A serological re-evaluation of acute non-A non-B hepatitis from the early 1970s

Background: The epidemiology and natural history of recently discovered vir uses, which may be responsible for cases of seronegative infectious hepatit is, are currently being investigated. Retrospective studies of stored sera can provide a historical perspective of these infections. Aims: To re-evaluate the serological, demographic and clinical characterist ics of patients hospitalised in the early 1970s with acute hepatitis. Methods: The stored sera of 57 patients hospitalised between 1971 and 1974 with acute hepatitis, designated at that time as non-A non-B (NANB) hepatit is, were re-tested using commercially available enzyme-linked immunosorbent assays (ELISAs) for the presence of anti-hepatitis A virus (HAV) IgM, hepa titis B surface antigen (HBsAg), anti-hepatitis C virus (HCV) IgG, and anti -hepatitis E virus (HEV) IgG. Stored sera from a group of 57 patients concu rrently hospitalised for other conditions were also tested. Detailed record s of the original epidemiological interviews were examined to compare patie nt demographics, risk factors for infectious hepatitis and clinical data fo r the NANB hepatitis group and an original control group of 604 hospitalise d patients. Results: Serum from 15 of the 57 (26%) previously designated NANB hepatitis cases had elevated anti-HAV IgM and are likely to represent missed cases o f hepatitis A. Thirteen (23%) of cases previously designated as NANB hepati tis had positive hepatitis C antibody tests. These patients were younger an d significantly more likely to have used intravenous drugs than control pat ients. Three NANB hepatitis and two hospital control patients were anti-HEV IgG antibody positive. All of these individuals were born in, or had trave lled to, developing countries. Serum from 27 (47%) of the NANB hepatitis pa tients were negative on all tests. These hepatitis non-A-E cases included c hildren and elderly adults, but as a group were significantly more likely t o have used intravenous drugs than hospitalised control patients. Conclusions: Both HCV and probable non-A-E virus(es) were important causes of acute NANB hepatitis during the early 1970s.