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Prion diseases arise in three different ways |
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2. In inherited forms, mutations in the prion gene are transmitted from parent to child. 3. They can arise spontaneously. Route of infection When cows are fed with offals prepared from infected sheep, prions are taken up from the gut and transported along nerve fibers to the brain stem. Here prions accumulate and convert normal prion proteins to the disease-causing form, PrPSc. Years later, BSE results when a sufficient number of nerve cells have become damaged, affecting the behaviour of the cows. |
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| Kuru disease | Mad cow disease | |
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| The graph shows how kuru disappeared among the Fore-people when they stopped their cannibalistic rituals. In children the disease disappeared more rapidly, while adults continued to be affected. An incubation time of up to 30 years has been reported. | The graph shows the course of
the BSE epidemic. It reached its maximum in 1992 with
37,000 affected animals. When feedstuff containing
sheep offals was banned, the incidence of BSE decreased
rapidly. There is now a fear that humans might have
been infected by eating products from BSE-affected cows
giving rise to a new variant type of CJD. |
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