Multilevel analysis of hepatitis A infection in children and adolescents: a household survey in the Northeast and Central-west regions of Brazil

Abstract

Background The objectives were to estimate the prevalence of hepatitis A among children and adolescents from the Northeast and Midwest regions and the Federal District of Brazil and to identify individual-, household- and area-levels factors associated with hepatitis A infection.Methods This population-based survey was conducted in 2004–2005 and covered individuals aged between 5 and 19 years. A stratified multistage cluster sampling technique with probability proportional to size was used to select 1937 individuals aged between 5 and 19 years living in the Federal capital and in the State capitals of 12 states in the study regions. The sample was stratified according to age (5–9 and 10- to 19-years-old) and capital within each region. Individual- and household-level data were collected by interview at the home of the individual. Variables related to the area were retrieved from census tract data. The outcome was total antibodies to hepatitis A virus detected using commercial EIA. The age distribution of the susceptible population was estimated using a simple catalytic model. The associations between HAV infection and independent variables were assessed using the odds ratio and corrected for the random design effect and sampling weight. Multilevel analysis was performed by GLLAMM using Stata 9.2.Results The prevalence of hepatitis A infection in the 5–9 and 10–19 age-group was 41.5 and 57.4%, respectively for the Northeast, 32.3 and 56.0%, respectively for the Midwest and 33.8 and 65.1% for the Federal District. A trend for the prevalence of HAV infection to increase according to age was detected in all sites. By the age of 5, 31.5% of the children had already been infected with HAV in the Northeast region compared with 20.0% in the other sites. By the age of 19 years, seropositivity was ∼70% in all areas. The curves of susceptible populations differed from one area to another. Multilevel modeling showed that variables relating to different levels of education were associated with HAV infection in all sites.Conclusion The study sites were classified as areas with intermediate endemicity area for hepatitis A infection. Differences in age trends of infection were detected among settings. This multilevel model allowed for quantification of contextual predictors of hepatitis A infection in urban areas.

Shifting susceptibility to hepatitis A among children and adolescents over the past decade

“…No grupo 1 o percentual de positividade do anti-VHA aumentou conforme o avanço da idade, o que é esperado para doenças infecciosas que dependem de exposição ambiental 13 . Nos sujeitos do grupo 2, a distribuição inversa da prevalência de anti-VHA, com taxas maiores nos estratos menores, não está em concordância com os resultados de estudos brasileiros 12,14,15 e de análises internacionais 24 (Tabela 1).…”

“…No Brasil, estudos sorológicos têm demonstrado que a endemicidade da hepatite A está mudando na maioria das regiões, com taxas significativamente menores de anticorpo anti-VHA (anti-VHA) entre as crianças e os adolescentes [12][13][14][15] , especialmente de classe socioeconômica mais favorecida 12,14,15 . A região Norte 12 e algumas comunidades isoladas de outras regiões [16][17][18] , entretanto, continuam a apresentar prevalên-cia elevada, significativamente maior do que a taxa média de 65% estimada para o Brasil em estudo realizado entre 1996 e 1997 12 .…”

Methodology of a nationwide cross-sectional survey of prevalence and epidemiological patterns of hepatitis A, B and C infection in Brazil

“…In Brazil, the HAV vaccine is not universally recommended within the National Immunization Program and only a small proportion of the population has access to it. In a partial analysis of the ongoing Brazilian survey, hepatitis A infection was classified as an intermediate endemicity in the Northeast and Central-West regions of Brazil 19 .…”

Declining prevalence of hepatitis A virus antibodies among children from low socioeconomic groups reinforces the need for the implementation of hepatitis A vaccination in Brazil

“…In addition to these improvements, both a decrease in the circulation of HAV (Clemens et al 2000, Vitral et al 2006, 2008, Jacobsen & Wiersma 2010) and a progressive decline in the number of fatal HAV infections have been observed in all regions of Brazil (Vitral et al 2006). However, the HAV seroprevalence studies that have been performed have focused on the urban populations of Brazil that experience lower incidence rates than the rural populations (Ferreira et al 1996, Vitral et al 1998a, b, Clemens et al 2000, Zago-Gomes et al 2005, Dinelle et al 2006, Fiaccadori et al 2006, de Alencar Ximenes et al 2008, Krebs et al 2011. Having an accurate understanding of the epidemiology of HAV infection is important for understanding its effect on population groups that have not benefited from the recent improvements in sanitation conditions in Brazil.…”