Was disease associated with hepatitis C virus recognized before discovery of the agent, and how does this microorganism compare with other known hepatitis viruses?
Early case investigations of post-transfusion hepatitis in the 1950s suggested a possible infectious etiology for the condition. This finding led to the practice of screening potential blood donors for blood or liver abnormalities in an effort to reduce the incidence of post-transfusion hepatitis.2-4 Later discoveries of hepatitis A virus (HAV) and hepatitis B virus as organisms responsible for two forms of viral hepatitis were facilitated by major scientific advances in serology and tissue culture technologies and provided the tools for further viral investigations.5-9 As more cases of hepatitis A and hepatitis B were diagnosed in the 1970s, clinicians noted that sera from a number of patients presenting with hepatitis signs and symptoms were negative for HAV and HBV immunological markers. Subsequent reports described another form of post-transfusion and percutaneous injury hepatitis that could not be attributed to any microorganism. Since diagnosis of this condition was based on abno
