title: Hepatitis A and E seroprevalence and associated risk factors: a community-based cross-sectional survey in rural Amazonia.
abstract: BACKGROUND
  Hepatitis A virus (HAV) and hepatitis E virus (HEV) are both transmitted by the faecal-oral route, and represent common causes of acute hepatitis in developing countries. The endemicity of HAV infection has shifted from high to moderate in Brazil. Human cases of HEV infection seem to be rare, although the virus has been detected in swine livestock and effluents of slaughterhouses. This study was to determine the epidemiology of hepatitis A and E in one of the largest agricultural settlements in the Amazon Basin of Brazil.
  
  
  METHODS
  Serum samples collected from 397 individuals aged between 5 and 90 years during a population-based cross-sectional survey were tested for anti-HAV and anti-HEV antibodies. Associated risk factors and spatial clustering of HAV and HEV seropositivity were also analyzed.
  
  
  RESULTS
  The overall rate of HAV seropositivity was 82.9% (95% confidence interval (CI), 79.2-86.6%). Multilevel logistic regression analysis identified increasing age (in years; odds ratio (OR), 1.097; 95% CI, 1.050-1.147; P < 0.001) and crowding (OR, 1.603; 95% CI, 1.054-2.440; P = 0.028) as significant risk factors for HAV seropositivity. Anti-HEV IgG was detected in 50/388 settlers (12.9%, 95% CI, 9.5-16.2%). Anti-HEV IgM was detected in 7/43 (16.3%) anti-IgG positive samples, and 4 of them had a confirmed result by immunoblot. Increasing age was the only significant determinant of HEV seropositivity (OR, 1.033; 95% CI, 1.016-1.050; P < 0.001). No significant spatial clustering of HAV and HEV seropositivity was detected in the area.
  
  
  CONCLUSIONS
  Both HAV and HEV are endemic, with differing rates of infection in children and adults in this rural setting of the Brazilian Amazon. Anti-HEV prevalence was considerably higher than those previously reported in Brazil. The detection of HEV- specific IgM antibodies in four asymptomatic individuals is highly suggestive of the circulation of HEV in this rural population.
authors.forename: Claudia Lamarca
authors.initials: CL
authors.lastname: Vitral
authors.forename: Mônica
authors.initials: M
authors.lastname: da Silva-Nunes
authors.affiliation: Laboratory of Technological Development in Virology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil. marcelop@ioc.fiocruz.br.
authors.forename: Marcelo Alves
authors.initials: MA
authors.lastname: Pinto
authors.forename: Jaqueline Mendes
authors.initials: JM
authors.lastname: de Oliveira
authors.forename: Ana Maria Coimbra
authors.initials: AM
authors.lastname: Gaspar
authors.forename: Rebeca Cristina Costa
authors.initials: RC
authors.lastname: Pereira
authors.forename: Marcelo Urbano
authors.initials: MU
authors.lastname: Ferreira
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology*; D035922:Hepatitis A Antibodies / Q000097:blood*; D030041:Hepatitis A virus; D006508:Hepatitis Antibodies / Q000097:blood*; D016751:Hepatitis E / Q000453:epidemiology*; D016752:Hepatitis E virus; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies; D006508:Hepatitis Antibodies; D007074:Immunoglobulin G