The age-specific prevalence of antibodies to hepatitis A virus (anti-HAV)
was determined in two different population groups with low socio-economic
status from Rio de Janeiro city, Brazil, whose serum samples were collected
17 years apart (Population 1, 1978; Population 2, 1995). In Population 2,
analysis of the anti-HAV prevalence was also carried out with respect to
environmental factors. Population 1 was composed of 520 stored sera
collected from the umbilical cord of term neonates and children aged 1
month to 6 years. In population 2, 720 serum samples were collected from
children and adolescents with ages ranging from 1 to 23 years. The overall
prevalence rate of anti-HAV in Population 1 and Population 2 was 65.6% and
32.1%, respectively. In Population 1, 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 result of improved environmental hygiene and sanitation, as
demonstrated by the presence of piped water, waste and sewage disposal
systems in most houses from this population group. These findings indicate
a possible change in the prevalence of hepatitis A in Rio de Janeiro.