Hepatitis C, other types of non-B parenteral hepatitis and blood transfusion

Since the implementation of sensitive screening tests for hepatitis B virus infection, the majority of post-transfusion hepatitis has been due to infection with hepatitis C virus (HCV). The recent introduction of tests for antibodies to this virus has demonstrably reduced the incidence of post-transfusion HCV infection. There is some residual post-transfusion and sporadic hepatitis, which may possibly be caused by an as yet undescribed aetiologic agent. However, evidence for or against such an agent is by no means definitive. The majority of cases of this residual hepatitis seem to be mild and progression to chronicity is less frequent than for HCV infection. There is no evidence to suggest that modern, fully inactivated pooled plasma products transmit this poorly characterized form of hepatitis. However, in some circumstances, the potential for transmission of non-enveloped viruses by clotting factors may persist.