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Iatrogenic CJD (iCJD) is a form of acquired CJD and one of the least common types, accounting for less than 1% of cases. Both laboratory and clinical research has determined that human-to-human transmission of CJD can occur as the result of tissue implant, use of contaminated neurosurgical instruments, or administration of human hormones extracted from the organs of human cadavers. Although blood transmission of CJD has been reported only in variant CJD, the American Red Cross currently does not accept donations from persons with a history of permanence in certain foreign countries or family history of CJD (See Will et al. British Medical Bulletin, 66: 213. 2003.)
Variant CJD (vCJD) is also a form of acquired CJD, and is thought to be transmitted through the ingestion of contaminated meat. In 1996, the first ten cases of vCJD were reported in the UK. As of November 2004, 151 cases have been reported in the UK. In addition, six have been reported in France, and one each in Italy, Ireland, Canada, and the USA. The cases reported in Canada and the USA very likely acquired the disease in the UK. There is strong evidence that vCJD has been acquired from cattle affected by bovine spongiform encephalopathy, or “mad cow” disease, which occurred with epidemic proportions in the UK in the 1980s. vCJD has well defined and consistent clinical and pathological features that make it relatively easy to identify and distinguish from sporadic CJD. Furthermore, vCJD is the only type of prion disease in which a definitive diagnosis can be made with a biopsy of the tonsils. Recently, two cases of vCJD acquired via blood transfusion have been reported in the UK. In both of these cases, the blood was extracted from persons with vCJD prior to their diagnosis (See Will et al. British Medical Bulletin, 66: 213. 2003 and Ironside et al. Haemophilia, 4: 64. 2004.)
Kuru is an acquired prion disease that is virtually extinct. It was originally described in members of a native tribe in New Guinea known to practice cannibalism. The epidemics probably originated from the consumption of contaminated meat by a member of the tribe affected by sporadic CJD. Clinically and pathologically, Kuru is fairly different from vCJD. (For details, see Will et al. British Medical Bulletin, 66: 213. 2003.)
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