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

Abstract

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.

The epidemiology of hepatitis A in Rio de Janeiro: environmental and domestic risk factors

“…1) suggests, at least in the first decade of life, a mean incidence of seroconversion of the order of 6 % per year of age. This is greater than reported in other studies from Brazil [14], and is to be expected as the study population was selected from a low income community, whereas other studies have used representative samples of the population as a whole.…”

Early infection and asymptomatic spread of hepatitis A virus in a public child care center in Rio de Janeiro, Brazil: should attending children under two years of age be vaccinated?

“…These children might have contracted the illness outside the The high prevalence of total anti-HAV (71.4%) in children under 7 months of age who tested negative for IgM anti-HAV strongly suggests passive acquisition of maternal antibodies. However, previous studies have shown that, after 7 months of age, maternal antibodies diminish rapidly, favoring the occurrence of early infection (Vitral et al 1998, Linder et al 1999). In our study, 26.7% of the children aged 7 months to 1 year had already had acute HAV infection.…”

Prevalence of hepatitis A virus infection in Goiânia, Goiás, Brazil, by molecular and serological procedures, 1995-2002

“…Previous studies have shown that HAV infection in regions with a high endemicity pattern occur mainly in children under five years old (Ferreira et al 1996, Vitral et al 1998, Cardoso et al 2000. Studies carried out in Latin America, including Brazil, as well as in other regions of the world have described a variation in the endemicity pattern of HAV infection, which has demonstrated a reduction of this infection in children under five and a gradual increase among adolescents and adults (TapiaConyer et al 1999, Barzaga 2000, Cianciara 2000, Tanaka 2000, Tufenkeji 2000, Villar et al 2002b).…”