Hepatitis C virus infections in post-transfusion hepatitis: an analysis with first- and second-generation assays

Article Abstract:

In 1974, it was first recognized that not all cases of viral hepatitis were hepatitis A or hepatitis B. It proved difficult to identify the infectious agent responsible for these cases of non-A, non-B hepatitis. However, it has recently become clear that many cases of post-transfusion non-A, non-B hepatitis are the result of infection with a new virus, hepatitis C. Modern immunological and genetic engineering techniques have resulted in tests that can detect antibody to hepatitis C virus (HCV). A major study has now been conducted to compare the first HCV antibody tests with more recently developed tests, and to determine the fraction of transfusion recipients with non-A, non-B hepatitis due to infection with hepatitis C. The study was conducted on 1,247 transfusion recipients and 1,235 matched controls. A total of 115 transfusion recipients developed non-A, non-B hepatitis; HCV antibodies were already present in four patients prior to the bout of hepatitis. Of the remaining 111, 46 percent developed antibodies, as indicated by the first generation tests. When the new antibody test was used, a total of 60 percent were found to have HCV antibodies. Forty of the control patients developed hepatitis from causes unrelated to transfusion during the study period. Of these, three already had antibodies to HCV. In contrast, however, none of the remaining 37 patients developed HCV antibodies after developing hepatitis. This suggests that the rate of non-A, non-B hepatitis is about three percent in those who have not received transfusions. Assuming the same rate holds for the 1,247 transfusion recipients, then 37 of the 111 cases of non-A, non-B hepatitis would likely have happened anyway. The remaining 74 cases may be attributable to the transfusion, and since 67 of these cases were positive by the second-generation antibody test, 91 percent of post-transfusion hepatitis cases clearly involve hepatitis C infection. The study also found that not all the donor blood that transmitted HCV was positive by the antibody test. However, many specimens had elevated alanine aminotransferase; increases in this liver enzyme strongly hint at the presence of subclinical hepatitis. Testing donor blood for both HCV and alanine aminotransferase could greatly reduce the transmission of hepatitis C to transfusion recipients. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Disease transmission, Blood-borne diseases, Bloodborne diseases

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Epidemiology of hepatitis C virus: a preliminary study in volunteer blood donors

Article Abstract:

Viral hepatitis occurs to approximately 7 to 10 percent of all individuals receiving blood transfusions within the United States. In 90 percent of these cases the known hepatitis viruses, Hepatitis A or B, were found not to be responsible for the resulting infection. These cases are referred to as non-A, non-B Hepatitis, or NANB hepatitis. Although the causative factor of NANB hepatitis was unknown until recently, another virus had been suspected. A newly discovered virus, which is genetically related to the known hepatitis viruses, has been found and designated hepatitis C virus (HCV). The current study correlates the occurrence of immunologic evidence of hepatitis C infection in individuals who suffer from NANB hepatitis. The new assay method, anti-HCV test, directly identifies elements of the hepatitis C virus itself by an immunological method which is based on genetic engineering techniques. Before this development there was no direct assay of NANB hepatitis; physicians and researchers were required to rely on so-called surrogate tests that measured nonspecific markers which were empirically associated with NANB hepatitis. A group of nearly 500,000 blood donations from 18,268 donors in New York were used in this study. A questionnaire was filled out by all participants who detailed their demographic background and their exposure to HCV. The blood of these volunteers was analyzed for the presence of surrogate measures of HCV infection, and 10 percent was analyzed with the anti-HCV test. The test results were compared. Between 0.9 and 1.4 percent of those tested were found to be positive for HCV. Those positive for HCV tended to be between 30 and 39 years old, and either black or hispanic. There was good correlation between the surrogate tests and the direct immunologic determination of anti-HCV. These data suggest that screening blood with the surrogate testing method prevented a large amount of blood infected with HCV from entering the blood pool. However, the results also show that many units of blood contaminated with HCV entered the blood pool when only surrogate testing was used to protect the blood supply. It is expected that the anti-HCV test will further reduce the possibility of transfusion-induced NANB hepatitis.

Diagnosis, Liver diseases, Hepatitis

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Non-A, non-B hepatitis and antibody to hepatitis C virus

Article Abstract:

Several forms of hepatitis have been found to be caused by specific viruses. The current terminology speaks of hepatitis-A which is caused by Hepatitis-A virus (HAV), and hepatitis-B which is caused by Hepatitis-B virus (HBV). Those individuals who have hepatitis which can not be identified on immunologic grounds as being A or B are classified as having non-A non-B (NANB) hepatitis. This disease is credited with being responsible for a large percentage of all hepatitis within the United States. NANB remains the major complication of blood transfusion with some 5 to 10 percent of all transfusions leading to infection. Recently an immunologic test reagent has been made against another newly-discovered virus, designated Hepatitis-C virus (HCV). Using recombinant gene systems, an artificial viral protein or antigen has been prepared that reacts with antibodies in the blood of HCV-infected individuals. This antigen has been used to test for evidence of HCV infection in the blood of individuals who have demonstrated NANB hepatitis. In a small group of 14 NANB hepatitis patients, five showed the presence of HCV infection. A group of four individuals who did not receive transfusions, but who developed hepatitis after hospitalization were also examined. Three of the four did not show the presence of HCV. These data strongly suggest that approximately 50 percent of all cases of NANB hepatitis that occur within the United States are due to infection with HCV. Of those cases of NANB hepatitis that are not linked to HCV, some may be caused by yet another hepatitis virus. These findings pave the way for new blood screening procedures to protect the integrity of the blood supply.

Hepatitis E

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