Implications of prion-induced diseases for animal-derived pharmaceutical products

The implications of prion-induced diseases for the use of medications that theoretically could harbor the infectious pathogens are discussed. Prions have been identified as protein particles that lack nucleic acids. There is evidence that prions cause the transmissible neurodegenerative diseases known as transmissible spongiform encephalopathies. Of these diseases, bovine spongiform encephalopathy (BSE) and the human spongiform encephalopathy to which it has been linked, new variant Creutzfeldt-Jakob disease (CJD), have generated the most attention. The first cases of new variant CJD appeared in Britain in the mid-1990s. Ingestion of prion-infected beef remains the only known cause of new variant CJD. No cases of BSE or new variant CJD have been documented in the United States. The time from exposure to the development of clinical sequelae appears to be about 10 years. The median duration of illness is 14 months, and the outcome is invariably death. There is no treatment; currently the only available approach is prevention. There is no reliable method of predicting the number of new cases that might occur because of lack of definitive information on the efficiency of transmission from animals to humans and the number of people currently infected and at risk for infection. The infectivity of medications and plasma fractionation products containing material from cattle with BSE is unknown, but the risk is believed to be very low. No cases of such transmission have been identified. Guidelines to keep the risk of transmission via medications low have been promulgated by FDA, and further research is warranted. There have been no reports of medications or plasma fractionation products being contaminated with the prions that cause new variant CJD. Ongoing vigilance and research are appropriate, however.