Discovered by Carleton Gajdusek in the 1950’s and 60’s among the South Fore people of New Guinea.
Transmitted through ritual mortuary cannibalism where deceased individuals were consumed by their relatives to honor them.
Shirley Lindenbaum reported that maternal kin would remove the arms and feet of the corpse, strip the muscles and remove the internal organs, including the brain.
Between 1957 and 1968, over 1,100 South Fore succumbed to kuru. Early on it affected mostly women (80% vs men) but later also affected elderly and children at high rates as well.
Symptoms of Kuru
Ambulatory Stage – myoclonus, unsteadiness of stance/gait/hands/eyes, dysarthria, slurring of speech, tremor, uncoordination of lower extremities that progresses upwards.
Sedentary Stage – victim can no longer walk, severe tremors, ataxia, shock-like muscle jerks, emotional lability, inappropriate laughter and extreme depression, cognitive decline.
Terminal Stage – intensifying symptoms above, urinary and fecal incontinence, dysphagia (difficulty swallowing), lapse into coma, and lose control of breathing.
Transmissibility was unintentially demonstrated by inoculation of a Scottish sheep herd with a vaccine extract prepared from formalin treated brain of a scrapie-infected animal.
Within 2 yrs, 10% of the flock contracted scrapie.
Gajdusek notes similarity in brain pathology between Kuru and scrapie. He goes on to inject chimpanzees with Kuru brain extracts, after which they exhibit TSE pathology.
Investigators follow up by showing transmissibility to animals of CJD, familial TSE, and GSS.
Paradigm Shift
In 1967, Alper and his group report the extreme resistance of scrapie infectivity to UV light and ionizing radiation.
They previously isolate this activity to 200kD, eliminating the role of even viruses as the vehicle.
In 1967, JS Griffith proposes three possibilities for these findings:
1) agent is a protein that turns on its own transcription
2) agent is a variant protein form that can corrupt the native form of protein to its state via oligomerization.
3) agent is an antibody that stimulates its own production.
Progression of BSE
1986: First case of BSE discovered in a cow that was fed livestock feed produced from a sheep that died of scrapie.
Dr. Richard Lacey annouces that scrapie and BSE are the same disease and that “this beef was in the meat supply”.
British government dismisses Lacey and cuts his research funding. They announce that scrapie renderings are still an acceptable form of livestock feed.
Progression of BSE (cont)
1987: 700 BSE infected cows are reported in Great Britain.
1988: 7,000 infected cows. Law is passed declaring sheep rendering illegal.
1992: 36,000 infected livestock reported.
1994: 150,000 infected livestock reported and is identified in half of British cattle herds.
Crossing the line…..
In 1996, a new form of CJD is discovered in the UK, termed variant CJD (vCJD).
Linked with consumption of BSE-contaminated beef.
Shares the symptoms of classic CJD, except the median age of death is 28 (contrasting with 68) and feature psychiatric and sensory symptoms with neurologic effects occuring later.
Secondary routes of transmission (iatrogenic CJD)
Dura and corneal transplants.
Being operated on with surgical tools used on a CJD patient.
EEG depth probes contaminated by previous patients.
Blood transfusions?
Molecular prion characteristics
Usually rich in polar amino acids such as glutamine or asparagine.
