title: A comparative epidemiological study of hepatitis B and hepatitis D virus infections in Yanomami and Piaroa Amerindians of Amazonas State, Venezuela.
abstract: OBJECTIVE
  To report the prevalences of hepatitis B (HBV) and hepatitis D (HDV) infections in remote and more accessible Yanomami and Piaroa Venezuelan Amazonian Amerindian populations; to estimate incidence per susceptible.
  
  
  METHODS
  Clinico-epidemiological evaluation was carried out in 9 Piaroa villages. Blood samples were tested for HBV core antibody (anti-HBc), surface antigen (HBsAg) and HDV antibody (anti-HDV). Results were analysed using logistic regression, and estimates made of HBV forces of infection (FOI). Prevalences and FOI were also estimated for 4 Yanomami villages.
  
  
  RESULTS
  Mean Piaroa anti-HBc and HBsAg prevalences were 27.4% and 5.1%, respectively (up to 53% and 19% in the remote Autana region). Mean Yanomami anti-HBc and HBsAg prevalences were, respectively, 58.0% (range 43-70%) and 14.3% (31% in the village with highest HBsAg). No significant difference was found between sexes, with age and maternal HBsAg the only risk factors for HBV identified in multivariate regression of Piaroa data. Only 4 Piaroa and 2 Yanomami individuals were anti-HDV positive.
  
  
  CONCLUSIONS
  Piaroa HBV prevalences were generally higher in remote villages than in less remote ones, with prevalences in Yanomami villages even higher. Anti-HBc prevalence was 47% in one Yanomami village with a history of HBV vaccination but no HBsAg cases were identified, suggestive of previously cleared or possibly transient infection or vaccine escape. Despite a past history of HDV epidemic outbreaks and HBsAg levels in some villages appearing sufficient to facilitate HDV transmission, anti-HDV prevalence was low; it remains to be established why no recent outbreaks have been reported.
authors.affiliation: Servicio Autónomo Centro Amazónico de Investigación y Control de Enfermedades Tropicales, Puerto Ayacucho, Venezuela.
authors.forename: María Carolina
authors.initials: MC
authors.lastname: Duarte
authors.forename: Nathalia
authors.initials: N
authors.lastname: Cardona
authors.forename: Fresia
authors.initials: F
authors.lastname: Poblete
authors.forename: Kenia
authors.initials: K
authors.lastname: González
authors.forename: Mayila
authors.initials: M
authors.lastname: García
authors.forename: Milian
authors.initials: M
authors.lastname: Pacheco
authors.forename: Carlos
authors.initials: C
authors.lastname: Botto
authors.forename: Flor H
authors.initials: FH
authors.lastname: Pujol
authors.forename: John R
authors.initials: JR
authors.lastname: Williams
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004812:Epidemiologic Methods; D005260:Female; D006508:Hepatitis Antibodies / Q000097:blood; D006509:Hepatitis B / Q000175:diagnosis / Q000453:epidemiology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood; D003699:Hepatitis D / Q000175:diagnosis / Q000453:epidemiology*; D003698:Hepatitis Delta Virus / Q000276:immunology; D006801:Humans; D007199:Indians, South American; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012423:Rural Health / Q000706:statistics & numerical data; D017678:Sex Distribution; D014687:Venezuela / Q000453:epidemiology; D055815:Young Adult
chemical_list: D006508:Hepatitis Antibodies; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens