Hepatitis types A, B, and non A--non B in childhood.

199 children with acute hepatitis hospitalized between 1968 and 1978 were tested for serological markers of hepatitis A and B infection. In 24 out of 28 HBsAg-positive patients, hepatitis B infection was diagnosed because of the disappearance of the antigen during convalescence. The histories of the 171 HBsAg-negative children suggested acute hepatitis A infection in 69% of the patients. This diagnosis could be confirmed in 110 of the 116 tested cases (95%) by a more than fourfold increase in the anti-HAV titer or by detection of anti-HAV of the IgM class. In the 55 HBsAg-negative patients without epidemiological clues as to the type of hepatitis, 40 children exhibited anti-HAV which could be related to acute A infection in 21 out of 22 tested cases. At least 11 patients had to be classified as having nonn A--non B infection. The results indicate that a combination of evaluation of the patient's history and selected serological tests will permit a fast preliminary diagnosis. This is important in the clinical management of patients and protection of contacts with immunoglobulin.