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From: TSS ()
Subject: Kuru in the 21st century—an acquired human prion disease
Date: June 22, 2006 at 5:16 pm PST

CJD WATCH MESSAGE BOARD
TSS
Kuru in the 21st century—an acquired human prion disease
Thu Jun 22, 2006 19:44
70.110.82.186

The Lancet 2006; 367:2068-2074

DOI:10.1016/S0140-6736(06)68930-7

Kuru in the 21st century—an acquired human prion disease with very long incubation periods
John Collinge a , Jerome Whitfield a b, Edward McKintosh a, John Beck a, Simon Mead a, Dafydd J Thomas a and Michael P Alpers a c

Summary
Background
Kuru provides the principal experience of epidemic human prion disease. Its incidence has steadily fallen after the abrupt cessation of its route of transmission (endocannibalism) in Papua New Guinea in the 1950s. The onset of variant Creutzfeldt-Jakob disease (vCJD), and the unknown prevalence of infection after the extensive dietary exposure to bovine spongiform encephalopathy (BSE) prions in the UK, has led to renewed interest in kuru. We investigated possible incubation periods, pathogenesis, and genetic susceptibility factors in kuru patients in Papua New Guinea.

Methods
We strengthened active kuru surveillance in 1996 with an expanded field team to investigate all suspected patients. Detailed histories of residence and exposure to mortuary feasts were obtained together with serial neurological examination, if possible.

Findings
We identified 11 patients with kuru from July, 1996, to June, 2004, all living in the South Fore. All patients were born before the cessation of cannibalism in the late 1950s. The minimum estimated incubation periods ranged from 34 to 41 years. However, likely incubation periods in men ranged from 39 to 56 years and could have been up to 7 years longer. PRNP analysis showed that most patients with kuru were heterozygous at polymorphic codon 129, a genotype associated with extended incubation periods and resistance to prion disease.

Interpretation
Incubation periods of infection with human prions can exceed 50 years. In human infection with BSE prions, species-barrier effects, which are characteristic of cross-species transmission, would be expected to further increase the mean and range of incubation periods, compared with recycling of prions within species. These data should inform attempts to model variant CJD epidemiology.

Affiliations

a. MRC Prion Unit and Department of Neurodegenerative Disease, Institute of Neurology, University College London, London WC1N 3BG, UK
b. Papua New Guinea Institute of Medical Research, Goroka, EHP, Papua New Guinea
c. Centre for International Health, Curtin University, Perth, Australia

Correspondence to: Prof John Collinge

http://www.thelancet.com/journals/lancet/article/PIIS0140673606689307/abstract

TSS


Listen to The Lancet
This week's audio summary discusses an Article entitled "Kuru in the 21st century - an acquired human prion disease with very long incubation periods". Also covered is a Lecture assessing climate change and its impact on health, and an Editorial about the roll-out of cervical cancer vaccines worldwide. >>

http://www.thelancet.com/webfiles/images/clusters/thelancet/audio/24June2006.mp3

vCJD 'may develop over 50 years'

vCJD, like kuru, is a prion disease
A disease linked to cannibalism has given clues about how long mad cow disease (BSE) can lurk in the human body before it develops into vCJD.

A University College London team said it could take 50 years for vCJD, the human form of the disease, to develop.

They studied Papua New Guineans with a related condition - kuru disease, which is contracted through cannibalism.

In The Lancet, the team said people with a certain genetic make-up risked long-term vCJD incubation.

By investigating kuru, the only known example of a major epidemic of a prion disease, we will begin to narrow our present uncertainties about vCJD

The Lancet

Exposure to BSE (bovine spongiform encephalopathy) in the UK has been widespread, although just 160 vCJD (variant Creutzfeldt-Jakob) patients have been identified, leading scientists to investigate why more people have not been affected so far.

Kuru disease, like vCJD, is a prion disease. Prions are mutated proteins.

It reached epidemic proportions in some Papua New Guinea communities early in the 20th Century.

Eating dead relatives as a mark of respect and mourning was ritual practice until it was banned in the 1950s.

In the study, 11 patients with kuru were identified between July 1996 to June 2004, with the last one born in 1959.

Although it was not possible to know the exact date the patients contracted kuru, the possible incubation periods ranged from 34 to 56 years.

Genetic differences

The researchers believe the incubation period for BSE prions in humans could be even longer than that seen in kuru because infection between different species typically takes longer to develop than one passed within the same species.

Professor John Collinge, who led the study, said vCJD patients identified so far "could represent a distinct genetic subpopulation with unusually short incubation periods for BSE".

He said a human BSE epidemic might have a number of phases, and added: "Recent estimates of the size of the vCJD epidemic based on uniform genetic susceptibility could be substantial underestimations."

An editorial in the Lancet stated: "The eventual size of the vCJD epidemic remains uncertain.

"The number of infected individuals is still unknown.

"By investigating kuru, the only known example of a major epidemic of a prion disease, we will begin to narrow our present uncertainties about vCJD.

"Any belief that vCJD incidence has peaked and that we are now through the worst of this sinister disease must now be treated with extreme scepticism."

http://news.bbc.co.uk/1/hi/health/5106808.stm


TSS



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