Kuru is a very rare, incurable disorder that used to be common among the Fore people of Papua New Guinea.
The condition was transmitted within the tribe when they cooked and ate the bodies of dead family members.
It was traditionally believed that eating the body would help free the spirit of the dead.
Females and children usually consumed the brain, the organ in which infectious prions were most concentrated, thus allowing for the transmission of kuru. The disease was therefore more prevalent among women and children.
The epidemic is thought to have originated when a villager developed sporadic Creutzfeldt–Jakob disease and subsequently died.
When villagers ate the infected brain, they contracted the disease, thereby spreading it to others, who in turn ate their brains and infected more people.
The term kuru derives from the Fore word kuria or guria (“to shake”), due to the body tremors that are a classic symptom of the disease.
It is also known as the “laughing sickness” due to the pathological bursts of laughter which are a symptom of the disease.
Although the Fore people stopped eating human meat in the early 1960s, when it was first thought that this is how kuru was transmitted, the disease lingered due to kuru’s long incubation period of anywhere from 10 to over 50 years.
The epidemic declined sharply after cannibalism was abandoned, from 200 deaths per year in 1957 to 1 or no deaths annually in 2005, with sources disagreeing on whether the last known kuru victim died in 2005 or 2009.
Signs and symptoms
Kuru is a disease of the nervous system that causes physiological and neurological effects which ultimately lead to death.
The incubation period averages between 10–13 years, but can be as short as 5 and has been estimated to last as long as 50 years or more after initial exposure. The youngest individual recorded to have kuru was 11 years old
At its peak, kuru was eight to nine times more prevalent in women and children than in men.
It is believed this is because Fore men considered consuming human flesh to weaken them in times of conflict or battle, while the women and children were more apt to eat the bodies of the deceased, including the brain, where the infected particles were particularly concentrated.
It is also possible that it was passed on to women and children more easily because they were the ones in charge of cleaning relatives after death and may have had open sores and cuts on their hands.
Initially, the Fore people believed the causes of kuru to be sorcery or witchcraft.
It was also believed that it was caused by ghosts because of the shaking and strange behaviour that comes with kuru.
In an attempt to cure this, they would feed victims pork and casuarinas bark.
Prior to the late 1950s, patrol officers thought that kuru was psychosomatic and was caused by the trauma of Western colonisation and perpetuated by beliefs in sorcery and witchcraft.
It was not until 1957 that cannibalism was investigated and found, using data, to be the cause of kuru. However, it was not considered a priority because it was thought to be too strange or evidence that theorised cannibalism as a cause lacked proper evidence.
Cannibalism, however, was a reasonable enough explanation for kuru that the Australian administration banned the practice of feasting on the dead until it was nearly obsolete by 1960.
As the number of cases of kuru decreased, those in medical research were able to properly investigate kuru, which then led to the modern proposition of prions being the cause of kuru.
Kuru was first described in official reports by Australian officers patrolling the Eastern Highlands of Papua New Guinea in the early 1950s.
Some unofficial accounts place kuru in the region as early as 1910.
In 1951, it was Arthur Carey who first used the term ‘kuru’ in his report to describe a new disease afflicting the Fore tribes of Papua New Guinea.
In his report, Carey noted that kuru mostly afflicted Fore women, eventually killing them.
In 1953, kuru was observed by patrol officer John McArthur who provided a description of the disease in his report. McArthur believed that kuru was merely a psychological episode resulting from the confirmed sorcery practices of the tribal people in the region.
It was not until the time that the Kuru disease had spread into an epidemic when Daniel Carleton Gajdusek, a virologist, and Vincent Zigas, a medical doctor, first started doing research on the disease in 1957.
In an effort to understand the pathology of Kuru disease, Gajdusek established the first experimental tests on chimpanzees for Kuru at the National Institutes of Health (NIH).
The methods of the experiment would be to introduce the kuru brain material to the closest human relative, the chimpanzee, and to document the behaviours of the animal until death or a negative outcome would occur.
Michael Alpers, an Australian doctor, collaborated with Gajdusek in providing the samples of brain tissues he had taken from an 11-year-old Fore girl who had died of Kuru.
Within two years, one of the chimps, Daisy, had developed kuru, demonstrating that the unknown disease factor was transmitted through infected biomaterial and that it was capable of crossing the species barrier to other primates.
Daniel Carleton Gajdusek was awarded the Nobel Prize in Physiology or Medicine in 1976 for his work on the transmission of kuru.