Hepatitis A virus infections in Belgian children.

In childhood HAV infection most often passes subclinically. In this study we evaluate the percentages of clinically and subclinically developing HAV infections and the age distribution of the prevalence of immunity to HAV. The study population (n = 1,008) included newborns, children and teenagers up to 20 years of age from the Brussels area. Sera were randomly collected at a general hospital. Subjects were stratified into six age groups. Among children and teenagers, the overall prevalence of anti-HAV (IgG) was 13.4%; this prevalence increased from 4.8% among children in the first group (1-2-year-olds) to 33.9% in the group of teenagers (16-20-year-olds). Among children and teenagers, 10% HAV infections on average is clinically recognized. For the different age groups, these figures are 3.5%, 18.7%, 12.3% and 5.5%, respectively. It can be concluded that, relative to the overall population of each age group, 0.3%, 1.8%, 1.6% and 0.3%, respectively, will have a clinically recognized HAV infection as members of that specific age group.