title: Prevalence of hepatitis B virus infection and carriage after nineteen years of vaccination program in the Western Brazilian Amazon.
abstract: BACKGROUND
  Reductions in the prevalence of hepatitis B virus (HBV) infection and carriage, decreases in liver cancer incidence, and changes in patterns of liver dysfunctions are described after hepatitis B vaccination.
  
  
  METHODS
  We conducted a population-based seroprevalence study aimed at estimating the HBV prevalence and risk of infection in the rural area of Lábrea following nineteen years of HBV vaccination.
  
  
  RESULTS
  Half of the subjects showed total anti-HBc of 52.1% (95% CI 49.6-54.7). The HBsAg prevalence was 6.2% (95% CI 5.1-7.6). Multivariate analysis showed an inverse association between HBV infection and vaccination (OR 0.62; 95% CI 0.44-0.87). HBsAg remained independently associated with past hepatitis (OR 2.44; 95% CI 1.52-3.89) and inversely to vaccination (OR 0.43; 95% CI 0.27-0.69). The prevalence of HBeAg among HBsAg-positive individuals was 20.4% (95% CI 12.8-30.1), with the positive subjects having a median age of 11 years (1-46) p=0.0003.
  
  
  CONCLUSIONS
  We demonstrate that HBV infection is still an important public health issue and that HBV vaccination could have had better impact on HBV epidemiology. If we extrapolate these findings to other rural areas in the Brazilian Amazon, we can predict that the sources of chronic infected patients remain a challenge. Future studies are needed regarding clinical aspects, molecular epidemiology, surveillance of acute cases, and risk groups.
authors.affiliation: Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, Manaus, AM.
authors.forename: Wornei Silva Miranda
authors.initials: WS
authors.lastname: Braga
authors.forename: Márcia da Costa
authors.initials: Mda C
authors.lastname: Castilho
authors.forename: Fabiane Giovanella
authors.initials: FG
authors.lastname: Borges
authors.forename: Ana Cristina de Souza
authors.initials: AC
authors.lastname: Martinho
authors.forename: Ivo Seixas
authors.initials: IS
authors.lastname: Rodrigues
authors.forename: Eliete Pereira de
authors.initials: EP
authors.lastname: Azevedo
authors.forename: Márcia
authors.initials: M
authors.lastname: Scazufca
authors.forename: Paulo Rossi
authors.initials: PR
authors.lastname: Menezes
mesh_terms: D000293:Adolescent; D001938:Brazil / Q000453:epidemiology; D002353:Carrier State / Q000453:epidemiology / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000097:blood*; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D008297:Male; D015995:Prevalence; D015397:Program Evaluation; D012424:Rural Population; D016036:Seroepidemiologic Studies; D013997:Time Factors; D055815:Young Adult
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines