Pooled human plasma, untreated, has been a frequent cause of serum hepatitis. Blood from one donor carrying the virus can make a whole pool infectious. Obviously the likelihood of plasma being infected varies with the number of donors making up the pool. Plasma from a large pool is more frequently infected than plasma from a small pool. The probability of contracting serum hepatitis from a whole blood transfusion is extremely small. Paine and Janeway1 have analyzed reports on this subject.
Exposing plasma to ultraviolet light seemed to obviate this hazard. Known icterogenic serum so treated has been given in small quantities to volunteers without causing hepatitis.2 MacCallum,3 on the other hand, used a different technique of irradiation that failed to prevent the transmission of hepatitis. Irradiation of plasma has been required by the National Institutes of Health since April, 1949, as a prerequisite to licensing manufacturers.
Albrecht RM, Korns RF, Beadenkopf WG, Goodman MB, Locke FB, Marks V. SERUM HEPATITIS APPARENTLY ACQUIRED FROM IRRADIATED PLASMA. JAMA. 1953;152(15):1423-1426. doi:10.1001/jama.1953.03690150027008