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

BACKGROUND: The epidemiology and natural history of recently discovered viruses, which may be responsible for cases of seronegative infectious hepatitis, 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 characteristics 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) hepatitis, were re-tested using commercially available enzyme-linked immunosorbent assays (ELISAs) for the presence of anti-hepatitis A virus (HAV) IgM, hepatitis 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 concurrently hospitalised for other conditions were also tested. Detailed records of the original epidemiological interviews were examined to compare patient demographics, risk factors for infectious hepatitis and clinical data for the NANB hepatitis group and an original control group of 604 hospitalised 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 of hepatitis A. Thirteen (23%) of cases previously designated as NANB hepatitis had positive hepatitis C antibody tests. These patients were younger and significantly more likely to have used intravenous drugs than control patients. Three NANB hepatitis and two hospital control patients were anti-HEV IgG antibody positive. All of these individuals were born in, or had travelled to, developing countries. Serum from 27 (47%) of the NANB hepatitis patients were negative on all tests. These hepatitis non-A-E cases included children and elderly adults, but as a group were significantly more likely to have used intravenous drugs than hospitalised control patients.

CONCLUSION: Both HCV and probable non-A-E virus(es) were important causes of acute NANB hepatitis during the early 1970s.