Kuru | The Generative Brain

Kuru comes up on this site for two reasons. It is part of the history of how prion disease came to be understood, and it is often raised in conversations about whether CJD can be caught, where the answer is no. Kuru is not a risk to anyone today.

What was it?

A prion disease among the Fore people and their neighbours in the eastern highlands of Papua New Guinea. The name comes from the local word for the trembling that was one of its signs.

It appeared in the region in roughly the first half of the twentieth century. Australian patrol officers reported it from the early 1950s, and the first medical descriptions were published by Carleton Gajdusek and Vincent Zigas in 1957.

How did it spread?

Through funeral practices. The Fore honoured their dead by eating the body, and women and children took part most. Prions from the brain tissue of someone who had died of kuru could pass on this way.

The practice was suppressed by 1956 and had effectively ended by 1960, which stopped the transmission. No other route was found: it did not spread by living together, by touching or by nursing someone who was ill.

Why did cases keep appearing for so long?

Because prion diseases can stay silent for decades. Researchers who studied 11 patients identified between 1996 and 2004 estimated that at least 34 to 41 years had passed since the last possible exposure, and for the men in the group the likely interval was 39 to 56 years. Some incubation periods exceeded 50 years.

This is the clearest human evidence that exposure and illness can be separated by most of a lifetime, and it is why researchers took the long view when estimating how variant CJD might behave.

What did it look like?

It usually began with headache and aching limbs and joints for several months. Then came unsteadiness in walking that worsened steadily: first walking became difficult, then impossible without support, then sitting unsupported. In the group of 11 patients, the illness lasted between 10 and 25 months, with an average of 17 months.

Memory and thinking were usually affected late, though two of the 11 patients had clear cognitive problems earlier than older descriptions had suggested.

What did it teach?

A great deal of what is now known. The resemblance between kuru and scrapie in sheep, pointed out in 1959, led to laboratory work showing that this kind of brain disease could be transmitted, and from there to the understanding that a misfolded protein was the agent. Gajdusek received a Nobel Prize in 1976 for the kuru work.

Kuru also showed that the prion protein gene affects the course. Of the 10 patients with gene results in the study above, 8 had one methionine and one valine at the position known as codon 129, and the two who had two identical copies had the shortest illnesses. That position still appears in almost every discussion of prion disease risk. The history of prion disease carries the story forward.

Could this happen again?

Not by this route. The practices that spread it ended more than 60 years ago, and kuru is not among the prion diseases occurring now. CDC lists it with the historical human prion diseases.

The acquired prion diseases that did occur later came from different routes: iatrogenic CJD from medical treatments, and variant CJD from beef affected by BSE. Neither is spread by everyday contact, which is covered in myths and facts.

Where next?

Kuru: more detail is the clinical version of this page, and kuru for researchers the scientific one. Prion diseases is the way back to the forms that do occur today.

Sources for this page