[Hepatitis A of children. Seroepidemiological study among French urban population (author's transl)].

A prevalence survey of hepatitis A antibody (anti-HAV) was conducted among 145 children living in the area of Tours (France). Thirty-four per cent of children's sera was found anti-HAV positive when tested by both immune adherence hemagglutination assay (IAHA) and specific radio-immunoassay (RIA). The prevalence of anti-HAV among infants less than one year and children between 1 to 5 years, was 35 per cent and 15 per cent respectively. From 6 years old, the prevalence of anti-HAV increased abruptly and reached 47 per cent in the 11 to 15 age group. Anti-HAV titers as measured by IAHA also increased according to age. In this study, the prevalence of anti-HAV was not related to sex, history of past surgery and/or blood transfusions. Only 12 per cent of children with anti-HAV positive test had history of jaundice. These results show that, in France, primary contact with hepatitis A virus (HAV) appear early in childhood, at school age, and that in children more than 80% of HAV infections remain asymptomatic.