Parenterally transmitted non-A, non-B hepatitis: an epidemic reassessed.

In 1972 a nonsocomial outbreak of parenterally transmitted hepatitis affected both marrow transplant patients and normal platelet donors in an oncology unit. Because of the characteristics of the clinical illness, the incubation period of 27 days, and the effect of immune serum globulin on the clinical illness, the outbreak was attributed to hepatitis A; there was no serologic evidence of either hepatitis B virus or cytomegalovirus infection. Stored serums from this outbreak were re-examined by more recently developed serologic techniques for evidence of hepatitis A (HA) virus infection. Ten patients and donors had undetectable anti-HA titers before illness and none seroconverted; five persons had pre-existent anti-HA titers and showed no further rise in convalescent serums. The serum of one patient was inevaluable. With the availability of serologic techniques for the diagnosis of both hepatitis A and hepatitis B virus infections, it is clear that most cases of post-transfusion hepatitis are not due to either of these agents, and short-incubation-period hepatitis can not be assumed to be hepatitis A without further investigation.