What was called acute catarrhal jaundice in years past later was identified as an infectious disease, presumably due to a virus. Still later, two forms of viral hepatitis were recognized, one retaining the name infectious hepatitis (IH), transmissible perorally or by transfusion of blood from a viremic donor. In either instance, the incubation period was found to be about the same—one month. That fact distinguished IH from the second form of the disease, serum hepatitis (SH), having an incubation period of about two months.
SH was thought to be transmissible only (1) by transfusion from a donor whose blood contained the SH virus; or (2) by administration of pooled plasma, the pool having been contaminated by one or more donors; or (3) by inoculation, accidental or otherwise. Outstanding examples of SH caused by inoculation were (1) the outbreak during World War II among the members of the armed forces who