AGE-SPECIFIC PREVALENCE OF ANTIBODIES TO HEPATITIS-A IN CHILDREN AND ADOLESCENTS FROM RIO-DE-JANEIRO, BRAZIL, 1978 AND 1995, RELATIONSHIP OF PREVALENCE TO ENVIRONMENTAL-FACTORS

The age-specific prevalence of antibodies to hepatitis A virus (anti-H AV) was determined in two different population groups with low socio-e conomic status from Rio de Janeiro city, Brazil, whose serum samples w ere collected 17 years apart (Population 1, 1978; Population 2, 1995). In Population 2, analysis of the anti-HAV prevalence was also cal vie d out with respect to environmental factors. Population I was composed of 520 stored sera collected from the umbilical cord of term neonates and children en aged I month to 6 years. In population 2, 720 ser um samples were collected from children and adolescents with ages ranging from I to 23 years. The over all prevalence rate of anti-HAV in Popul ation I and Population 2 was 65.6% and 32.1 %, respectively. In Popula tion I, the anti-HAV prevalence reached 88% at the age of 3, while in Population 2, it increased from 4.5% in children under the age of 3 to 66% in the group of adolescents over the age of 14. The low exposure to HAV infection in younger children from Population 2 could be a resu lt of improved environmental hygiene and sanitation, as demonstrated b y the presence of piped water; waste and sewage disposal systems in mo st houses from this population group. These findings indicate a possib le change in the prevalence of hepatitis A in Rio de Janeiro.