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The Laughing Death(Kuru)

In the mid-1950s an unusual and deadly phenomenon threatened to extinguish a small tribe of people in New Guinea. Most of the women and many of the children were being attacked by a fatal neurological disorder that began by causing its victims to giggle uncontrollably.  The syndrome baffled American epidemiologist Carleton Gajdusek, who analyzed soil, drinking water, food and even the ashes in the fires in search of the etiologic agent and its mode of transmission. After months of inquiry, Gajdusek discovered that the tribe was cannibalistic. As an expression of respect for their dead relatives, the survivors would consume portions of the corpses, including the brain. Years after preparing the brains for cooking, the women and children would begin the fatal giggles
.Kuru, as the disease was named, was subsequently shown by Gajdusek to be caused by a previously undiscovered type of pathogen originally called a slow virus because of its 2 to 20 years incubation period. The agent now recognized as a prion, is transmitted by eating the infected neurological tissue of someone who has died from the laughing death or by cutaneous inoculation of the virus while preparing the brain. The tribe’s extinction was avoided when they were persuaded to abandon their cannibalistic tribute to their dead. Gajdusek’s detective work on slow viruses won him the 1976 Noble prize in medicine.
Although kuru has been virtually controlled, another prion-mediated disease, Creutzfeld-Jakob disease (CJD) continues to cause invariably fatal neurological infections throughout the world. The transmission of this rare disease is still an enigma, but two cases were caused when contaminated electrodes were inserted into the brain during neurosurgery. Another case followed a corneal transplant from a patient from a patient with undiagnosed CJD. CJD is also an occupational hazard among neurosurgeons and neuropathologists. Each year 200 people in the United States die of the disease.

Several animal diseases are also caused by prions. The oldest documented animal’s disease is scrapie, an infection of sheep. The striking similarities between the symptoms and agents of scrapie and those of certain human diseases have led some scientists t hypothesized that prions originally entered the human population in scrapie-contaminated food. Some evidence to support this idea comes from our understanding of a prion disease of cattle called mad cow disease. The appearance of mad cow disease in England coincided with a change in cattle feed a change that included the addition of tissue from sheep (although the sheep were not symptomatic with scrapie).
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