Risk of post-transfusion infection with the hepatitis delta virus. A multicenter study.

Hepatitis delta virus is a defective virus that can replicate only in the presence of hepatitis B virus. To determine the prevalence, circumstances of transmission, and clinical importance of infection with hepatitis delta virus, we obtained data on 262 patients with post-transfusion hepatitis who were positive for the hepatitis B surface antigen (HBsAg) even though they had received blood screened for it. We also studied 94 HBsAg carriers who were receiving repeated blood transfusions for other diseases, and 103 HBsAg carriers with hemophilia who were receiving various forms of coagulation factors. Antibody to hepatitis delta virus was found in 9 of 262 patients (3.5 per cent) with post-transfusion hepatitis, 5 of 234 (2 per cent) with self-limited disease, and 4 of 28 (14.5 per cent) with fulminant disease (P less than 0.05). The absence of IgM antibodies to the hepatitis B core antigen indicated that three of the nine patients with both HBsAg and antibodies to hepatitis delta virus had been carriers of HBsAg at the time of transfusion, and the acute disease represented the combined effects of the two viruses. Antibody to hepatitis delta virus was found in 3 of 94 Italian carriers of HBsAg who were receiving repeated blood transfusions, in none of 24 Brazilian, East German, or Australian hemophiliac carriers infused with clotting factors prepared from single or mini-pool volunteer plasma, and in 27 to 100 per cent of 79 hemophiliac carriers from European and U.S. series who received coagulation factors manufactured from large pools of plasma. We conclude that infection with hepatitis delta virus is likely to be more severe than infection with hepatitis B virus alone and that screening for HBsAg provides a high degree of safety in preventing infection with hepatitis delta virus, but that the risk is considerably greater in patients who are already carriers of HBsAg. We recommend that HBsAg carriers be given only blood derivatives prepared from a single donor or mini-pool donors.