Maternal and neonatal Australia antigen.

Four hundred and fourteen pairs of maternal and cord blood specimens from a county hospital population in southern California were assayed for Australia antigen by complement fixation and immunodiffusion techniques. Four maternal specimens were found to be positive (1 percent). One of the mothers with positive reaction was ill with viral hepatitis at time of delivery. Three had no evidence of symptomatic liver disease during pregnancy; two were born and raised where the prevalence of Australia antigen (Au(1)) is higher than in the United States. Although none of the cord blood specimens were positive for Au(1), one infant whose mother had Au(1) at delivery became positive at one month of age, and positive titers have persisted through 12 months of life. The significance of chronic Au(1) antigenemia in this infant is uncertain. However, it may be of importance in understanding the pathogenesis of viral hepatitis in the neonatal period.