title: Shifting susceptibility to hepatitis A among children and adolescents over the past decade.
abstract: OBJECTIVE
  To estimate the prevalence of anti-hepatitis A virus (anti-HAV) antibodies in serum samples from children and adolescents obtained at two clinical pathology laboratories in the city of Porto Alegre, south of Brazil, and to compare findings to those of a study carried out in the 1990s.
  
  
  METHODS
  In this cross-sectional study conducted between 2007 and 2008, 465 serum samples obtained from subjects aged 1-19 years were consecutively tested to determine the prevalence of total anti-HAV antibodies. Samples were provided by a public laboratory (group 1) that serves the Unified Health System exclusively, meant to represent the lowest socioeconomic strata, and by a private laboratory (group 2), meant to represent the higher socioeconomic classes. Tests were performed at a single laboratory using commercially available electrochemiluminescence kits. Antibody levels ≥ 20 UI/L were considered positive.
  
  
  RESULTS
  The seroprevalence of anti-HAV in Group 1 was 37.6%. The percentage of anti-HAV reactivity increased from 19.4% in the 1-to-4 group to 54.1% in the 15-to-19 group. In Group 2, overall anti-HAV positivity was 46.1% and was inversely correlated with age, declining from roughly 50% in the youngest groups to 29.1% in the 15-to-19 group. Comparison of sample findings to those reported in a 1990s study showed a significant reduction in anti-HAV prevalence among 5-to-9-year-olds in group 1 (p = 0.03).
  
  
  CONCLUSIONS
  The results suggest that the endemicity of hepatitis A in Porto Alegre has been declining over the past decade, and that children and adolescents, particularly those in the lowest socioeconomic strata, are more susceptible to the disease.
authors.affiliation: Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil. lskrebs@via-rs.net
authors.forename: Lenita S
authors.initials: LS
authors.lastname: Krebs
authors.forename: Tani M S
authors.initials: TM
authors.lastname: Ranieri
authors.forename: Carlos O
authors.initials: CO
authors.lastname: Kieling
authors.forename: Cristina T
authors.initials: CT
authors.lastname: Ferreira
authors.forename: Themis R da
authors.initials: TR
authors.lastname: Silveira
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004198:Disease Susceptibility; D006506:Hepatitis A / Q000453:epidemiology / Q000276:immunology*; D035922:Hepatitis A Antibodies / Q000097:blood*; D006801:Humans; D007223:Infant; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012959:Socioeconomic Factors; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies