Viral hepatitis: enzyme assays and serologic procedures in the study of an epidemic.

An epidemic of viral hepatitis beginning in late 1975 in a residence for multiply handicapped children, recognized very early in its course, was investigated prospectively to permit comparison of enzymatic and serologic tests. Thirty-three residents of the institution and 46 full- and part-time employees were studied by the immune adherence hemagglutination procedure for antibody (anti-HAV) to hepatitis A virus (HAV). Of these, 31 residents and 37 staff members were susceptible at the beginning of the epidemic. Nineteen and six, respectively, had anti-HAV seroconversion indicating HAV infection. Thus, 12 children (39%) and 31 staff members (81%) of presumed susceptibles did not have serologic evidence of infection. The subclinical/clinical ratio for the children was 1.1:1; for personnel, it was 1:1. Serum alanine aminotransferase (ALT) levels compatible with viral hepatitis occurred in 21 persons (84%) who had anti-HAV seroconversion; conversely, there were 10 persons who had ALT abnormality without detectable anti-HAV in late specimens among the total of 68 susceptibles. There was no evidence the latter could be attributed to hepatitis B virus infection; therefore, they may represent the endemic occurrence of non-A, non-B agent(s).