western medicine in 1957 by Gajdusek and Zigas.[ncbi.nlm.nih.gov]
  • Occasionally, their muscles may twitch or jerk uncontrollably, or their fingers, hands, toes, and feet may move in a slow, writhing motion.[humanillnesses.com]
Triphasic Waves
  • Repeated EEGs showed symmetrical slowing in one case and periodic generalised bursts of triphasic waves at 1 cps superimposed upon a slow (3-4 cps) background activity in the other.[ncbi.nlm.nih.gov]
  • Triphasic waves in the EEG were detected only later in the disease course, while 14-3-3 assay was positive. PRNP genotyping revealed methionine homozygosity (MM) at codon 129.[ncbi.nlm.nih.gov]
Suppression
  • As cannibalism was suppressed by government patrol officers during the 1950s, most transmission had ceased by 1957, when the kuru research programme first commenced.[ncbi.nlm.nih.gov]
Intranuclear Inclusion Bodies
  • This rare morphology was associated with neuropathological signs of intranuclear inclusion body disease and advanced stage of argyrophilic grain disease.[ncbi.nlm.nih.gov]

Treatment

So far there is no known treatment for either curing or managing the disease condition. Kuru is a fatal disease that gradually destructs the neurological functioning of the individuals. No medications and therapies can help people affected by kuru.

Prognosis

This disease has a long incubation period causing prevalence of this disease even several years after the practice of cannibalism was banned. There is no cure to this deadly disease and death occurs within 1 year after the appearance of first symptom.

Complications

As there is no known treatment for Kuru, complications are bound to set in. These include:

  • Chronic brain failure
  • Ataxia 

Etiology

The primary and the only causative factor behind development of kuru is the consumption of contaminated protein found in dead human brains which is the most infectious organ in victims [4].

The practice of cannibalism during the funeral rituals lead to the development of kuru amongst the Fore people of the New Guinea. Even after several years of discontinued practice, cases are still being reported due to the long incubation period of this disease [5].

Epidemiology

New Guinea was the only place where such a ritual was practiced and people suffered the deadly disease as a result of it [6]. Cases of kuru were mostly reported during the year 1950 to 1960 when the ritual of cannibalism was still in use.

This decade, witnessed the maximum number of deaths due to kuru. Statistics have revealed about 100 deaths from kuru during this period. Once such a cruel practice was banned by the government, there was a steady decline in the incidences of kuru.

The death rates reduced to 6 per year from the 1990s. Only 2 deaths were reported in the period of 2003 to 2008. In addition, no new case of kuru was detected amongst those born after the year 1959.

Sex distribution
Age distribution

Pathophysiology

Kuru belongs to the class of prion disease which is also known as transmissible spongiform encephalopathies (TSEs). In this group of disease, protein molecules have the ability to change shape and function causing irreversible damages in the body.

These proteins bind together to form lumps in the brain. As a result of infection, researchers believe that even the normal proteins mimic the prions and behave in an abnormal fashion. All these sequences of events cause neurological disorder of the brain. Although 15% of prion acquired disorders in humans are associated with an autosomal-dominant mutation involving the PrP gene [7].

Women and children are more affected by this disease than men. This is so because, women generally do the cleaning part of the dead body and the men are offered the choicest part for the meal. Women and children generally feed on the leftovers such as the brain which is the most infectious part. Other diseases that belong to the group of TSEs affect only the animals.

Prevention

The only way to prevent this is disease is to avoid cannibalism which has already been achieved by efforts of the government and society.

As a result, this disease is now a matter of the past and no new cases of kuru are being reported. Researches are still on going in the newer means of transmission of prion diseases to humans like zooanthropologic transmission from bovine species in the Papua New Guinea region [10].

Summary

Kuru is a rare infectious disease characterized by neurological disorders of the brain. This is an incurable disease and is only prevalent amongst the population of New Guinea. This rare form of disease occurs due to infected protein that is found in the human contaminated brain.

The people of New Guinea as a part of a peculiar ritual consumed dead brains of human. This was customary to their funeral process. These dead brains were infected with prion which is a protein that leads to the causation of this deadly disease [1].

Kuru is the most popular example of a prion acquired form of disease in man [2]. This practice has been discontinued since 1960, but the cases were reported at a much later date, as this disease has a long incubation period. The rarity of kuru cases in the turn of the decade is suggestive that the epidemic may come to its conclusion very soon [3].

Patient Information

Definition

Kuru is a rare neurological disorder that occurs due to ingestion of infectious proteins called prions. This disease cannot be cured and has no treatment. The symptoms worsen overtime causing death of the affected individuals. In the past, the practice of cannibalism was prevalent amongst the New Guinea population. This practice called for feeding on the dead bodies as part of the funeral rites. This deadly practice leads to the ingestion of prions that caused Kuru in healthy people.

Cause

Kuru is caused due to consuming the infected human brain or contact with the open sores of the dead. The infected proteins known as “prion” present in the brain of the dead individuals is known to play foul.

Symptoms

Symptoms of kuru include difficulty in eating and swallowing food, lack of coordination, headache, difficulty in walking, pain in the arms and legs, muscle tremors, difficulty in talking, bouts of laughing and crying spells.

Diagnosis

Kuru is diagnosed through neurological examination and electrodiagnostic tests. These help to identify the poor coordination and can also assess the walking ability of the affected individuals.

Treatment

So far, there is no known treatment for kuru. The disease gradually disrupts the neurological functioning and causes death. No medications or therapies have been designed to help treat this condition.

References

Article

  1. Belay ED, Schonberger LB. The public health impact of prion diseases. Annu Rev Public Health. 2005; 26:191-212.
  2. Wadsworth JD, Collinge J. Update on human prion disease. Biochim Biophys Acta. Jun 2007; 1772(6):598-609.
  3. Alpers MP. Review. The epidemiology of kuru: monitoring the epidemic from its peak to its end. Philos Trans R Soc Lond B Biol Sci. Nov 27 2008; 363(1510):3707-13.
  4. Whitfield JT, Pako WH, Collinge J, Alpers MP. Mortuary rites of the South Fore and kuru. Philos Trans R Soc Lond B Biol Sci.Nov 27 2008; 363(1510):3721-4.
  5. McKintosh E, Frosh A, Mead S, Hill AF, Brandner S, Thomas D, Alpers MP, Collinge J, Whitfield J. A clinical study of kuru patients with long incubation periods at the end of the epidemic in Papua New Guinea.Philos Trans R Soc Lond B Biol Sci. 2008; 363(1510):3725-39 (ISSN: 1471-2970)
  6. Wadsworth JD, Joiner S, Linehan JM, Asante EA, Brandner S, Collinge J. The origin of the prion agent of kuru: molecular and biological strain typing. Philos Trans R Soc Lond B Biol Sci. 2008; 363(1510):3747-53 (ISSN: 1471-2970)
  7. Collinge J. Human prion diseases and bovine spongiform encephalopathy (BSE). Hum Mol Genet. 1997; 6(10):1699-705.
  8. Brandner S, Whitfield J, Boone K, Puwa A, O'Malley C, Linehan JM. Central and peripheral pathology of kuru: pathological analysis of a recent case and comparison with other forms of human prion disease. Philos Trans R Soc Lond B Biol Sci. 2008; 363(1510):3755-63 (ISSN: 1471-2970)
  9. Collinge J. New diagnostic tests for prion diseases. N Engl J Med. Sep 26 1996;335(13):963-5
  10. Collinge J. Lessons of kuru research: background to recent studies with some personal reflections. Philos Trans R Soc Lond B Biol Sci. 2008; 363(1510):3689-96 (ISSN: 1471-2970)

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Last updated: 2017-08-09 18:25