Acquired Human Prion Diseases

The acquired prion diseases account for less than 1 % of all human prion disease cases and these include variant CJD, iatrogenic CJD (iCJD), and kuru (reviewed by Will, 2003). In these cases, prion infection is either orally acquired or associated with accidental transmission via medical practices. Many of these latter cases involve contamination with brain tissue, which contains the highest amount of prion infectivity, from the donor host. 

Iatrogenic CJD is the second most common acquired human prion disease and these cases are the result of accidental infection due to contact with prion contaminated tissues or instruments during medical procedures (Table 29.1). The mode of prion infection include surgical equipment (e.g., surgical instruments, depth electrodes), transplantation of human tissues (corneal, dura mater), intramuscular injections with growth hormone or gonadotrophin extracted from human pituitary tissues, or blood transfusion (reviewed by Will, 2003). The most likely source of infection is from donors with subclinical sCJD, except for the two transfusion-related cases that have been linked to blood donors who developed vCJD several years later (reviewed by Ironside, 2006). The incubation period in these transfusion related cases was 5 to 6 years, which is shorter than primary vCJD infection in humans. 

---

Acquired human prion diseases include kuru and variant CJD 794 Prion protein polymorphism contributes genetic susceptibility to prion disease 794... 

Acquired human prion diseases include kuru and variant... 

The immune system plays a central role in the pathogenesis of prion infection. In the acquired human prion diseases, it is the initial site of agent replication prior to entry into the nervous system but the immune system does not appear to be essential in the pathogenesis of the familial and sporadic human prion diseases. Followdng peripheral exposure to the prion agent, the immune system can amplify prion infection but, interestingly, the adaptive immune response does not play a role in the clearance of the prion agent. 

Collinge J, Whitfield J, McKintosh E, Beck J, Mead S, Thomas DJ, Alpers MP (2006) Kuru in the 21st century-an acquired human prion disease with very long incubation periods. Lancet 367 2068-2074... 

Human prion diseases encompass the three etiological types of prion disease inherited, sporadic and acquired forms. 

Genetic Susceptibility to Acquired and Sporadic Human Prion Disease... 

Creutzfeldt-Jakob disease (CJD) the most common prion disease of humans and can have a sporadic, familial or acquired etiology. 

In other acquired prion diseases, notably scrapie of sheep and variant Creutzfeldt-Jakob disease (vCJD) in humans, amino acids encoded at certain key positions in the endogenous host prion protein are strongly associated with susceptibility to prion infection [57-59]. Studies of CWD in elk, mule deer, white-tailed deer, and moose have found that similar correlations between PrP amino acid sequence and likelihood of CWD infection could exist in these species as well. 

Bovine spongiform encephalopathy (BSE or mad cow disease) is a progressive neurological degenerative disease in cattle. It is caused by a mutated protein called a prion. BSE was first reported in the United Kingdom in 1986. Creutzfeldt-Jakob disease (CJD) is a rare disease that occurs in humans. Evidence to date indicates it is possible for humans to acquire CJD after consuming BSE-contaminated cattle products. 

Human blood, given by blood donors, is a source not only of cellular material (red cells, white cells, platelets) but also of blood plasma, which is subjected to protein fractionation to give albumin, anti-hemophilia factors and immunoglobulins. The possibility of transmission of Creutzfeld-Jakob disease (CJD) - prions are not really understood - and acquired immune deficiency syndrome (AIDS), if sterilization procedures fail, combined with the feasibility of manufacturing proteins by recombinant DNA technology, mean that there is uncertainty about the long-term future of the blood products industry. Indeed, the problems with bovine spongiform encephalitis (BSE) and the related fatal human brain disorder, CJD, have led to unease about cattle-derived substances. 

---