(This is a silent clip of a Fore women infected with Kuru in Papua New Guinea)
The first transmissible spongiform encephalopathy to be identified in humans was Kuru. Kuru affected the Fore Indians in remote areas of Papua New Guinea. A number of researchers recognized scrapie as an infectious malady and Creutzfeldt-Jakob disease (CJD). However, it was through the investigation of kuru that the detailed study of TSEs and the elucidation of prion transmission was possible (McElroy & Townsend, 2004).
Papua New Guinea is the second largest island in the world and is home to numerous aboriginal tribes, separated by geography, language and cultural practices. It was not until 1949, when Papua New Guinea became a trust territory of Australia that these tribes were discovered and later studied. The resident Fore Tribe lived in small communities, often separated by sex. The men hunted and lived communally in large huts, while the women cohabitated with children in smaller, almost satellite shelters and were responsible for agriculture. Missionaries started exploring the land, and it was then in 1954 that JR McArthur, a patrol officer, became the first outsider to observe what would be determined 'kuru'; a young girl was spotted shaking violently, her head bouncing from side to side. The natives believed it to be sorcery and witchcraft, however the patrol officers found it to be endemic and potentially psychosomatic. After more investigating, it was found that this particularly malady accounted for half of all Fore female mortality. In fact, a number of the above mentioned satellite villages had almost been completely wiped out (McElroy & Townsend, 2004).
photo courtesy of http://nobelprize.org
Photo of the region of the brain infected by Kuru
Where does Kuru come from? How does it spread?
After the death of an individual who belonged to the Fore tribe, women of the village would prepare the body for a ritual, which began with cooking. The flesh, viscera, and brains were typically steamed with vegetables in bamboo tubes or in an earth oven with hot stones. Maternal relatives had a right to their kin's flesh, and specific kin had specific rights to certain body parts. For example, a woman's brain would be eaten by her son's wife or her brother's wife. Men typically avoided eating human flesh because they believed it would make them vulnerable to the arrows of enemies. It was mostly women who practiced cannibalism, and they often shared the funeral meal with their children of both sexes. The women scooped the brain tissue out with their bare hands and did not subsequently wash them for weeks. During this time, they were handling, caring for, and possibly infecting their young children (McElroy & Townsend, 2004). This might help to explain why men were much less likely to be afflicted with kuru than women and children. Kuru is again associated with a prion and has served as the prototype for a group of these, prion diseases (e.g., scrapie in sheep, mink spongiform encephalopathy which is transmissible, bovine spongiform encephalopathy; BSE or mad cow disease; McElroy & Townsend, 2004).
One of the most interesting mysteries surrounding kuru is its origin. If it did not exist until roughly the 20th century (when the Fore started to participate in cannibalism), where does it come from? Researchers now think that kuru is related to vCJD, which is associated with BSE and scrapie. It is plausible that kuru originally came from infected meat of cows or sheep. Because of the high elevation of Papua New Guinea, it is harder to boil water and a lot of the meat consumed is not cooked all of the way, which makes the spread of bacteria and disease from one species to another much easier (Lindenbaum, 1979). Although even thoroughly cooking prion infected meat will not kill the infectious agent.
Mortality and Morbidity
This disease has no effective treatment and is uniformly fatal within six months to two years after symptoms begin to appear. The incubation period of the disease may be as short as four years or as long as three decades (Prusiner, 1995).
Presentation and Symptoms in Fore Tribe
Kuru has an insidious onset. Typically it begins with a minor disorder or abnormal gait that becomes more pronounced when the individual is tired. Headaches and leg aches usually follow. Typically, within a few months, the individual is almost helpless. Loss of balance is an indication of progression, and eventually standing is impossible, followed by lack of ability to sit independently. Eventually a number of motor functions, along with the ability to talk completely disappear. Overall, the illness might typically last between 18 months and 2 years. Eventually, the individual would die because kuru is always fatal (Prusiner, 1995).
photo courtesy of http://nobelprize.org
Photo of a Fore child with Kuru
Kuru presented itself only in the Fore Tribe, but has now disappeared after the cessation of endocannibalism. Kuru has not presented itself outside of this context, so the potential of encountering new cases is unlikely. When encountered in a clinical setting, practitioners typically saw:
~A history of the consumption of brain or nervous tissue.
~The amount of infected tissue eaten is a factor in the development of the disease. The incubation period may be as long as three decades.
~The clinical presentation of kuru was extremely uniform. Again, symptoms of headache and joint pains are followed 6-12 weeks later by difficulty in walking and then a cerebellar tremor.
~This tremor typically disappeared during sleep but worsened during periods of high stress and anxiety.
~As the tremor become worse, an upright position was difficult for patients to maintain, and they eventually became bedridden.
~Eventually, patients could no longer swallow or eat, and they become extremely fragile and thin.
~Death follows a clinical course of three months to two years; however, most patients die within a year of the onset of symptoms.
~Patients with kuru had a bizarre tendency to laugh or cry without apparent reason.
~Memory was usually relatively untouched until the disease became advanced, some patients did not even recognize their own families towards their end.
~The disease has such little variability in its presentation that members of the Fore were eventually capable of diagnosing kuru with great accuracy. A report exists of a 4-year-old child who was able to diagnose himself: His mother had already died of kuru. No evidence indicates spread in utero or via human milk (Mestel, 1996).