Kuru Disease Prions
The brain disease Kuru is classified as a transmissible spongiform encephalopathy (TSE) also commonly referred to as a prion disease. The notable characteristic of such disorders is that they are caused by mis-folded prion proteins. It is believed that these in turn cause other prion proteins to take on abnormal shapes with the overall result that the protein molecules clump together and accumulate in the brain. Other TSEs include Creutzfeldt-Jakob (CJD) disease in humans and bovine spongiform encephalopathy (BSE) in cattle which is also known as mad cow disease.
At the time of writing (November 2009) there are no cures for any TSEs, and there was no way of stopping or controlling Kuru other than the cessation of cannibalistic rituals.
Kuru came to worldwide attention in the 1950s when it was discovered by western scientists among the people of the Fore tribe, who live in the jungle highlands of Papua New Guinea. Symptoms start with joint pains but progress to dementia, trembling, uncontrollable laughing and paralysis.
Originally researchers thought that the condition might be hereditary as they didn’t detect any classic signs of infection such as inflammation, fever or raised levels of antibodies. But then Dr Carleton Gajdusek, an American physician had an inkling that the disease might have something to do with the tribe’s eating habits. One of their funeral rituals was to eat the body of the recently deceased. Men would get the meaty parts, the best cuts in other words whilst the women and children were left with the brain tissue which they scooped out of the skull with their bare hands. The ritual was to honour the departed and to return his or her life force to the community.
Autopsies of those who had died from the disease revealed that their brains had small cavities, like holes in sponges. To Gajdusek this looked like the effects of CJD. His next step was to inject brain tissue of Kuru disease victims into monkeys. After two years these primates developed Kuru symptoms and Gajdusek came to the conlusion that Kuru was caused by an infectious agent, though he was unable to determine which. Further research by others discovered the cause of the disease to be prions.
This idea that a disease could be caused not by a virus or a bacteria, but by a misshapen protein that contained no DNA or RNA was a scientific revelation. For his work on Kuru Gajdusek was awarded the 1976 Nobel Prize in Physiology or Medicine.
Further Brain Disease Kuru Research
Since the cannibalistic ritual was banned the incidence of Kuru amongst the Fore people tapered off with no children born since the late 1950s developing the disease. However, it was still rife amongst the elderly population which has led scientists to the conclusion that it has a long incubation period which they think could also be true of another prion disease - the human form of mad cow disease.
Kuru research could further help CJD research as scientists have discovered a gene variant in the Papua New Guinea tribe that provided resistance against Kuru. Understanding more about this genetic mechanism opens up a new area of research that will not only improve understanding of prion diseases, but could also lead to treatments and maybe one day prevention.