Transmissible spongiform incubation period

Because they are derived from cattle, there is a concern that gelatins might be vehicles for the transmission of the prion agent responsible for bovine spongiform encephalopathy (BSE) in cattle and variant Creutzfeldt-Jakob disease (vGD) in humans. There is at present no evidence that these products have contributed to the transmission of BSE or vCJD. However, the incubation period may be up to several years, and due prudence is warranted when such products are used. 

Prion diseases In the 1990s, four patients were infected with variant Creutzfeldt-Jakob disease (vCJD) after transfusions of non-leukodepleted blood. The incubation periods in the recipients were 6.5-8.3 years after transfusion. Leukocytes are now removed from blood used for transfusion [60, 96, 9T]. Plasma products carry a low risk of transmission of transmissible spongiform encephalopathies because of production processes [96 ]. The estimated risk depends on the prion load. Of plasma products, vCJD-implicated batches of clotting factor concentrates were categorized as likely to transmit prion diseases [9T]. In the UK, and before the exclusion of the use of British plasma, the risk of prion transmission by blood was estimated to be 7-14 per 10000 patients with hemophilia, assuming a vCJD population prevalence of 1 in 10000... 

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