title: Hepatitis B virus exposure during childhood in Cameroon, Central African Republic and Senegal after the integration of HBV vaccine in the expanded program on immunization.
abstract: BACKGROUND
  More than 2 billion people worldwide have been exposed to hepatitis B virus (HBV). To prevent these infections, Senegal and Cameroon integrated the HBV vaccine into their Expanded Program on Immunization (EPI) in 2005, as did the Central African Republic (CAR) in 2008. We evaluated the prevalence of HBV exposure and infection after the integration of the HBV vaccine in the EPI.
  
  
  METHODS
  An observational cross-sectional study was conducted among the hospitalized children 3 months to 6 years of age in Cameroon, CAR and Senegal. Plasma was collected for the detection of anti-HBc, anti-HBs and hepatitis B surface antigen in children with anti-HBc and anti-HBs.
  
  
  RESULTS
  Between April 2009 and May 2010, 1783 children were enrolled, 19.4% of whom were anti-HBc positive. The percentage of children with anti-HBc was 44.4% among the children younger than 6 months, decreasing after 6 months to reach 18.8% at 12 months. This decline was followed by a rapid increase in anti-HBc positivity rate in CAR observed as early as 12 months of age compared with Cameroon and Senegal, where the anti-HBc increased between 18 and 36 months of age, respectively. The prevalence of hepatitis B surface antigen-positive children was significantly higher in CAR than that in Cameroon and Senegal (5.1% versus 0.7% and 0.2%; P < 0.001). Socioeconomic level, age and country were factors associated with the presence of anti-HBc.
  
  
  CONCLUSIONS
  Passive transfer of anti-HBc maternal antibodies versus HBV exposure could be differentiated as early as 12 months of age. The low prevalence of anti-HBc and hepatitis B surface antigen among children born after the integration of HBV vaccine in the EPI in Cameroon and Senegal suggests a positive impact of HBV vaccination.
authors.affiliation: From the *Unité de Recherche et d'Expertise en Epidémiologie des Maladies Emergentes, Institut Pasteur, Paris, France; †Institut des Sciences Biologiques, CNRS, Paris, France; ‡Service de Virologie, Centre Pasteur du Cameroun, Yaoundé, Cameroun; §Laboratoire des Virus Oncogènes, Institut Pasteur de Bangui, Bangui, République Centrafricaine; ¶Laboratoire de Biologie Médicale, Institut Pasteur, Dakar, Sénégal; **Complexe Pédiatrique, Bangui, République Centrafricaine; and ††Département de virologie, Hôpital Saint Louis, Paris, France.
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Rey-Cuille
authors.forename: Richard
authors.initials: R
authors.lastname: Njouom
authors.forename: Claudine
authors.initials: C
authors.lastname: Bekondi
authors.forename: Abdoulaye
authors.initials: A
authors.lastname: Seck
authors.forename: Chrysostome
authors.initials: C
authors.lastname: Gody
authors.forename: Petulla
authors.initials: P
authors.lastname: Bata
authors.forename: Benoit
authors.initials: B
authors.lastname: Garin
authors.forename: Sarah
authors.initials: S
authors.lastname: Maylin
authors.forename: Loic
authors.initials: L
authors.lastname: Chartier
authors.forename: François
authors.initials: F
authors.lastname: Simon
authors.forename: Muriel
authors.initials: M
authors.lastname: Vray
mesh_terms: D002163:Cameroon / Q000453:epidemiology; D002488:Central African Republic / Q000453:epidemiology; 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; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000097:blood; D017325:Hepatitis B Vaccines / Q000008:administration & dosage* / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D008297:Male; D012307:Risk Factors; D012675:Senegal / Q000453:epidemiology
chemical_list: D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines