The Funeral Ritual that Led to an Epidemic

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   Kuru is a neurodegenerative disease: a member of the class of transmissible spongiform encephalopathy diseases. The disease was named ‘kuru’ due to its origination in the Papa New Guinea’s Easter Highlands. To the indigenous Fore linguistic people, kuru translates into ‘shiver’ – the identifying symptom they looked for in their patients. The Fore linguistic group and its neighbouring linguistic groups contracted the disease through endocannibalistic rituals of their deceased as well as through open cuts and wounds. The highly infectious disease was spread through consumption of the affected tissue in the body and reached its peak in the 1950s and 60s due to this funeral ritual; it was so prominent in this time period that epidemic levels were reached. It was at this point that the government began to publicly discourage cannibalism; which then reduced number of locals practising it and eventually led to the decline of the disease in the future. Nevertheless, a few cases would still surface in the following decades as a result of the disease’s long incubation period (ranging from five to sixty years), before symptoms could be seen. However, children born after 1954 who never took part in the funeral rituals showed almost a total absence of the disease in their lives. [1] [2]

   Unlike most diseases, kuru is not caused by a bacteria, virus or fungus, but instead by abnormal, inanimate prion proteins. These would be present in the deceased’s tissue and would then contaminate any who took part in the cannibalistic funeral ritual – specifically the women and children as they were given the brain tissue. The transmitted prion proteins (PrPsc) are misshapen – they have altered secondary and tertiary structures. These then go ahead and trigger the surrounding normal prion proteins (PrPc) to also fold abnormally. Subsequently a chain reaction begins allowing for rapid propagation. The new structure results in the prions becoming extremely resistant to protein degradation by enzymes or other chemical and physical means. As the prions multiply, they clump together to hinder normal brain processes and create fatal sponge-like holes. It is believed that kuru first arose in a single individual as a result of a spontaneous change that created the pathogenic prions in the brain – a similar manner to sporadic Creutzfeldt-Jakob disease. [3]

   Diagnosis of the disease occurs through neurological exams and blood tests to rule out alternative causes. This is because symptoms often resemble Parkinson’s disease and strokes. To confirm the presence of the disease, a brain biopsy can be undergone after death. However, the disease is rarely diagnosed today as its spread was mainly confined in Papa New Guinea and transmission slowed down in the 1960s. [4]

   Symptoms of the disease present themselves as three clinical stages, following initial prodromal symptoms: ambulant, sedentary and recumbent/ terminal. The symptoms are often to do with coordination as the disease mainly affects the cerebellum. The prodromal symptoms such as headaches and joint pain can last for several months before the patient even begins experiencing the clinical stages symptoms. Due to the varying lengths of the different stages, the mean clinical duration of the onset of symptoms up until death is twelve months but can also range from three months to two years.

The first stage (ambulatory stage) has a mean clinical duration of approximately eight months in which the prodromal symptoms tend to disappear. Instead the patient begins to experience unsteadiness when walking and standing due to imbalance, tremors, withdrawn behaviour and possible depression. The lost ability to walk without support marks the transition between the ambulatory stage and the sedentary stage. At this point, one experiences reduced muscle power, emotional liability in the form of euphoria and inappropriate laughter, and even obesity, all over a period of two to three months. When the patient is also then unable to sit up unsupported, the recumbent stage is reached and the person becomes bedridden due to flaccid muscle weakness, exhaustion and weight loss from dysphagia (difficulty swallowing) and the loss of voluntary control over urination and defecation. These symptoms are occasionally paired with primitive reflexes until a terminal stage is encountered; prolonging the one to two month sedentary stage. Death is most often a result of respiratory failure and bronchopneumonia or septicaemia and is usually preceded by a comatose state. [5]

   Much like the other prion diseases in the transmissible spongiform encephalopathy class (Creutzfeldt-Jakob disease, fatal familial insomnia, mad cow disease etc.) there is no treatment for kuru. Doctors solely recommend preventative measures that are now predominantly adhered to. But in the off chance of contracting this rare disease, palliative care is provided.


References

  1. “Kuru Information Page”, National Institute of Neurological Disorders and Stroke, Mar. 27, 2019, https://www.ninds.nih.gov/Disorders/All-Disorders/Kuru-Information-Page
  2. Pawel P. Liberski, Agata Gajos, Beata Sikorska, Shirley Lindenbaum, “Kuru, the First Human Prion disease”, NCBI, Mar. 7, 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6466359/
  3. “Kuru (disease)”, Wikipedia, Jul. 21, 2020, https://en.wikipedia.org/wiki/Kuru_(disease)
  4. “Kuru”, Healthline, Aug. 4, 2016, https://www.healthline.com/health/kuru#outlook
  5. John Collinge, Jerome Whitfield, Edward McKintosh, Adam Frosh, Simon Mead, Andrew F. Hill, Sebastian Brandner, Dafydd Thomas, Michael P. Alpers, “A clinical study of kuru patients with long incubation periods at the end of the epidemic in Papua New Guinea”, NCBI, Nov. 27, 2008, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2581654/

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