Prevalence of antibody to hepatitis A virus in healthy individuals of Milan.

We have studied by radioimmunoassay the prevalence of antibody to hepatitis A virus in 436 randomly selected individuals of Milan according to age and sex. Taken together, 70% of subjects provided serological evidence of exposure to HAV. Both sexes resulted similarly immunized (69.7% females and 70.7% males). The anti-HAV prevalence was found to be directly related to age, being on the increase from childhood to adulthood and reaching its peak (9l.5%) in people over fifty. An analysis of the distribution of anti-HAV according to presence or absence of anti-HBs in induviduals under 30 years, revealed that anti-HAV was detectable more frequently in individuals anti-HBs positive than in those without such evidence in sera (71.4% versus 39.7%; P less than 0.01). Finally, 96 sera from children and adolescents of low socioeconomic standard of living were also investigated. In these subjects anti-HAV prevalence was found to be higher than in their counterparts randomly slected from general population.