Prions and haemophilia: assessment of risk.

Based on information accumulated to date, it is still difficult to assess the risk of Creutzfeldt-Jakob disease (CJD) and blood transfusion with any degree of confidence. However, it is reasonable to conclude that CJD is produced by a transmittable agent which is probably contained in low titer in the blood of infected people and animals. From the present clinical and epidemiological studies, transmission by blood or blood products appears to be a rare or non-existent cause of current and past cases of CJD in humans. Since blood products are necessary to prevent the immediate risk of death or significant morbidity in many clinical conditions, therapeutic decisions should be made after consideration of the known risk in these situations vs the theoretical long-term risk of the rare occurrence of CJD.