Transmission of spongiform encephalopathy through biological products

The transmissible spongiform encephalopathies (TSE) are rare but fatal neurological diseases that exist in sporadic, familial, and environmentally acquired forms. Environmentally acquired disease has until now been mostly iatrogenic in origin, recognized as responsible for nearly 200 deaths during the past 20 years. The two most important causes have been contamination of cadaver-derived human growth hormone and dura mater grafts, but a few instances related to contaminated neurosurgical instruments and corneal grafts have also occurred. Currently, a great deal of concern is being voiced about the potential risk of acquiring disease through blood or blood products, and although there is no supporting epidemiological evidence for such a danger, experiments are underway to define which blood components or plasma derivatives might pose the greatest problem.